<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Progesterone and can you explain it in depth? [/INST] Progesterone (P4) is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens and is the major progestogen in the body. Progesterone has a variety of important functions in the body. It is also a crucial metabolic intermediate in the production of other endogenous steroids, including the sex hormones and the corticosteroids, and plays an important role in brain function as a neurosteroid.In addition to its role as a natural hormone, progesterone is also used as a medication, such as in combination with estrogen for contraception, to reduce the risk of uterine or cervical cancer, in hormone replacement therapy, and in feminizing hormone therapy. It was first prescribed in 1934.

Biological activity
Progesterone is the most important progestogen in the body. As a potent agonist of the nuclear progesterone receptor (nPR) (with an affinity of KD = 1 nM) the resulting effects on ribosomal transcription plays a major role in regulation of female reproduction. In addition, progesterone is an agonist of the more recently discovered membrane progesterone receptors (mPRs), of which the expression has regulation effects in reproduction function (oocyte maturation, labor, and sperm motility) and cancer although additional research is required to further define the roles. It also functions as a ligand of the PGRMC1 (progesterone receptor membrane component 1) which impacts tumor progression, metabolic regulation, and viability control of nerve cells. Moreover, progesterone is also known to be an antagonist of the sigma σ1 receptor, a negative allosteric modulator of nicotinic acetylcholine receptors, and a potent antagonist of the mineralocorticoid receptor (MR). Progesterone prevents MR activation by binding to this receptor with an affinity exceeding even those of aldosterone and glucocorticoids such as cortisol and corticosterone, and produces antimineralocorticoid effects, such as natriuresis, at physiological concentrations. In addition, progesterone binds to and behaves as a partial agonist of the glucocorticoid receptor (GR), albeit with very low potency (EC50 >100-fold less relative to cortisol).Progesterone, through its neurosteroid active metabolites such as 5α-dihydroprogesterone and allopregnanolone, acts indirectly as a positive allosteric modulator of the GABAA receptor.Progesterone and some of its metabolites, such as 5β-dihydroprogesterone, are agonists of the pregnane X receptor (PXR), albeit weakly so (EC50 >10 μM). In accordance, progesterone induces several hepatic cytochrome P450 enzymes, such as CYP3A4, especially during pregnancy when concentrations are much higher than usual. Perimenopausal women have been found to have greater CYP3A4 activity relative to men and postmenopausal women, and it has been inferred that this may be due to the higher progesterone levels present in perimenopausal women.Progesterone modulates the activity of CatSper (cation channels of sperm) voltage-gated Ca2+ channels. Since eggs release progesterone, sperm may use progesterone as a homing signal to swim toward eggs (chemotaxis). As a result, it has been suggested that substances that block the progesterone binding site on CatSper channels could potentially be used in male contraception.

Biological function
Hormonal interactions
Progesterone has a number of physiological effects that are amplified in the presence of estrogens. Estrogens through estrogen receptors (ERs) induce or upregulate the expression of the PR. One example of this is in breast tissue, where estrogens allow progesterone to mediate lobuloalveolar development.Elevated levels of progesterone potently reduce the sodium-retaining activity of aldosterone, resulting in natriuresis and a reduction in extracellular fluid volume. Progesterone withdrawal, on the other hand, is associated with a temporary increase in sodium retention (reduced natriuresis, with an increase in extracellular fluid volume) due to the compensatory increase in aldosterone production, which combats the blockade of the mineralocorticoid receptor by the previously elevated level of progesterone.

Reproductive system
Progesterone has key effects via non-genomic signalling on human sperm as they migrate through the female tract before fertilization occurs, though the receptor(s) as yet remain unidentified. Detailed characterisation of the events occurring in sperm in response to progesterone has elucidated certain events including intracellular calcium transients and maintained changes, slow calcium oscillations, now thought to possibly regulate motility. It is produced by the ovaries. Progesterone has also been shown to demonstrate effects on octopus spermatozoa.Progesterone is sometimes called the "hormone of pregnancy", and it has many roles relating to the development of the fetus:

Progesterone converts the endometrium to its secretory stage to prepare the uterus for implantation. At the same time progesterone affects the vaginal epithelium and cervical mucus, making it thick and impenetrable to sperm. Progesterone is anti-mitogenic in endometrial epithelial cells, and as such, mitigates the tropic effects of estrogen. If pregnancy does not occur, progesterone levels will decrease, leading, in the woman, to menstruate. Normal menstrual bleeding is progesterone-withdrawal bleeding. If ovulation does not occur and the corpus luteum does not develop, levels of progesterone may be low, leading to anovulatory dysfunctional uterine bleeding.
During implantation and gestation, progesterone appears to decrease the maternal immune response to allow for the acceptance of the pregnancy.
Progesterone decreases contractility of the uterine smooth muscle. This effect contributes to prevention of preterm labor.
A drop in progesterone levels is possibly one step that facilitates the onset of labor.
In addition, progesterone inhibits lactation during pregnancy. The fall in progesterone levels following delivery is one of the triggers for milk production.The fetus metabolizes placental progesterone in the production of adrenal steroids.

Breasts
Lobuloalveolar development
Progesterone plays an important role in breast development in women. In conjunction with prolactin, it mediates lobuloalveolar maturation of the mammary glands during pregnancy to allow for milk production and thus lactation and breastfeeding of offspring following parturition (childbirth). Estrogen induces expression of the PR in breast tissue and hence progesterone is dependent on estrogen to mediate lobuloalveolar development. It has been found that RANKL is a critical downstream mediator of progesterone-induced lobuloalveolar maturation. RANKL knockout mice show an almost identical mammary phenotype to PR knockout mice, including normal mammary ductal development but complete failure of the development of lobuloalveolar structures.

Ductal development
Though to a far lesser extent than estrogen, which is the major mediator of mammary ductal development (via the ERα), progesterone may be involved in ductal development of the mammary glands to some extent as well. PR knockout mice or mice treated with the PR antagonist mifepristone show delayed although otherwise normal mammary ductal development at puberty. In addition, mice modified to have overexpression of PRA display ductal hyperplasia, and progesterone induces ductal growth in the mouse mammary gland. Progesterone mediates ductal development mainly via induction of the expression of amphiregulin, the same growth factor that estrogen primarily induces the expression of to mediate ductal development. These animal findings suggest that, while not essential for full mammary ductal development, progesterone seems to play a potentiating or accelerating role in estrogen-mediated mammary ductal development.

Breast cancer risk
Progesterone also appears to be involved in the pathophysiology of breast cancer, though its role, and whether it is a promoter or inhibitor of breast cancer risk, has not been fully elucidated. Most progestins, or synthetic progestogens, like medroxyprogesterone acetate, have been found to increase the risk of breast cancer in postmenopausal women in combination with estrogen as a component of menopausal hormone therapy. The combination of natural oral progesterone or the atypical progestin dydrogesterone with estrogen has been associated with less risk of breast cancer than progestins plus estrogen. However, this may simply be an artifact of the low progesterone levels produced with oral progesterone. More research is needed on the role of progesterone in breast cancer.

Skin health
The estrogen receptor, as well as the progesterone receptor, have been detected in the skin, including in keratinocytes and fibroblasts. At menopause and thereafter, decreased levels of female sex hormones result in atrophy, thinning, and increased wrinkling of the skin and a reduction in skin elasticity, firmness, and strength. These skin changes constitute an acceleration in skin aging and are the result of decreased collagen content, irregularities in the morphology of epidermal skin cells, decreased ground substance between skin fibers, and reduced capillaries and blood flow. The skin also becomes more dry during menopause, which is due to reduced skin hydration and surface lipids (sebum production). Along with chronological aging and photoaging, estrogen deficiency in menopause is one of the three main factors that predominantly influences skin aging.Hormone replacement therapy, consisting of systemic treatment with estrogen alone or in combination with a progestogen, has well-documented and considerable beneficial effects on the skin of postmenopausal women. These benefits include increased skin collagen content, skin thickness and elasticity, and skin hydration and surface lipids. Topical estrogen has been found to have similar beneficial effects on the skin. In addition, a study has found that topical 2% progesterone cream significantly increases skin elasticity and firmness and observably decreases wrinkles in peri- and postmenopausal women. Skin hydration and surface lipids, on the other hand, did not significantly change with topical progesterone. These findings suggest that progesterone, like estrogen, also has beneficial effects on the skin, and may be independently protective against skin aging.

Sexuality
Libido
Progesterone and its neurosteroid active metabolite allopregnanolone appear to be importantly involved in libido in females.

