Medroxyprogesterone acetate (MAP) and tamoxifen (TMX) plasma levels after simultaneous treatment with 'low' TMX and 'high' MAP doses.

Plasma levels of medroxyprogesterone acetate (MAP), tamoxifen (TMX) and its major metabolites, 4-hydroxy TMX and desmethyl TMX, were determined in five patients with advanced breast cancer following simultaneous MAP (2,000 mg/day) and TMX (20 mg/day) oral therapy. The interindividual variance in MAP plasma levels was wide; the mean plasma levels of both drugs were nearly identical, despite the large difference in the administered doses.