Drug Interactions between Colcigel Gel and valbenazine

Drinking large amounts of grapefruit juice can increase your blood levels of colchicine to dangerous levels. You should avoid the consumption of grapefruit or grapefruit juice during treatment with colchicine. Let your doctor know if you experience abdominal pain, nausea, vomiting, diarrhea, fever, muscle pain, weakness, fatigue, and/or numbness or tingling in your hands and feet, as these may be early symptoms of colchicine toxicity.

Grapefruit and grapefruit juice may increase the blood levels and effects of valbenazine, such as drowsiness and an irregular heart rhythm problem called QT prolongation. Irregular heart rhythm problems 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). Talk to your doctor if you have questions or concerns. Do not add grapefruit products to your diet, or increase or decrease the amount currently in your diet without first talking to your doctor. You may need a dose adjustment of valbenazine or more frequent monitoring by your doctor to safely use both valbenazine and grapefruit products. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with these medications. 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.