Clozapine/Myelosuppressive Agents that Prolong QT Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

Clozapine can affect your heart's rhythm and your bone marrow's ability to make new white blood cells. Your other medicine can have the same effect.

What might happen:

Taking clozapine with your other medicine may increase your risk of irregular heartbeat, which may be life-threatening. If your white blood cells are too low (also called the ANC or absolute neutrophil count), your risk for infection is increased.

What you should do about this interaction:

Make sure your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together and all other medicines you are taking. Your doctor may want to perform an electrocardiogram (ECG) on you to check your heart rate and rhythm. Your doctor may want to check your blood frequently to be sure your white blood cells are in a safe range. It is important to keep laboratory appointments.Let your doctor know right away if you notice any irregular heartbeat or have any dizziness or fainting episodes. You should contact your healthcare provider right away if you have symptoms of infection such as fever, sore throat or flu-like symptoms.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

  • 1.Clozaril (clozapine tablets) US prescribing information. Novartis Pharmaceuticals Corporation April, 2020.
  • 2.USDepartment of Health and Human Services Food and Drug Administration. ICH E14 Clinical Evaluation of QT/QTc Interval Prolongation and Proarrhythmic Potential for Non-Antiarrhythmic Drugs. Available at: https://www.fda.gov/media/71372/download October, 2005.
  • 3.Drew BJ, Ackerman MJ, Funk M, Gibler WB, Kligfield P, Menon V, Philippides GJ, Roden DM, Zareba W. Prevention of torsade de pointes in hospital settings: a scientific statement from the American Heart Association and the American College of Cardiology Foundation. J Am Coll Cardiol 2010 Mar 2;55(9):934-47.
  • 4.FDA (US Food and Drug Administration). Clozapine: Drug Safety Communication - FDA Modifies Monitoring for Neutropenia; Approves New Shared REMS Program. accessed at: https://www.fda.gov/drugs/drugsafety/ucm461853.htm September 15, 2015.

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CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.