Drug Interactions between methadone and tazemetostat

Do not use alcohol or medications that contain alcohol while you are receiving treatment with methadone. This may increase nervous system side effects such as drowsiness, dizziness, lightheadedness, difficulty concentrating, and impairment in thinking and judgment. In severe cases, low blood pressure, respiratory distress, fainting, coma, or even death may occur. You should also avoid consuming grapefruit and grapefruit juice, as this may increase the blood levels and effects of oral methadone. High blood levels of methadone can also occasionally cause an irregular heart rhythm that may be serious. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or fast or pounding heartbeats. Do not exceed the dose of methadone prescribed for you or use the medication more frequently or for a longer duration than prescribed by your doctor. Also avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. Talk to your doctor or pharmacist if you have questions on how to take this or other medications you are prescribed. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medication without first talking to your doctor.

Do not consume grapefruit or grapefruit juice during treatment with tazemetostat. Grapefruit juice can significantly increase the blood levels and effects of tazemetostat, which may increase the risk of serious side effects such as bleeding complications, pain, bone pain, tiredness, shortness of breath, excess fluid around the lungs, and development of new (second) cancers. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.