Standard laboratory cages prevent mice from performing several natural behaviours for which they are highly motivated. As a consequence,  laboratory mice  sometimes develop abnormal behaviours indicative of emotional disorders such as depression and anxiety. To improve welfare, these cages are sometimes enriched with items such as nesting material, shelters and running wheels. Sherwin and Olsson [ 37 ]  tested whether such enrichment influenced the consumption of  Midazolam , a drug widely used to treat anxiety in humans.  Mice in standard cages, standard cages but with unpredictable husbandry, or enriched cages, were given a choice of drinking either non-drugged water or a solution of the Midazolam.  Mice in the standard and unpredictable cages drank a greater proportion of the anxiolytic solution than mice from enriched cages, presumably because they had been experiencing greater anxiety.  Early studies indicated that  autoimmune  (MRL/lpr) mice readily consume solutions with  cyclophosphamide , an immunosuppressive drug that prevents inflammatory damage to internal organs. However, further studies provided contradictory evidence. [ 1 ]


During the cold and rainy seasons, the crested porcupines ( Hystrix cristata ) in Central Italy tend to become infected by seven different species of ectoparasites and seven different species of  endoparasites . [ 38 ]  During this time, it is observed that these porcupine populations actively sought out a rather large variety of medicinal plants, mostly with antiparasitic properties, to consume. When ingested, these plants appeared to be relieving the symptoms of the infections, such as inflammation.


Many animals eat soil or clay, a behaviour known as  geophagy .  Clay is the primary ingredient of  kaolin . [ 39 ]   It has been proposed that for primates, there are four hypotheses relating to geophagy in alleviating gastrointestinal disorders or upsets: [ 40 ]


Furthermore, two hypotheses pertain to geophagy in supplementing minerals and elements:


Tapirs ,  forest elephants ,  colobus monkeys ,  mountain gorillas  and chimpanzees seek out and eat clay, which absorbs intestinal bacteria and their toxins and alleviates stomach upset and  diarrhoea . [ 41 ]   Cattle eat clay-rich termite mound soil, which deactivates ingested pathogens or fruit toxins. [ 1 ]


Some animals apply substances with medicinal properties to their skin.  Again, this can be prophylactic or curative. In some cases, this is known as  self-anointing .


A female  capuchin monkey  in captivity was observed using tools covered in a sugar-based syrup to groom her wounds and those of her infant. [ 42 ] [ 43 ]


North American  brown bears  ( Ursos arctos ) make a paste of Osha roots ( Ligusticum porteri ) and saliva and rub it through their fur to repel insects or soothe bites. This plant, locally known as "bear root", contains 105 active compounds, such as  coumarins  that may repel insects when topically applied.  Navajo Indians  are said to have learned to use this root medicinally from the bear for treating stomach aches and infections. [ 28 ] [ 44 ] [ 45 ]


A range of primates rub  millipedes  onto their fur and skin; millipedes contain  benzoquinones , compounds known to be potently repellent to insects. [ 46 ] [ 47 ] [ 48 ]  As the millipede secretions are also  psychoactive , the behavior may also be a form of  recreational drug use in animals . [ 49 ] [ 50 ]


Tufted capuchins  ( Cebus apella ) rub various parts of their body with  carpenter ants  ( Camponotus rufipes ) or allow the ants to crawl over them, in a behaviour called  anting .  The capuchins often combine anting with urinating into their hands and mixing the ants with the urine. [ 51 ]


Callicebus oenanthes  have been observed rubbing leaves of  Piper aduncum  on their furs and abdominal areas. Since these leaves contain insecticides like  dillapiole  and  phenylpropanoids , it is speculated that this fur-rubbing is an indication of a preventative measure to ward off insects. [ 52 ]  Additionally, another species of titi monkeys,  Plecturocebus   cupreus , were seen rubbing their furs with the leaves of  Psychotria , whose compounds have antiviral, antifungal, and analgesic properties. [ 10 ]


A male Sumatran orangutan known to researchers as Rakus "appeared to have used the plant intentionally" when he chewed up leaves of the "antibacterial, anti-inflammatory, anti-fungal, antioxidant, pain-killing and anticarcinogenic" vine  Fibraurea tinctoria  and applied the masticated plant material to an open wound on his face. According to primatologists who had been observing Rakus at a nature preserve, "Five days later the facial wound was closed, while within a few weeks it had healed, leaving only a small scar". [ 53 ] [ 54 ] [ 55 ]


More than 200 species of song birds rub insects, usually ants, on their feathers and skin, a behaviour known as  anting . [ 14 ]  Birds either grasp ants in their bill and wipe them vigorously along the spine of each  feather  down to the base, or sometimes roll in ant hills twisting and turning so the ants crawl through their feathers. Birds most commonly use ants that spray formic acid. In laboratory tests, this acid is harmful to feather lice.  Its vapour alone can kill them.


Some birds select nesting material rich in anti-microbial agents that may protect themselves and their young from harmful infestations or infections.  European starlings  ( Sturnus vulgaris ) preferentially select and line their nests with wild carrot ( Daucus carota ); chicks from nests lined with this have greater levels of  haemoglobin  compared to those from nests which are not, although there is no difference in the weight or feather development of the chicks.  Laboratory studies show that wild carrot substantially reduces the emergence of the  instars  of mites. [ 56 ]   House sparrows  ( Passer domesticus ) have been observed to line their nests with materials from the  neem  tree ( Azadirachta indica ) but change to  quinine -rich leaves of the Krishnachua tree ( Caesalpinia pulcherrima ) during an outbreak of  malaria ; quinine controls the symptoms of malaria. [ 28 ] [ 57 ]


Zoopharmacognosy is not always exhibited in a way that benefits the individual.  Sometimes the target of the medication is the group or the colony.


Wood ants ( Formica paralugubris ) often incorporate large quantities of solidified  conifer  resin into their nests. Laboratory studies have shown this resin inhibits the growth of bacteria and fungi in a context mimicking natural conditions. [ 58 ]   The ants show a strong preference for resin over twigs and stones, which are building materials commonly available in their environment. There is seasonal variation in the foraging of ants: the preference for resin over twigs is more pronounced in spring than in summer, whereas in autumn the ants collect twigs and resin at equal rates. The relative collection rate of resin versus stones does not depend on infection with the entomopathogenic fungus  Metarhizium anisopliae  in laboratory conditions, indicating the resin collection is prophylactic rather than therapeutic. [ 59 ]


Honey bees also incorporate plant-produced resins into their nest architecture, which can reduce chronic elevation of an individual bee's immune response. When colonies of honey bees are challenged with the fungal parasite ( Ascophaera apis ), the bees increase their resin foraging. Additionally, colonies experimentally enriched with resin have decreased infection intensities of the fungus. [ 60 ]


Zoopharmacognosy can be classified depending on the target of the medication.  Some animals lay their eggs in such a way that their offspring are the target of the medication.


Adult  monarch butterflies  preferentially lay their eggs on toxic plants such as milkweed which reduce parasite growth and disease in their offspring caterpillars. [ 61 ]   This has been termed  transgenerational therapeutic medication . [ 62 ]


When detecting  endoparasitoid  wasps, fruit flies ( Drosophila melanogaster ) lay their eggs in leaves with high  ethanol  content as a means of protection for their offspring. [ 63 ]  These wasps, especially those of the  Leptopilina  genus, will inject their eggs in approximately 80% of fruit fly larvae. [ 64 ]  As these wasp eggs develop, they will consume extensively through the larvae. To combat this, the fruit fly larvae will consume a large amount of ethanol from the food source to medicate themselves after wasp infection. Specifically, as the wasps are consuming more of the larvae, they will unknowingly consume more ethanol, which promptly leads to their deaths. This has been termed  transgenerational prophylaxis . [ 62 ]


In an interview with  Neil Campbell , Eloy Rodriguez describes the importance of  biodiversity to medicine :


Some of the compounds we've identified by zoopharmacognosy kill parasitic worms, and some of these chemicals may be useful against  tumors . There is no question that the templates for most drugs are in the natural world. [ 29 ]


Bacillus  isolates  have a variety of  biotechnological  applications.


Nattō -derived  Bacillus  isolates include nootropics  pyrazine  and  tetramethylpyrazine , as well as the anticoagulant enzyme  nattokinase .


Bacillus  is utilized in the production of the chemotherapy medicine  L-asparaginase .  Bacillus subtilis  is utilized in the production of  hyaluronic acid  and  α-amylase .  Bacillus thuringiensis  isolates are utilized as  biopesticides .


Bacillus megaterium  has been an important industrial organism for decades. It produces  penicillin amidase  used to make synthetic penicillin, various  amylases  used in the baking industry and  glucose dehydrogenase  used in glucose blood tests.  B. megaterium  is also used for the production of  pyruvate ,  vitamin B12 , drugs with  fungicidal  and  antiviral  properties, etc. [ 2 ]  It produces enzymes for modifying  corticosteroids , as well as several amino acid  dehydrogenases .


Bacillus subtilis  can biosynthesize  silver nanoparticles .  Bacillus badius  can be used to cleaves penicillin G to 6-amino penicillanic acid (6-APA) and phenyl acetic acid (PAA). Certain  Bacillus  have  mycorrhiza -like activity and potential  bioremediation  applications.


Bacillus isolates are used industrially as nutritional  probiotics . [ 3 ]  Additional  Bacillus  isolates include  gamma-D-Glutamyl-meso-diaminopimelate peptidase , sonorensin, [ 4 ]  gamma-cyclodextrin,   2,5-Diketopiperazines ,  laccases ,  bacteriocin , paenicidin A, tridecaptin A₁, and paenicidin B.


Bark isolates  are chemicals which have been extracted from  bark . Prominent medical examples are  salicylic acid  (active metabolite of  aspirin ) and  paclitaxel  ( Taxol ). The  pharmacology  of bark isolates is an ongoing topic of medical research.


Fungal isolates  have been researched for decades. Because  fungi  often exist in thin  mycelial   monolayers , with no protective shell,  immune system , and limited mobility, they have developed the ability to synthesize a variety of unusual compounds for survival. Researchers have discovered fungal isolates with  anticancer ,  antimicrobial ,  immunomodulatory , and other  bio-active  properties. The first  statins ,  β-Lactam antibiotics , as well as a few important antifungals, were discovered in fungi.


BMS  manufactures  paclitaxel  using  Penicillium  and plant cell fermentation. Fungi can synthesize  podophyllotoxin  and  camptothecin , precursors to  etoposide ,  teniposide ,  topotecan , and  irinotecan .


Lentinan ,  PSK , and  PSP , are registered anticancer immunologic adjuvants.  Irofulven  and  acylfulvene  are anticancer derivatives of  illudin S .  Clavaric acid  is a reversible farnesyltransferase inhibitor.  Inonotus obliquus  creates  betulinic acid  precursor  betulin .  Flammulina velutipes  creates  asparaginase .  Plinabulin  is a fungal isolate derivative currently being researched for anticancer applications.


The statins  lovastatin ,  mevastatin , and  simvastatin  precursor monacolin J, are fungal isolates. Additional fungal isolates that inhibit cholesterol are  zaragozic acids ,  eritadenine , and  nicotinamide riboside .


Ciclosporin ,  mycophenolic acid ,  mizoribine ,  FR901483 , and  gliotoxin , are immunosuppressant fungal isolates.


Penicillin ,  cephalosporins ,  fusafungine ,  usnic acid ,  fusidic acid ,  fumagillin ,  brefeldin A ,  verrucarin A ,  alamethicin , are antibiotic fungal isolates. Antibiotics  retapamulin ,  tiamulin , and  valnemulin  are derivatives of the fungal isolate  pleuromutilin .  Griseofulvin ,  echinocandins ,  strobilurin ,  azoxystrobin ,  caspofungin ,  micafungin , are fungal isolates with antifungal activity.


