What to Know About Verelan (Verapamil)

A calcium channel blocker with multiple clinical uses

In This Article

Verelan (verapamil) is a calcium channel blocking drug with several important cardiovascular uses, including the treatment of anginahypertensionatrial fibrillation and other supraventricular arrhythmias, and hypertrophic cardiomyopathy. Verapamil is also sometimes prescribed for migraine headaches. It is also marketed as Calan, and is available in generic forms.

Uses

Verapamil is one of a large class of drugs called calcium channel blockers. Calcium channel blockers work by slowing the transit of calcium ions into various types of cells, in particular, smooth muscle and cardiac muscle cells.

When this calcium influx is slowed in smooth muscle cells, the cells are caused to relax. Relaxing the smooth muscle cells results in the dilation of blood vessels (thus tending to lower blood pressure).

By slowing calcium influx into cardiac muscle cells, calcium channel blockers reduce the force of cardiac contraction, thus reducing cardiac work and the vigor of the heartbeat.

In addition, blocking the calcium channels slows the function of the heart's sinus node and the rate at which the heart's electrical impulse transits the AV node. These actions on the heart's electrical system can be used to help treat several cardiac arrhythmias.

Verapamil (along with diltiazem) belong to a sub-class of calcium channel blockers called the non-dihydropyridines. In contrast to the dihydropyridine calcium channel blockers (such as amlodipine, felodipine, nicardipine, isradipine, and nisoldipine), Verapamil's ability to dilate blood vessels is relatively limited, while its effect on the heart muscle and the cardiac electrical system is relatively pronounced.

Common clinical uses for verapamil are:

Treatment of stable angina. Verapamil has several effects that can reduce symptoms in people with stable angina due to atherosclerotic coronary artery disease. By dilating blood vessels, reducing heart muscle contraction, and slowing the heart rate, verapamil lowers the heart's demand for oxygen, and therefore helps to prevent the cardiac ischemia (oxygen starvation) that brings on the symptoms of angina. In addition, verapamil can be particularly useful in people with angina due to coronary artery spasm (Prinzmetal's angina), by directly preventing the arterial spasm from occurring.

Treatment of hypertension. The extended-release form of verapamil is effective in treating hypertension, because of its effect on dilating blood vessels. However, the dihydropyridine calcium blockers are often preferred over non-dihydropyridines like verapamil, since their direct effects on the heart itself are less pronounced.

Treatment of cardiac arrhythmias. By its effects on the heart's sinus node and AV node, verapamil can be useful in treating several types of cardiac arrhythmias. Verapamil can be given by mouth or intravenously to stop episodes of AV nodal reentrant tachycardia or atrioventricular reentrant tachycardia, and can be given chronically (by mouth) to prevent recurrences of these arrhythmias. Verapamil can be used to help control the heart rate in people with atrial fibrillation or atrial flutter. It can also be useful in slowing the heart rate and reducing symptoms in people with inappropriate sinus tachycardia. While verapamil is of limited use in treating ventricular arrhythmias, it may be effective in treating a specific type of ventricular tachycardia called repetitive monomorphic ventricular tachycardia. 

Treatment of hypertrophic cardiomyopathy. In people who have hypertrophic cardiomyopathy with left ventricular outflow obstruction, verapamil has been used to reduce symptoms of heart failure. It is theorized that, by reducing the force of contraction of the heart muscle, verapamil can reduce the degree of outflow obstruction. However, this treatment has not been evaluated in randomized clinical trials. Furthermore, in some people with severe hypertrophic cardiomyopathy that has failed to respond to other drugs, treatment with verapamil has resulted in a worsening of their condition.

Reducing proteinuria in chronic kidney disease. Verapamil can significantly reduce the amount of protein spilled into the urine in people with chronic kidney disease caused by hypertension or diabetes, and by doing so, is thought to slow the progression of these kidney diseases.

Treating migraine. Some doctors use verapamil for the treatment of migraines, but clinical studies that have evaluated its effectiveness for this use are less than convincing. While several drugs with proven efficacy are now available for treating migraines, anecdotal reports do suggest that verapamil may offer some benefit to some individuals.

Treating Peyronie's disease. Verapamil by injection can be effective in treating Peyronie's disease. Peyronie's disease is a condition in which patches of fibrosis develop in the penis, producing some combination of deformity, lumps, pain, and erectile dysfunction. When injected locally, verapamil can help to inhibit the patches of fibrous tissue that cause this condition. Verapamil is thought to be most effective when used in combination with other treatments for Peyronie's disease.

Before Taking

Before you are prescribed verapamil, your doctor will need to do an evaluation to determine whether this is the optimal drug to treat your condition. Each of the conditions for which verapamil is often used can be treated with other medicines, and sometimes verapamil may not always be the first choice. 

For instance, if a calcium blocker is being used to treat stable angina, a doctor may choose to use a dihydropyridine calcium blocker (like nifedipine) instead of verapamil, because a dihydropyridine may be more useful in treating any concomitant hypertension.

Also, because verapamil can depress cardiac contraction and slow the heart rate, it may not be the optimal drug for a person with either heart failure or sinus node disease, especially if a beta blocker is also being used.

Precautions and Contradictions

Allergic reactions do occur with verapamil, including anaphylaxis, but are uncommon.

In people with weakened heart muscles, verapamil can precipitate episodes of heart failure. This is especially a concern in people with angina and reduced left ventricular ejection fractions, who are being treated with both beta blockers and verapamil.

