Highly sensitive and specific time-resolved fluoroimmunoassay (TR-FIA) of cyproterone acetate and free cyproterone

We have developed a non-isotopic TR-FIA for Cyproterone acetate and Cyproterone in plasma. Synthesis of the biotinylated tracers, biotinylated Cyproterone acetate, and Cyproterone, as well as the preparation of anti-Cyproterone acetate and anti-Cyproterone antisera are reported. The specificity of anti-Cyproterone acetate antiserum resulting from the coupling of link bridge (link bridge between steroid and BSA), on the 3-position on the steroid skeleton, allowed to carry out the Cyproterone acetate assay directly on extracted plasma (without chromatography). On the other hand Cyproterone assays require a purification step, including extraction plus chromatography, because the plasma Cyproterone acetate concentrations in Cyproterone acetate-treated women are 200 times higher than for Cyproterone. Theses plasma TR-FIA of Cyproterone acetate and Cyproterone presented the advantage of needing only small doses of radioactivity for recovery controls, and better practicability related to the only existing RIA described to date.

Determination of megestrol acetate and cyproterone acetate in serum of patients with advanced breast cancer by high-performance liquid chromatography

A reversed-phase high-performance liquid chromatographic method with ultraviolet detection of megestrol acetate and cyproterone acetate in human sera is described. The proposed assay is linear up to 1400 ng/ml (r = 0.999) and has a detection limit of 5 ng/ml. Recoveries of both compounds in spiked sera were ca. 95%; inter-assay coefficients of variation were 4.0 and 3.1% and intra-assay values were 1.3 and 1.4%, respectively. For validation of the method we also developed a gas chromatographic-mass spectrometric method for both steroids. The results obtained by the two methods showed good correlation: for megestrol acetate r = 0.98, n = 31, p less than 0.0001, and for cyproterone acetate r = 0.94, n = 0, p less than 0.0001. Large inter-individual differences in the serum concentrations of both substances were found in groups of patients with metastatic breast cancer receiving the same oral load of either steroid.

Increase in H-Y antigen-positive lymphocytes in hirsute women: effects of cyproterone acetate and estradiol treatment

To investigate a possible relationship between lymphocyte H-Y antigen expression and plasma androgen concentrations in hirsute women, 27 hirsute women were studied. A significant increase in the percentage of H-Y-positive lymphocytes was found in both hirsute women with idiopathic hirsutism [13.4 +/- 2.9% (+/- SD); n = 15] and hirsute women with the polycystic ovary syndrome (13.0 +/- 2.8%; n = 12) compared to that in normal women (10.0 +/- 1.9%; n = 30; P less than 0.0005). Plasma testosterone and androstenedione concentrations, % H-Y+ lymphocytes, and hirsutism scores diminished during oral cyproterone acetate (50 mg/day) and percutaneous estradiol (3 mg/day) treatment. Significant correlations between % H-Y+ lymphocytes and hirsutism scores (P less than 0.001), % H-Y+ lymphocytes and plasma T concentrations (P less than 0.01) were found. We conclude that 1) women can produce H-Y antigen in the same way as men; 2) hirsutism is associated with an increase in H-Y antigen; and 3) the antiandrogen cyproterone acetate reduces H-Y antigen expression on lymphocytes.

Interactions of an anti-androgen (cyproterone acetate) with the androgen receptor system and its biological action in the rat ventral prostate

Male Wistar rats were castrated and implantated with testosterone-filled silastic depots (in vitro release rate: 60 micrograms/24 h) prior to treatment with 10 mg cyproterone acetate (CyAc) on day 1, and 5 mg on days 4, 7, 10 and 13. Animals were sacrificed on day 14. Control animals were treated identically, with the exception of CyAc administration. Blood was collected and the ventral prostates of 6-8 animals were pooled, homogenized and processed into cytosol and purified nuclei. Steroid determinations (CyAc, testosterone, 5 alpha-dihydrotestosterone (DHT), 5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-diol)) were performed by RIA. Specifically bound DHT (charcoal resistant DHT = CR-DHT) represents DHT values (RIA) following treatment of cytosol or nuclear extract with dextran coated charcoal. The androgen receptor was determined in cytosol and nuclear extract by 'exchange assay' using [3H]methyltrienolone (MT) (18 h, 15 degrees C). The main results were: 1) The steroid levels in plasma (testosterone, DHT, 3 alpha-diol) were in the range of untreated adult animals and not significantly influenced by the CyAc treatment. Final CyAc levels were 305 +/- 58 nmol/l (mean +/- SD, n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)

