17-ALPHA-HYDROXYPROGESTERONE-CAPROATE: A NEW SUBSTANCE WITH PROLONGED PROGESTATIONAL ACTIVITY. A COMPARISON WITH CHEMICALLY PURE PROGESTERONE*

Abstract

IT IS the purpose of this paper to compare the progestational activity of a new substance, 17-alpha-hydroxyprogesterone-17-caproate, with the activity of chemically pure progesterone. 17-Alpha-hydroxyprogesterone-caproate is of interest because of the following factors: 1. 17-Alpha-hydroxyprogesterone, without esterification, has no progestational activity (1, 2). 2. The 17-ester (caproate or acetate), however, shows marked progestational activity in animal experiments (1). 3. The 17-ester (caproate or acetate), however, shows marked progestational activity in animal experiments (1). 4. Esterification of sex hormones generally causes a prolongation and, to some extent, an increase of their effects. The character of these effects (inert to highly active), however, is not changed by esterification (3, 4). 17-Alpha-hydroxyprogesterone seems to be an exception to this general rule. 5. 17-Alpha-hydroxyprogesterone is not metabolized to pregnanediol in the human (5). 6. The metabolism of 17-alpha-hydroxyprogesterone and the metabolism of 17-alpha-hydroxyprogesterone-caproate in the human female are not yet fully established. There is only one report by Langecker and Prescher (6), who found that in a male patient the excretion of pregnanediol was decreased after the administration of 17-alpha-hydroxyprogesterbne.