Calcium channel blockers exhibit a wide spectrum of therapeutic activity, including coronary vasodilation and antiarrhythmic effects, by inhibiting calcium entry across cell membranes.
The calcium antagonists are an exciting "class" of drugs that are already making an important impact in the treatment of coronary artery disease. All three drugs in use in the US, verapamil, nifedipine, and diltiazem, are effective coronary vasodilators. In addition, verapamil and diltiazem have antiarrhythmic activity against certain supraventricular abnormalities. Since the calcium antagonists dilate peripheral resistance vessels, they may also be useful in hypertension. There are reports also that they may be effective in migraine headache, probably because of their "antispastic" activity in cerebral vessels. Since calcium is ultimately involved in all processes that require stimulation, either electrical or chemical, it is not surprising that drugs whose primary effect appears to be an inhibition of the entry of calcium across or through cell membranes should exhibit a wide spectrum of therapeutic activity. The stereospecific binding of dihydropyridine derivatives to membrane preparations, and the effects of those and other calcium antagonists on the binding process, should yield important information on the mechanisms of calcium antagonist action.
Schwartz et al. (Wed,) studied this question.