Cyproterone acetate as initial treatment and maintenance therapy for hirsutism

Thirty-four patients with hirsutism were treated for 9 months with 100 mg cyproterone acetate (CA) given on days 5-15 of the menstrual cycle together with a combination oral contraceptive containing 2 mg CA and 50 micrograms ethinyloestradiol (Diane) given on days 5-25 of the cycle. After 9 months treatment patients were randomised to a 12 month double-blind cross-over trial comparing Diane plus 25 mg CA with Diane plus placebo, to test the efficacy of low-dose CA as maintenance therapy. Thirty-one patients (92%) experienced moderate or good subjective improvement in hirsutism on high-dose CA, associated with a 40% mean overall improvement in objective hirsutism grade and 13% overall reduction in hair growth rate measured by a photographic technique. Minor or moderate side effects were experienced by 64% of patients and severe side effects by 11% at this dosage. There was a mean subjective relapse rate of 33% when patients were changed to low dose CA, and relapse rates were not significantly different between the two regimens with 28% relapsing on 25 mg CA + Diane and 48% on placebo and Diane (P less than 0.05). Despite significant subjective relapse with low-dose treatment there was no significant deterioration in objective hirsutism grade or hair growth rate determined photographically. Levels of plasma testosterone, sex hormone binding globulin, free testosterone (derived) and androstenedione fell significantly on high dose CA and this reduction was maintained during low dose therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

15-Hydroxycyproterone acetate and cyproterone acetate levels in plasma and urine

15 beta-Hydroxycyproterone acetate (15HOCPA) and cyproterone acetate (CPA) have been quantitated in human plasma and urine by a selective high-performance liquid chromatographic assay. The levels of 15HOCPA in plasma are generally twice those of its precursor CPA, although both compounds appear to have similar clearance rates. Approximately 6% of the dose is excreted into the urine, predominantly (greater than 90%) as the free form of 15HOCPA and CPA.

Plasma levels of levonorgestrel, gestodene, norethisterone and cyproterone acetate on single-dose subcutaneous administration in oily solution in the rat, beagle and rhesus monkey

This report describes the pharmacokinetics of levonorgestrel, gestodene, norethisterone and cyproterone acetate following subcutaneous administration of oily solutions in the rat, beagle dog and rhesus monkey. The plasma levels of the progestogens were measured by means of specific radioimmunoassays. Half-lives calculated for the disposition process of a particular metabolically unchanged drug in plasma revealed marked differences in different animal species. Furthermore, comparison of the different progestogens showed large variations in this parameter in all the animal species. It became obvious that there are physico-chemical properties as well as metabolic rate limitations effecting the release and elimination of synthetic progestogens administered in oily solution. The results are compared with the half-lives of these progestogens administered intravenously as reported previously. A prolongation of half-life as a result of the depot effect of subcutaneous administration was demonstrated for all the progestogens in the rat, the beagle dog and the rhesus monkey.

[Treatment of virilized women with intramuscular administration of cyproterone acetate]

Management of hirsutism with high-dose oral cyproterone acetate (CPA) is associated with a failure rate of about 30%. The present investigation analyses the efficacy of parenteral CPA administration in non-tumorous hyperandrogenism. Medium-dose CPA (300 mg) was injected intramuscularly once per month, followed by oral ethinylestradiol (40 micrograms daily) for 21 days in 42 patients (total of 293 treatment cycles). The onset of withdrawal bleeding was 3 to 8 days later. This regimen was used as primary therapy (group A; n = 18) as well as follow-up therapy in low-dose (group B; n = 10) and high-dose oral standard CPA failures (group C; n = 14). The following satisfactory or good response rates were observed in regard to hirsutism: group A 83,5%, group B 100%, group C 57%; seborrhea A and B 100%, C 89%; acne and androgenetic alopecia A and B and C 100%. Clinical side effects occurred in 20 patients; they corresponded in type and frequency to those elicited by the high-dose oral standard medication and resulted in termination of treatment in only 3 patients. Pilot studies regarding the pharmacokinetics of CPA as well as the effects on plasma total and free testosterone and prolactin failed to explain the therapeutic superiority of parenteral CPA (n = 7 women). Still, it may be concluded that intramuscular CPA administration represents a new and highly effective means of managing hirsute females.

