Comparative pharmacokinetics of medroxyprogesterone acetate administered by oral and intramuscular routes

Abstract

The present study was undertaken to elucidate (1) the relationship between plasma concentration of medroxyprogesterone acetate (MPA; Clinovir) administered by the PO and the IM routes; and (2) the relationship between dose and plasma concentration of MPA. Nineteen patients entered the study. In each patient the plasma concentration was monitored after a single PO and IM administration of MPA at the following dose levels: 100 mg (5 patients), 400 mg (5 patients), 800 mg (5 patients) and 1,200 mg (4 patients). The time interval between PO and the IM administration was 1 week. The results show (1) a very large interindividual variation in plasma concentration; (2) increasing plasma concentration with both PO and IM dose; (3) after the IM administration plasma levels are steady or increase slightly within the test period; (4) after the oral administration the concentration increases rapidly to reach a peak before 2-7 h and subsequently decreases again, peak concentrations being 2-10 times higher than after IM administration; and (5) within the test periods the plasma concentration x time (0-168 h) is comparable with the two methods of administration.

Oral high-dose medroxyprogesterone acetate (MAP) in treatment of advanced breast cancer

“…Oral high-dose MAP in breast cancer 129 following oral administration are scarce (14). The present results demonstrated that a sufficient blood level of MAP, over 50 ng/ml, was reached and maintained and produced clinical effects, although some variations were observed in individual cases.…”

The pharmacokinetics of medroxyprogesterone acetate following two different loading dose schedules in advanced carcinoma of the breast

“…Following a single oral dose, the time to reach peak serum level increases proportionally dependent upon the dose given from 2 h after doses of 100 to 400mg to 7 h after 1,200mg (Salimtschik et al, 1980). The absolute value of the peak serum level achieved is also dose dependent with a linear increase proportional to dose up to 1,200mg (Pannutiet al 1982).…”

Pharmacologic Doses of Medroxyprogesterone May Cause Bone Loss Through Glucocorticoid Activity: An Hypothesis

“…Ortiz et al [37] reported that endocrine effects of MPA have been recognized at concentrations less than 1.5610 -8 M in patients receiving MPA as a contraceptive. Concentrations of MPA in plasma samples taken throughout a 24-h period after a single oral administration of 10, 100 and 400 mg/day in humans reached a maximum, after 2-3 h, of 3.5-6.7610 -9 M, 2610 -8 M and 1.7610 -7 M respectively, and declined slowly with a mean t 1/2 of 2.1 h [38][39][40]. Importantly, Ohtsu et al [41] found that greater than 10-fold differences in peak plasma MPA concentrations existed between patients receiving the same dose, suggesting that some patients receiving low doses of MPA may still have high plasma concentrations of MPA.…”