Medroxyprogesterone Aminoglutethimide

The contraceptive efficacy of depot medroxyprogesterone acetate does not appear to be affected by interactions with other drugs some interactions are known (6), but the doses used for contraceptive purposes are sufficient to remain effective even if metabolism is increased, for example by aminoglutethimide or phenytoin. 

Wander HE, Nagel GA, Blossey HC, Kleeberg U. Aminoglutethimide and medroxyprogesterone acetate in the treatment of patients with advanced breast cancer. A phase II study of the Association of Medical Oncology of the German Cancer Society (AIO). Cancer 1986 58(9) 1985-9. 

Both interactions appear to be established and are possibly clinically important. A 50% reduction in the plasma levels of medroxyprogesterone and megestrol should be expected during concurrent use, and this may reduce the adrenal suppressive effect. The authors of one report say that to achieve adequate plasma medroxyprogesterone acetate levels in breast cancer (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 for this condition. 

Aminoglutethimide markedly reduces the plasma levels of medroxyprogesterone and m estroL... 

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