Homosexuality
Dr. Diana Fleischman, of the University of Portsmouth, and colleagues looked for a relationship between progesterone and sexual attitudes in 92 women. Their research, published in the Archives of Sexual Behavior found that women who had higher levels of progesterone scored higher on a questionnaire measuring homoerotic motivation. They also found that men who had high levels of progesterone were more likely to have higher homoerotic motivation scores after affiliative priming compared to men with low levels of progesterone.

Nervous system
Progesterone, like pregnenolone and dehydroepiandrosterone (DHEA), belongs to an important group of endogenous steroids called neurosteroids. It can be metabolized within all parts of the central nervous system.Neurosteroids are neuromodulators, and are neuroprotective, neurogenic, and regulate neurotransmission and myelination. The effects of progesterone as a neurosteroid are mediated predominantly through its interactions with non-nuclear PRs, namely the mPRs and PGRMC1, as well as certain other receptors, such as the σ1 and nACh receptors.

Brain damage
Previous studies have shown that progesterone supports the normal development of neurons in the brain, and that the hormone has a protective effect on damaged brain tissue. It has been observed in animal models that females have reduced susceptibility to traumatic brain injury and this protective effect has been hypothesized to be caused by increased circulating levels of estrogen and progesterone in females.

Proposed mechanism
The mechanism of progesterone protective effects may be the reduction of inflammation that follows brain trauma and hemorrhage.Damage incurred by traumatic brain injury is believed to be caused in part by mass depolarization leading to excitotoxicity. One way in which progesterone helps to alleviate some of this excitotoxicity is by blocking the voltage-dependent calcium channels that trigger neurotransmitter release. It does so by manipulating the signaling pathways of transcription factors involved in this release. Another method for reducing the excitotoxicity is by up-regulating the GABAA, a widespread inhibitory neurotransmitter receptor.Progesterone has also been shown to prevent apoptosis in neurons, a common consequence of brain injury. It does so by inhibiting enzymes involved in the apoptosis pathway specifically concerning the mitochondria, such as activated caspase 3 and cytochrome c.
Not only does progesterone help prevent further damage, it has also been shown to aid in neuroregeneration. One of the serious effects of traumatic brain injury includes edema. Animal studies show that progesterone treatment leads to a decrease in edema levels by increasing the concentration of macrophages and microglia sent to the injured tissue. This was observed in the form of reduced leakage from the blood brain barrier in secondary recovery in progesterone treated rats. In addition, progesterone was observed to have antioxidant properties, reducing the concentration of oxygen free radicals faster than without. There is also evidence that the addition of progesterone can also help remyelinate damaged axons due to trauma, restoring some lost neural signal conduction. Another way progesterone aids in regeneration includes increasing the circulation of endothelial progenitor cells in the brain. This helps new vasculature to grow around scar tissue which helps repair the area of insult.

Addiction
Progesterone enhances the function of serotonin receptors in the brain, so an excess or deficit of progesterone has the potential to result in significant neurochemical issues. This provides an explanation for why some people resort to substances that enhance serotonin activity such as nicotine, alcohol, and cannabis when their progesterone levels fall below optimal levels.
Sex differences in hormone levels may induce women to respond differently than men to nicotine. When women undergo cyclic changes or different hormonal transition phases (menopause, pregnancy, adolescence), there are changes in their progesterone levels. Therefore, females have an increased biological vulnerability to nicotines reinforcing effects compared to males and progesterone may be used to counter this enhanced vulnerability. This information supports the idea that progesterone can affect behavior.
Similar to nicotine, cocaine also increases the release of dopamine in the brain. The neurotransmitter is involved in the reward center and is one of the main neurotransmitters involved with substance abuse and reliance. In a study of cocaine users, it was reported that progesterone reduced craving and the feeling of being stimulated by cocaine. Thus, progesterone was suggested as an agent that decreases cocaine craving by reducing the dopaminergic properties of the drug.

Societal
In a 2012 University of Amsterdam study of 120 women, womens luteal phase (higher levels of progesterone, and increasing levels of estrogen) was correlated with lower level of competitive behavior in gambling and math contest scenarios, while their premenstrual phase (sharply-decreasing levels of progesterone, and decreasing levels of estrogen) was correlated with a higher level of competitive behavior.

Other effects
Progesterone also has a role in skin elasticity and bone strength, in respiration, in nerve tissue and in female sexuality, and the presence of progesterone receptors in certain muscle and fat tissue may hint at a role in sexually dimorphic proportions of those.
During pregnancy, progesterone is said to decrease uterine irritability.
During pregnancy, progesterone helps to suppress immune responses of the mother to fetal antigens, which prevents rejection of the fetus.
Progesterone raises epidermal growth factor-1 (EGF-1) levels, a factor often used to induce proliferation, and used to sustain cultures, of stem cells.
Progesterone increases core temperature (thermogenic function) during ovulation.
Progesterone reduces spasm and relaxes smooth muscle. Bronchi are widened and mucus regulated. (PRs are widely present in submucosal tissue.)
Progesterone acts as an antiinflammatory agent and regulates the immune response.
Progesterone reduces gall-bladder activity.
Progesterone normalizes blood clotting and vascular tone, zinc and copper levels, cell oxygen levels, and use of fat stores for energy.
Progesterone may affect gum health, increasing risk of gingivitis (gum inflammation).
Progesterone appears to prevent endometrial cancer (involving the uterine lining) by regulating the effects of estrogen.
Progesterone plays an important role in the signaling of insulin release and pancreatic function, and may affect the susceptibility to diabetes or gestational diabetes.

Biochemistry
Biosynthesis
In mammals, progesterone, like all other steroid hormones, is synthesized from pregnenolone, which itself is derived from cholesterol.
Cholesterol undergoes double oxidation to produce 22R-hydroxycholesterol and then 20α,22R-dihydroxycholesterol. This vicinal diol is then further oxidized with loss of the side chain starting at position C22 to produce pregnenolone. This reaction is catalyzed by cytochrome P450scc.
The conversion of pregnenolone to progesterone takes place in two steps. First, the 3β-hydroxyl group is oxidized to a keto group and second, the double bond is moved to C4, from C5 through a keto/enol tautomerization reaction. This reaction is catalyzed by 3β-hydroxysteroid dehydrogenase/δ5-4-isomerase.
Progesterone in turn is the precursor of the mineralocorticoid aldosterone, and after conversion to 17α-hydroxyprogesterone, of cortisol and androstenedione. Androstenedione can be converted to testosterone, estrone, and estradiol, highlighting the critical role of progesterone in testosterone synthesis.
Pregnenolone and progesterone can also be synthesized by yeast.Approximately 25 mg of progesterone is secreted from the ovaries per day in women, while the adrenal glands produce about 2 mg of progesterone per day.

Distribution
Progesterone binds extensively to plasma proteins, including albumin (50–54%) and transcortin (43–48%). It has similar affinity for albumin relative to the PR.

Metabolism
The metabolism of progesterone is rapid and extensive and occurs mainly in the liver, though enzymes that metabolize progesterone are also expressed widely in the brain, skin, and various other extrahepatic tissues. Progesterone has an elimination half-life of only approximately 5 minutes in circulation. The metabolism of progesterone is complex, and it may form as many as 35 different unconjugated metabolites when it is ingested orally. Progesterone is highly susceptible to enzymatic reduction via reductases and hydroxysteroid dehydrogenases due to its double bond (between the C4 and C5 positions) and its two ketones (at the C3 and C20 positions).The major metabolic pathway of progesterone is reduction by 5α-reductase and 5β-reductase into the dihydrogenated 5α-dihydroprogesterone and 5β-dihydroprogesterone, respectively. This is followed by the further reduction of these metabolites via 3α-hydroxysteroid dehydrogenase and 3β-hydroxysteroid dehydrogenase into the tetrahydrogenated allopregnanolone, pregnanolone, isopregnanolone, and epipregnanolone. Subsequently, 20α-hydroxysteroid dehydrogenase and 20β-hydroxysteroid dehydrogenase reduce these metabolites to form the corresponding hexahydrogenated pregnanediols (eight different isomers in total), which are then conjugated via glucuronidation and/or sulfation, released from the liver into circulation, and excreted by the kidneys into the urine. The major metabolite of progesterone in the urine is the 3α,5β,20α isomer of pregnanediol glucuronide, which has been found to constitute 15 to 30% of an injection of progesterone. Other metabolites of progesterone formed by the enzymes in this pathway include 3α-dihydroprogesterone, 3β-dihydroprogesterone, 20α-dihydroprogesterone, and 20β-dihydroprogesterone, as well as various combination products of the enzymes aside from those already mentioned. Progesterone can also first be hydroxylated (see below) and then reduced. Endogenous progesterone is metabolized approximately 50% into 5α-dihydroprogesterone in the corpus luteum, 35% into 3β-dihydroprogesterone in the liver, and 10% into 20α-dihydroprogesterone.Relatively small portions of progesterone are hydroxylated via 17α-hydroxylase (CYP17A1) and 21-hydroxylase (CYP21A2) into 17α-hydroxyprogesterone and 11-deoxycorticosterone (21-hydroxyprogesterone), respectively, and pregnanetriols are formed secondarily to 17α-hydroxylation. Even smaller amounts of progesterone may be also hydroxylated via 11β-hydroxylase (CYP11B1) and to a lesser extent via aldosterone synthase (CYP11B2) into 11β-hydroxyprogesterone. In addition, progesterone can be hydroxylated in the liver by other cytochrome P450 enzymes which are not steroid-specific. 6β-Hydroxylation, which is catalyzed mainly by CYP3A4, is the major transformation, and is responsible for approximately 70% of cytochrome P450-mediated progesterone metabolism. Other routes include 6α-, 16α-, and 16β-hydroxylation. However, treatment of women with ketoconazole, a strong CYP3A4 inhibitor, had minimal effects on progesterone levels, producing only a slight and non-significant increase, and this suggests that cytochrome P450 enzymes play only a small role in progesterone metabolism.