The headache medications  cafergot ,  dihydroergotamine ,  methysergide ,  methylergometrine , the dementia medications  hydergine ,  nicergoline , the Parkinson's disease medications  lisuride ,  bromocriptine ,  cabergoline , and  pergolide  were all derived from  Claviceps  isolates.  Polyozellus multiplex  synthesizes prolyl endopeptidase inhibitors  polyozellin ,  thelephoric acid , and  kynapcins .  Boletus badius  synthesizes  L-theanine .


Researchers have discovered other interesting fungal isolates like the antihyperglycemic compounds  ternatin ,  aspergillusol A ,  sclerotiorin , and antimalarial compounds  codinaeopsin ,  efrapeptins , and  antiamoebin . The fungal isolate  ergothioneine  is actively absorbed and concentrated by the human body via  SLC22A4 . Other notable fungal isolates include vitamin D 1 , vitamin D 2 , and vitamin D 4 .


Lacking an  immune system , protective shell, or mobility,  sponges  have developed an ability to synthesize a variety of unusual compounds for survival.  C- nucleosides  isolated from Caribbean  Cryptotethya crypta , were the basis for the synthesis of  zidovudine  ( AZT ),  aciclovir  ( Cyclovir ),  cytarabine  ( Depocyt ), and cytarabine derivative  gemcitabine  ( Gemzar ).


Semisynthetic analogs of the sponge isolate jasplakinolide, were submitted to  National Cancer Institute ’s Biological Evaluation Committee in 2011.


Trabectedin ,  aplidine ,  didemnin , were isolated from  sea squirts .  Monomethyl auristatin E  is a derivative of a dolastatin 10, a compound made by  Dolabella auricularia .  Bryostatins  were first isolated from  Bryozoa .


Salinosporamides  are derived from  Salinispora tropica .  Ziconotide  is derived from the sea snail  Conus magus .


Streptomyces  isolates  have yielded the majority of human, animal, and agricultural antibiotics, as well as a number of fundamental chemotherapy medicines.  Streptomyces  is the largest  antibiotic -producing genus of  Actinomycetota , producing chemotherapy, antibacterial,  antifungal , antiparasitic drugs, and  immunosuppressants . [ 1 ]   Streptomyces  isolates are typically initiated with the aerial  hyphal  formation from the  mycelium . [ 2 ]


Streptomyces , yielded the medicines  doxorubicin  ( Doxil ),  daunorubicin  ( DaunoXome ), and  streptozotocin  ( Zanosar ). Doxorubicin is the precursor to  valrubicin  ( Valstar ),  myocet , and  pirarubicin . Daunorubicin is the precursor to  idarubicin  ( Idamycin ),  epirubicin  ( Ellence ), and  zorubicin . [ citation needed ]


Streptomyces  is the original source of  dactinomycin  ( Cosmegen ),  bleomycin  ( Blenoxane ),  pingyangmycin  ( Bleomycin A 5 ),  mitomycin C  ( Mutamycin ),  rebeccamycin ,  staurosporine  (precursor to  stauprimide  and  midostaurin ),  neothramycin ,  aclarubicin , tomaymycin,  sibiromycin , and mazethramycin. [ citation needed ]


Derivatives of  Streptomycetes  isolate  migrastatin , including  isomigrastatin , dorrigocin A & B, and the synthetic derivative  macroketone , are being researched for anticancer activity. [ citation needed ]


Most clinical antibiotics were found during the "golden age of antibiotics" (1940s–1960s).  Actinomycin  was the first antibiotic isolated from  Streptomyces  in 1940, followed by  streptomycin  three years later. Antibiotics from  Streptomyces  isolates (including various  aminoglycosides ) would go on to comprise over two-thirds of all marketed antibiotics. [ citation needed ]


Streptomyces -derived antibiotics include:


Clavulanic acid  ( Streptomyces clavuligerus ) is used in combination with some antibiotics (such as  amoxicillin ) to weaken bacterial-resistance. Novel anti-infectives being developed include the  guadinomines  (from  Streptomyces  sp. K01-0509), [ 14 ]  inhibitors of the  type III secretion system .


Non- Streptomyces   actinomycetes , filamentous  fungi , and non-filamentous  bacteria , have also yielded important antibiotics. [ citation needed ]


Nystatin  ( Streptomyces noursei ),  amphotericin B  ( Streptomyces nodosus ),  ossamycin  ( Streptomyces hygroscopicus ), and  natamycin  ( Streptomyces natalensis ) are antifungals isolated from  Streptomyces . [ citation needed ]


Sirolimus  ( Rapamycin ),  ascomycin , and  tacrolimus  were isolated from  Streptomyces .   Pimecrolimus  is a derivative of ascomycin.  Ubenimex  is derived from  S. olivoreticuli . [ 15 ]


Streptomyces avermitilis  synthesizes the antiparasitic  ivermectin  ( Stromectol ). Other antiparasitics made by  Streptomyces  include,  milbemycin oxime ,  moxidectin , and  milbemycin . [ citation needed ]


Traditionally,  Escherichia coli  is the choice bacterium to express  eukaryotic  and  recombinant  genes.  E. coli  is well understood and has a successful track record producing  insulin , the  artemisinin  precursor artemisinic acid, and  filgrastim  ( Neupogen ). [ 16 ] [ 17 ]  However, use of  E. coli  has limitations including misfolding of eukaryotic proteins, insolubility issues, deposition in inclusion bodies, [ 18 ]  low secretion efficiency, secretion to periplasmic space.


Streptomyces  offers potential advantages including superior secretion mechanisms, higher yields, a simpler end-product purification process, making  Streptomyces  an attractive alternative to  E. coli  and  Bacillus subtilis . [ 18 ]


Streptomyces coelicolor ,  Streptomyces avermitilis ,  Streptomyces griseus , and  Saccharopolyspora erythraea , are capable of secondary metabolite production.  Streptomyces coelicolor  has shown useful for the  heterologous expression  of proteins. Methods like "ribosome engineering" have been used to achieve 180-fold higher yields with  S. coelicolor . [ 19 ]


StreptomeDB, a directory of  Streptomyces  isolates, contains over 2400 compounds isolated from more than 1900 strains. [ 20 ] [ 21 ]   Streptomyces hygroscopicus  and  Streptomyces viridochromeogenes  produce the herbicide  bialaphos .  Expansion of  Streptomyces  screenings have included  endophytes ,  extremophiles , and  marine  varieties. [ citation needed ]


A recent screening of  TCM  extracts revealed a  Streptomyces  that produces a number of antitubercular  pluramycins . [ 22 ]  Wailupemycins are bio-active  pyrones  isolated from marine  Streptomyces . [ 23 ]


Mayamycin  has been shown to have  cytotoxic  properties. [ 24 ] [ 25 ]


Germicidin  are a group of four compounds that act as autoregulatory inhibitors of  spore germination . [ 26 ] [ 27 ]


An  anticarcinogen  (also known as a  carcinopreventive  agent) is a substance that counteracts the effects of a  carcinogen  or inhibits the development of  cancer . [ 1 ]   Anticarcinogens are different from  anticarcinoma agents  (also known as anticancer or anti-neoplastic agents) in that anticarcinoma agents are used to selectively destroy or inhibit cancer cells  after  cancer has developed.  Interest in anticarcinogens is motivated primarily by the principle that it is preferable to prevent disease ( preventive medicine ) than to have to treat it ( rescue medicine ). [ medical citation needed ]


In theory, anticarcinogens may act via different mechanisms including enhancement of natural defences against cancer, deactivation of  carcinogens , and blocking the mechanisms by which carcinogens act (such as  free radical  damage to  DNA ).  Confirmation that a substance possesses anticarcinogenic activity requires extensive  in vitro ,  in vivo , and  clinical  investigation.  Health claims for anticarcinogens are regulated by various national and international organizations like the  US Food and Drug Administration (FDA)  and  European Food Safety Authority (EFSA) . [ medical citation needed ]


This  antineoplastic  or  immunomodulatory   drug  article is a  stub . You can help Wikipedia by  expanding it .


Barbigerone  is one of a few  pyranoisoflavones  among several groups of  isoflavones . It was first isolated from the seed of a  leguminous plant   Tephrosia barbigera ; hence the name "barbigerone". [ 1 ]  Members of the  genus   Millettia  are now known to be rich in barbigerone, including  M. dielsiena , [ 2 ]   M. ferruginea , [ 3 ]   M. usaramensis , [ 4 ]  and  M. pachycarpa . [ 5 ]  It has also been isolated from the medicinal plant  Sarcolobus globosus . [ 6 ]  Barbigerone from  S. globosus  is validated to have significant  antioxidant  property. [ 7 ]  Barbigerone exhibits profound antiplasmodial activity against the  malarial parasite   Plasmodium falciparum . [ 8 ]  It is also demonstrated that it has  anti-cancer  potential as it causes  apoptosis  of  murine   lung-cancer cells . [ 9 ]


Fluasterone , also known as  3β-dehydroxy-16α-fluoro- DHEA  or  16α-fluoroandrost-5-en-17-one , is a  fluorinated   synthetic   analogue  of  dehydroepiandrosterone  (DHEA) which was under investigation by Aeson Therapeutics for a variety of therapeutic indications including  cancer ,  cardiovascular diseases ,  diabetes ,  obesity , and  traumatic brain injury  among others but was ultimately never marketed. [ 1 ] [ 2 ]  It is a  modification  of DHEA in which the C3β  hydroxyl  has been removed and a  hydrogen  atom has been  substituted  with a  fluorine  atom at the C16α position. Fluasterone reached  phase II   clinical trials  prior to the discontinuation of its development. [ 3 ]


The  mechanism of action  of DHEA and fluasterone is unknown. [ 4 ] [ 5 ] [ 6 ]  However, similarly to DHEA but more strongly, fluasterone is a  potent   uncompetitive inhibitor  of  G6PDH Tooltip glucose-6-phosphate dehydrogenase  (K i  = 0.5 μM versus 17 μM for DHEA). [ 4 ]  The drug retains the  antiinflammatory ,  antihyperplastic ,  chemopreventative ,  antihyperlipidemic ,  antidiabetic , and  antiobesic , as well as certain  immunomodulating  activities of DHEA, much but not all of which it is thought may possibly be mediated via G6PDH inhibition (with some experimental evidence to support this notion available). [ 4 ] [ 6 ] [ 7 ] [ 8 ]


Conversely, unlike DHEA, fluasterone has minimal or no  androgenic  or  estrogenic  activity, and due to the presence of the fluorine atom at the C16α position, its  metabolism  at the C17α position is  sterically hindered  and thus it cannot be metabolized into  androgens  like  testosterone  or  estrogens  like  estradiol . [ 6 ] [ 9 ] [ 4 ]  Also in contrast to DHEA, fluasterone does not produce  sedation  or  seizures  in animals and hence is not thought to interact with the  GABA A  receptor . [ 10 ]  In addition, unlike DHEA, fluasterone has reduced or no effects as a  peroxisome proliferator  (i.e., lacks activity at the  PPARα Tooltip peroxisome proliferator-activated receptor alpha ), and hence does not pose a risk of  liver toxicities  such as  hepatomegaly  or  hepatocellular carcinoma . [ 4 ]  It is for these reasons that fluasterone was developed and was considered to be advantageous to DHEA. [ 4 ] [ 6 ]


Due to extensive  first-pass   hepatic  and/or  gastrointestinal  metabolism, very high doses of DHEA and fluasterone are necessary for effectiveness. [ 4 ]  In animals, the  efficacy  of fluasterone is increased 40-fold when administered  parenterally , and for this reason, a non- oral  formulation of fluasterone was selected for clinical development. [ 4 ]  However, the development of fluasterone was nonetheless stopped reportedly due to its low potency and low oral  bioavailability , which are said to have rendered it unsuitable for clinical use. [ 11 ]


In  biochemistry ,  medicine , and related sciences,  inositol  generally refers to  myo -inositol  (formerly  meso -inositol ), the most important  stereoisomer  of the  chemical compound   cyclohexane-1,2,3,4,5,6-hexol . Its  formula  is  C 6 H 12 O 6 ; the molecule has a ring of six  carbon  atoms, each with an  hydrogen  atom and a  hydroxyl  group (–OH). In  myo -inositol, two of the hydroxyls, neither adjacent not opposite, lie above the respective hydrogens relative to the mean plane of the ring.


