Pharmacokinetics of Medroxyprogesterone Acetate Administered by Oral and Intramuscular Route

The present study was undertaken to elucidate: 1) The relationship between plasma concentration of medroxyprogesterone‐acetate (MPA, Clinovir R , Depo‐Provera, Upjohn) administered both orally and intramuscularly. 2) The relation between dose and plasma concentration of MPA. Nineteen patients entered the study. In each patient the plasma concentration was monitored after the administration of a single oral and one intramuscular dose of MPA at the following dosage levels: 100 mg (5 patients), 400 mg (5 patients), 800 mg (5 patients) and 1 200 mg (4 patients). The interval between the oral and i.m. administration was 1 week. The results show: 1) A very large interindividual variation in plasma concentration. 2) An increase in plasma concentration after both oral and i.m. dose. 3) After the i.m. administration, plasma levels remained steady or increased slightly throughout the test period. 4) After the oral administration the concentration increased rapidly to reach a peak by 2‐7 hours, subsequently decreasing. Peak concentrations were 2‐ 10 times higher than after i.m. administration. 5) Over the test period, the plasma concentration x time (0‐168 h) is similar in the two modes of administration.