Verapamil Drug Interactions
Verapamil may interact with other medicines. It is extremely important for you to tell your doctor about all the medications you are currently taking, including your over-the-counter (non-prescription) medications. The migraine journal can help you keep a list of all of your medications so that any possible drug interactions can be evaluated. Do not stop taking any medication without telling your doctor.
Verapamil Drug Interactions with Drugs that Affect Liver Enzymes ( CYP3A4 Inhibitors)
Inhibitors of CYP3A4 (such as erythromycin and ritonavir) taken along with Verapamil cause increased blood levels of Verapamil. Inducers of CYP3A4 (such as rifampin) cause a decrease in blood levels of Verapamil.
Verapamil Drug Interaction with Aspirin
In a few reported cases, use of Verapamil with aspirin has led to increased bleeding times greater than seen with aspirin alone.
Verapamil Drug Interactions with Blood Pressure Medications
Beta-adrenergic blockers like Toprol or Inderal taken along with Verapamil may result in more side effects on heart rate and how the heart works.
Verapamil and high blood pressure medications (such as vasodilators, angiotensin-converting enzyme inhibitors, diuretics, and beta-blockers) taken together have additional effects on lowering blood pressure and may reduce blood pressure to an extreme level in some people. Your doctor will monitor you and adjust the dose that is right for you.
Verapamil Drug Interaction with Digitalis
Verapamil and digoxin used together can increase blood digoxin levels up to 75% during the first week of therapy and may cause digitalis toxicity (harmful effects. When these two drugs are used together, their doses should be closely monitored.
Verapamil Drug Interaction with Irregular Heartbeat Medications
Verapamil should be used with caution with certain medications that treat irregular heartbeat including:
- Disopyramide: should not be taken within 48 hours before or 24 hours after Verapamil is taken.
- Flecainide: may have added effects on the heart
- Quinidine: may cause low blood pressure.
Other Drug Interactions
Verapamil should be closely monitored when using the following other medications:
- Lithium: Used to treat depression and bipolar disorder
- Carbamazepine and phenobaribital : seizure medications..
- Rifampin: used for infections.
- Cyclosporine: a drug that is used in organ transplants.
- Theophylline: for asthma and COPD
- Telithromycin: side effects include low blood pressure and slower heart rate.
- Clonidine: side effects include slow heart rate resulting in hospitalization and pacemaker.
- Verapamil and Grapefruit Juice – Grapefruit juice may significantly increase concentrations of Verapamil. This increase in Verapamil plasma concentration is not expected to have any clinical consequences in most people however, caution should be exercised in people with fragile health conditions.
If you are taking any of these medicines along with Verapamil or Verapamil SR, your response should be closely monitored, because of a possible drug interaction. When you stop taking any of the above drugs, but continue taking Verapamil or Verapamil SR, continue checking your blood pressure or other health measures regularly .
Written & reviewed by: Lisa Erwin R.Ph. CGP | Last review date: Dec 2010. Click the References Link below for a complete list of references.