The compound is a  carbohydrate , specifically a  sugar alcohol  (as distinct from  aldoses  like  glucose ) with half the  sweetness  of  sucrose  (table sugar). It is one of the most ancient components of living beings with multiple functions in eukaryotes, including structural lipids and  secondary messengers . [ 3 ]  A human kidney makes about two grams per day from  glucose , but other tissues synthesize it too. The highest concentration is in the brain, where it plays an important role in making other  neurotransmitters  and some  steroid hormones  bind to their receptors. [ 4 ]  In other tissues, it mediates cell signal transduction in response to a variety of  hormones ,  neurotransmitters , and growth factors and participates in  osmoregulation . [ 5 ]  In most mammalian cells the concentrations of  myo -inositol are 5 to 500 times greater inside cells than outside them. [ 6 ]


A 2023 meta-analysis found that inositol is a safe and effective treatment in the management of  polycystic ovary syndrome  (PCOS). [ 7 ]  However, there is only evidence of very low quality for its efficacy in increasing fertility for IVF in women with PCOS. [ 8 ]


The other naturally occurring stereoisomers of cyclohexane-1,2,3,4,5,6-hexol are  scyllo -,  muco -,  D - chiro -,  L - chiro -, and  neo -inositol , although they occur in minimal quantities compared to  myo -inositol. The other possible isomers are  allo -,  epi -, and  cis -inositol .


myo -Inositol was first isolated from muscle extracts by Johanes Joseph Scherer (1814–1869) in 1850. [ 3 ]  It was formerly called  meso -inositol to distinguish it from the  chiro - isomers. However, since all other isomers are meso (non- chiral ) compounds, the name  myo -inositol is now preferred ( myo - being a  medical prefix  for "muscle").


Inositol was once considered a member of the  vitamin B  complex, namely  vitamin B 8  before the discovery that it is made naturally in the human body, and therefore cannot be a  vitamin  or  essential nutrient . [ 9 ]


myo -Inositol is a  meso compound , meaning it is  optically inactive  because it has a  plane of symmetry . [ 10 ]  It is a white crystalline powder, relatively stable in the air. It is highly soluble in water, slightly soluble in  glacial acetic acid ,  ethanol ,  glycol , and  glycerin , but insoluble in  chloroform  and  ether . [ 3 ]


In its most stable  conformation , the  myo -inositol isomer assumes the  chair conformation , which moves the maximum number of hydroxyls to the equatorial position, where they are farthest apart from each other. In this conformation, the natural  myo  isomer has a structure in which five of the six  hydroxyls  (the first, third, fourth, fifth, and sixth) are  equatorial , whereas the second hydroxyl group is  axial . [ 11 ]


myo -Inositol plays an important role as the structural basis for a number of  secondary messengers  in  eukaryotic   cells , the various  inositol phosphates . In addition, inositol serves as an important component of the structural lipids  phosphatidylinositol  (PI) and its various phosphates, the  phosphatidylinositol phosphate  (PIP) lipids.


In humans,  myo -Inositol is  synthesized  de novo  but  D - chiro -inositol is not. [ 6 ]   myo -Inositol is synthesized from  glucose 6-phosphate  (G6P) in two steps. First, G6P is  isomerised  by an  inositol-3-phosphate synthase  enzyme (for example,  ISYNA1 ) to  myo -inositol 1-phosphate, which is then dephosphorylated by an  inositol monophosphatase  enzyme (for example,  IMPA1 ) to give free  myo -inositol. In humans, most inositol is synthesized in the kidneys, followed by testicles, typically in amounts of a few grams per day. [ 5 ]


At the peripheral level,  myo -inositol is converted to  D - chiro -inositol by a specific epimerase. Only a minor fraction of  myo -inositol is converted into  D - chiro -inositol. [ 6 ]  The activity of this epimerase is insulin dependent, causing a reduction of  D - chiro -inositol in muscle, fat, and liver when there is  insulin resistance . [ 12 ] [ 6 ]   D - chiro -inositol reduces the conversion of testosterone to estrogen, thereby increases the levels of testosterone and worsening PCOS. [ 6 ]


Inositol hexaphosphate, also called  phytic acid  or IP6, is a  phytochemical  and the principal storage form of  phosphorus  in many  plant   tissues , especially  bran  and  seed . [ 13 ]  Phosphorus and inositol in phytate form are not generally  bioavailable  to non- ruminant  animals because these animals lack the digestive  enzyme   phytase  required to remove the phosphate groups. Ruminants readily digest phytate because of the phytase produced by microorganisms in the  rumen . [ 14 ]  Moreover, phytic acid also  chelates  important minerals such as  calcium ,  magnesium ,  iron , and  zinc , making them unabsorbable, and contributing to mineral deficiencies in people whose diets rely highly on bran and seeds for their mineral intake, such as occurs in  developing countries . [ 15 ] [ 16 ]


Inositol penta- (IP5), tetra- (IP4), and triphosphate (IP3) are also called "phytates".


Inositol or its phosphates and associated lipids are found in many foods, in particular fruit, especially  cantaloupe  and  oranges . [ 17 ]  In plants, the hexaphosphate of inositol,  phytic acid  or its salts, the phytates, serve as phosphate stores in seed, for example in nuts and beans. [ 18 ]  Phytic acid also occurs in  cereals  with high  bran  content. Phytate is, however, not directly  bioavailable  to humans in the diet, since it is not digestible. Some food preparation techniques partly break down phytates to change this. However, inositol in the form of  phospholipids , as found in certain plant-derived substances such as  lecithins , is well absorbed and relatively bioavailable.


Inositol, phosphatidylinositol, and some of their mono- and polyphosphates function as  secondary messengers  in a number of intracellular  signal transduction  pathways. They are involved in a number of biological processes, including:


In one important family of pathways,  phosphatidylinositol 4,5-bisphosphate  (PIP 2 ) is stored in cellular membranes until it is released by any of a number of signalling proteins and transformed into various secondary messengers, for example  diacylglycerol  and  inositol trisphosphate . [ 25 ]


' myo -Inositol has very low toxicity, with a reported  LD 50  10,000 mg/kg body weight (oral) in rats. [ 3 ]


At the 1936 meeting of the  American Chemical Society , professor  Edward Bartow  of the  University of Iowa  presented a commercially viable means of extracting large amounts of inositol from the phytic acid naturally present in waste corn. As a possible use for the chemical, he suggested 'inositol nitrate' as a more stable alternative to  nitroglycerin . [ 26 ]  Today, inositol nitrate is used to gelatinize  nitrocellulose  in many modern explosives and solid rocket propellants. [ 27 ]


When plants are exposed to increasing concentrations of  road salt , the plant cells become dysfunctional and undergo  apoptosis , leading to inhibited growth. Inositol pretreatment could reduce these effects. [ 28 ]


High doses of inositol may be used to treat  trichotillomania  (compulsive hair-pulling) and related disorders. [ 29 ]


D- chiro -inositol is an important messenger molecule in insulin signaling. [ 30 ]  Inositol supplementation has been shown to significantly decrease  triglycerides  and  LDL cholesterol  in patients with  metabolic diseases . [ 30 ]


myo -Inositol is important for  thyroid hormone  synthesis. [ 31 ]  Depletion of  myo -inositol may predispose to development of  hypothyroidism . [ 31 ]  Patients with hypothyroidism have a higher demand for  myo -inositol than healthy subjects. [ 31 ]


Inositol should not be routinely implemented for the management of preterm babies who have or are at a risk of  infant respiratory distress syndrome  (RDS). [ 32 ]   Myo -inositol helps prevent  neural tube defects  with particular efficacy in combination with  folic acid . [ 33 ]


Inositol is considered a safe and effective treatment for  polycystic ovary syndrome  (PCOS). [ 7 ]  It works by increasing insulin sensitivity, which helps to improve ovarian function and reduce  hyperandrogenism . [ 34 ]  It is also shown to reduce the risk of  metabolic disease  in women with PCOS. [ 35 ]  In addition, thanks to its role as FSH second messenger,  myo -inositol is effective in restoring FSH/LH ratio and menstrual cycle regularization. [ 36 ]   myo -Inositol's role as FSH second messenger leads to a correct ovarian follicle maturation and consequently to a higher oocyte quality. Improving the oocyte quality in both women with or without PCOS,  myo -inositol can be considered as a possible approach for increasing the chance of success in assisted reproductive technologies. [ 37 ] [ 38 ]  In contrast,  D - chiro -inositol can impair oocyte quality in a dose-dependent manner. [ 39 ]  The high level of DCI seems to be related to elevated insulin levels retrieved in about 70% of PCOS women. [ 40 ]  In this regard, insulin stimulates the irreversible conversion of  myo -inositol to  D - chiro -inositol causing a drastic reduction of  myo -inositol.  myo -Inositol depletion is particularly damaging to ovarian follicles because it is involved in FSH signaling, which is impaired due to  myo -inositol depletion. [ 12 ]  Recent evidence reports a faster improvement of the metabolic and hormonal parameters when these two isomers are administered in their physiological ratio. The plasmatic ratio of  myo -inositol and  D - chiro -inositol in healthy subjects is 40:1 of  myo - and  D - chiro -inositol respectively. [ 41 ]  The use of the 40:1 ratio shows the same efficacy of  myo -inositol alone but in a shorter time. In addition, the physiological ratio does not impair oocyte quality. [ 42 ]


The use of inositols in PCOS is gaining more importance, and an efficacy higher than 70% with a strong safety profile is reported. On the other hand, about 30% of patients could show as inositol-resistant. [ 43 ]  New evidence regarding PCOS aetiopathogenesis describes an alteration in the species and the quantity of each strain characterizing the normal gastrointestinal flora. This alteration could lead to chronic, low-level inflammation and malabsorption. [ 44 ]  A possible solution could be represented by the combination of  myo -inositol and  α-lactalbumin . This combination shows a synergic effect in increasing myo-inositol absorption. [ 45 ]  A recent study reported that the  myo -inositol and α-lactalbumin combination increases  myo -inositol plasmatic content in inositol-resistant patients with a relative improvement of hormonal and metabolic parameters. [ 46 ]


Inositol has been used as an adulterant or  cutting agent  for many illegal drugs, such as  cocaine ,  methamphetamine , and sometimes  heroin , [ 47 ]  probably because of its solubility, powdery texture, or reduced  sweetness  (50%) compared to more common sugars.


