Formulations and pharmacokinetics of
progestins
1. Natural progesterone: micronized progesterone, 17-hydroxyprogesterone Different routes of administration effect plasma concentration, bioavailability and side effects of progesterone.
Oral progesterone is not recommended because of its first-pass hepatic metabolism, high side effects and extreme ariability in plasma concentrations.
Transvaginal administration, avoids first-pass hepatic metabolism, has rapid absorption, high bioavailability, no local pain and less side effects.
2. Synthetic progestins: 17 alpha-hydroxyprogesterone caproate (17 OHP-C)
17 OHP-C is a 17-hydroxyprogesterone derivative which is inactive by oral route, but working as a longacting
progestin when given intramuscularly.
Half-life is approximately 7.8 days for intramuscular injection.