Levels
In women, progesterone levels are relatively low during the preovulatory phase of the menstrual cycle, rise after ovulation, and are elevated during the luteal phase, as shown in the diagram above. Progesterone levels tend to be less than 2 ng/mL prior to ovulation and greater than 5 ng/mL after ovulation. If pregnancy occurs, human chorionic gonadotropin is released, maintaining the corpus luteum and allowing it to maintain levels of progesterone. Between 7 and 9 weeks, the placenta begins to produce progesterone in place of the corpus luteum in a process called the luteal-placental shift.After the luteal-placental shift, progesterone levels start to rise further and may reach 100 to 200 ng/mL at term. Whether a decrease in progesterone levels is critical for the initiation of labor has been argued and may be species-specific. After delivery of the placenta and during lactation, progesterone levels are very low.
Progesterone levels are low in children and postmenopausal women. Adult males have levels similar to those in women during the follicular phase of the menstrual cycle.

Ranges
Blood test results should always be interpreted using the reference ranges provided by the laboratory that performed the results. Example reference ranges are listed below.

Sources
Animal
Progesterone is produced in high amounts in the ovaries (by the corpus luteum) from the onset of puberty to menopause, and is also produced in smaller amounts by the adrenal glands after the onset of adrenarche in both males and females. To a lesser extent, progesterone is produced in nervous tissue, especially in the brain, and in adipose (fat) tissue, as well.
During human pregnancy, progesterone is produced in increasingly high amounts by the ovaries and placenta. At first, the source is the corpus luteum that has been "rescued" by the presence of human chorionic gonadotropin (hCG) from the conceptus. However, after the 8th week, production of progesterone shifts to the placenta. The placenta utilizes maternal cholesterol as the initial substrate, and most of the produced progesterone enters the maternal circulation, but some is picked up by the fetal circulation and used as substrate for fetal corticosteroids. At term the placenta produces about 250 mg progesterone per day.
An additional animal source of progesterone is milk products. After consumption of milk products the level of bioavailable progesterone goes up.

Plants
In at least one plant, Juglans regia, progesterone has been detected. In addition, progesterone-like steroids are found in Dioscorea mexicana. Dioscorea mexicana is a plant that is part of the yam family native to Mexico. It contains a steroid called diosgenin that is taken from the plant and is converted into progesterone. Diosgenin and progesterone are also found in other Dioscorea species, as well as in other plants that are not closely related, such as fenugreek.
Another plant that contains substances readily convertible to progesterone is Dioscorea pseudojaponica native to Taiwan. Research has shown that the Taiwanese yam contains saponins — steroids that can be converted to diosgenin and thence to progesterone.Many other Dioscorea species of the yam family contain steroidal substances from which progesterone can be produced. Among the more notable of these are Dioscorea villosa and Dioscorea polygonoides. One study showed that the Dioscorea villosa contains 3.5% diosgenin. Dioscorea polygonoides has been found to contain 2.64% diosgenin as shown by gas chromatography-mass spectrometry. Many of the Dioscorea species that originate from the yam family grow in countries that have tropical and subtropical climates.

Medical use
Progesterone is used as a medication. It is used in combination with estrogens mainly in hormone therapy for menopausal symptoms and low sex hormone levels in women. It is also used in women to support pregnancy and fertility and to treat gynecological disorders. Progesterone has been shown to  prevent miscarriage in women with 1) vaginal bleeding early in their current pregnancy and 2) a previous history of miscarriage. Progesterone can be taken by mouth, through the vagina, and by injection into muscle or fat, among other routes.

Chemistry
Progesterone is a naturally occurring pregnane steroid and is also known as pregn-4-ene-3,20-dione. It has a double bond (4-ene) between the C4 and C5 positions and two ketone groups (3,20-dione), one at the C3 position and the other at the C20 position.

Synthesis
Progesterone is commercially produced by semisynthesis. Two main routes are used: one from yam diosgenin first pioneered by Marker in 1940, and one based on soy phytosterols scaled up in the 1970s.  Additional (not necessarily economical) semisyntheses of progesterone have also been reported starting from a variety of steroids. For the example, cortisone can be simultaneously deoxygenated at the C-17 and C-21 position by treatment with iodotrimethylsilane in chloroform to produce 11-keto-progesterone (ketogestin), which in turn can be reduced at position-11 to yield progesterone.

Marker semisynthesis
An economical semisynthesis of progesterone from the plant steroid diosgenin isolated from yams was developed by Russell Marker in 1940 for the Parke-Davis pharmaceutical company. This synthesis is known as the Marker degradation.

The 16-DPA intermediate is important to the synthesis of many other medically important steroids. A very similar approach can produce 16-DPA from solanine.

Soy semisynthesis
Progesterone can also be made from the stigmasterol found in soybean oil also. c.f. Percy Julian.

Total synthesis
A total synthesis of progesterone was reported in 1971 by W.S. Johnson. The synthesis begins with reacting the phosphonium salt 7 with phenyl lithium to produce the phosphonium ylide 8. The ylide 8 is reacted with an aldehyde to produce the alkene 9. The ketal protecting groups of 9 are hydrolyzed to produce the diketone 10, which in turn is cyclized to form the cyclopentenone 11. The ketone of 11 is reacted with methyl lithium to yield the tertiary alcohol 12, which in turn is treated with acid to produce the tertiary cation 13. The key step of the synthesis is the π-cation cyclization of 13 in which the B-, C-, and D-rings of the steroid are simultaneously formed to produce 14. This step resembles the cationic cyclization reaction used in the biosynthesis of steroids and hence is referred to as biomimetic. In the next step the enol orthoester is hydrolyzed to produce the ketone 15. The cyclopentene A-ring is then opened by oxidizing with ozone to produce 16. Finally, the diketone 17 undergoes an intramolecular aldol condensation by treating with aqueous potassium hydroxide to produce progesterone.

History
George W. Corner and Willard M. Allen discovered the hormonal action of progesterone in 1929. By 1931–1932, nearly pure crystalline material of high progestational activity had been isolated from the corpus luteum of animals, and by 1934, pure crystalline progesterone had been refined and obtained and the chemical structure of progesterone was determined. This was achieved by Adolf Butenandt at the Chemisches Institut of Technical University in Danzig, who extracted this new compound from several thousand liters of urine.Chemical synthesis of progesterone from stigmasterol and pregnanediol was accomplished later that year. Up to this point, progesterone, known generically as corpus luteum hormone, had been being referred to by several groups by different names, including corporin, lutein, luteosterone, and progestin. In 1935, at the time of the Second International Conference on the Standardization of Sex Hormones in London, England, a compromise was made between the groups and the name progesterone (progestational steroidal ketone) was created.

Veterinary use
The use of progesterone in tests dog breeding to pinpoint ovulation is becoming more widely used.  There are several tests available but the most reliable test is a blood test with blood drawn by a veterinarian and sent to a lab for processing.  Results can usually be obtained with 24 to 72 hours </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Diflorasone diacetate and can you explain it in depth? [/INST]  </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Azelaic acid and can you explain it in depth? [/INST] Azelaic acid (AzA) is an organic compound with the formula HOOC(CH2)7COOH. This saturated dicarboxylic acid exists as a white powder. It is found in wheat, rye, and barley. It is a precursor to diverse industrial products including polymers and plasticizers, as well as being a component of a number of hair and skin conditioners. AzA inhibits tyrosinase.

