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PubMed2002

Comparison of the clinical efficacy and safety of flutamide versus flutamide plus an oral contraceptive in the treatment of hirsutism.

OBJECTIVE: To compare the clinical, hormonal, biochemical and hemotological effects of flutamide versus flutamide plus an oral contraceptive (OC) in the treatment of hirsutism. PATIENTS: Eighty-four women with hirsutism were equally randomized to receive either flutamide or flutamide plus OC. DESIGN: Eighty-four women with hirsutism were recruited from patients presenting to our hospital. Each patient underwent a complete medical and gynecological examination as well as blood cell counts, biochemical and endocrine profiles. Hirsutism scores and laboratory tests were done during the 1st, 3rd and 6th months of therapy. Thirty-seven women in the flutamide group (taking 250 mg flutamide per day) and 32 women in the flutamide plus OC group (taking 250 mg flutamide plus 35 microg ethinyl estradiol and 2 mg cyproterone acetate per day) regularly followed the therapy regimens. RESULTS: There were no significant differences in Ferriman-Gallway scores at the beginning and at the end of the therapies between the two groups (p > 0.05). At the 6th month, the decreases in Ferriman-Gallway scores were significant in both flutamide (from 18.95 +/- 4.44 to 14.46 +/- 5.02; p < 0.05) and flutamide plus OC groups (from 19.94 +/- 4.31 to 15.58 +/- 4.28; p < 0.05). In the first group, 2 of 6 oligomenorrheic women had regular cycles at the end of the therapy. Oligomenorrhea in 8 women was all changed to regular cycles in the flutamide plus OC group. Regarding the hormonal profile, only in the second group were prolactin, free testosterone and dehydroepiandrosterone sulfate levels significantly decreased (p < 0.05). Hepatic function tests were significantly increased in both groups, but they were all within normal ranges. CONCLUSION: These data suggest that both therapies were similarly effective and safe in the treatment of hirsutism. In women with oligomenorrhea and/or needing contraception, adding an OC shows better results than flutamide treatment alone in providing regular cycles.

Administration, Oral↗
PubMed1999

[Flutamide-induced hepatic disorder and serum concentrations of flutamide and its metabolites in patients with prostate cancer].

Severe hepatotoxicity occurred in a prostate cancer patient treated with 375 mg of flutamide per day, 125 mg three times a day, for 11 weeks. Serial measurements of serum concentrations of flutamide and its metabolites in the patient showed an unusually high serum level and delayed elimination of flutamide and suggested decreased metabolic activity of oxidation of flutamide to OH-flutamide. In 37 patients with prostate cancer we periodically monitored the serum concentrations of flutamide as well as liver function parameters. In 2 patients, glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) elevated over 100 IU/L, and treatment with flutamide was discontinued. Slight elevation of GOT and GPT over 40 to 100 IU/L was also detected in 5 patients, and flutamide was withdrawn. The elevated GOT and GPT in these 7 patients recovered to the pretreatment levels after discontinuation of the treatment. In these patients with flutamide-induced hepatic disorders, the average serum concentration of flutamide was higher (2.76 times, and that of OH-flutamide was lower (0.76 times), as compared with patients who maintained normal liver function.

Aged↗
PubMed1993

A randomized phase II trial of flutamide vs chlormadinone acetate in previously untreated advanced prostatic cancer. The Japan Flutamide Study Group.

We have conducted a double-blind comparative study of flutamide and chlormadinone acetate (CMA) on patients with stage C or D prostatic cancer and with no prior experience of hormone therapy. This is believed to be the first such trial entered in the medical literature, fifty-four patients were randomly selected to undergo flutamide (p.o.) monotherapy at a daily dose of 375 mg, which was determined as the optimal dose in Japan in our previous phase II study. Forty-nine others were randomly selected to undergo CMA (p.o.) monotherapy at a daily dose of 100 mg, which is the most commonly used dosage in Japan for patients with prostatic cancer. Ultimately, 47 patients from the flutamide group and 40 patients from the CMA group were judged eligible, with efficacy being evaluated after 12 weeks of treatment. Similar objective responses were seen in both groups: 48.9% (95% confidence limits 34.1-63.9%) in the flutamide group, 45% (95% confidence limits 29.3-61.5%) in the CMA group. The response at each organ site was also similar between the groups. Serum prostatic specific antigen decreased by more than 50% of the abnormal pretreatment level in 87.5% of the flutamide group and in 85.7% of the CMA group. Serum luteinizing hormone, follicle-stimulating hormone, testosterone and 5 alpha-dihydrotestosterone decreased significantly in the CMA group, but increased significantly in the flutamide group. The serum testosterone level after 12 weeks of treatment was 0.955 +/- 0.13 ng/ml in the CMA group and 6.64 +/- 0.38 ng/ml in the flutamide group. The serum estradiol level also increased significantly in patients in the flutamide group. The serum prolactin level decreased significantly in the flutamide group, but increased significantly in the CMA group. Eight patients on flutamide manifested gynecomastia. Diarrhea and hepatic toxicity were observed in both groups, but only rarely, and were well tolerated. We have thus concluded that flutamide is as effective as CMA in maintaining libido and potency without decreasing testosterone levels.

