<qa>  What is the drug that interacts with methadone?3. Patient is receiving drugs that interacting with methadone, such as delavirdine, fluconazole, fluvoxamine, bravavir, amprenavir, efavirenz, lopinavir, nelfinavir, nevirapine, carbamazepine, dexamethasone Patients receiving short term chemotherapy-related doses are permitted , phenytoin, rifampin, or grapefruit,. 