Identification and anti-androgenic activity of the metabolites of 17alpha-acetoxy-6-chloropregna-4,6-diene-3,20-dione (chlormadinone acetate) in the rat, rabbit, dog and man

Chlormadinone acetate (CMA) in oral contraception--a new opportunity

Chlormadinone acetate (CMA) is a derivative of naturally secreted progesterone that shows high affinity and activity at the progesterone receptor. It has an anti-estrogenic effect and, in contrast to natural progesterone, shows moderate anti-androgenic properties. CMA acts by blocking androgen receptors in target organs and by reducing the activity of skin 5alpha-reductase. It suppresses gonadotropin secretion and thereby reduces ovarian and adrenal androgen production. CMA shows high contraceptive efficacy by inhibiting ovulation due to its ability to suppress or disrupt endogenous gonadotropin secretion and, by this, inhibits follicular growth and maturation. In addition, it suppresses endometrial thickness and increases the viscosity of cervical mucus. Pharmacokinetic studies have shown rapid and almost complete absorption after oral administration, and CMA is being bound to albumin rather than SHBG (Sex-Hormone-Binding-Globulin). Multiple dosing studies have demonstrated that steady state is reached by day 7 after oral administration with peak plasma concentrations in the region of 2 ng/ml. After a single dose of CMA the half-life time is around 34 hours and after multiple dose administration approximately 38 hours. Safety studies have indicated that CMA has no clinically relevant effect on a wide range of metabolic parameters in normal subjects. Further studies in groups at high thromboembolic risk have shown that CMA alone produces a relative risk of 0.8 which is not considered significant. These results indicated the potential for CMA to be combined with ethinylestradiol in an oral contraceptive which provides highly effective contraception and excellent cycle control.

Ethinylestradiol/Chlormadinone Acetate

Ethinylestradiol/chlormadinone acetate 0.03/2mg (EE/CMA) is a combined monophasic contraceptive pill with antiandrogenic properties. In a large, noncomparative, multicentre trial (< or =24 cycles of treatment per woman) and two (6- and 12-cycle) postmarketing surveillance studies, EE/CMA was effective in preventing pregnancy. EE/CMA was significantly more effective than EE/levonorgestrel 0.03/0.15 mg/day in treating women with mild-to-moderate papulopustular acne of the face and related disorders in a randomised, single-blind, multicentre trial. EE/CMA was well tolerated in clinical trials and the postmarketing surveillance studies. Adverse events were those commonly reported with oral contraceptives. As expected, the most common menstrual disturbances were breakthrough bleeding, spotting and amenorrhoea.

Progestogens with antiandrogenic properties

Chlormadinone acetate, cyproterone acetate and dienogest are potent, orally active progestogens, which have antiandrogenic instead of partial androgenic activity. They act mainly by blocking androgen receptors in target organs, but also reduce the activity of skin 5alpha-reductase, the enzyme responsible for converting testosterone to the more potent androgen, 5alpha-dihydrotestosterone, in sebaceous glands and hair follicles. Chlormadinone acetate and cyproterone acetate also suppress gonadotropin secretion, thereby reducing ovarian and adrenal androgen production. Combined oral contraceptives (COCs) containing antiandrogenic progestogens provide highly effective contraception (gross and adjusted Pearl indices: 0-0.7 and 0-0.3, respectively) with excellent cycle control. Furthermore, COCs containing 2mg of chlormadinone acetate or cyproterone acetate plus 30 or 35 microg of ethinylestradiol produced improvement or resolution of seborrhoea in 80% of users, acne in 59-70%, hirsutism in 36% and androgen-related alopecia in up to 86%. These COCs are generally well tolerated, the main adverse effects being nonspecific or as expected for a COC (headache, breast tenderness and nausea). They have no clinically relevant effects on metabolic or liver functions or on bodyweight. Effects on mood and libido are uncommon (<3.5% and <6% of women, respectively). COCs containing antiandrogenic progestogens are likely to be particularly valuable in women with pre-existing androgen-related disorders who require contraception. They also increase the choice of products available for women with normal skin and hair who are concerned about the possibility of developing seborrhoea or acne with other COCs.