Aged↗
PubMed2006

Flutamide metabolism in four different species in vitro and identification of flutamide metabolites in human patient urine by high performance liquid chromatography/tandem mass spectrometry.

A new metabolic scheme of flutamide is proposed in this article. Some patients treated with flutamide, a nonsteroidal antiandrogen, have developed severe hepatic dysfunction. Toxic metabolites have been proposed to be responsible for these negative effects. In this study, the qualitative aspects of the in vitro metabolism of flutamide in liver microsomes from human, dog, pig, and rat were evaluated. A direct comparison of the flutamide metabolism in liver and prostate microsomes from pig was made, and the in vivo metabolism of flutamide was investigated in urine from orally treated prostate cancer patients. Liquid chromatography/tandem mass spectrometry was used for analysis. The mass spectrometer was equipped with an electrospray interface and operated in the negative ion mode. In liver microsomes from pig, dog, and rat, extensive hydroxylation of flutamide occurred. One, two, or three hydroxy groups were attached, and isomeric forms were detected for both monohydroxylated and trihydroxylated drug. In pig liver microsomes, isomers of a third metabolite, hydroxylated 4-nitro-3-(trifluoromethyl)-aniline, were also found after incubation with either flutamide or 2-hydroxyflutamide. In human liver microsomes, the pharmacologically active 2-hydroxyflutamide was the only metabolite detected. Several phase I metabolites as well as four intact phase II metabolites could be recovered from the urine samples. For the first time in humans, glucuronic acid conjugates of hydroxylated 4-nitro-3-(trifluoromethyl)-aniline, and mono- and dihydroxylated flutamide were identified, together with hydroxylated 4-nitro-3-(trifluoromethyl)-aniline conjugated with sulfate. In addition, one mercapturic acid conjugate of hydroxylated flutamide, probably formed from flutamide via a reactive intermediate, was detected.

Androgen Antagonists↗
PubMed2003

Flutamide-induced hepatic dysfunction in relation to steady-state plasma concentrations of flutamide and its metabolites.

The frequency, severity, and outcome of flutamide-induced hepatic injury were prospectively evaluated in 55 patients with prostate cancer who received 125 mg of flutamide 3 times a day (daily dose: 375 mg) combined with an agonistic analogue of luteinizing hormone-releasing hormone. In addition, we examined plasma and urine concentrations of flutamide and its major metabolites 4 weeks after the beginning of flutamide therapy, and evaluated their significance in predicting flutamide-induced hepatic dysfunction. Hepatic function could be assessed in 50 patients and hepatic dysfunction during therapy was observed in 9 patients (18%); 3 patients (6%) were classified as having moderate liver dysfunction and 6 (12%) were classified as having mild liver dysfunction. The steady-state plasma levels of flutamide and its biologic active metabolite, hydroxyflutamide (OH-Flu), were not related to hepatic dysfunction. However, the concentration of another major metabolite, 4-nitro-3-(trifluoromethyl)phenylamine (FLU-1) was considerably higher in 2 patients who developed clinically significant hepatic dysfunction. These findings suggest that clinically significant hepatic dysfunction could be induced in patients with compromised flutamide metabolism, which leads to a high concentration of FLU-1. Based on results of this study, we propose that plasma FLU-1 levels are one of the predictive factors for flutamide-induced hepatic dysfunction. This hypothesis will be confirmed in a large-scale study.

Aged↗
PubMed2003

Metabolite profiles of flutamide in serum from patients with flutamide-induced hepatic dysfunction.

