Ok I have a question concerning Depo Provera (medroxyprogesterone acetate).
My question is - How does Depo Provera work to maintain Birth control for the 3-month period?
Ok - Let me go more into detail..... I understand that the patient receives the shot (150mg) q 3 months and that the mechanism of action is exerted by preventing the females egg cells from ripening. If an egg is not released from the ovaries during the menstrual cycle, it cannot become fertilized by sperm and result in pregnancy. Depo Provera also causes changes in the lining of the uterus that make it less likely for pregnancy to occur. The reason that the periods stops is because Depo Provera causes a resting state in the ovaries by inhibiting the secretion of gonadotropins which, in turn, prevents follicular maturation and ovulation and results in endometrial thinning. These actions produce its contraceptive effect.. When the ovaries do not release an egg monthly, the regular monthly growth of the lining of the uterus does not occur and, therefore, the bleeding that comes with the normal menstruation does not take place. When the female stops using the Depo Provera the menstrual period will usually, in time, return to its normal cycle.
Radioimmunoassay procedure for the assay of medroxy-progesterone acetate in serum, the apparent half-life for medroxy progesterone acetate following IM administration of Depo Provera is approximately 50 days. Therefore, if the half-life of the Depo Provera is 50 days why wouldn't the female not need the shot q 2months?
If my understanding of half-life is correct then at the 50-day mark there would be 75mg of Depo Provera still active. Would this still be an effective therapeutic level?
I understand that when Test injections are given for HRT that the length of carbon chains has a direct impact on half life (longer the carbon chain on C19 the longer the half life) (half life of Test is between 1 to 10 days--depending on ester chain) but this is not the situation with Depo Provera.
