Two metabolites of sulphinpyrazone and their identification and determination by mass spectrometry.

Sulphinpyrazone is an antiplatelet in vivo and in vitro. Two active metabolites, a sulphide (S) and a hydroxylated sulphide (S-OH) have been identified in rabbit and human plasma and a selective and sensitive g.c.-m.s.-method for quantitative determination of the sulphide and hydroxylated sulphide in plasma and urine has been evolved which allows concentrations down to 5 ng ml-1 for the sulphide and 30 ng ml-1 for the hydroxylated sulphide to be detected. The time course of the metabolite concentrations in plasma corresponds to the biological findings, suggesting that the metabolites contribute significantly to the in vivo effects of the drug.