theophylline, Respbid, Slo-Bid, Theo-24, Theolair
Omudhome Ogbru, PharmD
Medical and Pharmacy Editor:
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 (CCBs), which includes amlodipine (Norvasc), diltiazem (Cardizem, Dilacor), nifedipine (Adalat, Procardia) as well as others. These medications block the movement of calcium into the muscle cells of the coronary arteries (the arteries supplying the heart with blood) as well as the other arteries of the body. Since calcium triggers contraction of muscles, blocking entry of calcium relaxes the muscles that surround the arteries. This relaxation allows 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 muscles in the arteries of 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). 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.
GENERIC AVAILABLE: Yes
PREPARATIONS: Immediate release tablets: 40, 80, and 120 mg; sustained release caplets: 120, 180, 240,and 360 mg; extended release tablets: 100, 120, 180, 200, 240, and 300 mg; Injection: 2.5 mg/mL
STORAGE: Verapamil should be stored at room temperature 15-30 C (59-86 F) in a 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 the 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. Although it is not approved by the FDA for migraines, verapamil is used for preventing migraine.
DOSING: 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 cause profound and dangerous reductions in heart rate. Verapamil can raise the levels of some drugs in blood including digoxin (Lanoxin), theophylline (Slo-Bid), cyclosporin, and carbamazepine (Tegretol). Therefore, monitoring of the levels of these drugs is important to avoid toxicity.
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