Drug Interaction Report

Larotrectinib may increase the blood levels of sirolimus. In some cases, this can increase the risk of serious side effects such as kidney problems, diabetes, nervous system disorders, hyperkalemia (high potassium levels in the blood), high blood pressure, irregular heart rhythm, heart failure, infections, and various types of malignancies including lymphoma and skin cancer. You may need a dose adjustment if you have been taking sirolimus and are starting treatment with larotrectinib. Contact your doctor if you develop signs and symptoms of infection such as fever, chills, diarrhea, sore throat, muscle aches, shortness of breath, blood in phlegm, weight loss, red or inflamed skin, body sores, and pain or burning during urination. Also seek medical attention if you experience frequent urination, increased hunger or thirst, loss of appetite, confusion, tremor, numbness or tingling, seizures, vision changes, sudden dizziness, lightheadedness, fainting, shortness of breath, heart palpitations, and chest pain. 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.

Grapefruit and grapefruit juice may interact with sirolimus and could lead to potentially dangerous effects. Avoid eating grapefruit or drinking grapefruit juice while you are taking sirolimus. Also, you should preferably take sirolimus at least one hour before eating. If you do take it with food, you should take it each time with food to avoid changes in sirolimus levels. The oral liquid form of sirolimus must be mixed with water or orange juice only. Do not use grapefruit juice to mix this medication.

Grapefruit juice can increase the blood levels of larotrectinib. This may increase the risk and/or severity of side effects such as dizziness, confusion, coordination problems, memory problems, liver problems, and tingling, numbness or burning in the hands and feet. You should avoid the consumption of grapefruit and grapefruit juice during treatment with larotrectinib. Talk to your doctor or pharmacist if you have questions on 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 medications without first talking to your doctor.