Hepatic dysfunction due to flutamide administration has been reported and this side effect often limits the use of the agent. The prediction of flutamide-induced hepatotoxicity is attributed to the proper use of the antiandrogen. In this study, we investigated whether hepatic dysfunction could be assessed by the metabolite profile in serum from patients receiving this drug. Serum samples were obtained from 15 patients with prostate cancer, 12 patients with no sign of hepatotoxicity and 3 patients with slight hepatic dysfunction during long-term flutamide treatment. We analyzed the metabolite profiles by LC/MS in selected ion monitoring mode and detected a new metabolite (M3) that was an oxidation product of flutamide. However, there were no consistent differences in the serum flutamide metabolites between patients with normal function and those suffering hepatic dysfunction. The metabolite profiles in the beta-glucuronidase-treated serum showed a similar pattern between normal functioning and dysfunctional groups. Thus, the profile of flutamide metabolites determined in serum may not contribute to the risk prediction of flutamide-related hepatotoxicity.

Aged↗
PubMed2004

[Examination of the change in plasma concentration of OH-flutamide in low-dose flutamide (250 mg/day) monotherapy for prostate cancer patients].

An examination of the change in plasma concentration of OH-flutamide in low-dose flutamide (250 mg/day) monotherapy for 5 prostate cancer patients was performed. We treated 5 patients diagnosed with prostate cancer between September and November 2002. The plasma concentrations of OH-flutamide, PSA and AST/ALT were measured before and after low-dose flutamide monotherapy was started. The plasma concentrations of OH-flutamide were stable in the third day after medication was started, and even when compared with the plasma concentrations of OH-flutamide 375 mg/day, there was no significant difference. Although at the observation period was short, PSA fell favorably in all patients. The AST/ALT were in the normal range in all patients. The low-does flutamide therapy has been one of medical treatments if its safety and effectiveness has been demonstrated.

Aged↗
PubMed1996

Effect of flutamide and flutamide plus castration on prostate size in patients with previously untreated prostate cancer.

OBJECTIVES: Transrectal ultrasonography (TRUS) was used in previously untreated men with prostate cancer undergoing hormonal therapy to provide objective observations on the decrease in prostate size and to assess the usefulness of prostate size in estimating treatment response. METHODS: In this retrospective study, 31 patients with previously untreated prostate cancer (Stage T1c to D2) who received hormonal therapy (flutamide, n = 18; flutamide plus castration, n = 13) were followed with serial estimations of prostate size by TRUS and by serum prostate-specific antigen (PSA). RESULTS: In both treatment groups, the major decreases in prostate size were noted within the first 6 months of therapy, whereas further follow-up examinations failed to show statistically significant changes. Prostate size decreased by 48% in men treated with flutamide, whereas those treated with flutamide plus castration showed a statistically significant greater decrease, mean of 56% (P < or = 0.01). Six patients (33%) in the flutamide group and 5 (38%) men in the total androgen deprivation group ultimately failed therapy as indicated by a rising PSA level. Only 55% (n = 6) of the patients who progressed showed an increase in prostate size. CONCLUSIONS: Total androgen deprivation in comparison to flutamide alone caused a larger reduction in prostate size. As a marker of hormonal failure, a rising PSA was more sensitive than an increase in prostate size.

Aged↗
PubMed2004

Flutamide-metformin plus ethinylestradiol-drospirenone for lipolysis and antiatherogenesis in young women with ovarian hyperandrogenism: the key role of early, low-dose flutamide.

A low-dose combination of flutamide-metformin and ethinylestradiol-drospirenone was recently found to reduce the excess of total and abdominal fat, to diminish the deficit in lean mass, and to attenuate the dysadipocytokinemia of young women with ovarian hyperandrogenism, a variant of polycystic ovary syndrome. We questioned the need to give flutamide, an androgen receptor blocker, together with an oral contraceptive that contains drospirenone, a progestin claimed to have antiandrogen properties. The additive effects of low-dose flutamide (62.5 mg/d) were assessed over 3 months in young patients with hyperinsulinemic ovarian hyperandrogenism (n = 40; age, approximately 17 yr; body mass index, approximately 22 kg/m(2)); all participants started on metformin (850 mg/d) and a fourth-generation contraceptive (ethinylestradiol 30 microg plus drospirenone 3 mg, 21 d/month), and they were randomized to receive flutamide in addition (n = 20) or not (n = 20). Fasting blood glucose, serum insulin, lipid profile, testosterone, adiponectin, and IL-6 were determined at baseline and after 3 months, together with body composition (by dual x-ray absorptiometry) and with Doppler assessment of ovarian arterial resistance. At start, the pulsatility and resistance indices of ovarian arteries were elevated. By comparison of 3-month changes between randomized subgroups, the addition of low-dose flutamide was found to have consistently (more) normalizing effects on low-density lipoprotein cholesterol, IL-6, and adiponectin, lean body mass, total and abdominal fat mass, and arterial flow in the ovaries. In conclusion, low-dose flutamide is herewith identified as a pivotal component within a first contraceptive combination therapy that has been shown to attenuate the hypoadiponectinemia, ovarian vascular hyperresistance, lean mass deficit, and central adiposity of young women with polycystic ovary syndrome. Finally, these data challenge any claim that drospirenone, as currently used in a contraceptive, is a clinically significant antiandrogen.

