Increased exposure w/ strong CYP3A inhibitors (eg, boceprevir, clarithromycin, conivaptan, grapefruit juice, indinavir, itraconazole, ketoconazole, lopinavir/ritonavir, nefazodone, nelfinavir, posaconazole, ritonavir, saquinavir, & voriconazole). Decreased plasma exposure w/ strong CYP3A inducers (eg, phenytoin, rifampin, carbamazepine & St. John's Wort). Increased exposure of midazolam & other CYP3A substrates w/ narrow therapeutic index (eg, alfentanil, cyclosporine, dihydroergotamine, ergotamine, everolimus, fentanyl, pimozide, quinidine, sirolimus & tacrolimus). Avoid co-administration w/ medicinal products w/ a known potential to prolong QT eg, antiarrhythmic medicines (eg, amiodarone, disopyramide, procainamide, quinidine & sotalol), chloroquine, halofantrine, clarithromycin, haloperidol, methadone, moxifloxacin, bepridil, pimozide & ondansetron.