Increased clearance (diminished efficacy) w/ CYP3A4 inducers eg, phenytoin, barbiturates, primidone, carbamazepine, rifampicin & possibly oxcarbazepine, topiramate, felbamate, griseofulvin, St. John's wort. Increased/decreased plasma conc w/ combinations of HIV/HCV PIs & NNRTIs. Increased plasma conc w/ strong CYP3A4 inhibitors eg, ketoconazole & moderate inhibitor erythromycin. May influence lab test results including liver, thyroid, adrenal, renal function, protein plasma levels, carbohydrate metabolism, coagulation & fibrinolysis parameters.