Increased clearance w/ enzyme inducers eg, phenytoin, barbiturates, primidone, carbamazepine, rifampicin, & possibly also oxcarbazepine, topiramate, felbamate, griseofulvin, ketoconazole & products containing St. John's wort. Increased or decreased plasma conc w/ combinations of HIV PIs & NNRTIs (eg, ritonavir, nevirapine, efavirenz), including combinations w/ HCV inhibitors. Increased plasma conc w/ strong CYP3A4 inhibitors eg, ketoconazole; moderate inhibitors eg, erythromycin. May influence results of lab tests, including biochemical parameters of liver, thyroid, adrenal & renal function, plasma levels of (carrier) proteins (eg, corticosteroid-binding globulin & lipid/lipoprotein fractions), parameters of carbohydrate metabolism & parameters of coagulation & fibrinolysis.