Production
Azelaic acid is industrially produced by the ozonolysis of oleic acid. The side product is nonanoic acid. It is produced naturally by Malassezia furfur (also known as Pityrosporum ovale), a yeast that lives on normal skin. The bacterial degradation of nonanoic acid gives azelaic acid.

Biological function
In plants, azelaic acid serves as a "distress flare" involved in defense responses after infection. It serves as a signal that induces the accumulation of salicylic acid, an important component of a plants defensive response.

Applications
Polymers and related materials
Esters of this dicarboxylic acid find applications in lubrication and plasticizers. In lubricant industries it is used as a thickening agent in lithium complex grease. With hexamethylenediamine, azelaic acid forms Nylon-6,9, which finds specialized uses as a plastic.

Medical
Azelaic acid is used to treat mild to moderate acne, both comedonal acne and inflammatory acne. It belongs to a class of medication called dicarboxylic acids. It works by killing acne bacteria that infect skin pores. It also decreases the production of keratin, which is a natural substance that promotes the growth of acne bacteria. Azelaic acid is also used as a topical gel treatment for rosacea, due to its ability to reduce inflammation. It clears the bumps and swelling caused by rosacea </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Clobazam and can you explain it in depth? [/INST] Clobazam, sold under the brand names Frisium, Onfi and others, is a benzodiazepine class medication that was patented in 1968. Clobazam was first synthesized in 1966 and first published in 1969. Clobazam was originally marketed as an anxioselective anxiolytic since 1970, and an anticonvulsant since 1984. The primary drug-development goal was to provide greater anxiolytic, anti-obsessive efficacy with fewer benzodiazepine-related side effects.

Medical uses
Clobazam is used for its anxiolytic effect, and as an adjunctive therapy in epilepsy.
As an adjunctive therapy in epilepsy, it is used in patients who have not responded to first-line drugs and in children who are refractory to first-line drugs. It is unclear if there are any benefits to clobazam over other seizure medications for children with Rolandic epilepsy or other epileptic syndromes. It is not recommended for use in children between the ages of six months and three years, unless there is a compelling need. In addition to epilepsy and severe anxiety, clobazam is also approved as a short-term (2–4 weeks) adjunctive agent in schizophrenia and other psychotic disorders to manage anxiety or agitation.Clobazam is sometimes used for refractory epilepsies. However, long-term prophylactic treatment of epilepsy may have considerable drawbacks, most importantly decreased antiepileptic effects due to drug tolerance which may render long-term therapy less effective. Other antiepileptic drugs may therefore be preferred for the long-term management of epilepsy. Furthermore, benzodiazepines may have the drawback, particularly after long-term use, of causing rebound seizures upon abrupt or over-rapid discontinuation of therapy forming part of the benzodiazepine withdrawal syndrome.
Clobazam is approved in Canada for add-on use in tonic-clonic, complex partial, and myoclonic seizures. Clobazam is approved for adjunctive therapy in complex partial seizures, certain types of status epilepticus, specifically the mycolonic, myoclonic-absent, simple partial, complex partial, and tonic varieties, and non-status absence seizures. It is also approved for the treatment of anxiety.
In India, clobazam is approved for use as an adjunctive therapy in epilepsy, and in acute and chronic anxiety. In Japan, clobazam is approved for adjunctive therapy in treatment-resistant epilepsy featuring complex partial seizures. In New Zealand, clobazam is marketed as Frisium In the United Kingdom clobazam (Frisium) is approved for short-term (2–4 weeks) relief of acute anxiety in patients who have not responded to other drugs, with or without insomnia and without uncontrolled clinical depression. It was not approved in the United States until October 25, 2011, when it was approved for the adjunctive treatment of seizures associated with Lennox-Gastaut syndrome in patients 2 years of age or older.

Contraindications
Clobazam should be used with great care in patients with the following disorders:

Myasthenia gravis.
Sleep apnea.
Severe liver diseases such as cirrhosis and hepatitis.
Severe respiratory failure.Benzodiazepines require special precaution if used in the elderly, during pregnancy, in children, alcohol or drug-dependent individuals, and individuals with comorbid psychiatric disorders.

Side effects
In September 2020, the U.S. Food and Drug Administration (FDA) required the boxed warning be updated for all benzodiazepine medicines to describe the risks of abuse, misuse, addiction, physical dependence, and withdrawal reactions consistently across all the medicines in the class.

Common
Common side effects include fever,  drooling, and constipation.

Post-marketing experience
Hives.
Rashes.

Warnings and precautions
In December 2013, the FDA added warnings to the label for clobazam, that it can cause serious skin reactions, Stevens–Johnson syndrome, and toxic epidermal necrolysis, especially in the first eight weeks of treatment.

Drug interactions
Alcohol increases bioavailability by 50%; compounded depressant effect may precipitate life-threatening toxicity.
Cimetidine increases the effects of clobazam.
Valproate.

Overdose
Overdose and intoxication with benzodiazepines, including clobazam, may lead to CNS depression, associated with drowsiness, confusion, and lethargy, possibly progressing to ataxia, respiratory depression, hypotension, and coma or death. The risk of a fatal outcome is increased in cases of combined poisoning with other CNS depressants, including alcohol.

Abuse potential and addiction
Classic (non-anxioselective) benzodiazepines in animal studies have been shown to increase reward-seeking behaviours which may suggest an increased risk of addictive behavioural patterns. Clobazam abuse has been reported in some countries, according to a 1983 World Health Organisation report.

Dependence and withdrawal
In humans, tolerance to the anticonvulsant effects of clobazam may occur and withdrawal seizures may occur during abrupt or overrapid withdrawal.Clobazam as with other benzodiazepine drugs can lead to physical dependence, addiction, and what is known as the benzodiazepine withdrawal syndrome. Withdrawal from clobazam or other benzodiazepines after regular use often leads to withdrawal symptoms which are similar to those seen during alcohol and barbiturate withdrawal. The higher the dosage and the longer the drug is taken, the greater the risk of experiencing unpleasant withdrawal symptoms. Benzodiazepine treatment should only be discontinued via a slow and gradual dose reduction regimen.

Pharmacology
Clobazam is predominantly a positive allosteric modulator at the GABAA receptor with some speculated additional activity at sodium channels and voltage-sensitive calcium channels.Like other 1,5-benzodiazepines (for example, arfendazam, lofendazam, or CP-1414S), the active metabolite N-desmethylclobazam has less affinity for the α1 subunit of the GABAA receptor compared to the 1,4-benzodiazepines. It has higher affinity for α2 containing receptors, where it has positive modulatory activity.In a double-blind placebo-controlled trial published in 1990 comparing it to clonazepam, 10 mg of clobazam was shown to be less sedative than either 0.5 mg or 1 mg of clonazepam.The α1 subtype of the GABAA receptor, was shown to be responsible for the sedative effects of diazepam by McKernan et al. in 2000, who also showed that its anxiolytic and anticonvulsant properties could still be seen in mice whose α1 receptors were insensitive to diazepam.In 1996, Nakamura et al. reported that clobazam and its active metabolite, N-desmethylclobazam (norclobazam), work by enhancing GABA-activated chloride influx at GABAA receptors, creating a hyperpolarizing, inhibitory postsynaptic potential. It was also reported that these effects were inhibited by the GABA antagonist flumazenil, and that clobazam acts more efficiently in GABA-deficient brain tissue.

Metabolism
Clobazam has two major metabolites: N-desmethylclobazam and 4′-hydroxyclobazam, the former of which is active </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Siltuximab and can you explain it in depth? [/INST]  </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Aminocaproic acid and can you explain it in depth? [/INST] Aminocaproic acid (also known as ε-aminocaproic acid, ε-Ahx, or 6-aminohexanoic acid) is a derivative and analogue of the amino acid lysine, which makes it an effective inhibitor for enzymes that bind that particular residue. Such enzymes include proteolytic enzymes like plasmin, the enzyme responsible for fibrinolysis. For this reason it is effective in treatment of certain bleeding disorders, and it is sold under the brand name Amicar. Aminocaproic acid is also an intermediate in the polymerization of Nylon-6, where it is formed by ring-opening hydrolysis of caprolactam. The crystal structure determination showed that the 6-aminohexanoic acid is present as a salt, at least in the solid state.

Medical use
Aminocaproic acid (Amicar) is FDA-approved for use in the treatment of acute bleeding due to elevated fibrinolytic activity. It also carries an orphan drug designation from the FDA for the prevention of recurrent hemorrhage in patients with traumatic hyphema. In clinical practice, aminocaproic acid is frequently used off-label for control of bleeding in patients with severe thrombocytopenia, control of oral bleeding in patients with congenital and acquired coagulation disorders, control of perioperative bleeding associated with cardiac surgery, prevention of excessive bleeding in patients on anticoagulation therapy undergoing invasive dental procedures, and reduction of the risk of catastrophic hemorrhage in patients with acute promyelocytic leukemia.

