See also the following individual entries:
Nicardipine hydrochloride Nifedipine Nimodipine Verapamil Action/Kinetics: The calcium channel blocking agents inhibit the influx of calcium through the cell membrane, resulting in a depression of automaticity and conduction velocity in both smooth and cardiac muscle. This leads to a depression of contraction in these tissues. They also decrease total peripheral resistance by causing relaxation of vascular smooth muscle, thus reducing energy and oxygen requirements of the heart. Also effective against certain cardiac arrhythmias by slowing AV conduction and prolonging repola-rization. In addition, they depress the amplitude, rate of depolarization, and conduction in atria. Uses: See individual drugs. Contraindications: Sick sinus syndrome, second- or third-degree AV block (except with a functioning pacemaker). Use of bepridil, diltia-zem, or verapamil for hypotension (<90 mm Hg systolic pressure). Lactation.
Special Concerns: Abrupt withdrawal may result in increased frequency and duration of chest pain. Hypertensive clients treated with immediate-release dose forms of calcium channel blockers have a higher risk of heart attack than clients treated with diuretics or beta-adrenergic blockers. Safety and effectiveness of bepridil, diltiazem, felodipine, and isradipine have not been established in children.
Side Effects: Side effects vary from one calcium channel blocker to another; refer to individual drugs.
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