title: Disposition of medroxyprogesterone acetate and drug metabolism activity.
abstract: The role of drug-metabolizing enzyme activity on the disposition of medroxyprogesterone acetate (MPA) was investigated in male rats. The metabolizing enzyme system was induced by phenobarbital (PB) or inhibited by SKF 525A. Plasma concentrations of unmetabolized MPA and the amounts of MPA-related residues in various tissues were higher in the SKF 525A and slightly lower in the PB treated animals than in the controls. The disappearance of MPA-related substances from the lung, skeletal muscle and brain was slow, and in the lung there was even an increase in the amount of radioactivity in the PB and saline treated rats at 24 hr. Almost equal amounts of radioactivity were excreted in the urine and intestine in the control rats, while the induction of drug metabolism enhanced the excretion in the urine and its reduction enhanced elimination in the intestinal tract within 24 hours. The findings demonstrate that plasma and tissue levels of MPA and its elimination route are influenced by the drug metabolism activity.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D008658:Inactivation, Metabolic; D007413:Intestinal Mucosa / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008168:Lung / Q000378:metabolism; D008297:Male; D008525:Medroxyprogesterone / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism / Q000652:urine; D017258:Medroxyprogesterone Acetate; D010634:Phenobarbital / Q000494:pharmacology; D011335:Proadifen / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D011335:Proadifen; D017258:Medroxyprogesterone Acetate; D008525:Medroxyprogesterone; D010634:Phenobarbital