Drug Interaction Report

You should limit or avoid consumption of grapefruit and grapefruit juice during treatment with selpercatinib unless directed otherwise by your doctor. Grapefruit juice may increase the blood levels of selpercatinib. High levels of selpercatinib 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). The risk and/or severity of other side effects may also increase, including nausea, vomiting, constipation, diarrhea, rash, muscle and joint pain, swelling of arms or legs, liver problems, high blood pressure, and bleeding complications. Talk to your doctor if you experience intolerable or troublesome side effects, or you have other questions or concerns. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with selpercatinib. 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.

Using multivitamin with minerals together with liothyronine may decrease the effects of liothyronine. You should separate the administration of liothyronine and multivitamin with minerals by at least 4 hours. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both 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.