The oral bioavailability of progesterone is increased through micronization. The absolute bioavailability of micronized progesterone is not known. The pharmacokinetic parameters in male volunteers were generally consistent with those seen in postmenopausal women.
Progesterone is metabolized primarily by the liver largely to pregnanediols and pregnanolones.
Pregnanediols and pregnanolones are conjugated in the liver to glucuronide and sulfate metabolites. Progesterone metabolites which are excreted in the bile may be deconjugated and may be further metabolized in the gut via reduction, dehydroxylation, and epimerization. Progesterone metabolites which are excreted in the bile may undergo enterohepatic recycling or may be excreted in the feces. No formal studies have evaluated the effect of hepatic disease on the disposition of progesterone. If treatment with progesterone is indicated in patients with mild to moderate hepatic dysfunction, these patients should be monitored carefully.