S-nitrosothiols:: a class of nitric oxide-donor drugs

Nitric oxide (NO) was originally described as the principal endothelium-derived relaxing factor, but it is now known to subserve a variety of functions throughout the body, both physiological and pathophysiological. NO-donor drugs decompose in the body, by a variety of mechanisms, to generate NO. Such drugs have been used for many years in cardiovascular therapeutics, in particular the organic nitrates for the prevention and treatment of angina pectoris and sodium nitroprusside for the treatment of hypertensive emergencies. However, patients taking longterm nitrates often develop tolerance, and prolonged nitroprusside administration can give rise to cyanide accumulation in the body. Newer NO-donor drugs, in particular the S-nitrosothiols, offer advantages over the existing drugs, since they do not share these drawbacks, and initial small clinical studies suggest that they may be of benefit in a variety of cardiovascular disorders. Here we briefly review the chemistry and physiology of NO, and discuss the chemistry and clinical possibilities of the S-nitrosothiols.