Adiponectin↗
PubMed1997

In vitro evaluation of flutamide-carrier systems. Part 1: Preparation and evaluation of flutamide systems with polyvinyl pyrrolidone and polyethylene glycol 4000 and 6000.

Coprecipitates were prepared using different ratios of flutamide with polyvinyl pyrrolidine (PVP), polyethylene glycol (PEG) 4000 and 6000. Drug solubility in carrier solutions, thin layer chromatography (TLC), differential scanning calorimetry (DSC), infra-red spectroscopy (IR), uniformity of drug content, drug dissolution from its respective systems and effect of aging on the physico-chemical parameters of stored flutamide-polymer system were studied. PEG 6000 was found to be the most efficient polymer in increasing both the solubility and the release rate of flutamide. Interaction was found to be complete in certain ratios of drug/polymer systems. The dissolution pattern of flutamide from all the prepared systems appeared to fit a first order mechanism. Physico-chemical parameters of flutamide/carrier systems were not influenced by storage.

Antineoplastic Agents, Hormonal↗
PubMed1988

Plasma levels of hydroxy-flutamide in patients with prostatic cancer receiving the combined hormonal therapy: an LHRH agonist and flutamide.

The present study describes a method for the measurement of the plasma levels of hydroxy-flutamide (Flu-OH), the biologically active and main circulating metabolite of flutamide. We have observed that two to four hours after oral administration of 250 mg of flutamide to healthy young men, as well as to patients with prostate cancer, the plasma concentration of Flu-OH reaches a peak at approximately 1.7 microM. The plasma concentration of Flu-OH measured at months 6, 12, and 18 of treatment shows a minimal basal level of 3.4 microM with a maximal increase at 6.8 to 8.5 microM at 2 to 4 hours. Since the serum levels of testosterone in these patients are approximately 1 nM, the levels of the active antiandrogen are at a 5000- to 10000-fold excess. However, due to the low affinity of the antiandrogen for the androgen receptor, it is extremely important to maintain this concentration of the antiandrogen in plasma constant.

Adult↗
PubMedDate not supplied

Hydroxypropyl-beta-cyclodextrin-flutamide inclusion complex. II. Oral and intravenous pharmacokinetics of flutamide in the rat.

