Gale Drug Interactions

Diabetes: The requirement for oral antidiabetic treatment or insulin can change. See also Precautions. At high therapeutic cyproterone acetate doses of three times 100 mg per day, cyproterone acetate may inhibit CYP2C8 (see as follows). Thiazolidinediones (i.e. the anti-diabetics pioglitazone and rosiglitazone) are substrates of CYP2C8 (increased blood levels of these anti-diabetics may require dose adjustment).
Cyproterone acetate can influence carbohydrate metabolism. Parameters of carbohydrate metabolism should be examined carefully in all diabetics before and regularly during treatment.
Chronic alcoholism: Alcohol appears to reduce the effect of cyproterone acetate, which is of no value in chronic alcoholics.
Other interactions: Clinical interaction studies have not been performed. However, since cyproterone acetate is metabolised by CYP3A4, it is expected that ketoconazole, itraconazole, clotrimazole, ritonavir and other strong inhibitors of CYP3A4 inhibits the metabolism of cyproterone acetate. On the other hand, inducers of CYP3A4 such as rifampicin, phenytoin and products containing St. John's Wort may reduce the levels of cyproterone acetate.
Based on in vitro inhibition studies, an inhibition of the cytochrome P450 enzymes CYP2C8, 2C9, 2C19, 3A4 and 2D6 is possible at high cyproterone acetate doses of 100 mg three times per day. (This is three times the maximum total daily dose.)
The risk of statin-associated myopathy or rhabdomyolysis may be increased when those HMG-CoA inhibitors (statins) which are primarily metabolised by CYP3A4 are co-administered with high cyproterone acetate doses, since they share the same metabolic pathway.