Pharmacokinetics of progesterone a few other countries under the brand name Progestasert. It was marketed between 1976 and 2001. The IUD was never widely used due to a relatively high contraceptive failure rate of 2.9% and the requirement of annual replacement. It contained 38 mg progesterone and released 65 μg progesterone into the uterus per day (adding up to about 35 mg after one year). For comparison, a woman's body produces on average about 25 mg progesterone per day during the luteal phase. While effective as a form of contraception and for decreasing menstrual bleeding and discomfort, long-lived IUDs can fundamentally only deliver
Topical progesterone of tissue exposure to progesterone with this route of administration. These findings provide a possible explanation for how some studies found antiproliferative and atrophic changes in the endometrium with topical progesterone. However, elevated levels of progesterone in the endometrium with topical progesterone have not yet been demonstrated. Concern has been raised regarding topical progesterone in that the effects of such supraphysiological levels of progesterone in tissues are unknown and hence the potential for harmful effects has not been ruled out. Salivary monitoring of progesterone levels in women using topical progesterone and adjustment of dosage as necessary has been suggested as