Some medicines can affect how ribociclib works. Tell your doctor if you are using any of the following:Alfentanil, bepridil, boceprevir, carbamazepine, chloroquine, clarithromycin, conivaptan, cyclosporine, dihydroergotamine, ergotamine, everolimus, fentanyl, halofantrine, haloperidol, indinavir, itraconazole, ketoconazole, lopinavir/ritonavir, methadone, midazolam, moxifloxacin, nefazodone, nelfinavir, ondansetron, phenytoin, pimozide, posaconazole, quinidine, rifampin, ritonavir, saquinavir, sirolimus, St John's wort, tacrolimus, tamoxifen, or voriconazoleMedicine to treat heart rhythm problems (including amiodarone, disopyramide, procainamide, quinidine, sotalol)