Half-life antithrombotics

Sulfinpyrazone is a structural derivative of the anti-inflammatory drug phenylbutazone. Unlike phenylbutazone, however, sulfinpyrazone does not have significant anti-inflammatory activity. It does have potent uricosuric effects and frequently is used in the treatment of gout. At least four metabolites of sulfinpyrazone have been identified, including the sulfide, sulfone, p-hydroxysulfide, and p-hydroxysulfinpyrazone derivatives (Fig. 31.16) (24). Only the parent sulfinpyrazone and its reduced sulfide metabolite, however, are active as COX inhibitors (98). Because these compounds are reversible inhibitors, the antithrombotic activity lasts only as long as blood levels of the drug and metabolite persist (half-life, 4-6 hours for parent sulfinpyrazone, 11-14 hours for the sulfide metabolite). Sulfinpyrazone is not yet approved in the United States for use in acute myocardial infarction or for transient ischemic attack prophylaxis. 

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