Flutamide

src: www.cheap-generic.co

Flutamide, sold under the brand name Eulexin among others, is a nonsteroidal antiandrogen (NSAA) which is used primarily to treat prostate cancer. It is also used in the treatment of androgen-dependent conditions like acne, excessive hair growth, and high androgen levels in women. It is taken by mouth, usually three times per day.

Side effects in men include breast tenderness and enlargement, feminization, sexual dysfunction, and hot flashes. Conversely, the drug has fewer side effects and is better-tolerated in women. Diarrhea and elevated liver enzymes can occur in both sexes. Rarely, flutamide can cause liver damage, lung disease, sensitivity to light, elevated methemoglobin, elevated sulfhemoglobin, and deficient neutrophils. Numerous cases of liver failure and death have been reported, which has limited the use of flutamide.

Flutamide acts as a selective antagonist of the androgen receptor (AR), competing with androgens like testosterone and dihydrotestosterone (DHT) for binding to ARs in tissues like the prostate gland. By doing so, it prevents their effects and stops them from stimulating prostate cancer cells to grow. Flutamide is a prodrug to a more active form. Flutamide and its active form stay in the body for a relatively short time, which makes it necessary to take flutamide multiple times per day.

Flutamide was discovered in 1967 and was first introduced for medical use in 1983. It became available in the United States in 1989. The drug has largely been replaced by newer and improved NSAAs, namely bicalutamide and enzalutamide, due to their better efficacy, tolerability, safety, and dosing frequency (once per day), and is now relatively little-used.

Video Flutamide

Medical uses

Prostate cancer

GnRH is released by the hypothalamus in a pulsatile fashion; this causes the anterior pituitary gland to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH stimulates the testes to produce testosterone, which is metabolized to DHT by the enzyme 5?-reductase.

DHT, and to a significantly smaller extent, testosterone, stimulate prostate cancer cells to grow. Therefore, blocking these androgens can provide powerful treatment for prostate cancer, especially metastatic disease. Normally administered are GnRH analogues, such as leuprorelin or cetrorelix. Although GnRH agonists stimulate the same receptors that GnRH does, since they are present continuously and not in a pulsatile manner, they serve to inhibit the pituitary gland and therefore block the whole chain. However, they initially cause a surge in activity; this is not solely a theoretical risk but may cause the cancer to flare. Flutamide was initially used at the beginning of GnRH agonist therapy to block this surge, and it and other NSAAs continue in this use. In contrast to GnRH agonists, GnRH antagonists don't cause an initial androgen surge, and are gradually replacing GnRH agonists in clinical use.

There have been studies to investigate the benefit of adding an antiandrogen to surgical orchiectomy or its continued use with a GnRH analogue (combined androgen blockade (CAB)). Adding antiandrogens to orchiectomy showed no benefit, while a small benefit was shown with adding antiandrogens to GnRH analogues.

Unfortunately, therapies which lower testosterone levels, such as orchiectomy or GnRH analogue administration, also have significant side effects. Compared to these therapies, treatment with antiandrogens exhibits "fewer hot flashes, less of an effect on libido, less muscle wasting, fewer personality changes, and less bone loss." However, antiandrogen therapy alone is less effective than surgery. Nevertheless, given the advanced age of many with prostate cancer, as well as other features, many men may choose antiandrogen therapy alone for a better quality of life.

Flutamide has been found to be similarly effective in the treatment of prostate cancer to bicalutamide, although indications of inferior efficacy, including greater compensatory increases in testosterone levels and greater reductions in PSA levels with bicalutamide, were observed. The drug, at a dosage of 750 mg/day (250 mg three times daily), has also been found to be equivalent in effectiveness to 250 mg/day oral cyproterone acetate as a monotherapy in the treatment of prostate cancer in a large-scale clinical trial of 310 patients, though its side effect and toxicity profiles (including gynecomastia, diarrhea, nausea, loss of appetite, and liver disturbances) were regarded as considerably worse than those of cyproterone acetate.

