NEW USES FOR CALCIUM-CHANNEL BLOCKERS - THERAPEUTIC IMPLICATIONS

Calcium antagonists block calcium entry into cells, resulting in relax ation of smooth muscle and limitation of the cytotoxic effects of isch aemia in various organ systems. They are most frequently used for clin ical conditions requiring vasodilatation, i.e. hypertension and Raynau d's phenomenon, and this also suggests that the most common adverse ef fect of these drugs for noncardiovascular indications is an unwanted d ecline in blood pressure. Other uses include treatment of supraventric ular arrhythmias and angina. There is some evidence that these drugs r etard the development of atherosclerosis. Calcium channel blockers als o improve renal reperfusion and may reduce renal insufficiency due to various nephrotoxins, and are particularly useful in renal transplanta tion for protection against cyclosporin toxicity and post-transplant a cute tubular necrosis. These drugs are also useful in pregnancy-induce d hypertension and unwanted uterine contraction. Affective disorders a nd malignancies may be other conditions which benefit from calcium ant agonist therapy. Calcium antagonists, in particular nimodipine which i s most selective for the cerebral vasculature, have been approved for treating vasospasm after subarachnoid haemorrhage. They are probably a lso effective for treatment of migraine. Calcium channel blockers may be effective for treating acute cerebral infarction, but results of cl inical trials to date have been equivocal, largely because it has been difficult to recruit patients within the short interval after the ons et of stroke when these drugs would be most effective, and because of the unwanted hypotensive effect of high doses.