The new long-acting coronary artery dilator molsidomine and its metabolite SIN-1.

We studied the effects of intracoronary injections of SIN-1 (0.8 mg), the active metabolite of molsidomine, on coronary artery diameters and coronary stenoses. In nine patients with abnormal angiograms measurements were made 4 and 8 minutes after SIN-1 administration. There was a statistically significant increase in coronary luminal diameter in proximal, medial, and distal segments as well as at the level of the stenoses. At 4 minutes after administration distal segments showed a mean increase in diameter of 50%, compared to a mean increase of 26% in proximal segments. In six patients with normal angiograms SIN-1 abolished three of four coronary spasms induced by ergonovine maleate. A protective effect of SIN-1 against the vasoconstrictor effects of ergonovine was still present at 8 minutes after administration. Heart rate and blood pressure remained unchanged throughout the study. We conclude that the vasodilation induced by SIN-1 in normal and stenotic coronary arteries is probably an important contribution to the antianginal efficacy of molsidomine and suggests that molsidomine may be effective in the prophylaxis of variant angina.