Medications and Drugs
Medical and Pharmacy Editor: Jay W. Marks, MD
GENERIC NAME: verapamil
BRAND NAMES: Calan, Verelan, Verelan PM, Isoptin, Isoptin SR, Covera-HS
DRUG CLASS AND MECHANISM: Verapamil belongs to a class of medications called
calcium channel blockers. These medications block the movement of calcium into the muscle
cells of the coronary arteries (the arteries supplying the heart) as well as the
other arteries of the body. Since calcium is what triggers contraction of
muscles, blocking entry of calcium relaxes the arterial muscles. This relaxation
allows the arteries to become larger so that more blood can flow through them.
Thus, verapamil is useful in treating and preventing chest pain
(angina) resulting from
spasm (contraction) of the coronary arteries that reduces the flow of blood to
the heart. Relaxing the muscles lining the arteries in the rest of the body
lowers blood pressure and thereby reduces the pressure against which the heart
must pump blood. As a result, the heart works less and requires less
oxygen-carrying blood. This allows the heart to work with the reduced flow of
blood caused by coronary artery disease and prevents angina
(which occurs whenever the flow of blood to the heart is inadequate). For more
detailed information related to coronary artery disease, please read the Chest
Pain, Cholesterol, and Heart Attack articles.
Verapamil also decreases the conduction of electrical impulses through the heart
that control the coordination of contraction. As a result, the rate of
contraction slows. Verapamil was approved by the FDA in March, 1982.
PRESCRIPTION: Yes
GENERIC AVAILABLE: Yes
PREPARATIONS: Immediate release tablets: 40, 80, 120 mg; sustained release
caplets: 120, 180, 240, 360 mg; extended release tablets: 100, 120, 180, 200,
240, 300 mg; Injection: 2.5 mg/mL
STORAGE: Store at room temperature 15° to 30°C (59° to 86°F) in tight, light-
resistant container.
PRESCRIBED FOR: Chest pain (angina) occurs because insufficient
oxygen-carrying blood is delivered to the muscles of the heart. Insufficient
oxygen-carrying blood may be a result of blockage of blood flow in the coronary
arteries due to coronary artery disease or spasm, or an increase in physical
exertion that increases the workload of the heart and the demand by the heart
for oxygen. Verapamil is used for the treatment and prevention of angina
resulting from coronary artery disease and spasm as well as from exertion.
Verapamil also is used in the treatment of high blood pressure.
Verapamil slows electrical conduction of the electrical impulses through the
heart and has been used to in treat abnormally fast heart rhythms such as atrial
fibrillation, and
in the prevention of recurrent episodes of rapid heart rhythm originating from
the atria. For further information about abnormal heart rhythms, please read the
Atrial Fibrillation and Palpitation articles.
DOSING: The usual oral dose is 180-480 mg/day. Verapamil may be given once,
twice or three times daily depending on the formulation used. Verapamil can be
taken with food.
DRUG INTERACTIONS: Concurrent use of verapamil with a beta blocker (another class of medications
that slow heart rate) can occasionally cause profound and dangerous heart
slowing.
Verapamil can raise the levels of some drugs in blood including digoxin
(Lanoxin), theophylline (Slo-Bid), and carbamazepine (Tegretol). Therefore,
monitoring of the levels of these drugs is important to avoid toxicity.
Verapamil may reduce blood levels of lithium in some patients. For unclear
reasons some patients who took both verapamil and lithium have noticed increased
side effects of lithium without increases in their blood levels of lithium.
PREGNANCY: Safety during pregnancy has not been established. Verapamil
crosses the placenta and enters the fetus.
NURSING MOTHERS: Safety in nursing mothers has not been established.
Verapamil is excreted in human milk.
SIDE EFFECTS: Side effects from verapamil generally are mild and transient.
It can cause dizziness, weakness or fainting because of a slow heart rate or low
blood pressure. Other side effects include swelling of the lower extremities,
rash, headache, and constipation. Verapamil also can cause mildly abnormal liver
tests that usually return to normal with discontinuation of the medication.
Verapamil may reduce the heart rate. Verapamil also can cause excessive
lowering of blood pressure in rare instances. Verapamil can aggravate heart
failure, especially in patients with poor function of their heart muscle.
Reference: FDA Prescribing Information
Last Editorial Review: 12/21/2006
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
- Calcium Channel Blockers - Establishes the medication calcium channel blockers (CCBs), which are drugs used for treating high blood pressure, angina, and abnormal heart rhythms like atrial fibrillation.
- High Blood Pressure - Learn about high blood pressure symptoms like headache, dizziness, shortness of breath, blurred vision and more. Causes, and normal blood pressure information is included.
- Drug Interactions - Learn about potential drug interactions you may be exposed to. Drug interactions can occur with prescription drugs, OTC medication, vitamins, herbs, and supplements.
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