Skin and hair conditions

Flutamide has been researched and used extensively in the treatment of androgen-dependent skin and hair conditions in women including acne, seborrhea, hirsutism, and scalp hair loss, as well as in hyperandrogenism (e.g., in polycystic ovary syndrome or congenital adrenal hyperplasia), and is effective in improving the symptoms of these conditions. The dosages used are lower than those used in the treatment of prostate cancer. Although flutamide continues to be used for these indications, its use in recent years has been limited due to the risk of potentially fatal hepatotoxicity, and it is no longer recommended as a first- or second-line therapy. The related NSAA bicalutamide has also been found to be effective in the treatment of hirsutism in women and appears to have comparable effectiveness to that of flutamide, but has a far lower and only small risk of hepatotoxicity in comparison.

Acne and seborrhea

Flutamide has been found to be effective in the treatment of acne and seborrhea in women in a number of studies. In a long-term study of 230 women with acne, 211 of whom also had seborrhea, very-low-dose flutamide alone or in combination with an oral contraceptive caused a marked decrease in acne and seborrhea after 6 months of treatment, with maximal effect by 1 year of treatment and benefits maintained in the years thereafter. In the study, 97% of the women reported satisfaction with the control of their acne with flutamide. In another study, flutamide decreased acne and seborrhea scores by 80% in only 3 months. In contrast, spironolactone decreased symptoms by only 40% in the same time period, suggesting superior effectiveness for flutamide for these indications. Flutamide has, in general, been found to reduce symptoms of acne by as much as 90%, with several studies showing complete clearance.

Excessive hair growth

Flutamide has been found to be effective in the treatment of hirsutism (excessive body/facial growth) in numerous studies. It possesses moderate effectiveness for this indication, and the overall quality of the evidence is considered to be moderate. The drug shows equivalent or superior effectiveness to other antiandrogens including spironolactone, cyproterone acetate, and finasteride in the treatment of hirsutism, although its relatively high risk of hepatotoxicity makes it unfavorable compared to these other options. A study found that multiple dosages of flutamide significantly reduced hirsutism in women with polycystic ovary syndrome and that there were no significant differences in the effectiveness for dosages of 125 mg/day, 250 mg/day, and 500 mg/day. This supports the use of flutamide at lower doses for hirsutism without loss of effectiveness, which may help to lower the risk of hepatotoxicity. However, the risk has been found to remain even at very low doses.

Scalp hair loss

Flutamide has been found to be effective in the treatment of female pattern hair loss in a number of studies. In one study of 101 pre- and postmenopausal women, flutamide alone or in combination with an oral contraceptive produced a marked decrease in hair loss scores after 1 year of treatment, with maximum effect after 2 years of treatment and benefits maintained for another 2 years. In a small study of flutamide with an oral contraceptive, the drug caused an increase in cosmetically acceptance hair density in 6 of 7 women with diffuse scalp hair loss. In a comparative study, flutamide significantly improved scalp hair growth (21% reduction in Ludwig scores) in hyperandrogenic women after 1 year of treatment whereas cyproterone acetate and finasteride failed to do so.

Transgender hormone therapy

Flutamide has been used as a component of feminizing hormone therapy for transgender women. However, its use for this purpose is discouraged due to reports of hepatotoxicity in prostate cancer patients at comparable doses.

Maps Flutamide

Side effects

The side effects of flutamide are sex-dependent. In men, a variety of side effects related to androgen deprivation may occur, the most common being gynecomastia and breast tenderness. Others include hot flashes, decreased muscle mass, decreased bone mass and an associated increased risk of fractures, depression, and sexual dysfunction including reduced libido and erectile dysfunction. In women, flutamide is, generally, relatively well-tolerated, and does not interfere with ovulation. The only common side effect reported with flutamide in women is dry skin (75%), which is attributable to diminished androgen-mediated sebum production. General side effects that may occur in either sex include dizziness, anorexia, gastrointestinal side effects such as nausea, vomiting, and diarrhea, a greenish-bluish discoloration of the urine, and hepatic changes. Because flutamide is a pure antiandrogen, unlike steroidal antiandrogens like cyproterone acetate and megestrol acetate (which additionally possess progestogenic activity), it does not appear to have a risk of cardiovascular side effects (e.g., thromboembolism) or fluid retention.

