Aminoglutethimide reduces the
plasma levels of
medroxyprogesterone by at least half.
It has been suggested that to achieve adequate
plasma medroxyprogesterone acetate levels in breast
cancer therapy (above 100 nanograms/mL) a daily dose of 800 mg of Provera is probably necessary in the presence of
aminoglutethimide 125 or 250 mg twice daily. This is double the usual recommended dose of this preparation.