Drug Interaction Report

Using natalizumab together with crizotinib, or using them sequentially with little to no time in between, may increase the risk of serious and potentially life-threatening infections. Of particular concern is an infection known as progressive multifocal leukoencephalopathy (PML), which is a rare but serious viral infection of the brain that may lead to disability and death. If you are currently being treated or have recently been treated with crizotinib, you may not be able to use natalizumab, or you may require close monitoring and special tests by your doctor to minimize the risk of infection during treatment. Let your doctor know 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 immediate medical attention if you experience progressive weakness on one side of the body, clumsiness of limbs, disturbance of vision, confusion, or changes in thinking, memory and personality, as these may be early symptoms of PML. 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 crizotinib unless directed otherwise by your doctor. Grapefruit juice can increase the blood levels of crizotinib to dangerous levels and cause an irregular heart rhythm that may be serious. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or fast or pounding heartbeats during treatment with crizotinib. You may take crizotinib with or without food, but take it the same time each day. 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.