Must not be given w/ nelfinavir. Potential interaction w/ ataznavir, clopidogrel, ketoconazole, itraconazole, voriconazole, erlotinib, citalopram, imipramine, clomipramine, diazepam, phenytoin, anticoagulants eg, warfarin, cilostazol, cisapride, digoxin, MTX, tacrolimus, rifampicin; St. John's wort. Concomitant use w/ clopidogrel (CYP219 substrate) should be discouraged. Concomitant use of PPIs w/ MTX may elevate & prolong serum levels of MTX &/or its metabolite, possibly leading to MTX toxicities.