PURPOSE: The objective of this work was to determine the pharmacokinetics of flutamide (FLT) and its active metabolite, 2-hydroxy-flutamide (FLT-2-OH) in rats, following formulation in hydroxypropyl-Beta-cyclodextrin (FLT-HPBetaCyD). METHODS: The pharmacokinetics of FLT-HPBetaCyD, FLT-suspension (FLT-SUSP), and FLT-solution (FLT-COSOLV) were compared after oral (p.o.) and intravenous (i.v.) administration, respectively. In a non-crossover design, male Sprague-Dawley rats received each formulation as a single oral dose [15 mg (54 micro mol) FLT/kg] by oral gavage, or single i.v. dose [1.6 mg (5.8 micro mol) FLT/kg] via an indwelling jugular vein catheter. FLT and its metabolite, FLT-2-OH, were determined in plasma and urine aliquots by an HPLC method. RESULTS: In a preliminary in vitro experiment, using the dialysis bag dissolution method, 80% of a test dose of FLT was released from lyophilized FLT-HPBetaCyD into simulated gastric juice within 2 h, compared to less than 5% release from commercial FLT powder (FLT-SUSP). Following oral FLT-HPBetaCyD, the mean area under the plasma concentration curve (AUC(0- infinity)) for FLT, was 1580 +/- 228 ng x h/mL, with the maximum plasma concentration (Cmax; 1297 +/- 127 ng/mL) at 0.5 h (Tmax) after administration. The AUC(0- infinity) and C(max) were significantly higher than after FLT-SUSP (AUC(0- infinity) 748 +/- 206 ng x h/mL; C(max) 230 +/- 111 ng/mL and T(max) 2.33 +/- 0.29 h, respectively). After i.v. FLT-HPBetaCyD, the FLT AUC(0- infinity) was 1355 +/- 162 ng x h/mL, compared to 1421 +/- 283 ng x h/mL for FLT-COSOLV. FLT C(max) were 714 +/- 144 mL/h and 735 +/- 88 mL/h, respectively. The respective volumes of distribution (V(z)) were 369 +/- 191 mL and 242 +/- 25 mL. The plasma concentration-time profile and pharmacokinetic parameters of FLT after FLT-HPBetaCyD and FLT-COSOLV did not differ significantly. The pharmacokinetic parameters for FLT-2-OH were formulation independent after i.v. dosing, but AUC(0- infinity); C(max) and T(max), values were substantially greater with the FLT-HPBetaCyD in the oral study (40269 +/- 5875 ng x h/mL, 4062 +/- 502 ng/mL, and 3.50 +/- 0.41 h, respectively). CONCLUSIONS: FLT from FLT-HPBetaCyD was released rapidly into solution in vitro and in vivo. FLT-HPBetaCyD improved oral bioavailability relative to FLT-SUSP. Intravenous pharmacokinetic profiles for both FLT and FLT-2-OH were identical following either FLT-HPBetaCyD or FLT-COSOLV, indicating that the FLT-HPBetaCyD formulation behaved as a true solution.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMedDate not supplied

Effects of flutamide and hydroxy-flutamide on the growth of human benign prostatic hyperplasia cells in primary culture: a preliminary report.

Tissues from human benign prostatic hyperplasia [BPH] were collected from twelve patients undergoing routine transurethral resection of the prostate to relieve urine out-flow obstruction. Viable epithelial organoids were obtained after enzymatic digestion of the tissue. Primary cultures of epithelium were successfully maintained on collagen gel for up to 21 days. Immunocytochemical staining revealed that there was no expression of either desmin or vimentin in these cells; however, the anticytokeratin antibodies LP-34 (cytokeratins 4, 5, 6, 10, 13, 16, 17 and 18), LE-61 (cytokeratin 18) and CAM 5.2 (cytokeratins 7 and 8) all showed positive responses, indicating the epithelial nature of the cells. Cell growth was significantly increased in the presence of 3 x 10(-10) M testosterone propionate [TP] in the culture medium. The presence of the non-steroidal anti-androgens, Flutamide and Hydroxy-Flutamide [Flu-OH], in the concentration range 1.0-0.001 micrograms per ml of medium inhibited the growth in the presence of androgens in a dose-dependent manner. The anti-androgens failed to affect cell growth in the absence of TP. In view of these preliminary findings, it is postulated that the antiandrogens might be acting either by displacing the androgen from its receptor or alternately by inhibiting the activity of prostatic 5 alpha-reductase.

Aged↗
PubMed2001

Androgen-mediated development in male rat offspring exposed to flutamide in utero: permanence and correlation of early postnatal changes in anogenital distance and nipple retention with malformations in androgen-dependent tissues.

