Biological Profile of Quingestanol Acetate

Abstract

Summary

Like other 3-enol ethers of δ⁴δ3-ketosteroids, 17α-ethynyl-19-nor-testo-sterone acetate-3-cyclopentyl enol ether (EN TACP) possesses unusual biological properties. ENTACP is approximately twice as active as its parent ketone (ENTA) in producing endometrial proliferation in the immature estrogen-primed rabbit. In stimulating uterine growth ENTACP behaves like a true estrogen whereas ENTA or 17α-ethynyl-19-nor-testosterone (ENT) act as impeded estrogens, androgens, or progestogens, yielding a shallow dose-response curve. While ENTACP was significantly more androgenic than ENTA or ENT, the three compounds were equipotent in producing masculinization of female fetuses. Although adrenal hypertrophy was noted, neither ENT or ENTACP affected the corticoidogenic response of the adrenals to ACTH. However, when steroid output was corrected for differences in adrenal weight, both compounds either reduced the capacity of the adrenal cortical tissue to respond to ACTH or the increase in adrenal size was not due to an increase in corticosteroid producing tissue. When administered postcoitally, ENTACP was slightly more effective than ENTA in interfering with pregnancy. This may have been related to the inherent estrogenicity of each compound. Unlike methyltestosterone-3-cyclopentyl enol ether, orally administered ENTACP is not stored in body fat and does not have prolonged biological activity.