Clinical pharmacology of calcium antagonists

Verapamil, nifedipine, and diltiazem are effective in the treatment of stable effort angina and angiospastic (variant) angina. In addition, there is evidence that the agents are beneficial in patients diagnosed as having unstable angina. The efficacy of calcium antagonists for the treatment of effort angina appears to be augmented by combining them with beta-adrenergic blockers. Intravenous verapamil, but not nifedipine, is very effective in terminating paroxysmal supraventricular tachycardias caused by re-entrant mechanisms with or without involvement of accessory pathways (WPW syndrome). Verapamil is also effective in slowing the ventricular response to atrial fibrillation or flutter. The use of verapamil for the treatment of ectopic atrial or ventricular dysrhythmias is less well established and will require further evaluation.