Pharmacodynamics of progesterone women, this effect being the result of suppression of the mid-cycle surge in gonadotropin secretion, is 300 mg/day. However, this figure is based on limited clinical data. Conversely, treatment with a high dosage of oral progesterone of 100 mg four times per day (or 400 mg/day total) in men for 10 days that resulted in approximately mid-luteal phase levels of progesterone (7.9–9.4 ng/mL; measured by ) did not cause any change in testosterone levels, suggesting that progesterone has little or no antigonadotropic effect in males at typical clinical dosages. In addition, a study found that administration of 1,000 mg/day oral
Pharmacokinetics of progesterone 800 mg/day vaginal progesterone (about 70 ng/mL and 12 ng/mL, respectively), although local progesterone levels in the uterus were 10 times higher with the vaginal route due to a uterine first-pass effect (around 1.5 ng/mL and almost 12 ng/mL, respectively). The duration of progesterone is extended by the intramuscular route due to a depot effect in which it is stored locally in adipose tissue, and can be administered once every 1 to 3 days. The half-life of intramuscular progesterone is significantly longer when it is injected into the gluteal muscles of the buttocks rather than the deltoid muscle of the