Drug Interaction Report

Consumer information for this interaction is not currently available.

MONITOR: Coadministration with fenfluramine may decrease the plasma concentrations and therapeutic efficacy of drugs that are substrates of the CYP450 2B6 and/or CPY3A4 isoenzymes. The proposed mechanism, based on in vitro data, might be increased clearance due to induction of CYP450 2B6 and intestinal CYP450 3A4.

MANAGEMENT: Caution and monitoring are recommended if fenfluramine is used concomitantly with drugs that are substrates of CYP450 2B6 and/or CYP450 3A4, particularly sensitive substrates or those with a narrow therapeutic range. Monitoring for potential loss of therapeutic efficacy is recommended. The prescribing information for concomitant medications may be consulted to assess the benefits versus risks of coadministration, as well as any dosage adjustments that may be required during coadministration and/or following the discontinuation of a CYP450 2B6 and/or CYP450 3A4 inducer.

Using fenfluramine with alcohol can increase the risk of cardiovascular side effects such as increased heart rate, chest pain, or blood pressure changes. In addition, you may also be more likely to experience nervous system side effects such as dizziness, drowsiness, depression, and difficulty concentrating. You should avoid or limit the use of alcohol while being treated with fenfluramine. Do not use more than the recommended dose of fenfluramine, and avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medication without first talking to your doctor.

Ivacaftor should be taken with fat-containing foods such as eggs, avocados, nuts, meat, butter, peanut butter, cheese pizza, and whole-milk dairy products to help with its absorption. Do not consume grapefruit juice or any food that contains grapefruit or Seville oranges during treatment with ivacaftor unless directed otherwise by your doctor. Grapefruit juice can significantly increase the blood levels of ivacaftor. This may increase the risk and/or severity of serious side effects such as liver damage. Call your doctor immediately if you have fever, chills, joint pain or swelling, unusual bleeding or bruising, skin rash, itching, loss of appetite, fatigue, nausea, vomiting, abdominal pain, dark urine, pale stools, and/or yellowing of the skin or eyes, as these may be signs and symptoms of liver damage. 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.