Pharmacological profile of RU 58642, a potent systemic antiandrogen for the treatment of androgen-dependent disorders.

The pharmacological profile of RU 58642, a new non-steroidal antiandrogen was investigated both in vitro and in vivo. In vitro, the compound displays a strong and specific affinity for androgen receptor. In vivo, its antiandrogenic activity was evaluated in castrated rat supplemented with testosterone propionate and in intact animals on prostate, seminal vesicles weight and serum levels of testosterone by oral and subcutaneous route. In castrated rats RU 58642 induced a significant decrease in prostate weight at a dose as low as 0.3 mg/kg whatever the route of administration. In intact rats its activity was compared to that of other non-steroidal antiandrogens such as flutamide, nilutamide and bicalutamide. RU 58642 proved to be significantly more potent than the reference compounds in reducing prostate weight: 3-30 times orally and 3-100 times subcutaneously, and thus the most potent antiandrogen to date to our knowledge. These results suggest that this compound may be very useful in the treatment of systemic androgen-dependent diseases.

Preliminary pharmacokinetics and metabolism of novel non-steroidal antiandrogens in the rat: relation of their systemic activity to the formation of a common metabolite.

The non-steroidal antiandrogens, RU 58841 and RU 56187 are amongst the most active of a new series of N-substituted aryl hydantoins or thiohydantoins. Their pharmacokinetics and principal metabolic profiles have been evaluated in rat plasma after intravenous administration of a 10 mg/kg dose. Both compounds disappear relatively rapidly from the plasma (elimination half-life of the order of 1 h), but they form a common metabolite, the N-desalkyl derivative, RU 56279, which is eliminated much more slowly. The percentage transformations of each into RU 56279, estimated from the AUCs of the metabolite compared with the AUC obtained after administration of RU 56279 itself, were respectively 1% and 77%. In parallel, their in vivo activity, as well as that of their metabolites, was determined with respect to parameters related to systemic antiandrogenic effects (prostate and seminal vesicle weights). The results showed that: (1) the common metabolite, RU 56279, is clearly antiandrogenic; (2) there appears to be a relationship between the percentage formation of this metabolite and the systemic antiandrogenic activity of the compounds. Thus, the pharmacological profile of RU 58841 which displays a potent local antiandrogenic activity without systemic effects can be related to its very low propensity to form the N-desalkyl metabolite.

Non-steroidal antiandrogens: synthesis and biological profile of high-affinity ligands for the androgen receptor.

New N-substituted arylthiohydantoin antiandrogens were synthesized. These compounds presented exceptionally high relative binding affinities (RBAs) for the rat androgen receptor (AR): up to 3 times that of testosterone (T) and 100 times the RBAs of non-steroidal antiandrogens such as flutamide, Casodex and Anandron. Furthermore, unlike available markers for AR, they were totally devoid of any binding to the other steroid receptors. RU 59063, the molecule with the highest RBA, was tritiated. When it was compared to [3H]T for the assay of rat, mouse, hamster and human AR, it gave rise to the same number of binding sites but its K alpha (6 x 10(9) M-1) for rat and human AR were, respectively 3 and 8 times higher than that of T. Moreover RU 59063, unlike T, was devoid of any specific binding to human plasma. In vivo, these compounds displayed antiandrogenic activity while being devoid of any agonistic effect. Thus, RU 56187, given orally in castrated male animals, prevented in a dose-dependent manner the effects of 3 mg/kg testosterone propionate (TP) on mouse renal ornithine decarboxylase (acute test) and of 0.5 mg/kg TP on rat prostate weight (chronic test). In these two models, its ED50 was 0.6 and 1 mg/kg, respectively. In the intact rat, when given alone, it inhibited dose-dependently the effect of endogenous androgens on the seminal vesicles (ED50 approximately 1 mg/kg) and prostate (ED50 approximately 3 mg/kg) weights. These results suggest that these new compounds may be useful as specific markers for the androgen receptor as well as for the treatment of androgen-dependent diseases or disorders such as prostate cancer, acne, hirsutism and male pattern baldness.

RU 58841, a new specific topical antiandrogen: a candidate of choice for the treatment of acne, androgenetic alopecia and hirsutism.

A new topically active non-steroidal antiandrogen, RU 58841 has been synthesized. It displays high affinity for the hamster prostate and flank organ (F.O.) androgen receptors. In vivo, when topically applied, it exerts a potent dose-dependent regression of F.O. area at a dose as low as 1 microgram/animal while being devoid of antiandrogenic activity on deep accessory sex organs and of any effect on testosterone level up to 100 micrograms/animal. In the same species, after subcutaneous administration, it induces at the dose of 300 micrograms/animal, a small decrease in F.O. area equivalent to that of 1 microgram applied topically and a weak systemic activity. In intact rats, no effects were observed up to 1 microgram/animal whatever the route of administration. These results suggest that RU 58841 might useful for the topical treatment of androgen-dependent skin disorders such as acne, androgenetic alopecia and hirsutism.

In-vivo inhibition of the preovulatory LH surge by substance P and in-vitro modulation of gonadotrophin-releasing hormone-induced LH release by substance P, oestradiol and progesterone in the female rat.

The effects of substance P (SP) on the preovulatory surge of LH and on the inhibitory and stimulatory effects of oestradiol-17 beta and progesterone on gonadotrophin-releasing hormone (GnRH)-induced LH release were investigated in vivo and in vitro in the rat. A single s.c. injection of 100 micrograms SP at 12.00 h on the day of pro-oestrus significantly decreased the preovulatory surge of LH. In vitro, the inhibitory effect of oestradiol-17 beta on GnRH-induced LH release was not modified by treatment with SP. The stimulatory effect of progesterone on GnRH-induced LH release was reduced by treatment with SP. It is concluded that SP may play a modulatory role in the neuroendocrine control of the preovulatory LH surge.

Photosubstitution of cymantrenylalanine as a tool in peptide chemistry. Synthesis and biological activity of new GnRH analogs.

Beyond its aromatic character and important hydrophobicity, cymantrenylalanine, a metallocenic amino-acid, can be easily photosubstituted with phosphine and phosphite ligands to readily yield new analogs with different hydrophobicity and steric hindrance. The incorporation of phosphine and phosphite ligands is described. As an illustration of the offered possibilities, the synthesis and the biological activity of two new GnRH analogs modified in position 6 are reported.