Gynecomastia

Flutamide, as a monotherapy, causes gynecomastia and breast tenderness in most men. However, more than 90% of cases of gynecomastia with NSAAs including flutamide are mild to moderate. Tamoxifen, a selective estrogen receptor modulator (SERM) with predominantly antiestrogenic actions, can counteract flutamide-induced gynecomastia and breast pain in men.

Diarrhea

Diarrhea is more common and sometimes more severe with flutamide than with other NSAAs. In a comparative trial of combined androgen blockade for prostate cancer, the rate of diarrhea was 26% for flutamide and 12% for bicalutamide. Moreover, 6% of flutamide-treated patients discontinued the drug due to diarrhea, whereas only 0.5% of bicalutamide-treated patients did so. In the case of antiandrogen monotherapy for prostate cancer, the rates of diarrhea are 5-20% for flutamide, 2-5% for bicalutamide, and 2-4% for nilutamide. In contrast to diarrhea, the rates of nausea and vomiting are similar among the three drugs.

Rare reactions

Liver toxicity

Although rare, flutamide has been associated with severe hepatotoxicity and death. By 1996, 46 cases of severe cholestatic hepatitis had been reported, with 20 fatalities. There have been continued case reports since, including liver transplants and death. Based on the number of prescriptions written, the rate of serious hepatotoxicity associated with flutamide treatment is estimated to be 0.03% (3 per 10,000). However, other researchers have suggested that the incidence of significant hepatotoxicity may be as high as 6 to 9%. Another source reported a rate of 0.36%. Flutamide is also associated with liver enzyme elevations in 42 to 62% of patients. The risk of hepatotoxicity with flutamide treatment is far higher than with nilutamide or bicalutamide. Lower dosages of the drug appear to have a reduced but still significant risk. Liver function should be monitored regularly with liver function tests during flutamide treatment. In addition, due to the high risk of serious hepatotoxicity, flutamide should not be used in the absence of a serious indication.

The mechanism of action of flutamide-induced hepatotoxicity is thought to be due to mitochondrial toxicity. Specifically, flutamide and particularly its major metabolite hydroxyflutamide inhibit enzymes in the mitochondrial electron transport chain in hepatocytes, including respiratory complexes I (NADH ubiquinone oxidoreductase), II (succinate dehydrogenase), and V (ATP synthase), and thereby reduce cellular respiration via ATP depletion and hence decrease cell survival. Inhibition of taurocholate (a bile acid) efflux has also been implicated in flutamide-induced hepatotoxicity. In contrast to flutamide and hydroxyflutamide, which severely compromise hepatocyte cellular respiration in vitro, bicalutamide does not significantly do so at the same concentrations and is regarded as non-mitotoxic. It is thought that the nitroaromatic group of flutamide and hydroxyflutamide enhance their mitochondrial toxicity; bicalutamide, in contrast, possesses a cyano group in place of the nitro moiety, greatly reducing the potential for such toxicity.

The combination of paracetamol (acetaminophen) and flutamide may result in additive to synergistic hepatotoxicity, indicating a potential drug interaction.

Others

Flutamide has also been associated with interstitial pneumonitis (which can progress to pulmonary fibrosis). The incidence of interstitial pneumonitis with flutamide was found to be 0.04% (4 per 10,000) in a large clinical cohort of 41,700 prostate cancer patients. A variety of case reports have associated flutamide with photosensitivity. Flutamide has been associated with several case reports of methemoglobinemia. Bicalutamide does not share this risk with flutamide. Flutamide has also been associated with reports of sulfhemoglobinemia and neutropenia.