Male offspring exposed in utero to antiandrogens often display alterations in androgen-dependent developmental markers (e.g., anogenital distance [AGD], nipple retention) together with clearly adverse responses such as genital malformations and reproductive tract lesions. The objectives of this study were to determine whether in utero exposure to flutamide results in permanent changes in male AGD and nipple retention, characterize the dose-response relationship between flutamide-mediated alterations in these landmarks and clearly adverse antiandrogenic effects, and establish the predictive value and relationship between AGD and nipple retention, and other adverse manifestations. Male offspring were exposed in utero to 0, 6.25, 12.5, 25, or 50 mg/kg/day (po) of flutamide from gestation days 12 to 21. Offspring were uniquely identified at birth, and various androgen-mediated end points (AGD, areola/nipple retention, cryptorchidism, reproductive tract weights, and malformation incidence) were examined throughout life. In utero flutamide exposure significantly decreased the AGD on postnatal day (PND) 1 and increased areola/nipple retention in male rats on PND 13. Flutamide-induced alterations in AGD and areolae/nipples in early postnatal life correlated with a reduction in AGD and retained nipples observed in the adult. Prenatal flutamide exposure resulted in dose-responsive increases in cryptorchidism. Hypospadias were observed in all flutamide-exposed offspring. In utero flutamide exposure induced partial or complete prostate agenesis and decreased the weights of the seminal vesicles, levator ani bulbocavernosus (LABC) muscle, testes, and epididymides in a dose-dependent manner. Epididymal malformations were observed mainly in the 50 mg/kg/day flutamide dose group. In general, flutamide-induced alterations in dihydrotestosterone (DHT)- and testosterone (T)-dependent development each had similar respective dose-response curves. DHT-mediated development was more sensitive to in utero flutamide exposure than T-dependent processes. However, the dose-response curves for flutamide-induced changes in cryptorchidism and seminal vesicle weight were intermediate between the dose-response curves for DHT- and T-mediated development, indicating that proper development of these tissues may require both androgens. The LABC also displayed a dose-dependent decrease in weight that was similar to dose-response observed with seminal vesicle weight and was the most sensitive T-dependent end point measured. Flutamide-induced decreases in AGD predicted subsequent malformations as evidenced by logistic regression and receiver operator characteristic analysis of malformations versus AGD. However, the AGD that would predict a 10% incidence of seminal vesicle malformations is equivalent to a female AGD. An almost fully feminized phenotype of 10-12 nipples was observed in animals that had malformations in T-dependent tissues, whereas 6 or more nipples were observed in animals with malformation in DHT-dependent tissues. These data suggest that flutamide-mediated changes in AGD and nipple retention are not sensitive predictors of altered T-mediated development.

Anal Canal↗
PubMed2006

Effects of 17beta-estradiol and flutamide on inflammatory response and distant organ damage following trauma-hemorrhage in metestrus females.

We hypothesized that administration of androgen receptors antagonist flutamide following trauma-hemorrhage (T-H) in metestrus females will maintain immune function and reduce remote organ damage under those conditions. Female B57BL/J6 mice (metestrus state, 8-12 weeks old) underwent laparotomy and hemorrhagic shock (35.0+/-5.0 mmHg for 90 min) and then received 17beta-estradiol (E2; 50 microg/25 g), flutamide (625 microg/25 g), or E2 + flutamide. Four hours after resuscitation, plasma cytokine and chemokine (TNF-alpha, IL-6, IL-10, IFN-gamma, and MCP-1) concentrations and their release in vitro by hepatic and pulmonary tissue macrophages (M Phi) were determined by flow cytometry. Organ damage was assessed by edema formation (wet-to-dry weight ratio) and neutrophil infiltration [myeloperoxidase (MPO) activity]. Administration of E2, flutamide, or E2 + flutamide following T-H resulted in a significant decrease in systemic TNF-alpha, IL-6, and MCP-1 concentrations under those conditions. This was accompanied by significantly decreased in vitro TNF-alpha release by Kupffer cells after administration of E2, flutamide, or E2 + flutamide. The in vitro release of proinflammatory cytokines by alveolar M Phi, however, was reduced significantly only by the addition of E2 or E2 + flutamide but not by the addition of flutamide. A significant decrease in pulmonary and hepatic edema formation as well as neutrophil infiltration in the lung was observed after E2, flutamide and E2 + flutamide administration. In contrast, hepatic neutrophil infiltration was only significantly reduced following E2 and E2 + flutamide administration. Thus, although flutamide does not produce synergistic, salutary effects with E2, its administration in females following T-H also produces salutary effects on the immune and organ function, similar to E2 administration under those conditions.

Animals↗
PubMed1997

Metabolism of the antiandrogenic drug (Flutamide) by human CYP1A2.