Terminal half-lives in plasma and bioavailability of norethisterone, levonorgestrel, cyproterone acetate and gestodene in rats, beagles and rhesus monkeys

Norethisterone, levonorgestrel, cyproterone acetate and gestodene have been used for a long time in oral contraception and other indications, or are in the process of development for such indications. However, very little is known concerning the bioavailability and plasma levels of unmetabolized gestagens in the animal species used for chronic toxicity testing and pharmacological investigation. In this study the gestagens were administered intravenously, subcutaneously and orally to rats, beagles and rhesus monkeys. The drug plasma levels were determined by specific radioimmunoassay. The half-life of the terminal disposition phase was calculated following intravenous administration, and the extent of bioavailability was determined from the area under the drug level curves following subcutaneous and oral administration. The terminal half-lives of a particular compound in different animal species differed considerably. Furthermore, comparison of the different gestagens showed large variations in this parameter in all the animal species. In addition, inter-animal species comparison of a particular substance, and comparison of different substances in a single species, also showed great differences in bioavailability. The results are compared with the corresponding parameters in man. This investigation illustrates the fundamental problems inherent in the extrapolation of the results of toxicity studies and pharmacological investigations in animals, to man. The best tolerance and the lowest degree of pharmacological effect seem to occur where the bioavailability of a gestagen is poor and its terminal half-life short.

Cyproterone acetate, testosterone, LH, FSH, and prolactin levels in plasma after intramuscular application of cyproterone acetate in patients with prostatic cancer

Five patients with prostatic carcinoma (stages T3N0M0) were injected intramuscularly with 300 mg of cyproterone acetate (CPA) (Androcur-Depot) at weekly intervals. The concentrations of CPA, testosterone, LH, FSH, and prolactin in plasma after the first, third, and fifth injection were measured by specific radioimmunoassays. After five injections of Androcur-Depot, CPA levels were slightly higher than in previous determinations, suggesting that a balance between active substance release from the depot and excretion could be achieved after eight to twelve injections, with only slightly higher levels of active substance attained. Testosterone levels clearly were reduced after the first injection of CPA, but the lowest values were registered only after three injections. Plasma concentrations of FSH and LH were slightly diminished, whereas the prolactin level increased after CPA therapy.

Transfer of cyproterone acetate to the milk of lactating women

Cyproterone acetate (CPA) was administered in a dose of 50 mg to 6 lactating women delivered by caesarean section. All women had to discontinue breast feeding the day before treatment. Prior to, and 3 and 9 hours after ingestion of the drug, plasma and milk specimens were taken. Total daily milk volume was recorded. Concentration of CPA in plasma and milk was determined by RIA. The plasma levels of CPA were in the range of 65 - 450 ng/ml at 3 h and 76 - 270 ng/ml after 9 hours. The respective concentrations in milk were 16 - 260 ng/ml (3 h) and 55 - 130 ng/ml (9 h). The plasma/milk ratio of drug concentration varied between 1.1 and 9.3 (3 h) and 0.6 and 2.9 (9 h). The mean of all values amounted to 2.8 +/- 2.3. Taking into account a daily milk production of 1050 +/- 230 ml, 0.2% of the dose administered (range: 0.06 - 0.41 % of dose) would have been transferred to the newborn. Use of the CPA-containing oral contraceptive DIANER (2 mg of CPA + 50 microgram of ethinyl estradiol) by nursing women would therefore result in the transfer of 1 microgram/kg to the child.

[Bioavailability of cyproterone acetate after oral and intramuscular application in men (author's transl)]

Cyproterone acetate was administered orally and intramuscularly to 5 male patients. The level of the active substance in plasma was monitored at intervals during the period of application using radioimmunoassay specific for cyproterone acetate. The areas under the drug level curves were similar after oral and intramuscular application of cyproterone acetate when taking into consideration the different doses used. Accordingly, cyproterone acetate is not dependent upon a "first-pass" effect. The bioavailability of the active substance was complete following oral application.

