Drug Interaction Report

Using ceritinib together with promethazine 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). Talk to your doctor if you have any questions or concerns. Your doctor may already be aware of the risks, but has determined that this is the best course of treatment for you and has taken appropriate precautions and is monitoring you closely for any potential complications. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with these medications, whether together or alone. 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 ceritinib unless directed otherwise by your doctor. Grapefruit juice can increase the blood levels of ceritinib to dangerous levels, increasing the risk of an irregular heart rhythm that may be serious. Other, more common side effects such as diarrhea, nausea, vomiting, abdominal pain, and hyperglycemia (high blood sugar) may also increase. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with ceritinib. Food may also increase the blood levels of ceritinib. Therefore, you should take ceritinib on an empty stomach, meaning no food should be eaten for at least two hours before or after taking ceritinib. 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.

Ask your doctor before using promethazine together with ethanol (alcohol). This can cause uncontrollable movements, agitation, seizures, severe dizziness or fainting, coma, very deep sleep, irregular heartbeats, and high or low body temperature. Use caution when driving, operating machinery, or performing other hazardous activities, these medicaions may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities. 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.