Verapamil should not be used in people with severe congestive heart failure, since it can reduce the force of contraction of the heart muscle.

Verapamil should be used with caution in people with persistent sinus bradycardia, and should not be used at all in those with sick sinus syndrome or second- or third-degree AV block, unless they have received a permanent cardiac pacemaker.

Verapamil should not be used in people with significant hypotension (systolic pressure less than 90 mmHg).

Verapamil should be used with caution in people with liver disease. Because verapamil is metabolized in the liver, liver disease can cause blood levels of the drug to rise.

Because the metabolites of verapamil are excreted by the kidneys, the drug should be used with caution in people with kidney disease. If verapamil is given to people with liver or kidney disease, lower doses should be used, and they should be carefully monitored for signs of overdose.

It is not known whether verapamil causes particular problems during pregnancy, but because insufficient data exists this drug should not be used unless it is very necessary to do so.

Other Calcium Channel Blockers

  • Procardia (nifedipine)
  • Cardene (nicardipine)
  • Plendil (felodipine)
  • Norvasc (amlodipine)
  • Cardizem (diltiazem)

Dosage

The Verelan brand of verapamil is available as an extended release capsule in strengths of 120 milligrams (mg), 180 mg, 240 mg, and 360 mg. It is also available as Verelan PM extended-release capsules as in strengths of 100 mg, 200 mg, and 300 mg.

The Calan brand of verapamil is available as an immediate-release tablet at 80 mg and 120 mg strengths, and as an extended-release tablet in strengths of 120 mg and 240 mg.

In addition, generic verapamil is available as immediate-release tablets (40 mg, 80 mg, and 120 mg), as extended-release tablets (120 mg, 180 mg, and 240 mg), and as extended-release capsules (100 mg, 120 mg, 180 mg, 200 mg, 240 mg, and 300 mg).

Finally, verapamil is also available for intravenous injection. It is usually given as a 5 or 10 mg dose, slowly over at least two minutes.

Typical dosages of verapamil are as follows. (Note that these dosages are according to the drug manufacturer. Check your prescription and talk to your doctor to make sure you are taking the right dose for you.)

  • For the treatment of angina, extended-release forms of verapamil are typically used, in doses of 180 mg/day to 480 mg/day, usually taken at bedtime.
  • For the treatment of hypertension, extended-release forms of the drug are used, in doses of either 180 mg or 240 mg per day, usually taken in the morning, although taking it at bedtime is also effective.
  • For preventing the recurrence of AV nodal reentrant tachycardia or atrioventricular reentry tachycardia, divided doses of the immediate-release forms of verapamil are preferred—240 to 480 mg/day in three or four doses.
  • For acutely treating AV nodal reentrant tachycardia or atrioventricular reentrant tachycardia, or to acutely reduce the heart rate in a person with atrial fibrillation or atrial flutter, verapamil is usually given intravenously as a 5 to 10 mg bolus administered over at least two minutes. An additional 10 mg is often given after 30 minutes, if the arrhythmia persists. In children, the dose of intravenous verapamil is reduced to 0.1 mg/kg, up to 5 mg total.
  • For controlling the heart rate in chronic atrial fibrillation, atrial flutter, or multifocal atrial tachycardia, extended-release forms of verapamil are typically used, 180 to 480 mg taken once daily.
  • When treating hypertrophic cardiomyopathy, no optimal dosage has been established for verapamil. Investigators evaluating this type of treatment have used high doses, generally 320 to 640 mg per day.
  • For preventing migraines, no firm dosage has been established. Studies with verapamil in migraines have used 80 mg immediate-release tablets three to four times per day.

How to Take and Store

Verapamil should be stored at room temperature, and protected from light and moisture. Capsules should be swallowed whole, and not crushed or chewed. 

This drug may be taken with or without food, but you should avoid grapefruit juice as it can increase the amount of verapamil in your body. Alcohol can also increase blood levels of verapamil, and should be avoided.

Side Effects

The most common side effect with verapamil is constipation, which is related to the dosage taken. This problem can become significant enough to limit a person's ability to tolerate this drug. 

If verapamil lowers the blood pressure too much, you can experience lightheadedness, dizziness, or even syncope (fainting). Low blood pressure can also cause a rapid heart rate, palpitations, or chest pain.

Verapamil can also result in a heart rate that is too slow, potentially causing lightheadedness or dizziness. 

Verapamil can cause swelling in the legs or ankles.

Other side effects occasionally seen with verapamil include:

  • Headache
  • Nausea or heartburn
  • Flushing
  • Sleep disturbances
  • Erectile dysfunction
  • Muscle aches

Warnings and Interactions

A number of drugs can interact with verapamil to produce undesirable effects. Verapamil is metabolized by CYP3A4, and drugs that inhibit this enzyme (especially erythromycin and ritonavir) can cause elevated blood levels of verapamil. Drugs that induce CYP3A4 can cause low blood levels of verapamil.

Zocor (simvastatin) and Mevacor (lovastatin) levels can become increased in people taking verapamil, possibly leading to a higher risk of statin-induced myopathy.

Using beta blockers together with verapamil can worsen heart failure.

Using verapamil with antihypertensive drugs can cause low blood pressure.

Other drugs reported to interact with verapamil include:

  • Antiarrhythmic drugs
  • Aspirin
  • Tagamet (cimetidine)
  • Tegretol (carbamazepine)
  • Corlanor (ivabradine)
  • Luminal (phenobarbitol)
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