Plasma levels of active ingredients after single and repeated administration of a new oral contraceptive containing 2 mg of cyproterone acetate and 50 micrograms of ethinyl estradiol (DIANE) to five young women

Peripheral plasma from five young women was analyzed for cyproterone acetate and ethinyl estradiol during a period of 96 hours duration after single oral intake of a coated tablet of DIANE (2 mg of cyproterone acetate + 50 micrograms of ethinyl estradiol), and during a treatment cycle of 21 days during which the formulation was given daily. Radioimmunoassays were utilized for quantifications. A maximum concentration of 11.0 +/- 3.4 ng of cyproterone acetate/ml plasma was found 1.6 +/- 0.6 hours after a single administration of DIANE. Postmaximal disposition took place in two phases with half-lives of 1.9 +/- 0.6 hours and 2.2 +/- 0.2 days. The maximum level of 0.08 +/- 0.03 ng of ethinyl estradiol/ml plasma was found 1.6 +/- 0.6 hours after such single administration. Following commencement of a daily oral intake of DIANE a steady state was reached by the 5th to 8th days, during which 24 hours after each dose cyproterone acetate concentrations were found to be 2.4 +/- 0.7 times higher than at the corresponding time after a single administration. Accordingly, after the first third of the 21 day treatment cycle an almost constant plasma level was reached indicating an equilibrium of intake and elimination. Except for a change in the mean terminal half life after multiple dosing, there was evidently no change in the kinetics of cyproterone acetate. No pointers to an accumulation of ethinyl estradiol upon daily administration of DIANE could be found.

Sex hormone binding globulin: binding capacity and studies on the binding of cyproterone acetate and other steroids

Sex hormone binding globulin in blood is quantitated by ammonium sulphate precipitation technique with two radioactive ligands, [3H]testosterone and [3H5dihydrotestosterone. Plasma levels in normal men, normal women, women taking oral contraceptives containing oestrogens, and pregnant women are presented, measured with both ligands. Binding experiments with these ligands and several competing steroids show marked differences in displacement ability. For cyproterone acetate 100-500 ng per tube is required to obtain even a slight displacement of the radioactive ligands.

Radioimmunological determination of cyproterone acetate

A sensitive and specific radioimmunoassay for cyproterone acetate in serum has been developed. Antiserum was raised in rabbits by immunization with a conjugate of cyproterone acetate-11 alpha-hemisuccinate and bovine serum albumin. Radioactive tracers with high specific activities were synthesized by coupling the hemisuccinate with [3H]-tyrosine methyl ester of [125I]-iodohistamine. Competition studies with substances structurally related to cyproterone acetate have revealed that the structures of ring A and B are mainly responsible for binding to the antibody.

Metabolism and mode of action of androgens in target tissues of male rats. V. Uptake and metabolism of cyproterone acetate and its influence on the uptake and metabolism of testosterone and 5alpha-dihydrotestosterone in target organs and peripheral tissues

In order to get more information on the mode of action of anti-androgens, two series with low but biologically active doses of cyproterone acetate were started. In the first experiments 12 mug of [3H]cyproterone acetate was injected intravenously into adult rats castrated 3 days before treatment. Thirty min after injection the radioactivity uptake in the target organs and other tissues was measured. The metabolites were separated by thin layer chromatography. A large pool of radioactivity could be shown in the liver. Thin layer chromatography revealed that in this pool cyproterone acetate had been converted by more than 80% to one metabolite. In blood plasma, too, the metabolite accounted for the major part of radioactivity. When compared to skeletal muscle, the prostate, seminal vesicles, and m. bulbocavernosus and m. levator ani accumulated more radioactivity. Within 30 min unchanged cyproterone acetate was retained selectively thus showing its relative high affinity to target organs. In a second experimental series, adult castrated male rats were given 10 mug of cyproterone acetate intravenously 30 min before the injection of [3H]testosterone or [3H]5alpha-dihydrotestosterone. Under this condition androgen uptake in target tissues was reduced to about 70% of the control values. The data parallel the results of in vivo studies on cytosol receptor displacement of androgens by cyproterone acetate. In agreement with previous investigators no significant influence of the anti-androgen on androgen metabolism was observed. The importance of the findings concerning the mode of anti-androgen action is discussed.