Inositol is also used as a stand-in  film prop  for  cocaine  in  filmmaking . [ 48 ] [ 49 ]


myo -Inositol is naturally present in a variety of foods, although tables of food composition do not always distinguish between  lecithin , the relatively bioavailable lipid form and the biounavailable phytate/phosphate form. [ 17 ]  Foods containing the highest concentrations of  myo -inositol and its compounds include fruits, beans, grains, and nuts. [ 17 ]  Fruits in particular, especially oranges and cantaloupe, contain the highest amounts of  myo -inositol. [ 50 ]  It is also present in beans, nuts, and grains, however, these contain large amounts of  myo -inositol in the phytate form, which is not bioavailable without transformation by  phytase  enzymes.  Bacillus subtilis , the microorganism which produces the fermented food  natto , produces phytase enzymes that may convert  phytic acid  to a more bioavailable form of inositol polyphosphate in the gut. [ 51 ]  Additionally,  Bacteroides  species in the gut secrete vesicles containing an active enzyme which converts the phytate molecule into bioavailable phosphorus and inositol polyphosphate, which is an important signaling molecule in the human body. [ 52 ]


myo -Inositol can also be found as an ingredient in  energy drinks , [ 53 ]  either in conjunction with or as a substitute for glucose. [ 54 ]


In humans, myo-inositol is naturally made from glucose-6-phosphate through enzymatic dephosphorylation. [ 50 ]


As of 2021, the main industrial process for the production of  myo -inositol (mostly in China and Japan) started with phytate (IP6) extracted from the soaking water resulting from corn and rice bran processing. After purification, the phytate is hydrolized, and  myo -inositol is separated by crystallization. [ 3 ]


Another route is microbial fermentation of carbohydrates by various organisms, such as the fungus  Neurospora crassa  (Beadle and Tatum, 1945),  Candida boidini  (Shirai et al., 1997),  Saccharomyces cerevisiae  (Culbertson et al., 1976),  Escherichia coli  (Hansen, 1999). [ 3 ]  Alternatively, enzyme extracts from microbial cultures can be used in vitro to obtain  myo -inositol from various substrates, including glucose,  sucrose ,  starch ,  xylose , and  amylose . [ 3 ]


Miraculin  is a  taste modifier , a  glycoprotein  extracted from the fruit of  Synsepalum dulcificum . [ 2 ]  The berry, also known as the miracle fruit, was documented by explorer  Chevalier des Marchais , who searched for many different fruits during a 1725 excursion to its native West Africa.


Miraculin itself does not taste  sweet . When  taste buds  are exposed to miraculin, the protein binds to the sweetness receptors. This causes normally sour-tasting acidic foods, such as  citrus , to be perceived as sweet. [ 2 ] [ 3 ]  The effect can last for one or two hours. [ 4 ] [ 5 ]


The sweetening properties of  Synsepalum dulcificum  berries were first noted by des Marchais during expeditions to West Africa in the 18th century. [ 6 ]  The term  miraculin  derived from experiments to isolate and purify the active  glycoprotein  that gave the berries their sweetening effects, results that were published simultaneously by Japanese and Dutch scientists working independently in the 1960s (the Dutch team called the glycoprotein  mieraculin ). [ 7 ] [ 8 ]  The word  miraculin  was in common use by the mid-1970s. [ 9 ] [ 10 ] [ 11 ]


Miraculin was first sequenced in 1989 and was found to be a 24.6  kilodalton [ 2 ]  glycoprotein consisting of 191  amino acids [ 12 ]  and 13.9% by weight of various sugars. [ 2 ]


The sugars consist of a total of 3.4 kDa, composed of a molar ratio of  glucosamine  (31%),  mannose  (30%),  fucose  (22%),  xylose  (10%), and  galactose  (7%). [ 2 ]


The  native state  of miraculin is a  tetramer  consisting of two  dimers , each held together by a  disulfide  bridge. [ 14 ]  Both tetramer miraculin and native dimer miraculin in its crude state have the taste-modifying activity of turning sour tastes into sweet tastes. [ 15 ]  Miraculin belongs to the  Kunitz STI protease inhibitor  family.


Miraculin, unlike  curculin  (another taste-modifying agent), [ 16 ]  is not sweet by itself, but it can change the perception of sourness to sweetness, even for a long period after consumption. [ 4 ]  The duration and intensity of the sweetness-modifying effect depends on various factors, such as miraculin concentration, duration of contact of the miraculin with the tongue, and acid concentration. [ 3 ] [ 4 ]  Miraculin reaches its maximum sweetness with a solution containing at least 4*10 −7   mol/L  miraculin, which is held in the mouth for about 3 minutes. Maximum is equivalent in sweetness to a 0.4 mol/L solution of  sucrose . [ 17 ]  Miraculin degrades permanently via  denaturation  at high temperatures and at  pH  below 3 or above 12. [ 18 ]


Although the detailed mechanism of the taste-inducing behavior is unknown, it appears the sweet receptors are activated by acids which are related to sourness, an effect remaining until the  taste buds  perceive a neutral pH. [ 3 ] [ 4 ]  Sweeteners are perceived by the human sweet taste receptor, hT1R2-hT1R3, which belongs to  G protein-coupled receptors , [ 4 ]  modified by the two  histidine  residues (i.e. His30 and His60) which participate in the taste-modifying behavior. [ 19 ]  One site maintains the attachment of the protein to the membranes while the other (with attached  xylose  or  arabinose ) activates the sweet receptor membrane in acid solutions. [ 14 ]


As miraculin is a readily soluble protein and relatively heat stable, it is a potential  sweetener  in acidic food, such as  soft drinks . While attempts to express it in  yeast  and  tobacco plants  have failed, researchers have succeeded in preparing  genetically modified   E. coli  bacteria that express miraculin. [ 20 ]   Lettuce  and  tomato  have also been used for mass production of miraculin. [ 21 ] [ 22 ]


The use of miraculin as a food additive was denied in 1974 by the United States  Food and Drug Administration . [ 23 ]  However, it can still be sold in the form of whole berries or tablets (as "dietary supplements"). [ 24 ] [ 25 ]  In 2011 the FDA banned a certain brand of miraculin tablets imported from Taiwan as it was thought to be "hard candy" with non-approved sweeteners. [ 26 ]  Miraculin has a  novel food  status in the  European Union . [ 27 ]  It is approved in  Japan  as a safe  food additive , according to the List of Existing Food Additives published by the Ministry of Health and Welfare (published by the  Japan External Trade Organization ).


A  polyphenol antioxidant  is a  hypothesized type  of  antioxidant  studied  in vitro . Numbering over 4,000 distinct  chemical structures  mostly from  plants , such polyphenols have not been demonstrated to be antioxidants  in vivo . [ 1 ] [ 2 ] [ 3 ]


In vitro at high experimental doses, polyphenols may affect cell-to-cell signaling,  receptor  sensitivity, inflammatory  enzyme  activity or  gene regulation . [ 3 ] [ 4 ]  None of these hypothetical effects has been confirmed in humans by high-quality  clinical research , as of 2020 [update] . [ 1 ]


The main source of polyphenols is dietary, since they are found in a wide array of  phytochemical -bearing foods.  For example,  honey ; most  legumes ; fruits such as  apples ,  blackberries ,  blueberries ,   cantaloupe ,  pomegranate ,  cherries ,  cranberries ,  grapes ,  pears ,  plums ,  raspberries ,  aronia berries , and  strawberries  (berries in general have high polyphenol content [ 5 ] ) and  vegetables  such as  broccoli ,  cabbage ,  celery ,  onion  and  parsley  are rich in polyphenols.  Red wine ,  chocolate , black tea,  white tea ,  green tea ,  olive oil  and many  grains  are sources. [ 1 ]  Ingestion of polyphenols occurs by consuming a wide array of plant foods. [ 1 ]


The regulation theory considers a polyphenolic ability to scavenge  free radicals   and up-regulate certain metal  chelation  reactions. [ 1 ]   Various  reactive oxygen species , such as  singlet oxygen ,  peroxynitrite  and   hydrogen peroxide , must be continually removed from cells to maintain healthy metabolic function. Diminishing the concentrations of reactive oxygen species can have several benefits possibly associated with  ion transport  systems and so may affect  redox signaling . [ 1 ]  There is no substantial evidence, however, that dietary polyphenols have an antioxidant effect in vivo. [ 1 ] [ 6 ]


The “deactivation” of oxidant species by polyphenolic antioxidants (POH) is based, with regard to food systems that are deteriorated by peroxyl radicals (R•), on the donation of hydrogen, which interrupts chain reactions:


Phenoxyl radicals (PO•) generated according to this reaction may be stabilized through  resonance  and/or intramolecular hydrogen bonding, as proposed for  quercetin , or combine to yield  dimerisation  products, thus terminating the chain reaction:


Consuming dietary polyphenols have been evaluated for biological activity in vitro, but there is no evidence from high-quality  clinical research  as of 2015 [update]  that they have effects in vivo. [ 1 ]  Preliminary research has been conducted and regulatory status was reviewed in 2009 by the U.S.  Food and Drug Administration  (FDA), with no recommended intake values established, indicating absence of proof for nutritional value. [ 6 ]  Other possible effects may result from consumption of foods rich in polyphenols, but are not yet proved scientifically in humans; accordingly, health claims on food labels are not allowed by the FDA. [ 6 ]


It is difficult to evaluate the physiological effects of specific natural phenolic antioxidants, since such a large number of individual compounds may occur even in a single food and their fate in vivo cannot be measured. [ 1 ] [ 6 ] [ 8 ]


Other more detailed chemical research has elucidated the difficulty of isolating individual phenolics. Because significant variation in phenolic content occurs among various brands of tea, there are possible [ 9 ]  inconsistencies among epidemiological studies implying beneficial health effects of phenolic antioxidants of  green tea  blends. The  Oxygen Radical Absorbance Capacity  (ORAC) test is a laboratory indicator of antioxidant potential in foods and  dietary supplements . However, ORAC results cannot be confirmed to be physiologically applicable and have been designated as unreliable. [ 3 ] [ 10 ]


There is  debate regarding the total body absorption of dietary intake of polyphenolic compounds.  While some indicate potential health effects of certain specific polyphenols, most studies demonstrate low  bioavailability  and rapid excretion of polyphenols, indicating their potential roles only in small concentrations in vivo. [ 1 ] [ 2 ] [ 3 ] [ 4 ]  More research is needed to understand the interactions between a variety of these chemicals acting in concert within the human body. [ 1 ]


There is no substantial evidence that reactive oxygen species play a role in the process of skin  aging . [ 11 ]  The skin is exposed to various  exogenous  sources of  oxidative stress , including  ultraviolet  radiation whose spectral components may be responsible for the  extrinsic  type of skin aging, sometimes termed  photoaging . Controlled long-term studies on the efficacy of low molecular weight antioxidants in the prevention or treatment of  skin  aging in humans are absent.