References
Further reading
Alkjaersig N, Fletcher AP, Sherry S (April 1959). "xi-Aminocaproic acid: an inhibitor of plasminogen activation". The Journal of Biological Chemistry. 234 (4): 832–7. doi:10.1016/S0021-9258(18)70185-3 </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Merrem and can you explain it in depth? [/INST]  </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Alclometasone and can you explain it in depth? [/INST]  </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Efgartigimod alfa and can you explain it in depth? [/INST] Efgartigimod alfa, sold under the brand name Vyvgart, is a medication used to treat myasthenia gravis.The most common side effects include respiratory tract infections, headache, and urinary tract infections.Efgartigimod alfa is a neonatal Fc receptor blocker and is a new class of medication. It is an antibody fragment that binds to the neonatal Fc receptor (FcRn), preventing FcRn from recycling immunoglobulin G (IgG) back into the blood. The medication causes a reduction in overall levels of IgG, including the abnormal acetylcholine receptor (AChR) antibodies that are present in myasthenia gravis. It was approved for medical use in the United States in December 2021, and in the European Union in August 2022.

Medical uses
Efgartigimod alfa is indicated for the treatment of generalized myasthenia gravis (gMG) in adults who are anti-acetylcholine receptor (AChR) antibody positive.

History
The safety and efficacy of efgartigimod alfa were evaluated in a 26-week clinical study of 167 participants with myasthenia gravis who were randomized to receive either efgartigimod alfa or placebo. The study showed that more participants with myasthenia gravis with antibodies responded to treatment during the first cycle of efgartigimod alfa (68%) compared to those who received placebo (30%) on a measure that assesses the impact of myasthenia gravis on daily function. More participants receiving efgartigimod alfa also demonstrated response on a measure of muscle weakness compared to placebo.

Pharmacodynamics
Efgartigimod alfa as a drug is an antibody fragment that binds to the neonatal Fc receptor. When this binding happens, the IgG recycling process is blocked. The amount of circulating IgG decreases and therefore prevents the acetylcholine receptors from being degraded by the autoantibodies that are responsible for the myasthenia gravis.

Pharmacokinetics
The drug is mainly metabolized via proteolytic enzymes. The termination half-life of Efgartigimod alfa is 80 to 120 hours.

Side effects
Side effects of efgartigimod alfa include respiratory tract infections, headache, urinary tract infection, numbness and tingling and muscle pain.

Society and culture
Legal status
The U.S. Food and Drug Administration (FDA) granted the application for efgartigimod alfa fast track and orphan drug designations. The FDA granted the approval of Vyvgart to Argenx BV.On 23 June 2022, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Vyvgart, intended for the treatment of anti‑acetylcholine receptor (AChR) antibody positive generalized myasthenia gravis. The applicant for this medicinal product is Argenx. Efgartigimod alfa was approved for medical use in the European Union in August 2022.

Names
Efgartigimod alfa is the international nonproprietary name (INN).

References
This article incorporates public domain material from the United States Department of Health and Human Services.

Further reading
Howard JF, Bril V, Vu T, Karam C, Peric S, Margania T,  et al. (July 2021) </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Gatifloxacin and can you explain it in depth? [/INST]  </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Trifluridine/tipiracil and can you explain it in depth? [/INST] Trifluridine/tipiracil, sold under the brand name Lonsurf, is a fixed-dose combination medication that is used as a third- or fourth-line treatment of metastatic colorectal cancer or gastric cancer, after chemotherapy and targeted therapeutics have failed. It is a combination of  two active pharmaceutical ingredients: trifluridine, a nucleoside analog, and tipiracil, a thymidine phosphorylase inhibitor. Tipiracil prevents rapid metabolism of trifluridine, increasing the bioavailability of trifluridine.The most common side effects include neutropenia (low levels of neutrophils, a type of white blood cell that fights infection), feeling sick, tiredness and anemia (low red blood cell counts).

Medical uses
It is used as a third- or fourth-line treatment for metastatic colorectal cancer or gastric cancer, after chemotherapy and biologic therapy.

Contraindications
The combination caused harm to the fetus of pregnant animals, and it was not tested in pregnant women. Pregnant women should not take it, and women should not become pregnant while taking it.

Adverse effects
The combination severely suppresses bone marrow function, resulting in fewer red blood cells, white blood cells, and platelets, so many people taking it are at risk for infections, anemia, and blood loss from lack of clotting. It also causes digestive problems, with more than 10% of people experiencing loss of appetite, diarrhea, nausea, and vomiting.  More than 10% of people experience fatigue and fever.Between 1 and 10% of people have skin and mucosa issues, like rashes and itchiness, or mouth sores, as well as skin sloughing, numbness, redness, and swelling of their palms and soles.  Dizziness and confusion are common as well.

Interactions
Only in vitro interaction studies are available. In these, trifluridine used the concentrative nucleoside transporter 1 (CNT1) and equilibrative nucleoside transporters 1 (ENT1) and 2 (ENT2), and tipiracil was transported by the solute carrier proteins SLC22A2 and SLC47A1. Drugs that interact with these transporters could influence blood plasma concentrations of trifluridine and tipiracil. Trifluridine, being a thymidine phosphorylase inhibitor, could also interact with substrates of this enzyme such as zidovudine.

Pharmacology
Mechanism of action
The drug consists of the cytotoxin trifluridine and the thymidine phosphorylase inhibitor (TPI) tipiracil.  Trifluridine is incorporated into DNA during DNA synthesis and inhibits tumor cell growth.  Trifluridine (TFT) is incorporated into DNA by phosphorylation by thymidylate kinase (TK) to TF-TMP;  TF-TMP then covalently binds to tyrosine 146 of the active site of thymidylate synthase (TS) inhibiting the enzymes activity.  TS is vital to the synthesis of DNA because it is an enzyme involved in the synthesis of the deoxynucleotide, thymidine triphosphate (dTTP).  Inhibition of TS depletes the cell of dTTP and causes accumulation of deoxyuridine monophosphate (dUMP), which increases the likelihood that uracil gets misincorporated into the DNA.  Also, subsequent phosphorylations of TF-TMP cause an increased level of TF-TTP within the cell, which results in it being incorporated into DNA </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Dorzolamide and can you explain it in depth? [/INST] Dorzolamide, sold under the brand name Trusopt among others, is a medication used to treat high pressure inside the eye, including in cases of glaucoma. It is used as an eye drop. Effects begin within three hours and last for at least eight hours. It is also available as the combination dorzolamide/timolol.Common side effects include eye discomfort, eye redness, taste changes, and blurry vision. Serious side effects include Steven Johnson syndrome. Those allergic to sulfonamides may be allergic to dorzolamide. Use is not recommended in pregnancy or breastfeeding. It is a carbonic anhydrase inhibitor and works by decreasing the production of aqueous humour.Dorzolamide was approved for medical use in the United States in 1994. It is available as a generic medication. In 2017, it was the 281st most commonly prescribed medication in the United States, with more than one million prescriptions. It is a second-generation carbonic anhydrase inhibitor.

Medical uses
Dorzolamide hydrochloride is used to lower excessive intraocular pressure in open-angle glaucoma and ocular hypertension. This drug is able to cross the cornea, reach the ciliary body of the eye, and produce systemic effects on the carbonic anhydrase enzyme within the eye.

Side effects
Ocular stinging, burning, itching and bitter taste. It causes shallowing of the anterior chamber and leads to transient myopia. As a second generation carbonic anhydrase inhibitor, Dorzolamide avoids systemic effects associated with first generation carbonic anhydrase inhibitors such as Acetazolamide, Methazolamide, and Dichlorphenamide.

Pharmacodynamics
Dorzolamide lowers intraocular pressure by about 20%. Normally, carbonic anhydrase converts carbonic acid (H2CO3) into bicarbonate (HCO3), releasing a proton (H+) into solution. The H+ is then exchanged for  sodium (Na+) ions, which facilitates the production of aqueous humor. By blocking the function of carbonic anhydrase, the Na+/H+ exchange is unable to occur, which leads to a decrease in Na+ in the cell and prevents aqueous humor production.

History
This drug, developed by Merck, was the first drug in human therapy (market introduction 1995) that resulted from structure-based drug design. It was developed to circumvent the systemic side effects of acetazolamide which has to be taken orally.

