Topical progesterone

The pharmacokinetics of progesterone, concerns the pharmacodynamics, pharmacokinetics, and various routes of administration of progesterone.Progesterone levels with HPLC–MS/MS after a single dose of 200 mg oral progesterone with food in postmenopausal women. Although not depicted, Cmax levels were 89.2 ng/mL at a Tmax of 3.0 hours.Progesterone levels with RIA after a single dose of 200 mg oral progesterone with or without food in postmenopausal women. The pharmacokinetics of progesterone, concerns the pharmacodynamics, pharmacokinetics, and various routes of administration of progesterone. Progesterone is a naturally occurring and bioidentical progestogen, or an agonist of the progesterone receptor, the biological target of progestogens like endogenous progesterone. Progesterone also has antimineralocorticoid and inhibitory neurosteroid activity, whereas it appears to have little or no glucocorticoid or antiandrogenic activity and has no androgenic activity. Because of its progestogenic activity, progesterone has functional antiestrogenic effects in certain tissues such as the uterus, cervix, and vagina. In addition, progesterone has antigonadotropic effects due to its progestogenic activity and can inhibit fertility and suppress sex hormone production. Progesterone differs from progestins (synthetic progestogens) like medroxyprogesterone acetate and norethisterone, with implications for pharmacodynamics and pharmacokinetics as well as efficacy, tolerability, and safety. Progesterone can be taken by mouth, in through the vagina, and by injection into muscle or fat, among other routes. A progesterone vaginal ring and progesterone intrauterine device are also available as pharmaceutical products. The pharmacokinetics of progesterone are dependent on its route of administration. The medication is approved in the form of oil-filled capsules containing micronized progesterone for oral administration, termed 'oral micronized progesterone' ('OMP') or simply 'oral progesterone'. It is also available in the form of vaginal or rectal suppositories or pessaries, topical creams and gels, oil solutions for intramuscular injection, and aqueous solutions for subcutaneous injection. Routes of administration that progesterone has been used by include oral, intranasal, transdermal/topical, vaginal, rectal, intramuscular, subcutaneous, and intravenous injection. Oral progesterone has been found to be inferior to vaginal and intramuscular progesterone in terms of absorption (low) and clearance rate (rapid). Vaginal progesterone is available in the forms of progesterone gel, rings, and suppositories or pessaries. Advantages of intravaginal progesterone over oral administration include high bioavailability, rapid absorption, avoidance of first-pass metabolism, sustained plasma concentrations, and a local endometrial effect, while advantages of intravaginal progesterone relative to intramuscular injection include greater convenience and lack of injection site pain. Intranasal progesterone as a nasal spray has been found to be effective in achieving therapeutic levels, and was not associated with nasal irritation, but was associated with an unpleasant taste of the spray. Rectal, intramuscular, and intravenous routes may be inconvenient, especially for long-term treatment. Plasma levels of progesterone are similar after vaginal and rectal administration in spite of the different routes of administration, and rectal administration is an alternative to vaginal progesterone in conditions of vaginal infection, cystitis, recent childbirth, or when barrier contraception methods are used. Intramuscular injection of progesterone may achieve much higher levels of progesterone than normal luteal phase concentrations and levels achieved with other routes. For purposes of comparison with normal physiological circumstances, luteal phase levels of progesterone are 4 to 30 ng/mL (with levels of 5 to 9 ng/mL during the mid-luteal phase), while follicular phase levels of progesterone are 0.02 to 0.9 ng/mL, menopausal levels are 0.03 to 0.3 ng/mL, and levels of progesterone in men are 0.12 to 0.3 ng/mL. During pregnancy, levels of progesterone in the first 4 to 8 weeks are 25 to 75 ng/mL, and levels are typically around 140 to 200 ng/mL at term. Production of progesterone in the body in late pregnancy is approximately 250 mg per day, 90% of which reaches the maternal circulation.