Experiments on  linoleic acid  subjected to  2,2′-azobis (2-amidinopropane) dihydrochloride -induced oxidation with different combinations of phenolics show that binary mixtures can lead to either a  synergetic  effect or to an  antagonistic  effect. [ 12 ]


Antioxidant levels of purified anthocyanin extracts were much higher than expected from anthocyanin content indicating  synergistic  effect of anthocyanin mixtures. [ 13 ]


Tamoxifen , sold under the brand name  Nolvadex  among others, is a  selective estrogen receptor modulator  used to prevent  breast cancer  in women and men. [ 13 ]  It is also being studied for other types of  cancer . [ 13 ]  It has been used for  Albright syndrome . [ 14 ]  Tamoxifen is typically taken daily  by mouth  for five years for breast cancer. [ 14 ]


Serious side effects include a small increased risk of  uterine cancer ,  stroke , vision problems, and  pulmonary embolism . [ 14 ]  Common side effects include  irregular periods , weight loss, and  hot flashes . [ 14 ]  It may cause harm to the baby if taken during  pregnancy  or  breastfeeding . [ 14 ]  It is a  selective estrogen-receptor modulator  (SERM) and works by decreasing the growth of breast cancer cells. [ 14 ] [ 15 ]  It is a member of the  triphenylethylene  group of  compounds . [ 16 ]


Tamoxifen was initially made in 1962, by chemist  Dora Richardson . [ 17 ] [ 18 ]  It is on the  World Health Organization's List of Essential Medicines . [ 19 ]  Tamoxifen is available as a  generic medication . [ 14 ]   In 2020, it was the 317th most commonly prescribed medication in the United States, with more than 900   thousand prescriptions. [ 20 ] [ 21 ]


Dysmenorrhea  is the term for menstrual pain, usually centered in the lower abdomen but often spreading to the back and inner thighs. It is a common gynecological condition that can seriously affect daily activities and well-being. Tamoxifen has been identified and used to effectively improve blood flow, reduce uterine contractility and pain in dysmenorrhea patients. [ 22 ] [ 23 ]


Tamoxifen is used for the treatment of both early and advanced  estrogen receptor -positive (ER-positive or ER+) breast cancer in  pre-  and  postmenopausal  women. [ 24 ]  Tamoxifen increases the risk of  postmenopausal bleeding ,  endometrial polyps ,  hyperplasia , and  endometrial cancer ; using tamoxifen with an  intrauterine system  releasing  levonorgestrel  might increase vaginal bleeding after 1 to 2 years, but reduces somewhat endometrial polyps and hyperplasia, but not necessarily endometrial cancer. [ 25 ]  Additionally, it is the most common hormone treatment for male breast cancer. [ 26 ]  It is also approved by the  FDA  for the prevention of breast cancer in women at high risk of developing the disease. [ 27 ]  The effectiveness of tamoxifen is primarily influenced by estrogen receptor (ER) status, which was the key predictor of the proportional benefits observed. It has been further approved for the reduction of  contralateral  (in the opposite breast) cancer. Five years of adjuvant tamoxifen treatment significantly lowers the 15-year risk of breast cancer recurrence and mortality. The overall use of tamoxifen is recommended for 10 years. [ 28 ] [ 29 ]


In 2006, the large STAR clinical study concluded that  raloxifene  is also effective in reducing the incidence of breast cancer. Updated results after an average of 6.75 years of follow up found that raloxifene retains 76% of tamoxifen's effectiveness in preventing invasive breast cancer, with 45% fewer  uterine cancers  and 25% fewer blood clots in women taking raloxifene than in women taking tamoxifen. [ 30 ] [ 31 ] [ 32 ]


Tamoxifen is used for  ovulation induction  to treat infertility in women with  anovulatory  disorders. It is given at days three to seven of a woman's cycle. [ 33 ]


Tamoxifen improves fertility in males with infertility by disinhibiting the  hypothalamic–pituitary–gonadal axis  (HPG axis) via ER antagonism and thereby increasing the secretion of  luteinizing hormone  (LH) and  follicle-stimulating hormone  (FSH) and increasing testicular  testosterone  production. [ 34 ]  Some animal studies have suggested tamoxifen could have negative effects on sperm quality and prostatic and gonadal health. [ 35 ] [ 36 ]


Benign enlargement of the male breast, whether  asymptomatic  or painful, is a common condition thought to result from an increased estrogen/testosterone ratio or from heightened  estrogenic  or reduced  androgenic  activity via receptor interactions.Tamoxifen is used to prevent and treat  gynecomastia . [ 37 ] [ 38 ]  It is taken as a preventative measure in small doses, or used at the onset of any symptoms such as nipple soreness or sensitivity. Current treatments typically involve pain relief through medication or surgery. However, targeting the underlying estrogenic stimulation may offer a more specific therapeutic approach. In a double-blind crossover study, patients were given either a placebo or tamoxifen (10 mg orally twice daily) for one month, in random order. Seven out of ten patients saw a reduction in gynecomastia size with tamoxifen (P < 0.005), and the overall reduction for the group was statistically significant (P < 0.01). [ 39 ]  No benefits were observed with the placebo (P > 0.1). Additionally, all four patients with painful gynecomastia experienced relief of their symptoms, and no toxicity was noted. Although the breast size reduction was partial, this suggests that longer treatment may be necessary. Follow-up examinations conducted 9 to 12 months after treatment revealed no significant changes, except in two cases: one tamoxifen responder had a recurrence of breast tenderness after six months, and one non-responder developed increased breast size and new tenderness after ten months. Other medications are taken for similar purposes such as  clomifene  and  aromatase inhibitor  drugs; which are used in order to try to avoid the hormone-related adverse effects. Overall, tamoxifen appears to be a safe and effective treatment option for selected cases of gynecomastia.


Tamoxifen is useful in the treatment of  peripheral precocious puberty , for instance due to  McCune–Albright syndrome , in both girls and boys. [ 42 ] [ 43 ] [ 44 ]  It has been found to decrease  growth velocity  and the rate of  bone maturation  in girls with precocious puberty, and hence to improve final  height  in these individuals. [ 42 ] [ 43 ]


Tamoxifen is available as a tablet or oral solution. [ 45 ] [ 46 ]


Tamoxifen has a number of  contraindications , including known  hypersensitivity  to tamoxifen or other ingredients, individuals taking concomitant  coumarin -type  anticoagulant  therapy, and women with a history of  venous thromboembolism  ( deep vein thrombosis  or  pulmonary embolism ). [ 12 ]


A report in September 2009 from Health and Human Services' Agency for Healthcare Research and Quality suggests that tamoxifen, raloxifene, and tibolone used to treat breast cancer significantly reduce invasive breast cancer in midlife and older women, but also increase the risk of adverse side effects. [ 47 ]


Tamoxifen is a  selective estrogen receptor modulator  (SERM). [ 48 ]  Even though it is an  antagonist  in breast tissue it acts as  partial agonist  on the  endometrium  and has been linked to  endometrial cancer  in some women. Therefore, endometrial changes, including cancer, are among tamoxifen's side effects. [ 49 ]  With time, risk of endometrial cancer may be doubled to quadrupled, which is a reason tamoxifen is typically only used for five years. [ 50 ]


The  American Cancer Society  lists tamoxifen as a known  carcinogen , stating that it increases the risk of some types of uterine cancer while lowering the risk of breast cancer recurrence. [ 51 ]


Tamoxifen treatment of postmenopausal women is associated with beneficial effects on serum lipid profiles. However, long-term data from clinical trials have failed to demonstrate a cardioprotective effect. [ 52 ]  For some women, tamoxifen can cause a rapid increase in  triglyceride  concentration in the blood. In addition, there is an increased risk of  thromboembolism  especially during and immediately after major surgery or periods of immobility. [ 53 ]  Use of tamoxifen has been shown to slightly increase risk of  deep vein thrombosis ,  pulmonary embolism , and  stroke . [ 54 ]


Tamoxifen has been associated with a number of cases of  hepatotoxicity . [ 55 ]  Several different varieties of hepatotoxicity have been reported. [ 55 ]  Tamoxifen can also precipitate  non-alcoholic fatty liver disease  in obese and overweight women (not in normal weight women) at an average rate of 40% after a year use with 20 mg/day. [ 56 ]


Acute  overdose  of tamoxifen has not been reported in humans. [ 12 ]  In  dose-ranging studies , tamoxifen was administered at very high doses in women (e.g., 300 mg/m 2 ) and was found to produce acute  neurotoxicity  including  tremor ,  hyperreflexia ,  unsteady gait , and  dizziness . [ 12 ]  These symptoms occurred within three to five days of therapy and disappeared within two to five days of discontinuation of therapy. [ 12 ]  No indications of permanent neurotoxicity were observed. [ 12 ]   QT prolongation  was also observed with very high doses of tamoxifen. [ 12 ]  There is no specific  antidote  for overdose of tamoxifen. [ 12 ]  Instead, treatment should be based on  symptoms . [ 12 ]


Patients with variant forms of the gene  CYP2D6  may not receive full benefit from tamoxifen because of too slow metabolism of the tamoxifen prodrug into its active metabolites. [ 57 ] [ 58 ]  On 18 October 2006, the Subcommittee for Clinical Pharmacology recommended relabeling tamoxifen to include information about this gene in the package insert. [ 59 ]  Certain CYP2D6 variations in breast cancer patients lead to a worse clinical outcome for tamoxifen treatment. [ 60 ]   Genotyping  therefore has the potential for identification of women who have these CYP2D6 phenotypes and for whom the use of tamoxifen is associated with poor outcomes. Recent research has shown that 7–10% of women with breast cancer may not receive the full medical benefit from taking tamoxifen due to their genetic make-up. DNA Drug Safety Testing can examine DNA variations in the CYP2D6 and other important drug processing pathways. More than 20% of all clinically used medications are metabolized by CYP2D6 and knowing the CYP2D6 status of a person can help the doctor with the future selection of medications. [ 61 ]  Other molecular biomarkers may also be used to select appropriate patients likely to benefit from tamoxifen. [ 62 ]


Recent studies suggest that taking the  selective serotonin reuptake inhibitors  (SSRIs) antidepressants  paroxetine  (Paxil),  fluoxetine  (Prozac), and  sertraline  (Zoloft) can decrease the effectiveness of tamoxifen, as these drugs compete for the CYP2D6 enzyme which is needed to metabolize tamoxifen into its active forms. [ 63 ]  A U.S. study presented at the American Society of Clinical Oncology's annual meeting in 2009 found that after two years, 7.5% of women who took only tamoxifen had a recurrence, compared with 16% who took either paroxetine, fluoxetine or sertraline, drugs considered to be the most potent CYP2D6 inhibitors. That difference translates to a 120% increase in the risk of breast cancer recurrence. Patients taking the SSRIs Celexa ( citalopram ), Lexapro ( escitalopram ), and Luvox ( fluvoxamine ) did not have an increased risk of recurrence, due to their lack of competitive metabolism for the CYP2D6 enzyme. [ 64 ]  A newer study demonstrated a clearer and stronger effect from paroxetine in causing the worst outcomes. Patients treated with both paroxetine and tamoxifen have a 67% increased risk of death from breast cancer, from 24% to 91%, depending on the duration of coadministration. [ 65 ]


Tamoxifen interacts with certain other  antiestrogens . [ 5 ]  The  aromatase inhibitor   aminoglutethimide  induces the metabolism of tamoxifen. [ 5 ]  Conversely, the aromatase inhibitor  letrozole  does not affect the metabolism of tamoxifen. [ 5 ]  However, tamoxifen induces the metabolism of letrozole and significantly reduces its concentrations. [ 5 ]


Tamoxifen acts as a  selective estrogen receptor modulator  (SERM), or as a  partial agonist  of the  estrogen receptors  (ERs). It has mixed  estrogenic  and  antiestrogenic  activity, with its profile of effects differing by  tissue . For instance, tamoxifen has predominantly antiestrogenic effects in the  breasts  but predominantly estrogenic effects in the  uterus  and  liver . In breast tissue, tamoxifen acts as an ER  antagonist  so that  transcription  of estrogen-responsive genes is inhibited. [ 67 ]  A beneficial side effect of tamoxifen is that it prevents bone loss by acting as an ER  agonist  (i.e., mimicking the effects of estrogen) in this cell type. Therefore, by inhibiting  osteoclasts , it prevents  osteoporosis . [ 68 ] [ 69 ]  When tamoxifen was launched as a drug, it was thought that tamoxifen would act as an ER antagonist in all tissues, including bone, and therefore it was feared that it would contribute to osteoporosis. It was therefore very surprising that the opposite effect was observed clinically. Hence tamoxifen's tissue selective action directly led to the formulation of the concept of SERMs. [ 70 ]


Tamoxifen is a long-acting SERM, with a  nuclear retention  of the ER–tamoxifen (or metabolite) complex of greater than 48 hours. [ 71 ] [ 72 ]  It has relatively little  affinity  for the ERs itself and instead acts as a  prodrug  of  active metabolites  such as  endoxifen  (4-hydroxy- N -desmethyltamoxifen) and  afimoxifene  (4-hydroxytamoxifen; 4-OHT). [ 9 ]  These metabolites have approximately 30 to 100 times greater affinity for the ERs than tamoxifen itself. [ 8 ] [ 73 ]  Per one study, tamoxifen had 7% and 6% of the affinity of  estradiol  for the  ERα  and  ERβ , respectively, whereas afimoxifene had 178% and 338% of the affinity of estradiol for the ERα and ERβ, respectively. [ 74 ]  Hence, afimoxifene showed 25-fold higher affinity for the ERα and 56-fold higher affinity for the ERβ than tamoxifen. [ 75 ]  The antiestrogenic potencies of endoxifen and afimoxifene are very similar. [ 9 ]  However, endoxifen occurs in much higher concentrations than afimoxifene and is now thought to be the major active form of tamoxifen in the body. [ 8 ] [ 9 ] [ 76 ]


