Calcium Antagonists in Hypertension

Abstract

Calcium antagonists (or calcium channel blockers) are pharmacological agents that are widely used in clinical medicine, mostly for cardiovascular indications [1]. Early agents of this class were discovered and thought to be similar to g -blockers during laboratory investigations, but their unique pharmacological profiles and utility in many clinical conditions was recognized during the 1960s [2]. Although the first two indications approved by the US FDA were supraventricular tachycardia (verapamil, 1981) or angina pectoris (nifedipine, 1982), most prescriptions for agents in this drug class (see Table I) are currently written for hypertension. Some of these agents have established efficacy (i.e., significantly better than placebo) in other conditions, including Raynaud's syndrome, esophageal spasm, ureteral spasm (typically due to urolithiasis), migraine headache prophylaxis, pre-term labor, cancer chemotherapy, prevention of recurrent myocardial infarction, and left ventricular dysfunction of the diastolic type. Although calcium antagonists share some important pharmacological properties, there are clear and distinct differences across many of the available agents. Dividing these into "dihydropyridine or non-dihydropyridine" subclasses (see Table I) has the advantage of being a simple, dichotomous, and clinically-useful scheme [3].