Use of intravenous diltiazem in patients with acute coronary artery disease

The use of calcium antagonists for the treatment of patients with unstable angina and acute myocardial infarction has been a promising area of both basic and clinical research. Despite consistently beneficial effects experimentally, the clinical extrapolation of these results has been less than ideal, especially in patients with evolving myocardial infarction. Calcium antagonists have in some instances failed to manifest benefit and at times have been shown to have negative effects. One reason for this could be the use of oral or sublingual preparations, which result In variable absorption, variable volumes of distribution, and variable clearance. For this reason, an intravenous preparation of one of the calcium antagonists, diltiazem, may be more beneficial. Such a preparation has been developed and its safety confirmed in patients without cardiovascular disease and in patients with acute infarction. Substantial benefit has been documented in patients with stable angina and during noncardiac surgery. Preliminary data in patients with unstable angina suggest that the drug to effective, although studies comparing intravenous diltiazem with other agents or with the oral preparation of diltiazem have not yet been reported. Experimental data in animals wtth acute infarction have demonstrated that administration of intravenous diltiazem after occlusion, but prior to reperfusion, elicits a marked increase in the degree of myocardial salvage induced by thrombolysis. This appears to be due to the inhibition of lipid peroxidation rather than alterations in coronary perfusion. Thus, it appears that the intravenous preparation may permit the more effective use of diltiazem in patients with acute coronary artery disease.