Tamoxifen binds to ER competitively (with respect to the endogenous agonist estrogen) in tumor cells and other tissue targets, producing a nuclear complex that decreases DNA synthesis and inhibits estrogen effects. It is a nonsteroidal agent with potent antiestrogenic properties which compete with estrogen for  binding sites  in breast and other tissues. Tamoxifen causes cells to remain in the G 0  and G 1  phases of the  cell cycle . Because it prevents (pre)cancerous cells from dividing but does not cause cell death, tamoxifen is cytostatic rather than cytocidal. Tamoxifen binds to ER, the ER/tamoxifen complex recruits other proteins known as  co-repressors , and the complex then binds to DNA to modulate gene expression. Some of these proteins include  NCoR  and  SMRT . [ 77 ]  Tamoxifen function can be regulated by a number of different variables including growth factors. [ 78 ]  Tamoxifen needs to block growth factor proteins such as  ErbB2/HER2 [ 79 ]  because high levels of ErbB2 have been shown to occur in tamoxifen resistant cancers. [ 80 ]  Tamoxifen seems to require a protein  PAX2  for its full anticancer effect. [ 79 ] [ 81 ]  In the presence of high PAX2 expression, the tamoxifen/ER complex is able to suppress the expression of the pro-proliferative  ERBB2  protein. In contrast, when  AIB-1  expression is higher than PAX2, tamoxifen/ER complex upregulates the expression of ERBB2 resulting in stimulation of breast cancer growth. [ 79 ] [ 82 ]


Tamoxifen is  antigonadotropic  in  postmenopausal  women and partially suppresses levels of the  gonadotropins ,  luteinizing hormone  (LH) and  follicle-stimulating hormone  (FSH) in such women. [ 83 ]  However, it has  progonadotropic  effects in  premenopausal  women and increases estrogen levels by 6-fold in them. [ 83 ]  Due to the nature of tamoxifen as a competitive ER ligand, this increase in estrogen levels is liable to interfere with the antiestrogenic efficacy of tamoxifen. [ 83 ]  The effects of tamoxifen on  breast cancer   Ki-67   expression ,  sex hormone-binding globulin  (SHBG) levels, and IGF-1 levels are  dose-dependent  across a dosage range of 1 to 20 mg/day in women with breast cancer. [ 84 ]  Tamoxifen has been found to decrease  insulin-like growth factor 1  (IGF-1) levels by 17 to 38% in women and men. [ 85 ]  Suppression of IGF-1 production in the liver is a well-known action of estrogens and SERMs. [ 85 ]  A 10 mg/day dosage of tamoxifen is nearly as effective as a 20 mg/day dosage in suppressing IGF-1 levels. [ 5 ]


Afimoxifene is an  agonist  of the  G protein-coupled estrogen receptor  (GPER) with relatively low  affinity . [ 86 ]  Its affinity for the receptor is in the range of 100 to 1,000 nM, relative to 3 to 6 nM for estradiol. [ 86 ]


In addition to its activity as a SERM, afimoxifene binds to both the  estrogen-related receptor β  and  estrogen-related receptor γ  and is an antagonist of the  estrogen-related receptor γ  (ERRγ). [ 87 ]


Norendoxifen  (4-hydroxy- N , N -didesmethyltamoxifen), another  active metabolite  of tamoxifen, has been found to act as a  potent   competitive   aromatase inhibitor  ( IC 50  = 90 nM), and may also be involved in the antiestrogenic activity of tamoxifen. [ 88 ]


In addition to its activity as a SERM, tamoxifen is a  potent  and  selective   protein kinase C   inhibitor , and is active in this regard at therapeutic concentrations. [ 89 ]  This action is thought to underlie the efficacy of tamoxifen in the treatment of  bipolar disorder . [ 89 ]


Tamoxifen is an inhibitor of  P-glycoprotein . [ 12 ]


In 2018, it was discovered that tamoxifen directly interacts with the  dopamine transporter  (DAT) and acts as an atypical  dopamine reuptake inhibitor  (DRI). [ 90 ] [ 91 ]  It has weak  potency  (54% inhibition of dopamine uptake at 10   μM) and lacks any  stimulant  or  depressant  effects when administered by itself. [ 90 ] [ 91 ]  However, tamoxifen  dose-dependently  blocks  amphetamine -mediated  dopamine release  and psychostimulant-like effects in animals. [ 90 ] [ 91 ]  This unusual profile of DRI activity has made tamoxifen of potential interest as a starting point for  structural modification  to develop novel pharmaceutical drugs for treatment of  stimulant use disorder . [ 90 ] [ 91 ]


Tamoxifen is rapidly and extensively  absorbed  from the  intestines  with  oral administration . [ 5 ] [ 6 ]  The  oral   bioavailability  of tamoxifen is approximately 100%, which is suggestive of minimal  first-pass metabolism  in the intestines and  liver . [ 5 ]  Following intake,  peak levels  of tamoxifen occur after three to seven hours. [ 92 ] [ 5 ]   Steady state levels  of tamoxifen are reached typically after 3 to 4 weeks but possibly up to 16 weeks of daily administration. [ 5 ] [ 11 ]  Steady state levels of afimoxifene are achieved after 8 weeks of daily tamoxifen administration. [ 11 ] [ 7 ]  Peak levels of tamoxifen after a single 40 mg oral dose were 65 ng/mL and steady state levels at 20 mg/day were 310 ng/mL. [ 5 ]  Levels of tamoxifen show clear  dose dependency  across a dosage range of 1 to 20 mg/day. [ 5 ] [ 93 ]  Endoxifen levels are approximately 5 to 10 times higher than afimoxifene levels, with large  interindividual variability . [ 8 ] [ 9 ]  Endoxifen levels have been reported as 10.8 to 15.9 ng/mL at steady state in  CYP2D6  normal metabolizers during therapy with 20 mg/day tamoxifen. [ 8 ]  The most abundant  metabolites  of tamoxifen in terms of circulating concentrations are  N -desmethyltamoxifen ,  N , N -didesmethyltamoxifen ,  ( Z )-endoxifen , and tamoxifen  N -oxide. [ 10 ] [ 94 ]


The  volume of distribution  of tamoxifen is 50 to 60 L/kg and its  clearance  has been estimated as 1.2 to 5.1 L/hour. [ 5 ] [ 92 ]  High concentrations of tamoxifen have been found in  breast ,  uterus , liver,  kidney ,  lung ,  pancreas , and  ovary  tissue in animals and humans. [ 5 ]  Levels of tamoxifen in the uterus have been found to be 2- to 3-fold higher than in the circulation [ 5 ]  and in the breasts 10-fold higher than in the circulation. [ 93 ]  The  plasma protein binding  of tamoxifen and afimoxifene is greater than 99%. [ 7 ]  A majority of tamoxifen is bound to  albumin . [ 5 ]  Albumin alone binds 98.8% of tamoxifen while other  plasma proteins  are not greatly involved. [ 95 ]


Tamoxifen is a  prodrug  and is  metabolized  in the  liver  by the  cytochrome P450   isoforms   CYP3A4 ,  CYP2C9 , and  CYP2D6  into  active metabolites  such as  endoxifen  (4-hydroxy- N -desmethyltamoxifen) and  afimoxifene  (4-hydroxytamoxifen). [ 5 ] [ 12 ] [ 8 ]  Conversion of tamoxifen by  N -demethylation into  N -desmethyltamoxifen , which is catalyzed primarily by CYP3A4 and  CYP3A5 , is responsible for approximately 92% of tamoxifen metabolism. [ 9 ]  Conversely, 4-hydroxylation of tamoxifen into afimoxifene is responsible for only about 7% of tamoxifen metabolism. [ 9 ]  Following its formation,  N -desmethyltamoxifen is  oxidized  into several other metabolites, the most notable of which is endoxifen. [ 9 ]  Another active metabolite,  norendoxifen  (4-hydroxy- N , N -didesmethyltamoxifen), is formed via  N -demethylation of endoxifen or 4-hydroxylation of  N , N -didesmethyltamoxifen . [ 8 ]  Tamoxifen and its metabolites undergo  conjugation , including  glucuronidation  and  sulfation . [ 11 ]  Tamoxifen may inhibit its own metabolism. [ 5 ]


Tamoxifen has a long  elimination half-life  of typically 5 to 7 days, with a range of 4 to 11 days. [ 5 ] [ 8 ] [ 92 ]  Similarly, the half-life of afimoxifene is 14 days. [ 7 ]  Conversely, the half-life of  endoxifen  is 50 to 70 hours (2–3 days). [ 8 ]  The long half-lives of tamoxifen and afimoxifene are attributed to their high plasma protein binding as well as to  enterohepatic recirculation . [ 7 ]  Upon discontinuation of treatment, levels of tamoxifen and its metabolites persist in the circulation for at least 6 weeks. [ 7 ]  Tamoxifen is  excreted  in  bile  and is  eliminated  in  feces , while small amounts are eliminated in  urine . [ 5 ]


Tamoxifen is a  nonsteroidal  SERM of the  triphenylethylene  family and was structurally derived from  diethylstilbestrol -like estrogens and  antiestrogens  such as  chlorotrianisene  and  ethamoxytriphetol . [ 97 ] [ 98 ] [ 99 ] [ 100 ]  Initially,  clomifene  was synthesized, and tamoxifen was developed subsequently. [ 97 ] [ 99 ] [ 100 ]  Tamoxifen is closely related structurally to other triphenylethylenes, such as clomifene,  nafoxidine ,  ospemifene ,  toremifene , and numerous others. [ 101 ] [ 102 ]  Other SERMs, like  raloxifene , are structurally distinct from tamoxifen and other triphenylethylenes. [ 102 ]


In the late 1950s, pharmaceutical companies were actively researching a newly discovered class of anti-estrogen compounds in the hope of developing a morning-after contraceptive pill. Arthur L Walpole was a reproductive  endocrinologist  who led such a team at the  Alderley Park  research laboratories of  ICI  Pharmaceuticals. [ 18 ]  It was there in 1962 that chemist Dora Richardson first synthesized tamoxifen, back then known as ICI-46,474, when she was looking to create triphenylethylene derivatives for the contraceptive pill project that her team was researching. [ 103 ]


This compound was originally created to work as an estrogen inhibitor, but instead was found to stimulate ovulation in participants of the drug testing trial. [ 17 ]  Walpole and his colleagues filed a UK patent covering this compound in 1962, but patent protection on this compound was repeatedly denied in the US until the 1980s. [ 104 ]  Tamoxifen did eventually receive marketing approval as a fertility treatment, but the class of compounds never proved useful in human contraception. A link between estrogen and breast cancer had been known for many years, but cancer treatments were not a corporate priority at the time, and Walpole's personal interests were important in keeping support for the compound alive in the face of this and the lack of patent protection. [ 18 ]  It was only when Walpole threatened to leave his position that corporate decided to allow trials and testing for tamoxifen as a drug that could be used to treat breast cancer. Without Walpole's effort towards defending the work that his team had done in discovering a possibly revolutionary source for breast cancer treatment, tamoxifen could have become a discarded or under-researched idea. Walpole's team consisted of Dora Richardson and G. A. Snow, who worked on the chemistry portion of the project, along with G. E. Paget and J. K. Walley, who focused primarily on the biological side. [ 17 ]