References
Further reading
Kubinyi H (1999). "Chance favors the prepared mind--from serendipity to rational drug design". J Recept Signal Transduct Res. 19 (1–4): 15–39. doi:10.3109/10799899909036635. PMID 10071748.
Plummer C, MacKay E, Gelatt K (2006). "Comparison of the effects of topical administration of a fixed combination of dorzolamide-timolol to monotherapy with timolol or dorzolamide on IOP, pupil size, and heart rate in glaucomatous dogs". Veterinary Ophthalmology. 9 (4): 245–9. doi:10.1111/j.1463-5224.2006.00469.x. PMID 16771760.
Grover S, Apushkin M, Fishman G (2006) </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Tiagabine and can you explain it in depth? [/INST] Tiagabine (trade name Gabitril) is an anticonvulsant medication produced by Cephalon that is used in the treatment of epilepsy. The drug is also used off-label in the treatment of anxiety disorders and panic disorder.

Medical uses
Tiagabine is approved by U.S. Food and Drug Administration (FDA) as an adjunctive treatment for partial seizures in individuals of age 12 and up. It may also be prescribed off-label by physicians to treat anxiety disorders and panic disorder as well as neuropathic pain (including fibromyalgia). For anxiety and neuropathic pain, tiagabine is used primarily to augment other treatments. Tiagabine may be used alongside selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, or benzodiazepines for anxiety, or antidepressants, gabapentin, other anticonvulsants, or opioids for neuropathic pain. It is effective as monotherapy and combination therapy with other antiepileptic drugs in the treatment of partial seizure.The American Academy of Sleep Medicines 2017 clinical practice guidelines recommended against the use of tiagabine in the treatment of insomnia due to poor effectiveness and very low quality of evidence.

Side effects
Side effects of tiagabine are dose related. The most common side effect of tiagabine is dizziness. Other side effects that have been observed with a rate of statistical significance relative to placebo include asthenia, somnolence, nervousness, memory impairment, tremor, headache, diarrhea, and depression </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Cefpodoxime and can you explain it in depth? [/INST] Cefpodoxime is an oral, third-generation cephalosporin antibiotic. It is active against most Gram-positive and Gram-negative organisms </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Abacavir and can you explain it in depth? [/INST] Abacavir, sold under the brand name Ziagen among others, is a medication used to treat HIV/AIDS. Similar to other nucleoside analog reverse-transcriptase inhibitors (NRTIs), abacavir is used together with other HIV medications, and is not recommended by itself. It is taken by mouth as a tablet or solution and may be used in children over the age of three months.Abacavir is generally well tolerated. Common side effects include vomiting, insomnia (trouble sleeping), fever, and feeling tired. Other common side effects include loss of appetite, headache, nausea (feeling sick), diarrhea, rash, and lethargy (lack of energy). More severe side effects include hypersensitivity, liver damage, and lactic acidosis. Genetic testing can indicate whether a person is at higher risk of developing hypersensitivity. Symptoms of hypersensitivity include rash, vomiting, and shortness of breath. Abacavir is in the NRTI class of medications, which work by blocking reverse transcriptase, an enzyme needed for HIV virus replication. Within the NRTI class, abacavir is a carbocyclic nucleoside.Abacavir was patented in 1988, and approved for use in the United States in 1998. It is on the World Health Organizations List of Essential Medicines. It is available as a generic medication. Abacavir is used together with other HIV medications, such as abacavir/lamivudine/zidovudine, abacavir/dolutegravir/lamivudine, and abacavir/lamivudine. The combination abacavir/lamivudine is an essential medicine.

Medical uses
Abacavir, in combination with other antiretroviral agents, is indicated for the treatment of HIV-1 infection. Abacavir should be used in combination with other antiretroviral agents.

Contraindications
Abacavir is contraindicated for people who have the HLA‑B*5701 allele or who have moderate or severe liver disease (hepatic impairment).

Side effects
Common adverse reactions include nausea, headache, fatigue, vomiting, diarrhea, Anorexia (symptom) (loss of appetite), and insomnia (trouble sleeping). Rare but serious side effects include hypersensitivity reaction such as rash, elevated AST and ALT, depression, anxiety, fever/chills, URI, lactic acidosis, hypertriglyceridemia, and lipodystrophy.<

Hypersensitivity syndrome
Hypersensitivity to abacavir is strongly associated with a specific allele at the human leukocyte antigen B locus namely HLA-B*5701. The mechanism for this hypersensitivity reaction is due to abacavir binding in the antigen-binding cleft of HLA-B*57:01, allowing alternative peptides to bind, which appear as "non-self" when presented to T cells. There is an association between the prevalence of HLA-B*5701 and ancestry. The prevalence of the allele is estimated to be 3.4 to 5.8 percent on average in populations of European ancestry, 17.6 percent in Indian Americans, 3.0 percent in Hispanic Americans, and 1.2 percent in Chinese Americans. There is significant variability in the prevalence of HLA-B*5701 among African populations. In African Americans, the prevalence is estimated to be 1.0 percent on average, 0 percent in the Yoruba from Nigeria, 3.3 percent in the Luhya from Kenya, and 13.6 percent in the Masai from Kenya, although the average values are derived from highly variable frequencies within sample groups.Common symptoms of abacavir hypersensitivity syndrome include fever, malaise, nausea, and diarrhea. Some patients may also develop a skin rash. Symptoms of AHS typically manifest within six weeks of treatment using abacavir, although they may be confused with symptoms of HIV, immune reconstitution syndrome, hypersensitivity syndromes associated with other drugs, or infection. The U.S. Food and Drug Administration (FDA) released an alert concerning abacavir and abacavir-containing medications on 24 July 2008, and the FDA-approved drug label for abacavir recommends pre-therapy screening for the HLA-B*5701 allele and the use of alternative therapy in subjects with this allele. Additionally, both the Clinical Pharmacogenetics Implementation Consortium and the Dutch Pharmacogenetics Working Group recommend use of an alternative therapy in individuals with the HLA-B*5701 allele.

Skin-patch testing may also be used to determine whether an individual will experience a hypersensitivity reaction to abacavir, although some patients susceptible to developing AHS may not react to the patch test.The development of suspected hypersensitivity reactions to abacavir requires immediate and permanent discontinuation of abacavir therapy in all patients, including patients who do not possess the HLA-B*5701 allele. On 1 March 2011, the FDA informed the public about an ongoing safety review of abacavir and a possible increased risk of heart attack associated with the drug. A meta-analysis of 26 studies conducted by the FDA, however, did not find any association between abacavir use and heart attack

Immunopathogenesis
The mechanism underlying abacavir hypersensitivity syndrome is related to the change in the HLA-B*5701 protein product. Abacavir binds with high specificity to the HLA-B*5701 protein, changing the shape and chemistry of the antigen-binding cleft. This results in a change in immunological tolerance and the subsequent activation of abacavir-specific cytotoxic T cells, which produce a systemic reaction known as abacavir hypersensitivity syndrome.

Interaction
Abacavir, and in general NRTIs, do not undergo hepatic metabolism and therefore have very limited (to none) interaction with the CYP enzymes and drugs that effect these enzymes. That being said there are still few interactions that can affect the absorption or the availability of abacavir. Below are few of the common established drug and food interaction that can take place during abacavir co-administration:

Protease inhibitors such as tipranavir or ritonovir may decrease the serum concentration of abacavir through induction of glucuronidation. Abacavir is metabolized by both alcohol dehydrogenase and glucuronidation.
Ethanol may result in increased levels of abacavir through the inhibition of alcohol dehydrogenase. Abacavir is metabolized by both alcohol dehydrogenase and glucuronidation.
Methadone may diminish the therapeutic effect of Abacavir. Abacavir may decrease the serum concentration of Methadone.
Orlistat may decrease the serum concentration of antiretroviral drugs. The mechanism of this interaction is not fully established but it is suspected that it is due to the decreased absorption of abacavir by orlistat.
Cabozantinib: Drugs from the MRP2 inhibitor (Multidrug resistance-associated protein 2 inhibitors) family such as abacavir could increase the serum concentration of Cabozantinib.

Mechanism of action
Abacavir is a nucleoside reverse transcriptase inhibitor that inhibits viral replication. It is a guanosine analogue that is phosphorylated to carbovir triphosphate (CBV-TP). CBV-TP competes with the viral molecules and is incorporated into the viral DNA. Once CBV-TP is integrated into the viral DNA, transcription and HIV reverse transcriptase is inhibited.

