Drug Interaction Report

Using lefamulin together with vandetanib 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.

The following interaction applies only if you are taking lefamulin (Xenleta) orally:

Food may interfere with the absorption of lefamulin, which may lead to lower blood levels of the medication and possibly reduced effectiveness. You should take lefamulin at least 1 hour before or 2 hours after a meal. It is best to avoid or limit the consumption of grapefruit and grapefruit juice during treatment with lefamulin, as it may increase blood levels of the medication and increase side effects. Talk to your doctor or pharmacist if you have any questions or concerns.