Pharmacokinetics and biliary excretion of osaterone acetate, a new steroidal antiandrogen, in dogs

The pharmacokinetics and biliary excretion of osaterone acetate (17alpha-acetoxy-6-chloro-2-oxa-4,6-pregnadiene-3,20-dione; OA), a new steroidal antiandrogen, were investigated in intact dogs and biliary fistula dogs after bolus intravenous administration of (14)C-labeled drug. In intact dogs, OA exhibited a biexponential disposition with a very long half-life of 197.9 +/- 109.9 h. OA accounted for almost all the plasma radioactivity. The major route of excretion was in feces via the bile. One-third of the radioactivity in the bile was due to OA. The major biliary metabolite was identified as a glucuronide of 17alpha-acetoxy-6-chloro-21-hydroxy-2-oxa-4,6-pregnadiene-3,20-dione. A significant amount of biliary recycling occurs in dogs.

Androgenic and anti-androgenic effects of progesterone derivatives with different halogens as substituents at the C-6 position

The pharmacological activities of four pregnane derivatives: 17alpha-hydroxy-16beta-methylpregna-4,6-diene-3,20-dio ne (7), 17alpha-acetoxy-16beta-methylpregna-4,6-diene-3,20-dio ne (8), 17alpha-acetoxy-6-bromo-16beta-methylpregna-4,6-diene- 3,20-dione (10), and 17alpha-acetoxy-6-chloro-16beta-methylpregna-4,6-diene -3,20-dione (11), were determined. The derivatives were evaluated on gonadectomized male hamster flank organs and seminal vesicles. The results indicate that topical applications of testosterone (T) on the flank organs increased the diameter of the pigmented spot. Similarly, the same phenomenon occurred on the glands treated with compound 11, whereas compound 10 decreased the size of the spot significantly. In this study, we determined the effects of several new steroids on the conversion of T to DHT in flank organs and seminal vesicles. The results show that compound 10 inhibited T conversion to DHT, but compound 11, at a dose of 200 microg, stimulated T conversion in both flank organs and seminal vesicles. However, when 2 mg of compound 11 was applied, it inhibited the conversion of T to DHT, suggesting that this compound also represses gonadotropin release. The difference between compounds 10 and 11 involves the electronegativity of the halogen at the C-6 position of the progesterone skeleton. These data clearly indicate that by decreasing the electronegativity of the halogen at C-6 (compound 10), 5alpha-reductase is inhibited in both tissues and at different pHs. On the other hand, when the electronegativity of the halogen atom was increased (11), there was a much lower inhibitory effect on the conversion of T to DHT.

Relative potency of antiandrogens with reference to intracellular testosterone in the rat prostate

Mechanisms of relative potency in direct action of antiandrogens have not been fully elucidated. Using castrated rats, the effects of antiandrogens on the prostatic weight gain induced by exogenous testosterone (T), and on T uptake into prostatic cells were examined. Tested antiandrogens were cyproterone acetate, chlormadinone acetate, a new steroidal antiandrogen, 17acetoxy-6-chloro-2-oxa-4,6-pregnadiene-3,20-dione (TZP-4238), and one nonsteroidal type, flutamide (FL). Suppression of prostatic weight gain, T uptake and serum concentrations of compounds, correlated well each other among steroidal antiandrogens, while FL was five times more active in suppressing weight gain than TZP-4238, associated with a lower nuclear distribution of androgen. The results suggest that 1) suppression of T uptake is a major and common mechanism of steroidal antiandrogens and the relative potency is attributable to pharmacokinetic characteristics in vivo, and 2) FL suppress s nuclear T uptake more specifically than steroidal antiandrogens.