Gordon O. Potts

Trilostane, an orally active inhibitor of steroid biosynthesis.

Trilostane is a competitive inhibitor of 3beta-hydroxysteroid dehydrogenase. In vitro, the drug inhibits conversion of pregnenolone to progesterone but does not alter conversion of cholesterol to pregnenolone nor progesterone to corticoid hormones. When given orally to rats, trilostane inhibits corticosterone and aldosterone production and elevates circulating levels of pregnenolone at doses lower than those that produce adrenal hypertrophy or inhibit gonadal steroidogenesis.

Pituitary Gonadotropin Inhibitory Activity of Danazol

A steroid danazol (17-alpha-Pregn-4-en-20-yno(23-d)-isoxazol-17-ol) possesses a marked separation of pituitary gonadotropin inhibitory activity from overt sex hormonal activities. The effect of danazol on fertility in the rat was determined. Danazol produced a dose-related decrease in the weights of ventral prostate seminal vesicles and testes of mature male rats when given orally at 80 mg/kg daily for 6 months - 1 year. It also produced highly significant decreases in the weights of sex accessory organs and testes. Mature female rats showed a similar dose-related effect on ovaries adrenals and thymus. Body weight and ovaries increased during treatment. Danazol was not progestational in the Clauberg assay when adminsitered orally at doses as high as 80Omg/kg. A dose of 20Omg/kg for 6 days following insemination was completely effective in preventing pregnancy.

Inhibition of Ovarian, Placental, and Adrenal Steroidogenesis in the Rhesus Monkey by Trilostane *

Trilostane inhibits adrenal, ovarian, and placental steroidogenesis when administered orally to rhesus monkeys. By inhibiting 3 beta-hydroxysteroid dehydrogenase activity, it causes an increase in circulating levels of pregnenolone. Trilostane reverses the stimulation of luteal progesterone production and the delay in onset on menstruation induced by human chorionic gonadotropin. In pregnant monkeys it reduces circulating progesterone levels and is an effective interceptive agent if given for 5 days beginning on day 16, 25, or 50 of gestation. Concurrent administration of progesterone prevents this interceptive effect. Trilostane reduces plasma cortisol levels at doses lower than those necessary to terminate pregnancy.

Win 32,729, a new, potent interceptive agent in rats and rhesus monkeys

Win 32,729 [(2 alpha, 4 alpha, 5 alpha, 17 beta)-4,5-epoxy-17-hydroxy-4,17-dimethyl-3-oxoandrostane-2-carbonitrile] is an orally active interceptive agent in rats and rhesus monkeys (M mulatta). A single oral dose of 48 mg/kg terminated gestation when given on Day 10 of pregnancy. When given orally for up to 5 days to pregnant monkeys, it terminated pregnancy in 26 of 34 animals at a dose of 50 mg/monkey (ca 7 mg/kg), in 18 of 24 at a dose of 100 mg/monkey (ca 14 mg/kg) and in all 6 at 250 mg/monkey (ca 35 mg/kg). It did not inhibit ACTH-stimulated glucocorticoid production at 50 mg/monkey but did at a dose of 250 mg/monkey. This preferential gonadal inhibition was not evident in rodents. While in most cases five oral medications of 50-100 mg were required to terminate gestation in 50-day pregnant monkeys, a single subcutaneous medication with 250 mg was also effective, terminating pregnancy in 7 of 7 monkeys.

Oral contraceptive activity of danazol in the rhesus monkey.

Danazol (17-alpha-Pregna-4-en-20-yno(23-d)-isoxazole-17-ol) inhibits pituitary gonadotropin secretion in rodents rhesus monkeys and humans. 24 female rhesus monkeys were medicated with danazol orally for 90 days in doses of 50 100 200 and 400mg per monkey per day. Danazol was completely effective in preventing pregnancy during the 90-day treatment period at doses of 200 and 400mg. At 100mg the drug was partially effective in preventing pregnancy and at 50 mg it was ineffective. Pregnancy rates in appropriate controls were very high 12 out of 14 monkeys became pregnant in the first month.