Tamoxifen is one of three drugs in an  anti-angiogenetic  protocol developed by  Dr. Judah Folkman , a researcher at Children's Hospital at Harvard Medical School in Boston. Folkman discovered in the 1970s that  angiogenesis  – the growth of new blood vessels – plays a significant role in the development of cancer. Since his discovery, an entirely new field of cancer research has developed. Clinical trials on  angiogenesis inhibitors  have been underway since 1992 using many different drugs. The Harvard researchers developed a specific protocol for a golden retriever named Navy who was cancer-free after receiving the prescribed cocktail of  celecoxib ,  doxycycline , and tamoxifen – the treatment subsequently became known as the Navy Protocol. [ 105 ]  Furthermore, tamoxifen treatment alone has been shown to have anti-angiogenetic effects in animal models of cancer which appear to be, at least in part, independent of tamoxifen's ER antagonist properties. [ 106 ]


Other antiestrogens, such as  ethamoxytriphetol  (MER-25) and  clomifene  (MRL-41), were assessed for treatment of breast cancer and found to be effective before tamoxifen, but were plagued with  toxicity  issues. [ 107 ] [ 108 ]  The first clinical study of tamoxifen took place at the  Christie Hospital  in 1971, and showed a convincing effect in advanced breast cancer, but nevertheless ICI's development programme came close to termination when it was reviewed in 1972. [ 109 ]  In an unpublished article from the early days of the trial, Dora Richardson documented her team's excitement about tamoxifen's effects in counteracting infertility problems and the early positive effects found in breast cancer patients. Unfortunately, this work was not well received by everyone, as the team was supposed to be looking for a contraceptive pill. [ 17 ]  Tamoxifen's further development may have been bolstered by a second clinical study by Harold W.C. Ward  [ 110 ]  at the  Queen Elizabeth Hospital, Birmingham . Ward's study showed a more definitive response to the drug at a higher dosage. Walpole also may have helped to convince the company to market tamoxifen for late stage breast cancer in 1973. [ 104 ]  He was also instrumental in funding  V. Craig Jordan  to work on tamoxifen. In 1972, ICI Pharmaceuticals Division abandoned development of tamoxifen for financial reasons. The drug was subsequently reinvented from a failed contraceptive, to become tamoxifen, the gold standard for the adjuvant treatment of breast cancer and the pioneering medicine for chemprevention for high-risk women. [ 111 ] [ 112 ]  Two books,  Estrogen Action, Selective Estrogen Receptor Modulators and Women's Health  (Imperial College Press 2013) and  Tamoxifen: Pioneering Medicine in Breast Cancer  (Springer 2013) tell this story.


1980 saw the publication of the first trial to show that tamoxifen given in addition to chemotherapy improved survival for patients with early breast cancer. [ 114 ]  In advanced disease, tamoxifen is now only recognized as effective in ER+ patients, but the early trials did not select ER+ patients, and by the mid-1980s the clinical trial picture was not showing a major advantage for tamoxifen. [ 115 ]  Nevertheless, tamoxifen had a relatively mild side-effect profile, and a number of large trials continued.


The pharmacology of SERMs was discovered, defined, and deciphered during the 1980s. [ 116 ]  A clinical strategy was described [ 117 ]  that led to the creation of SERMs as a group of multifunctional medicines aimed at the treatment or prevention of many conditions in postmenopausal women, e.g. osteoporosis and breast cancer. [ 118 ]


The early sales of tamoxifen in both the UK and in the U.S. far exceeded ICI's original estimate, but despite this, at the annual portfolio review ICI's board members still asserted that "there was no market for cancer", leaving the drug's marketing success to rely on its clinical results and clinicians' and scientists' interests in it. Shortly after, Dora Richardson published a history of tamoxifen that, unusually for that type of paper, included personal accounts and letters from patients who attributed their healing to the drug. This testimony from cancer patients using tamoxifen helped to shape and push forward research, by justifying it both morally and scientifically to corporations. [ 17 ]


It was not until 1998 that the meta-analysis of the Oxford-based Early Breast Cancer Trialists' Collaborative Group showed definitively that tamoxifen was effective for early breast cancer. [ 119 ]


Tamoxifen is marketed under the brand names Nolvadex and Soltamox, and a variety of other brand names throughout the world. [ 1 ] [ 120 ]


Global sales of tamoxifen in 2001 were approximately $1.02 billion. [ 121 ]  Since the expiration of the patent in 2002, it is widely available as a  generic drug  around the world. As of 2004 [update] , tamoxifen was the world's largest selling hormonal drug for the treatment of breast cancer. [ 122 ]


In  McCune-Albright syndrome  (MAS) tamoxifen has been used to treat  premature puberty  and the consequences of premature puberty. Tamoxifen has been seen to decrease rapid  bone maturation  which is the result of  excessive estrogen  and alter predicted adult height (PAH). [ 123 ] [ 124 ]  The same effects have also been seen in short pubertal boys. [ 125 ]  However, one  in vitro  study in 2007 and later an  in vivo  study in 2008 have shown that tamoxifen induces apoptosis in growth plate chondrocytes, reduces serum  insulin-like growth factor 1  (IGF-1) levels and causes persistent retardation of longitudinal and cortical radial bone growth in young male rats, leading the researchers to express concern giving tamoxifen to growing individuals. [ 126 ] [ 127 ]


Tamoxifen has been studied in the treatment of the rare conditions of  retroperitoneal fibrosis [ 128 ]  and  idiopathic sclerosing mesenteritis . [ 129 ]  It has also been proposed as part of a treatment plan for  Riedel's thyroiditis . [ 130 ]


Tamoxifen is used as a research tool to trigger tissue-specific gene expression in many conditional expression constructs in  genetically modified animals  including a version of the  Cre-Lox recombination  technique. [ 131 ]  While widely used in transgenic research, the strong anabolic effect of tamoxifen on bone might confound this approach, especially as it relates to bone-targeted constructs.


Tamoxifen may be effective in the treatment of  mania  in people with  bipolar disorder . [ 132 ]  This is thought to be due to blockade of  protein kinase C  (PKC), an  enzyme  that regulates  neuron  activity in the  brain . [ 132 ] [ 133 ]  Researchers believe PKC is overactive during the mania in bipolar patients. [ 132 ] [ 133 ]  As of September 2019 [update] ,  endoxifen , a major active metabolite of tamoxifen with a 4-fold more potent PKC inhibition, was in  phase III  clinical trials for bipolar disorder. [ 134 ] [ 135 ]


The  FDA   animal efficacy rule  (also known as  animal rule ) applies to  development  and testing of  drugs  and  biologicals  to reduce or prevent serious or life-threatening conditions caused by exposure to lethal or permanently disabling toxic agents ( chemical ,  biological ,  radiological , or nuclear substances), where human efficacy  trials  are not feasible or  ethical . [ 1 ]  The animal efficacy rule was finalized by the FDA and authorized by the  United States Congress  in 2002, following the  September 11 attacks  and concerns regarding  bioterrorism . [ 2 ]


The FDA can rely on evidence from  animal studies  to provide substantial evidence of product effectiveness if:


FDA published a  Guidance for Industry  on the Animal Rule in October 2015. [ 3 ]


A  biopharmaceutical , also known as a  biological medical product , [ 1 ]  or  biologic , is any  pharmaceutical drug  product manufactured in, extracted from, or  semisynthesized  from  biological  sources. Different from  totally synthesized  pharmaceuticals, they include  vaccines ,  whole blood , blood components,  allergenics ,  somatic cells ,  gene therapies ,  tissues ,  recombinant therapeutic protein , and  living medicines  used in  cell therapy . Biologics can be composed of  sugars ,  proteins ,  nucleic acids , or complex combinations of these substances, or may be living cells or tissues. They (or their  precursors  or components) are isolated from  living  sources—human, animal, plant, fungal, or microbial. They can be used in both human and animal medicine. [ 2 ] [ 3 ]


Terminology surrounding biopharmaceuticals varies between groups and entities, with different terms referring to different subsets of therapeutics within the general biopharmaceutical category. Some  regulatory agencies  use the terms  biological medicinal products  or  therapeutic biological product  to refer specifically to engineered  macromolecular  products like protein- and  nucleic acid -based  drugs , distinguishing them from products like blood, blood components, or vaccines, which are usually extracted directly from a biological source. [ 4 ] [ 5 ] [ 6 ]   Biopharmaceutics  is  pharmaceutics  that works with biopharmaceuticals.  Biopharmacology  is the branch of  pharmacology  that studies biopharmaceuticals.  Specialty drugs , a recent classification of pharmaceuticals, are high-cost drugs that are often biologics. [ 7 ] [ 8 ] [ 9 ]  The  European Medicines Agency  uses the term  advanced therapy medicinal products  (ATMPs) for medicines for human use that are "based on genes, cells, or tissue engineering", [ 10 ]  including gene therapy medicines, somatic-cell therapy medicines, tissue-engineered medicines, and combinations thereof. [ 11 ]  Within EMA contexts, the term  advanced therapies  refers specifically to ATMPs, although that term is rather nonspecific outside those contexts.


Gene-based and cellular biologics, for example, often are at the forefront of  biomedicine  and  biomedical research , and may be used to treat a variety of medical conditions for which no other treatments are available. [ 12 ]


Building on the market approvals and sales of recombinant virus-based biopharmaceuticals for veterinary and human medicine, the use of engineered plant viruses has been proposed to enhance crop performance and promote sustainable production. [ 13 ]


In some jurisdictions, biologics are regulated via different pathways from other small molecule drugs and  medical devices . [ 14 ]


Some of the oldest forms of biologics are extracted from the bodies of animals, and other humans especially. Important biologics include: [ citation needed ]


Some biologics that were previously extracted from animals, such as insulin, are now more commonly produced by  recombinant DNA .


Biologics  can refer to a wide range of biological products in medicine. However, in most cases, the term is used more restrictively for a class of therapeutics (either approved or in development) that are produced using biological processes involving  recombinant DNA  technology. These medications are usually one of three types:


Biologics as a class of medications in this narrower sense have had a profound impact on many medical fields, primarily  rheumatology  and  oncology , but also  cardiology ,  dermatology ,  gastroenterology ,  neurology , and others. In most of these disciplines, biologics have added major therapeutic options for treating many diseases, including some for which no effective therapies were available, and others where previously existing therapies were inadequate. However, the advent of biologic therapeutics has also raised complex regulatory issues (see below), and significant pharmacoeconomic concerns because the cost for biologic therapies has been dramatically higher than for conventional (pharmacological) medications. This factor has been particularly relevant since many biological medications are used to treat  chronic diseases , such as rheumatoid arthritis or inflammatory bowel disease, or for the treatment of otherwise untreatable cancer during the remainder of life. The cost of treatment with a typical monoclonal antibody therapy for relatively common indications is generally in the range of €7,000–14,000 per patient per year.


Older patients who receive biologic therapy for diseases such as  rheumatoid arthritis ,  psoriatic arthritis , or  ankylosing spondylitis  are at increased risk for life-threatening infection, adverse cardiovascular events, and  malignancy . [ 15 ]


The first such substance approved for therapeutic use was biosynthetic "human"  insulin  made via  recombinant DNA . Sometimes referred to as rHI, under the  trade name   Humulin , was developed by  Genentech , but licensed to  Eli Lilly and Company , who manufactured and marketed it starting in 1982.


Major kinds of biopharmaceuticals include:


Research and development investment in new medicines by the biopharmaceutical industry stood at $65.2 billion in 2008. [ 16 ]  A few examples of biologics made with  recombinant DNA  technology include:


Many vaccines are grown in tissue cultures.


Viral gene therapy  involves artificially manipulating a  virus  to include a desirable piece of genetic material.


