Verapamil

Brand names

• Alti-Verap
• Apo-Verap
• Calan
• Calan SR
• Chronovera
• Covera-HS
• Dom-Verapamil SR
• Gen-Verapamil
• Isoptin
• Isoptin SR
• Med-Verapamil
• Novo-Veramil
• Nu-Verap
• PMS-Verapamil
• Tarka [CD]
• Verelan
• Verelan PM

Usage

To treat high blood pressure (hypertension), angina pectoris (chest pain associated with heart disease), and heartbeat irregularities (cardiac arrhythmias).

How it works

Verapamil interferes with the movement of calcium into heart muscle cells and the smooth muscle cells in the walls of the arteries. This action relaxes blood vessels (causing them to widen), which lowers blood pressure, increases the blood supply to the heart, and decreases the heart's overall workload.

Side effects

Serious

Breathing difficulty, coughing, or wheezing; irregular or pounding heartbeat; chest pain; extreme dizziness; fainting.

Common

Headache; dizziness; constipation; flushing and a feeling of warmth; swelling in the feet, ankles, or calves; heart palpitations; nausea.

Less common

Diarrhea, unusual fatigue and weakness, skin rash, increased urination, ringing in the ears, overgrowth of the gums.

Possible interactions

Other medicaments:

Verapamil may increase the effects of

• buspirone (Buspar).
• carbamazepine (Tegretol) and cause carbamazepine toxicity.
• digitoxin and digoxin (Lanoxin) and cause digitalis toxicity.
• lovastatin (Mevacor), simvastatin (Zocor) and other HMG CoA reductase inhibitors that use cytochrome P 450 3A4 for removal.
• sirolimus (Rapamune).
• tacrolimus (Prograf).
• tretinoin (Vesanoid).
• tricyclic antidepressants.
• vincristine (Oncovin).

Verapamil taken concurrently with:

• amiodarone (Cordarone) may result in cardiac arrest.
• aspirin (various) may result in excessive verapamil levels and excessive lowering of blood pressure.
• beta blockers may affect heart rate and rhythm adversely.
• calcium supplements (various) may blunt the therapeutic benefits of verapamil-separate calcium and verapamil dosing by 2 hours.
• cilostazol (Pletal) may result in cilostazol toxicity.
• cyclosporine (Sandimmune) may result in cyclosporine toxicity and renal compromise.
• dantrolene will cause elevated blood potassium and depression of the heart.
• dofetilide (Tikosyn) may result in dofetilide toxicity.
• disopyramide (Norpace) can cause congestive heart failure.
• flecainide (Tambocor) may have additive heart effects (excessively low heart rate or cardiogenic shock).
• lithium (Lithobid, others) may result in lithium toxicity and mania.
• midazolam (Versed) may result in midazolam toxicity.
• NSAIDs may blunt the therapeutic effect of verapamil on blood pressure.
• oral hypoglycemic agents may lead to excessively low blood sugar.
• phenytoin (Dilantin) may result in decreased effectiveness of verapamil.
• prazosin (Minipres, others) may increase risk of orthostatic hypotension.
• quinidine (Quinaglute, others) can result in quinidine toxicity.
• rifampin (Rifadin, others) will decrease the therapeutic benefits of verapamil.
• sulfinpyrazone increases the removal of verapamil and lessens its therapeutic effects.
• terazosin (Hytrin) can lead to excessive decreases in blood pressure.
• theophylline (Theo-Dur, others) can lead to theophylline toxicity.
• warfarin (Coumadin) or other oral anticoagulants may increase risk of stomach or intestinal (GI) hemorrhage.

The following medicaments may increase the effects of verapamil:

• cimetidine (Tagamet) and other histamine (H2) blocking medicaments.
• clarithromycin (Biaxin).
• ritonavir (Norvir) and perhaps other protease inhibitors.
• tricyclic antidepressants.

Foods:

Do not take this medicine with grapefruit or grapefruit juice. Avoid excessive salt intake.

Herbal medicines or minerals:

Ginseng may increase blood pressure, blunting the benefits of this medicine. Hawthorn, saw palmetto, ma huang, goldenseal, yohimbe and licorice may also cause increased blood pressure. Garlic and calcium may work to lower blood pressure. The combination may work to require lower verapamil doses. St. John's wort may work to lower calcium channel blocker levels. This combination may also increase sun sensitivity. Eleuthero root should be avoided by people living with hypertension.
Discuss any plans for herbal medicines or minerals with your doctor.

Beverages:

Caffeine levels will be increased if caffeine-containing beverages are consumed while you are on verapamil.

Alcohol:

Alcohol may exaggerate the drop in blood pressure and change the elimination of alcohol (experienced by some patients). This may lead to an exaggerated effect of alcohol.

Tobacco smoking:

Nicotine can reduce the effectiveness of this medicament.

Marijuana smoking:

Possible reduced effectiveness of this medicament; mild to moderate increase in angina; possible changes in electrocardiogram, confusing interpretation.

Exposure to sun:

This medicament may cause photosensitivity

Exposure to heat:

Hot environments can exaggerate the blood-pressure-lowering effects of this medicament.

Heavy exercise or exertion:

This medicament may improve your ability to be more active without resulting angina pain. Use caution and avoid excessive exercise that could impair heart function in the absence of warning pain.

Discontinuation:

Do not stop this medicament abruptly. Consult your physician regarding gradual withdrawal to prevent the development of rebound angina.

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