Drug Interaction Report

Using levomethadyl acetate together with darifenacin may increase the risk and/or severity of some side effects such as dizziness, drowsiness, confusion, difficulty concentrating, difficulty urinating, dry mouth, abdominal cramping, and constipation. Some people, especially the elderly, may also experience impairment in thinking, judgment, and motor coordination. You should avoid or limit the use of alcohol while being treated with these medications. Also avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medications affect you. 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.

Do not consume grapefruit or grapefruit juice during treatment with levomethadyl acetate unless directed otherwise by your doctor. Grapefruit juice may increase the blood levels of levomethadyl acetate. This can increase the risk of an irregular heart rhythm that may be serious and potentially life-threatening, although it is a relatively rare side effect. You may be more susceptible if you have a heart condition called congenital long QT syndrome, other cardiac diseases, conduction abnormalities, or electrolyte disturbances (for example, magnesium or potassium loss due to severe or prolonged diarrhea or vomiting). You should also avoid alcohol during treatment, as it may add to the central nervous system effects of levomethadyl acetate and increase the risk of serious side effects such as respiratory depression, low blood pressure, fainting, coma, and even death. Do not drive, operate machinery, or perform other hazardous activities until you know how the medication affects you. Talk to your doctor if you have any questions or concerns. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment. 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.

Information for this minor interaction is available on the professional version.