Viral gene therapies using engineered plant viruses have been proposed to enhance crop performance and promote sustainable production. [ 13 ]


With the expiration of many  patents  for  blockbuster biologics  between 2012 and 2019, the interest in biosimilar production, i.e., follow-on biologics, has increased. [ 17 ]  Compared to  small molecules  that consist of chemically identical  active ingredients , biologics are vastly more complex and consist of a multitude of subspecies. Due to their heterogeneity and the high process sensitivity, originators and follow-on biosimilars will exhibit variability in specific variants over time. The safety and clinical performance of both originator and biosimilar biopharmaceuticals must remain equivalent throughout their lifecycle. [ 18 ] [ 19 ]  Process variations are monitored by modern analytical tools (e.g.,  liquid chromatography ,  immunoassays ,  mass spectrometry , etc.) and describe a unique design space for each biologic. [ citation needed ]


Biosimilars require a different regulatory framework compared to small-molecule generics. Legislation in the 21st century has addressed this by recognizing an intermediate ground of testing for biosimilars. The filing pathway requires more testing than for small-molecule generics, but less testing than for registering completely new therapeutics. [ 20 ]


In 2003, the  European Medicines Agency  introduced an adapted pathway for biosimilars, termed  similar biological medicinal products . This pathway is based on a thorough demonstration of comparability of the product to an existing approved product. [ 21 ]  Within the United States, the  Patient Protection and Affordable Care Act  of 2010 created an abbreviated approval pathway for biological products shown to be biosimilar to, or interchangeable with, an FDA-licensed reference biological product. [ 20 ] [ 22 ]  Researchers are optimistic that the introduction of biosimilars will reduce medical expenses to patients and the healthcare system. [ 17 ]


When a new biopharmaceutical is developed, the company will typically apply for a  patent , which is a grant to exclusive manufacturing rights. This is the primary means by which the drug developer can recover the investment cost for development of the biopharmaceutical. The  patent laws  in the  United States  and  Europe  differ somewhat on the requirements for a patent, with the European requirements perceived as more difficult to satisfy. The total number of patents granted for biopharmaceuticals has risen significantly since the 1970s. In 1978 the total patents granted was 30. This had climbed to 15,600 in 1995, and by 2001 there were 34,527 patent applications. [ 23 ]  In 2012 the US had the highest IP (Intellectual Property) generation within the biopharmaceutical industry, generating 37 percent of the total number of granted patents worldwide; however, there is still a large margin for growth and innovation within the industry. Revisions to the current IP system to ensure greater reliability for R&D (research and development) investments is a prominent topic of debate in the US as well. [ 24 ]  Blood products and other human-derived biologics such as breast milk have highly regulated or very hard-to-access markets; therefore, customers generally face a supply shortage for these products. Institutions housing these biologics, designated as 'banks', often cannot distribute their product to customers effectively. [ 25 ]  Conversely, banks for reproductive cells are much more widespread and available due to the ease with which  spermatozoa  and  egg cells  can be used for fertility treatment. [ 26 ]


Biopharmaceuticals may be produced from microbial cells (e.g., recombinant  E. coli  or yeast cultures), mammalian cell lines (see  Cell culture ) and plant cell cultures (see  Plant tissue culture ) and  moss  plants in  bioreactors  of various configurations, including  photo-bioreactors . [ 27 ]  Important issues of concern are cost of production (low-volume, high-purity products are desirable) and microbial contamination (by  bacteria ,  viruses ,  mycoplasma ). Alternative platforms of production which are being tested include whole plants ( plant-made pharmaceuticals ).


A potentially controversial method of producing biopharmaceuticals involves  transgenic  organisms, particularly plants and animals that have been  genetically modified  to produce drugs. This production is a significant risk for its investor due to production failure or scrutiny from regulatory bodies based on perceived risks and ethical issues. Biopharmaceutical crops also represent a risk of cross-contamination with non-engineered crops, or crops engineered for non-medical purposes.


One potential approach to this technology is the creation of a transgenic mammal that can produce the biopharmaceutical in its milk, blood, or urine. Once an animal is produced, typically using the  pronuclear microinjection  method, it becomes efficacious to use cloning technology to create additional offspring that carry the favorable modified genome. [ 28 ]  The first such drug manufactured from the milk of a genetically modified  goat  was  ATryn , but marketing permission was blocked by the  European Medicines Agency  in February 2006. [ 29 ]  This decision was reversed in June 2006 and approval was given August 2006. [ 30 ]


In the  European Union , a biological medicinal product [ 31 ]  is one of the active substance(s) produced from or extracted from a biological (living) system, and requires, in addition to physicochemical testing, biological testing for full characterisation. The characterisation of a biological medicinal product is a combination of testing the active substance and the final medicinal product together with the production process and its control. For example:


In the  United States , biologics are licensed through the biologics license application (BLA), then submitted to and regulated by the FDA's  Center for Biologics Evaluation and Research  (CBER) whereas drugs are regulated by the  Center for Drug Evaluation and Research . Approval may require several years of  clinical trials , including trials with human volunteers. Even after the drug is released, it will still be monitored for performance and safety risks. The manufacture process must satisfy the FDA's "Good Manufacturing Practices", which are typically manufactured in a  cleanroom  environment with strict limits on the amount of airborne particles and other microbial contaminants that may alter the efficacy of the drug. [ 32 ]


In  Canada , biologics (and radiopharmaceuticals) are reviewed through the Biologics and Genetic Therapies Directorate within  Health Canada . [ 33 ]


Stromagen  is a product that is made of  stem cells  taken from a patient's  bone marrow  and grown in the laboratory. After a patient's bone marrow is destroyed by treatment with whole body  irradiation  or  chemotherapy , these cells are injected back into the patient to help rebuild bone marrow. Stromagen has been studied in the prevention of  graft-versus-host disease  during stem cell transplant in patients receiving  treatment  for  cancer . Stromagen is used in cellular therapy. Also called  autologous  expanded  mesenchymal stem cells  OTI-010. [ 1 ] [ 2 ]  Peripheral stem cell transplantation may allow doctors to give higher doses of chemotherapy and kill more tumor cells. It is not yet known whether Stromagen improves the success of stem cell transplantation in women with breast cancer. [ 3 ]


Bacterial therapy  is the  therapeutic  use of  bacteria  to treat  diseases . Bacterial therapeutics are  living medicines , and may be  wild type  bacteria (often in the form of  probiotics ) or bacteria that have been  genetically engineered  to possess  therapeutic  properties that is injected into a patient. [ 2 ] [ 3 ]
Other examples of living medicines include  cellular therapeutics  (including  immunotherapeutics ), activators of anti-tumor immunity, or synergizing with existing tools and approaches. and  phage therapeutics , or as delivery vehicles for treatment, diagnosis, or imaging, complementing or synergizing with existing tools and approaches.


Development of bacterial therapeutics is an extremely active research area in the fields of  synthetic biology  and  microbiology . [ 4 ] [ 5 ] [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 1 ] [ 10 ] [ 11 ]  Currently, there is a large focus on: 1) identifying bacteria that naturally produce therapeutic effects (for example, probiotic bacteria), and 2)  genetically programming  bacteria to produce therapeutic effects. [ 12 ] [ 13 ] [ 14 ]


Optimal strain design often requires a balance between strain suitability for function in the target microenvironment and concerns for feasibility of manufacturing and clinical development. [ 1 ]


The development workflow should incorporate technologies for optimizing strain potency, as well as predictive in vitro and in vivo assays, as well quantitative pharmacology models, to maximize translational potential for patient populations. [ 1 ]


There is tremendous interest in using bacteria as a therapy to treat tumors. In particular,  tumor-homing bacteria  that thrive in  hypoxic  environments are particularly attractive for this purpose, as they will tend to migrate to, invade (through the  leaky vasculature  in the  tumor microenvironment ) and  colonize  tumors. This property tends to increase their residence time in the tumor, giving them longer to exert their therapeutic effects, in contrast to other bacteria that would be quickly cleared by the immune system. [ 15 ] [ 16 ] [ 17 ]  In addition, colonized bacteria can lyze the tumor, activate anti-tumor immune response, can be engineered as a delivery vehicle for anti-cancer therapeutics and may have the potential as  contrast agents  for cancer imaging. Microbial-based cancer therapy may offer an opportunity to address the issue of global cancer therapy disparity and introduce more suitable cancer immunotherapy approach to low- and middle-income countries. [ 18 ]


After systemic administration, bacteria localize to the tumor microenvironment. The interactions between bacteria, cancer cells, and the surrounding microenvironment cause various alterations in  tumor-infiltrating immune cells , cytokines, and chemokines, which further facilitate tumor regression. ① Bacterial toxins from S. Typhimurium, Listeria, and Clostridium can kill tumor cells directly by inducing apoptosis or autophagy. Toxins delivered via Salmonella can upregulate Connexin 43 (Cx43), leading to bacteria-induced gap junctions between the tumor and dendritic cells (DCs), which allow cross-presentation of tumor antigens to the DCs. ② Upon exposure to tumor antigens and interaction with bacterial components, DCs secrete robust amounts of the proinflammatory cytokine IL-1β, which subsequently activates CD8+ T cells. ③ The antitumor response of the activated CD8+ T cells is further enhanced by bacterial flagellin (a protein subunit of the bacterial flagellum) via TLR5 activation. The perforin and granzyme proteins secreted by activated CD8+ T cells efficiently kill tumor cells in primary and metastatic tumors. ④ Flagellin and TLR5 signaling also decreases the abundance of CD4+ CD25+ regulatory T (Treg) cells, which subsequently improves the antitumor response of the activated CD8+ T cells. ⑤ S. Typhimurium flagellin stimulates NK cells to produce interferon-γ (IFN-γ), an important cytokine for both innate and adaptive immunity. ⑥ Listeria-infected MDSCs shift into an immune-stimulating phenotype characterized by increased IL-12 production, which further enhances the CD8+ T and NK cell responses. ⑦ Both S. Typhimurium and Clostridium infection can stimulate significant neutrophil accumulation. Elevated secretion of TNF-α and TNF-related apoptosis-inducing ligand (TRAIL) by neutrophils enhances the immune response and kills tumor cells by inducing apoptosis. ⑧ The macrophage inflammasome is activated through contact with bacterial components (LPS and flagellin) and Salmonella-damaged cancer cells, leading to elevated secretion of IL-1β and TNF-α into the tumor microenvironment. NK cell: natural killer cell. Treg cell: regulatory T cell. MDSCs: myeloid-derived suppressor cells. P2X7 receptor: purinoceptor 7-extracellular ATP receptor. LPS: lipopolysaccharide [ 15 ]


Alterations in the gut microbiome are thought to be associated with  C. difficile infection  and recurrence. [ 19 ]  Therapies include probiotics and  fecal microbiota transplantation .


There is considerable interest in using bacterial therapeutics to alter  human gastrointestinal microbiota  to help diseases like  small intestinal bacterial overgrowth , gut dysbiosis associated with the pathogenesis of food allergy, [ 20 ]  and other forms of  dysbiosis .


Biomanufacturing  (or  bioproduction ) is a type of  manufacturing  or  biotechnology  that utilizes biological systems to produce commercially important  biomaterials  and  biomolecules  for use in  medicines , food and beverage processing, and industrial applications.  Biomanufacturing products are recovered from natural sources, such as blood, or from cultures of  microbes ,  animal cells , or  plant cells  grown in specialized equipment.  The cells used during the production may have been naturally occurring or derived using  genetic engineering  techniques. [ citation needed ]


There are thousands of biomanufacturing products on the market today.  Some examples of general classes are listed below:


A partial listing of unit operations utilized during biomanufacturing includes the following:


Equipment and facility requirements are dictated by the product(s) being manufactured. Process equipment is typically constructed of stainless steel or plastic.  Stainless steel equipment can be cleaned and reused.  Some plastic equipment is disposed of after a single use.