Drug Interactions
Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor or pharmacist first. See also How to Use section. This drug should not be used with the following medications because very serious (possibly fatal) interactions may occur: certain HIV protease inhibitors (e.g., ritonavir, nelfinavir, saquinavir), azole antifungals (e.g., itraconazole, ketoconazole, voriconazole), propafenone, cisapride, arbutamine, mefloquine. If you are currently using any of these medications listed above, tell your doctor or pharmacist before starting quinidine. Many drugs besides quinidine may affect the heart rhythm (QT prolongation), including amiodarone, dofetilide, pimozide, procainamide, sotalol, macrolide antibiotics (such as erythromycin), ziprasidone, mesoridazine, thioridazine, among others. Therefore, before using quinidine, report all medications you are currently using to your doctor or pharmacist. Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially: large amounts of antacids (e.g., sodium bicarbonate), barbiturates (e.g., phenobarbital), carbamazepine, rifamycins (e.g., rifampin, rifabutin), phenytoin, carbonic anhydrase inhibitors (e.g., acetazolamide), aripiprazole, atomoxetine, codeine, hydrocodone, loperamide, medication for high blood pressure (e.g., nifedipine, verapamil, diltiazem), certain macrolide antibiotics (e.g., erythromycin, clarithromycin), quinupristin/dalfopristin, etravirine, amprenavir/fosamprenavir. This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.