Pharmacokinetics of progesterone administered by the oral and parenteral routes

Progestogens, which include the natural hormone, progesterone, and synthetic steroid derivatives, are used to treat a variety of reproductive disorders. Since synthetic progestogens are often associated with undesirable side effects, improved formulations and modes of administration of progesterone have been sought. In order to find an optimal therapeutic agent, different progesterone formulations and routes of administration have been studied. This paper explains several methods of measuring progesterone levels and summarizes clinical data on the pharmacokinetic profiles of natural progesterone administered by the oral, intramuscular, vaginal, intranasal, percutaneous, sublingual and rectal routes.