Drug Interaction Report

Selpercatinib may increase the blood levels of sonidegib. This may increase side effects such as muscle spasms, muscle pain, muscle weakness, fatigue, nausea, vomiting, diarrhea, loss of appetite, weight loss, hair loss, itching, and taste abnormalities. You may also have an increased risk of developing a rare but serious condition called rhabdomyolysis that involves the breakdown of skeletal muscle tissue. In some cases, rhabdomyolysis can cause kidney damage and even death. Talk to your doctor if you have any questions or concerns. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring to safely use both medications. Let your doctor know immediately if you have unexplained muscle pain, tenderness, or weakness during treatment with sonidegib, especially if these symptoms are accompanied by fever or dark colored urine. 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.

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.

Sonidegib should be taken on an empty stomach, at least 1 hour before or 2 hours after a meal. The presence of food can significantly increase the absorption of sonidegib into the blood stream. This may increase side effects such as muscle spasms, muscle pain, muscle weakness, fatigue, nausea, vomiting, diarrhea, loss of appetite, weight loss, hair loss, itching, and taste abnormalities. You may also have an increased risk of developing a rare but serious condition called rhabdomyolysis that involves the breakdown of skeletal muscle tissue. In some cases, rhabdomyolysis can cause kidney damage and even death. Let your doctor know immediately if you have unexplained muscle pain, tenderness, or weakness during treatment with sonidegib, especially if these symptoms are accompanied by fever or dark colored urine. Grapefruit juice may also increase the blood levels of sonidegib and should be avoided. Talk to your doctor or pharmacist if you have any questions or concerns.