Identification of a Novel Glutathione Conjugate of Flutamide in ...

src: dmd.aspetjournals.org

Pharmacology

Pharmacodynamics

Antiandrogenic activity

Flutamide acts as a selective, competitive, silent antagonist of the androgen receptor (AR). Its active metabolite, hydroxyflutamide, has between 10- to 25-fold higher affinity for the AR than does flutamide, and hence is a more powerful antiandrogen in comparison. However, at high concentrations, unlike flutamide, hydroxyflutamide is able to weakly activate the AR. Flutamide has far lower affinity for the AR than do steroidal antiandrogens like spironolactone and cyproterone acetate, and it is a relatively weak antiandrogen in terms of potency by weight, but the large dosages at which flutamide is used appear to compensate for this. In accordance with its selectivity for the AR, flutamide possesses no progestogenic, (direct) estrogenic, glucocorticoid, or antigonadotropic activity. However, it can have some indirect estrogenic effects via increased levels of estradiol secondary to AR blockade, and this involved in the gynecomastia it can produce. Because flutamide does not have any estrogenic, progestogenic, or antigonadotropic activity, the drug does not cause menstrual irregularities in women. This is in contrast to steroidal antiandrogens like spironolactone and cyproterone acetate. Similarly to nilutamide, bicalutamide, and enzalutamide, flutamide crosses the blood-brain barrier and exerts central antiandrogen actions.

Flutamide has been found to be slightly more potent than cyproterone acetate and substantially more potent than spironolactone as an antiandrogen in rats. This is in spite of the fact that it has on the order of 10-fold lower affinity for the AR relative to cyproterone acetate. Hydroxyflutamide shows about 2- to 4-fold lower affinity for the rat and human AR than does bicalutamide. In addition, whereas bicalutamide has an elimination half-life of around 6 days, hydroxyflutamide has an elimination half-life of only 8 to 10 hours, a roughly 17-fold difference. In accordance, at dosages of 50 mg/day bicalutamide and 750 mg/day flutamide (a 15-fold difference), circulating levels of flutamide at steady-state have been found to be approximately 7.5-fold lower than those of bicalutamide. Moreover, whereas flutamide at this dosage has been found to produce a 75% reduction in prostate-specific antigen levels in men with prostate cancer, a fall of 90% has been demonstrated with this dosage of bicalutamide. In accordance, 50 mg/day bicalutamide has been found to possess equivalent or superior effectiveness to 750 mg/day flutamide in a large clinical trial for prostate cancer. Also, bicalutamide has been shown to be 5-fold more potent than flutamide in rats and 50-fold more potent than flutamide in dogs. Taken together, flutamide appears to be a considerably less potent and efficacious antiandrogen than is bicalutamide.

CYP17A1 inhibition

Flutamide and hydroxyflutamide have been found in vitro to inhibit CYP17A1 (17?-hydroxylase/17,20-lyase), an enzyme which is required for the biosynthesis of androgens. In accordance, flutamide has been found to slightly but significantly lower androgen levels in GnRH analogue-treated male prostate cancer patients and women with polycystic ovary syndrome. As such, flutamide is a weak inhibitor of androgen biosynthesis. However, the clinical significance of this action may be limited when flutamide is given without a GnRH analogue to non-castrated men, as the drug markedly elevates testosterone levels into the high normal male range via prevention of AR activation-mediated negative feedback on the hypothalamic-pituitary-gonadal axis in this context.

Other activities

In addition to its antiandrogenic activity, flutamide has been identified as a putative ligand of the aryl hydrocarbon receptor.

Pharmacokinetics

The absorption of flutamide is complete upon oral ingestion. Food has no effect on the bioavailability of flutamide. Steady-state levels of hydroxyflutamide, the active form of flutamide, are achieved after 2 to 4 days administration. Levels of hydroxyflutamide are approximately 50-fold higher than those of flutamide at steady-state. The plasma protein binding of flutamide and hydroxyflutamide is high; 94 to 96% and 92 to 94%, respectively. Flutamide is metabolized by CYP1A2 (via ?-hydroxylation) in the liver during first-pass metabolism to its main metabolite hydroxyflutamide (which accounts for 23% of an oral dose of flutamide one hour post-ingestion), and to at least five other, minor metabolites. Flutamide is excreted in various forms in the urine, the primary form being 2-amino-5-nitro-4-(trifluoromethyl)phenol.

