[Calcium channel blockers (calcium antagonists). Background, effects and use].

The calcium ion plays a decisive role in the effect and regulation of several cellular processes. The heart muscle cells, pacemaker and channel systems and vascular smooth muscle are functionally dependent on Ca2+ influx mainly via potential sensitive L (long lasting)-Ca(2+)-channels, which are blocked by Ca(2+)-channel blockers, a group of organic substances binding to specific sites at the Ca2+ channels. The Ca2+ channel blockers are now well established in the treatment of angina pectoris, arterial hypertension, supraventricular arrhythmia and subarachnoidal haemorrhage. On the basis of chemistry and pharmacodynamics the Ca2+ channel blockers are divided into three groups, with verapamil, nifedipine and diltiazem representing 1. generation derivatives and prototypes for groups I, II and III, respectively. All Ca2+ channel blockers act as vasodilators, while group I (verapamil) and to a lesser degree group III (diltiazem) also have antiarrhythmic effects. All Ca(2+)-channel blockers are contraindicated in hypotension. In cases of pronounced bradycardia, sinoatrial and atriventricular block Ca2+ channel blockers with antiarrhythmic effects are contraindicated and must be used with care in combination with beta-blocker treatment and in heart failure. Headache, flushing, reflex tachycardia, nausea, obstipation and ankle oedema are the most important secondary effects. With respect to pharmacodynamics the newly marketed 2. generation derivatives do not differ essentially from the 1. generation derivatives. The clinical potential of the Ca2+ channel blockers is not fully explored and the possibilities for extending their indications are still to be elucidated.