Pharmacokinetics of progesterone concentrations was around 4 hours and the elimination half-life was in the range of 30 to 40 hours. The venous blood levels observed were very low. Because progesterone is a lipophilic and hydrophobic compound, it is not absorbed efficiently by the skin. Moreover, because the body produces about 25 mg progesterone per day on average during the luteal phase, around 50% of the body would need to be used as a surface of absorption to deliver a similar quantity of progesterone. As such, the transdermal route cannot easily achieve adequate circulating progesterone levels, and this makes transdermal progesterone impractical for
Pharmacokinetics of progesterone and has been found to result in higher serum peak progesterone levels relative to intramuscular oil formulations. In addition, subcutaneous injection of progesterone is considered to be easier, safer (less risk of injection site reactions), and less painful relative to intramuscular injection. The elimination half-life of this formulation is 13 to 18 hours, compared to 20 to 28 hours for intramuscular injection in oil. Progesterone has a very short elimination half-life of about 3 to 90 minutes when given by intravenous injection. A one-year progesterone intrauterine device (IUD) for hormonal birth control was previously available in the United States and