Flutamide has a fairly short elimination half-life of 5 to 6 hours. However, the elimination half-life of its active form, hydroxyflutamide, is somewhat longer at about 8 to 10 ours. Although hydroxyflutamide has an elimination half-life of 8 to 10 hours in elderly men, it has been reported to possess a shorter elimination half-life in younger men. The elimination half-lives of flutamide and hydroxyflutamide are regarded as too short to allow for once-daily dosing, and the drug is instead administered three times daily at 8-hour intervals. In contrast, the newer NSAAs nilutamide, bicalutamide, and enzalutamide all have much longer half-lives, and this allows for once-daily administration in their cases.

Flutamide prostate cancer drug (anti-androgen) molecule. Skeletal ...

src: c8.alamy.com

Chemistry

Unlike the hormones with which it competes, flutamide is not a steroid; rather, it is a substituted anilide. Hence, it is described as nonsteroidal in order to distinguish it from older steroidal antiandrogens such as cyproterone acetate and megestrol acetate.

Synthesis

Bioactivation of Flutamide Metabolites by Human Liver Microsomes ...

src: dmd.aspetjournals.org

History

Flutamide was first synthesized in 1967 by Neri and colleagues at Schering Plough Corporation. It was originally synthesized as a bacteriostatic agent, but was subsequently, and serendipitously found to possess antiandrogen activity. The code name of flutamide during development was SCH-13521. Clinical research of the drug began in 1971, and it was first marketed in 1983, specifically in West Germany under the brand name Flugerel. Flutamide was not introduced in the United States until 1989; it was specifically approved by the U.S. Food and Drug Administration for the treatment of metastatic prostate cancer in combination with a gonadotropin-releasing hormone (GnRH) analogue. The drug was first studied for the treatment of hirsutism in women in women in 1991. Flutamide was the first NSAA to be introduced, and was followed by nilutamide in 1989 and then bicalutamide in 1995.

src: dmd.aspetjournals.org

Society and culture

Generic names

Flutamide is the generic name of the drug and its INN, USAN, BAN, DCF, and JAN. Its names in Latin, German, and Spanish are flutamidum, flutamid, and flutamida, respectively.

Brand names

Brand names of flutamide include or have included Cebatrol, Cytomid, Drogenil, Etaconil, Eulexin, Flucinom, Flumid, Flutacan, Flutamid, Flutamida, Flutamin, Flutan, Flutaplex, Flutasin, Fugerel, Profamid, and Sebatrol, among others.

Availability

Flutamide is marketed widely throughout the world, including in the United States, Canada, Europe, Australia, New Zealand, South Africa, Central and South America, East and Southeast Asia, India, and the Middle East.

Cytomid, Flutamide | Buy Cytomid, Flutamide

src: www.express-buy.co

Research

Benign prostatic hyperplasia

Flutamide has been studied in the treatment of benign prostatic hyperplasia in men in several clinical studies. It has been found to reduce prostate volume by about 25%, which is comparable to the reduction achieved with the 5?-reductase inhibitor finasteride. Unfortunately, it has been associated with side effects in these studies including gynecomastia and breast tenderness (in about 50% of patients), gastrointestinal disturbances such as nausea, diarrhea, and flatulence, and hepatotoxicity, although sexual function including libido and erectile potency were maintained.

Bulimia nervosa

Flutamide has been studied in the treatment of bulimia nervosa in women.

src: dmd.aspetjournals.org

References

src: www.buypharma1.com

Flutamide

Sabtu, 17 Februari 2018

Flutamide

Video Flutamide