Pharmacokinetics
Abacavir is given orally and is rapidly absorbed with a high bioavailability of 83%. Solution and tablet have comparable concentrations and bioavailability. Abacavir can be taken with or without food.Abacavir can cross the blood-brain barrier. Abacavir is metabolized primarily through the enzymes alcohol dehydrogenase and glucuronyl transferase to an inactive carboxylate and glucuronide metabolites. It has a half-life of approximately 1.5-2.0 hours </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Patisiran and can you explain it in depth? [/INST] Patisiran, sold under the brand name Onpattro, is a medication used for the treatment of polyneuropathy in people with hereditary transthyretin-mediated amyloidosis, a fatal rare disease that is estimated to affect 50,000 people worldwide.It is the first small interfering RNA-based drug approved by the U.S </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Tranexamic acid and can you explain it in depth? [/INST] Tranexamic acid (TXA) is a medication used to treat or prevent excessive blood loss from major trauma, postpartum bleeding, surgery, tooth removal, nosebleeds, and heavy menstruation. It is also used for hereditary angioedema. It is taken either orally or by injection into a vein.

Mechanism of action
Tranexamic acid is a synthetic analog of the amino acid lysine. It serves as an antifibrinolytic by reversibly binding four to five lysine receptor sites on plasminogen. This decreases the conversion of plasminogen to plasmin, preventing fibrin degradation and preserving the framework of fibrins matrix structure. Tranexamic acid has roughly eight times the antifibrinolytic activity of an older analogue, ε-aminocaproic acid. Tranexamic acid also directly inhibits the activity of plasmin with weak potency (IC50 = 87 mM), and it can block the active-site of urokinase plasminogen activator (uPA) with high specificity (Ki = 2 mM), one of the highest among all the serine proteases.Side effects are rare. Some include changes in color vision, blood clots, and allergic reactions. Greater caution is recommended in people with kidney disease. Tranexamic acid appears to be safe for use during pregnancy and breastfeeding. Tranexamic acid is an antifibrinolytic medication.Tranexamic acid was first made in 1962 by Japanese researchers Shosuke and Utako Okamoto. It is on the World Health Organizations List of Essential Medicines. Tranexamic acid is available as a generic drug.

Medical uses
Tranexamic acid is frequently used following major trauma. Tranexamic acid is used to prevent and treat blood loss in a variety of situations, such as dental procedures, heavy menstrual bleeding, and surgeries with high risk of blood loss.

Trauma
Tranexamic acid has been found to decrease the risk of death due to any cause in people who have significant bleeding due to trauma. It is most effective if taken within the first three hours following major trauma. It also decreases the risk of death if given within the first three hours of brain injury.

Menstrual bleeding
Tranexamic acid is sometimes used to treat heavy menstrual bleeding. When taken by mouth it both safely and effectively treats regularly occurring heavy menstrual bleeding and improves quality of life. Another study demonstrated that the dose does not need to be adjusted in females who are between ages 12 and 16.

Childbirth
Tranexamic acid is sometimes used (often in conjunction with oxytocin) to reduce bleeding after childbirth. Death due to postpartum bleeding is reduced in women receiving tranexamic acid.

Surgery
Tranexamic acid is sometimes used in orthopedic surgery to reduce blood loss, to the extent of reducing or altogether abolishing the need for perioperative blood transfusion. It is of proven value in clearing the field of surgery and reducing blood loss when given before or after surgery. Drain and number of transfusions are reduced.
In surgical corrections of craniosynostosis in children it reduces the need for blood transfusions.
In spinal surgery (e.g., scoliosis), correction with posterior spinal fusion using instrumentation, to prevent excessive blood loss.
In cardiac surgery, both with and without cardiopulmonary bypass (e.g., coronary artery bypass surgery), it is used to prevent excessive blood loss.

Dentistry
In the United States, tranexamic acid is FDA approved for short-term use in people with severe bleeding disorders who are about to have dental surgery. Tranexamic acid is used for a short period of time before and after the surgery to prevent major blood loss and decrease the need for blood transfusions.Tranexamic acid is used in dentistry in the form of a 5% mouth rinse after extractions or surgery in patients with prolonged bleeding time; e.g., from acquired or inherited disorders.In China, TXA is allowed in over-the-counter toothpastes, with six products using the drug. As of 2018, there are no limits on dosage, nor requirements for labeling the concentration. 0.05% TXA in toothpaste is allowed OTC in Hong Kong. <5% TXA in over-the-counter toothpaste is first patented and marketed by Lion Corporation in Japan, where it is still sold. Presence of unauthorized TXA has led to the Canadian recall of a Yunnan Baiyao toothpaste in 2019.

Hematology
There is not enough evidence to support the routine use of tranexamic acid to prevent bleeding in people with blood cancers. However, there are several trials that are currently assessing this use of tranexamic acid. For people with inherited bleeding disorders (e.g. von Willebrands disease), tranexamic acid is often given. It has also been recommended for people with acquired bleeding disorders (e.g., directly acting oral anticoagulants (DOACs)) to treat serious bleeding.

Nosebleeds
The use of tranexamic acid, applied directly to the area that is bleeding or taken by mouth, appears useful to treat nose bleeding compared to packing the nose with cotton pledgets alone. It decreases the risk of rebleeding within 10 days.

Other uses
Tentative evidence supports the use of tranexamic acid in hemoptysis.
In hereditary angioedema
In hereditary hemorrhagic telangiectasia - Tranexamic acid has been shown to reduce frequency of epistaxis in patients with severe and frequent nosebleed episodes from hereditary hemorrhagic telangiectasia.
In melasma - tranexamic acid is sometimes used in skin whitening as a topical agent, injected into a lesion, or taken by mouth, both alone and as an adjunct to laser therapy; as of 2017 its safety seemed reasonable but its efficacy for this purpose was uncertain because there had been no large scale randomized controlled studies nor long term follow-up studies. It is allowed as a quasi-drug for skin whitening in Japan.
In hyphema - Tranexamic acid has been shown to be effective in reducing risk of secondary hemorrhage outcomes in people with traumatic hyphema.

Experimental uses
Tranexamic acid might alleviate neuroinflammation in some experimental settings.Tranexamic acid can be used in case of postpartum hemorrhage; it can decrease the risk of death due to bleeding by one third according to the WHO.

Contraindications
Allergic to tranexamic acid
History of seizures
History of venous or arterial thromboembolism or active thromboembolic disease
Severe kidney impairment due to accumulation of the medication, dose adjustment is required in mild or moderate kidney impairment

Adverse effects
Side effects are rare. Some reported adverse events include changes in color vision, blood clots, and allergic reactions such as anaphylaxis. Whether the risk of venous thromboembolism (blood clots) is actually increased is a matter of debate. The risk is mentioned in the product literature, and they were reported in post marketing experience. Despite this, and the inhibitory effect of tranexamic acid on blood clot breakdown, large studies of the use of tranexamic acid have not shown an increase in the risk of venous or arterial thrombosis, even in people who had previously experienced thrombosis under other circumstances.

Special populations
Tranexamic acid is categorized as pregnancy category B. No harm has been found in animal studies.
Small amounts appear in breast milk if taken during lactation. If it is required for other reasons, breastfeeding may be continued.
In kidney impairment, tranexamic acid is not well studied </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Cortisone and can you explain it in depth? [/INST] Cortisone is a pregnene (21-carbon) steroid hormone. It is a naturally-occurring corticosteroid metabolite that is also used as a pharmaceutical prodrug; it is not synthesized in the adrenal glands. Cortisol is converted by the action of the enzyme corticosteroid 11-beta-dehydrogenase isozyme 2 into the inactive metabolite cortisone, particularly in the kidneys. Cortisone is converted back to the active steroid cortisol by the action of the enzyme 11β-Hydroxysteroid dehydrogenase type 1, particularly in the liver.
The term "cortisone" is frequently misused to mean either any corticosteroid or hydrocortisone, which is actually another name for cortisol. Many who speak of receiving a "cortisone shot" or taking "cortisone" are actually receiving hydrocortisone or one of many other, much more potent synthetic corticosteroids; it is unlikely that the drug administered is actually cortisone.
Cortisone can be administered as a prodrug, meaning it has to be converted by the body (specifically the liver, converting it into cortisol) after administration to be effective. It is used to treat a variety of ailments and can be administered intravenously, orally, intra-articularly (into a joint), or transcutaneously. Cortisone suppresses various elements of the immune system, thus reducing inflammation and attendant pain and swelling.  Risks exist, in particular in the long-term use of cortisone. However, using cortisone only results in very mild activity, and very often more potent steroids are used instead.