The antiandrogenic drug, flutamide, is widely used in the treatment of carcinoma of the prostate. The present study examines the metabolism of flutamide by human liver microsomes and purified recombinant human cytochrome P450s (CYP), expressed as fusion proteins. These studies show the principal role of CYP1A2 in the metabolism of flutamide to 2-hydroxyflutamide. A minor metabolite is formed during the metabolism of flutamide by CYP3A4 in the presence of an excess of added purified NADPH-P450 reductase. The metabolism of flutamide is inhibited by low concentrations of alpha-naphthoflavone and ketoconazole. Other substrates of CYP1A2, such as phenacetin, imipramine, caffeine, and estradiol, are also inhibitors of flutamide metabolism by CYP1A2. Of interest is the inhibition of flutamide metabolism by its metabolite, 2-hydroxyflutamide, and the inhibition of the 2- and 4- hydroxylation of estradiol by flutamide. CV1 cells do not metabolize flutamide to 2-hydroxyflutamide. In assays performed using this cell line transfected with the cDNA for the androgen receptor, flutamide is a pure antagonist, and 2-hydroxyflutamide, while a more potent androgen receptor (AR) antagonist, activates the AR at higher concentrations. Stable expression of CYPIA2 in these CV1 cells causes flutamide to exhibit agonistic properties at higher concentrations, a behavior not exhibited by cells stably transfected only with the expression vector encoding the AR. These findings raise the possibility that increased conversion of flutamide to 2-hydroxyflutamide or accumulation of 2-hydroxyflutamide in cells may contribute to the anomalous responses to flutamide that are observed in some advanced prostate cancers.

Androgen Antagonists↗
PubMed1990

Flutamide has no effect on adrenal androgen response to acute ACTH stimulation in patients with prostatic cancer.

Basal levels and adrenocorticotropic hormone (ACTH)-induced increments (delta-values) of serum cortisol, dehydroepiandrosterone (DHA), dehydroepiandrosterone sulfate (DHAS), 4-androstene-3, 17-dione (A4), and 17-hydroxyprogesterone (170HP); basal testosterone (T), luteinizing hormone (LH), serum ASAT, gamma-GT, and albumin were measured in prostatic cancer patients before and after 6 months of treatment with LH-RH-agonist, with flutamide, and with LH-RH-agonist + flutamide, respectively. Basal DHA and DHAS were decreased during flutamide and LH-RH-agonist + flutamide treatment and basal A4 during treatment with LH-RH-agonist and with LH-RH-agonist + flutamide. Basal 170HP, T, and LH decreased during LH-RH-agonist and LH-RH-agonist + flutamide treatment and increased during single drug flutamide treatment. Slightly decreased delta cortisol values were observed during LH-RH-agonist and during flutamide treatment and slightly increased delta 170HP values during LH-RH-agonist and LH-RH-agonist + flutamide treatment. Values for delta DHA and delta A4 were completely unaffected by any of the treatment regimens. Elevated ASAT values were observed during treatment with flutamide and with LH-RH-agonist + flutamide. It is concluded that flutamide has no effect on the adrenal androgen response to acute ACTH stimulation.

Adrenocorticotropic Hormone↗
PubMed1997

Alteration by flutamide of neutrophil response to stimulation. Implications for tissue injury.

When activated, inflammatory cells such as polymorphonuclear leukocytes (PMNs) can damage isolated hepatocytes in vitro. These studies were performed to determine if flutamide activates PMNs. Flutamide (Eulexin) is an orally active, nonsteroidal antiandrogen that can cause liver injury associated with inflammation. Activation of PMNs was assessed from the production of superoxide anion and the release of myeloperoxidase in the presence or absence of flutamide and phorbol myristate acetate (PMA) or f-methionyl-leucyl-phenylalanine (fmlp). In addition, hepatocytes were cocultured with PMNs stimulated with PMA or fmlp in the presence or absence of flutamide, and cytotoxicity to hepatocytes was evaluated from the release of alanine aminotransferase into the medium. Flutamide alone did not stimulate the generation of superoxide anion by PMNs but potentiated its production in response to PMA. At lower concentrations of flutamide (i.e. 25 microM), there was a tendency toward increased release of myeloperoxidase, whereas at higher concentrations (i.e. 75-100 microM) flutamide inhibited degranulation in response to fmlp. In coculture with hepatocytes, PMNs exposed to either flutamide, fmlp, or PMA alone caused a significant increase in release of alanine aminotransferase. Hepatocellular toxicity caused by PMNs incubated with flutamide and PMA was additive and was not affected by the addition of superoxide dismutase and catalase. Flutamide had no significant effect on fmlp-induced injury in cocultures. These data indicate that flutamide alters the activation of PMNs by subsequent stimuli in vitro. In addition, in the presence of flutamide, minor PMN-mediated injury to isolated hepatocytes was observed.

Androgen Antagonists↗