Calcium Channel Blockers/Quinidine 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:

Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

When verapamil and quinidine are taken together, your body may not process quinidine properly and your blood levels of quinidine may increase. When nifedipine and quinidine are taken together, your body may not process quinidine properly and your blood levels of quinidine may increase or decrease. Quinidine may cause your body to process nifedipine more slowly and increase your blood levels of nifedipine.

What might happen:

If you are taking verapamil and quinidine, you may experience a decrease in blood pressure. If you are taking nifedipine and quinidine, you may experience an increase or decrease in the effects of quinidine on your heart and an increase in the effects of nifedipine. If nifedipine is stopped, you may experience a decrease in your blood levels of quinidine.

What you should do about this interaction:

If you are taking verapamil and quinidine and you experience weakness, fatigue, or dizziness, contact your doctor. It may be necessary to measure your blood levels of quinidine more often. Your doctor may need to adjust the dose of one or both of your medicines.If you are taking nifedipine and quinidine and you notice a fast or irregular heartbeat, contact your doctor. It may be necessary to measure your blood levels of quinidine more often. Your doctor may need to adjust the dose of one or both of your medicines. If your doctor stops your nifedipine and you experience nausea, vomiting, stomach pain, drowsiness, trouble breathing, ringing in the ears, vision problems, dizziness, or headache, contact your doctor.Your healthcare professionals (e.g. doctor or pharmacist) 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.

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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.