Inhibition of human placental progesterone synthesis and aromatase activity by synthetic steroidogenic inhibitors in vitro

The inhibitory effect in vitro of four synthetic steroids on enzyme systems of placental progesterone synthesis at term was analyzed. Cholesterol side chain cleavage enzyme (CSCC) was not influenced by azastene, trilostane, and WIN 32,729. A 50% inhibition of CSCC was found by 10 microM cyanoketone. The 3 beta-hydroxysteroid dehydrogenase was dose-dependently inhibited by azastene (I50 = 1 microM, trilostane (I50 = 4 nM), cyanoketone (I50 = 3 nM), and WIN 32,729 (I50 = 5 nM). A competitive inhibition of the 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSDH) by azastene (I50 = 0.6 microM), trilostane (I50 = 4.1 microM), cyanoketone (I50 = 0.6 microM), and WIN 32,729 (I50 = 1.5 microM) was observed. No difference in the effect of steroids on the 20 alpha-HSDH of early gestational and term placenta was found. The four steroidogenic inhibitors did not affect the activity of placental aromatase in vitro. Our results allow a comparison of inhibitory potencies of four steroidogenic inhibitors on different steroidogenic enzymes in vitro.

Andro-stanazole, a new orally active anabolic steroid.

Summary Andro-stanazole (17β-hydroxy-17α-methylandrostano[3,2-c] pyrazole) has been evaluated for its nitrogen-retaining and androgenic activities in castrated male rats. Orally, it appears to be 30 times more anabolic and 1/4 as androgenic as methyl-testosterone. Parenterally, it appears to be 1/20 as anabolic and 1/40 as androgenic as testosterone propionate. Andro-stanazole is clearly an agent which merits further investigation for oral administration to patients under conditions where maximum anabolic action with minimum androgenic side effects is desired.

A competitive radioligand assay for danazol (17α-pregn-4-en-20-yno[2,3-d]isoxazol-17-ol) using pregnant guinea pig plasma

Abstract A method is described for the radioligand assay of circulating levels of a novel, pituitary gonadotrophin inhibiting agent, danazol (17α-Pregn-4-en-20-yno[2,3-d]isoxazol-17-ol). The assay described is based upon the ability of danazol to bind avidly to pregnant guinea pig plasma proteins, a binding system hitherto considered highly specific for progesterone. Danazol is separated from progesterone and other possible interfering substances by paper chromatography. The method was used to measure danazol in a series of normal human subjects given the drug at 800 mg/day.

Myotrophic and Androgenic Activities of Androstanazole. A New Heterocyclic Steroid

Summary Myotrophic and androgenic activities of androstanazole have been evaluated using immature castrated male rats. The data indicate that androstanazole is 1/7 as myotrophic and 1/33 as androgenic as testosterone propionate when both agents are administered subcutaneously, whereas it is 2 times more myotrophic than. and 1/3 as androgenic as, methyltestosterone when the 2 agents are given orally. The data show that androstanazole is relatively more anabolic than androgenic regardless of route of administration. The results are discussed in light of nitrogen retention data previously reported for this compound.

A Model for the Evaluation of Estrogens: Withdrawal Bleeding in Ovariectomized Rhesus Monkeys

A system for evaluating estrogens in subhuman primates is presented. Estrone ethinyl estradiol mestranol Premarin diethylstilbestrol and pregpyrol (17alpha-pregn-4-en-20-yno(32-c)pyrazol-17-ol) were administered by gavage daily for 10 days at 4 different dose levels to ovariectomized rhesus monkeys. 10 mcg estradiol-17beta was injected for 10 days between experiments. Pregpyrol and estrone are considerably more potent in this species than in humans while the other estrogens showed relatively similar potencies which suggests that the conversion of estrone to estradiol may occur more readily in the rhesus monkey than in humans. The delay in the onset of withdrawal bleeding for each estrogen was comparable with that following estradiol-17beta. Evaluation of the perianal sex skin indicated that mestranol and pregpyrol produced an increase in color at a dose that did not cause bleeding. The observed uniformity of withdrawal bleeding permits a ready evaluation of the potency of an estrogen in the subhuman primate.