Effects and uses
Cortisone itself is inactive. It must be converted to cortisol by the action of 11β-Hydroxysteroid dehydrogenase type 1. This primarily happens in the liver, the main site at which cortisone becomes cortisol after oral or systemic injection, and can thus have a pharmacological effect. After application to the skin or injection into a joint, local cells that express 11β-hydroxysteroid dehydrogenase type 1 instead convert it to active cortisol.
A cortisone injection may provide short-term pain relief and may reduce the swelling from inflammation of a joint, tendon, or bursa in, for example, the joints of the knee, elbow and shoulder and into a broken coccyx.Cortisone is also used by dermatologists to treat keloids, relieve the symptoms of eczema and atopic dermatitis, and stop the development of sarcoidosis.

Side effects
Oral use of cortisone has a number of potential systemic adverse effects, including asthma, hyperglycemia, insulin resistance, diabetes mellitus, osteoporosis, anxiety, depression, amenorrhoea, cataracts, glaucoma, Cushings syndrome, increased risk of infections and impaired growth. With topical application, it can lead to thinning of the skin, impaired wound healing, increased skin pigmentation, tendon rupture and skin infections (including abscesses).

History
Cortisone was first identified by the American chemists Edward Calvin Kendall and Harold L. Mason while researching at the Mayo Clinic. During the discovery process, cortisone was known as compound E (while cortisol was known as compound F).
In 1949, Philip S. Hench and colleagues discovered that large doses of injected cortisone were effective in the treatment of patients with severe rheumatoid arthritis. Kendall was awarded the 1950 Nobel Prize for Physiology or Medicine along with Philip Showalter Hench and Tadeusz Reichstein for the discovery of the structure and function of adrenal cortex hormones including cortisone. Both Reichstein and the team of O. Wintersteiner and J. Pfiffner had separately isolated the compound prior to the discovery made by Mason and Kendall, but failed to recognize its biological significance. Masons contributions to the crystallization and characterization of the compound have generally been forgotten outside of the Mayo Clinic.Cortisone was first produced commercially by Merck & Co. in 1948 or 1949. On September 30, 1949, Percy Julian announced an improvement in the process of producing cortisone from bile acids. This eliminated the need to use osmium tetroxide, a rare, expensive, and dangerous chemical. In the UK in the early 1950s, John Cornforth and Kenneth Callow at the National Institute for Medical Research collaborated with Glaxo to produce cortisone from hecogenin from sisal plants.

Production
Cortisone is one of several end-products of a process called steroidogenesis. This process starts with the synthesis of cholesterol, which then proceeds through a series of modifications in the adrenal gland to become any one of many steroid hormones. One end-product of this pathway is cortisol. For cortisol to be released from the adrenal gland, a cascade of signaling occurs. Corticotropin-releasing hormone released from the hypothalamus stimulates corticotrophs in the anterior pituitary to release ACTH, which relays the signal to the adrenal cortex. Here, the zona fasciculata and zona reticularis, in response to ACTH, secrete glucocorticoids, in particular cortisol. In various peripheral tissues, notably the kidneys, cortisol is inactivated to cortisone by the enzyme corticosteroid 11-beta-dehydrogenase isozyme 2. This is crucial because cortisol is a potent mineralocorticoid and would cause havoc with electrolyte levels (raising blood sodium and lowering blood potassium levels) and raise blood pressure if it were not inactivated in the kidneys.Because cortisone must be converted to cortisol before being active as a glucocorticoid, its activity is less than simply administering cortisol directly (80–90%).

Popular culture
Addiction to cortisone was the subject of the 1956 motion picture Bigger Than Life, produced by and starring James Mason. Though it was a box-office flop upon its initial release, many modern critics hail the film as a masterpiece and brilliant indictment of contemporary attitudes toward mental illness and addiction. In 1963, Jean-Luc Godard named it one of the ten greatest American sound films ever made.John F. Kennedy was regularly administered corticosteroids such as cortisone as a treatment for Addisons disease.

See also
Biology portal
 Medicine portal
Central serous retinopathy
Corticosterol

Notes
Bibliography
Bonagura J., DVM;  et al. (2000). Current Veterinary Therapy. Vol. 13. pp. 321–381.
Ingle DJ (October 1950). "The biologic properties of cortisone: a review". J. Clin. Endocrinol </s>


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<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Zileuton and can you explain it in depth? [/INST] Zileuton (trade name Zyflo) is an orally active inhibitor of 5-lipoxygenase, and thus inhibits leukotrienes (LTB4, LTC4, LTD4, and LTE4) formation, used for the maintenance treatment of asthma.  Zileuton was introduced in 1996 by Abbott Laboratories and is now marketed in two formulations by Cornerstone Therapeutics Inc. under the brand names Zyflo and Zyflo CR.  The original immediate-release formulation, Zyflo, is taken four times per day. The extended-release formulation, Zyflo CR, is taken twice daily.
Although the 600 mg immediate release tablet (Zyflo) and extended release formulation of zileuton are still available (Zyflo CR), the 300 mg immediate release tablet was withdrawn from the U.S. market on February 12, 2008.

Pharmacotherapy
Indications and dosing
Zileuton is indicated for the prophylaxis and chronic treatment of asthma in adults and children 12 years of age and older.  Zileuton is not indicated for use in the reversal of bronchospasm in acute asthma attacks. Therapy with zileuton can be continued during acute exacerbations of asthma.
The recommended dose of Zyflo is one 600 mg tablet, four times per day.  The tablets may be split in half to make them easier to swallow.  The recommended dose of Zyflo CR is two 600 mg extended-release tablets twice daily, within one hour after morning and evening meals, for a daily dose of 2400 mg.  Do not split Zyflo CR tablets in half.
Related compounds include montelukast (Singulair) and zafirlukast (Accolate). These two compounds are leukotriene receptor antagonists which block the action of specific leukotrienes, while zileuton inhibits leukotriene formation.

ResearchResearch on mice suggests that Zileuton used alone or in combination with imatinib may inhibit chronic myeloid leukemia (CML). It has also been researched in a mouse model of dementia.

Contraindications and warnings
The most serious side effect of Zyflo and Zyflo CR is a potential elevation of liver enzymes (in 2% of patients).  Therefore, zileuton is contraindicated in patients with active liver disease or persistent hepatic function enzymes elevations greater than three times the upper limit of normal.  Hepatic function should be assessed prior to initiating Zyflo CR, monthly for the first 3 months, every 2–3 months for the remainder of the first year, and periodically thereafter.
Neuropsychiatric events, including sleep disorders and behavioral changes, may occur with Zyflo and Zyflo CR.  Patients should be instructed to notify their healthcare provider if neuropsychiatric events occur while using Zyflo or Zyflo CR.
Zileuton is a weak inhibitor of CYP1A2 and thus has three clinically important drug interactions, which include increasing theophylline, and propranolol levels.  It has been shown to lower theophylline clearance significantly, doubling the AUC and prolonging half-life by nearly 25%. Because of theophyllines relation to caffeine (both being a methylxanthine, and theophylline being a metabolite of caffeine), caffeines metabolism and clearance may also be reduced, but there are no drug interaction studies between zileuton and caffeine. The R-isomer of warfarin metabolism and clearance is mainly affected by zileuton, while the S-isomer is not (because of metabolism via different enzymes). This can lead to an increase in prothrombin time.

Chemistry
Zileuton is an active oral inhibitor of the enzyme 5-lipoxygenase, which forms leukotrienes, 5-hydroxyeicosatetraenoic acid, and 5-oxo-eicosatetraenoic acid from arachidonic acid.  The chemical name of zileuton is (±)-1-(1-Benzo[b]thien-2-ylethyl)-l-hydroxyurea.The molecular formula of zileuton is C11H12N2O2S with a molecular weight of 236.29. The formulation from the manufacturer is a racemic mixture of R(+) and S(-) enantiomers.

Pharmacokinetics
Following oral administration zileuton is rapidly absorbed with a mean time to peak blood serum concentration of 1.7 hours and an average half-life elimination of 2.5 hours. Blood plasma concentrations are proportional to dose, whereas the absolute bioavailability is unknown.
The apparent volume of distribution of zileuton is approximately 1.2 L/kg. Zileuton is 93% bound to plasma proteins, primarily to albumin, with minor binding to alpha-1-acid glycoprotein.
Elimination of zileuton is primarily through metabolites in the urine (~95%) with the feces accounting for the next largest amount (~2%). The drug is metabolized by the cytochrome P450 enzymes: CYP1A2, 2C9, and 3A4.

Adverse effects
The most common adverse reactions reported by patients treated with Zyflo CR were sinusitis (6.5%), nausea (5%), and pharyngolaryngeal pain (5%) vs. placebo, 4%, 1.5%, and 4% respectively.

Interactions
Drug interactions
Zileuton is a minor substrate of CYP1A2, 2C8/9, 3A4, and a weak inhibitor of CYP 1A2 </s>


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