Detailed Drug Information:

DRUG CLASS AND MECHANISM: Verapamil belongs to a class ofmedications called calcium channel blockers. These medications block thetransport of calcium into the smooth muscle cells lining the coronaryarteries and other arteries of the body. Since calcium is important inmuscle contraction, blocking calcium transport relaxes artery muscles anddilates coronary arteries and other arteries of the body. By relaxingcoronary arteries, verapamil is useful in treating and preventing chestpain (angina) resulting from coronary artery spasm. Relaxing the muscleslining the arteries of the rest of the body lowers blood pressure, whichreduces the burden on the heart as it pumps blood to the body. Reducingheart burden lessens the heart muscle's demand for oxygen, and furtherhelps to prevent angina in patients with coronary artery disease. For moredetailed information related to coronary artery disease, please read theChest Pain,Cholesterol, andHeart Attack articles.Verapamil can decrease electrical conduction in the heart and slow heartrate.

PREPARATIONS: tablets of 40, 80, 120mg; sustained releasecaplets of 120, 180, 240mg (Calan SR, Isoptin SR, Verelan, Verelan PM)

A controlled onset, extended-release verapamil delivery system (Covera-HS) was approved for the treatment of angina and hypertension in 1996. This preparation is designed to release active drug according to the body's natural circadian rhythm. Specifically, a night-time dose reaches its peak effectiveness in the early morning when surges in blood pressure often occur.}

STORAGE: Store at room temperature in tight, light-resistantcontainer.

PRESCRIBED FOR: Chest pain (angina) occurs because insufficientoxygen is delivered to the heart muscles. Insufficient oxygen may be aresult of a coronary artery blockage or spasm, or because of physicalexertion which increases heart oxygen demand in a patient with coronaryartery narrowing. Verapamil is used for the treatment and prevention ofangina resulting from coronary artery spasm as well as from exertion.Verapamil is also used in the treatment of high blood pressure. Verapamilslows electrical conduction in the heart. It has been used in treatingabnormally fast heart rhythms such as atrial fibrillation, and in theprevention of recurrent episodes of rapid heart rhythm originating fromthe atria. For further information about abnormal heart rhythms, pleaseread the Atrial Fibrillationand Palpitation articles.

PROPER USE: Verapamil can be taken with food. Since verapamil isexcreted by the kidney and metabolized by the liver, dosages may need tobe reduced in patients with liver or kidney dysfunction. Otherwise, excessaccumulation of verapamil in the body can cause profoundly slow heart rateand low blood pressure.

PRECAUTIONS: Verapamil slows heart electrical conduction, andcan cause a dangerously slow heart rate in patients with existingelectrical conduction disease of the heart. Concurrent use of verapamilwith a beta blocker (another class of medications that slow heart rate)can occasionally cause profound heart slowing. A small group of patientswith irregular heart rhythms has a condition called Wolff-Parkinson-White (WPW) syndrome. Verapamil can cause a dangerously rapid heart rate inthese individuals. Verapamil can aggravate heart failure, especially inpatients with poor ventricle muscle function. Verapamil can also causeexcessive lowering of blood pressure in rare instances.

Concurrent administration of verapamil with digoxin(Lanoxin),theophylline (Slo-Bid), and carbamazepine (Tegretol) can increase blooddrug levels of these other medications. Therefore, monitoring of druglevels is important to avoid toxicity. (Digoxin is commonly used intreating heart failure and fast heart rhythms. Theophylline is used intreating asthma. Carbamazepine is an anti-seizure medication.) Safety inchildren has not been established.

PREGNANCY: Safety during pregnancy has not been established.

NURSING MOTHERS: Safety in nursing mothers has not beenestablished.

SIDE EFFECTS: Side effects are generally mild and transient.Verapamil can cause difficulty breathing or wheezing as a result ofworsening heart failure. It can cause dizziness, weakness or faintingbecause of slow heart rate or low blood pressure. Other side effectsinclude swelling of the lower extremities, rash, headache, andconstipation. Verapamil can also cause mildly abnormal liver tests thatare generally reversible with discontinuation of the medication.