Determination of sulphinpyrazone in patient plasma by gas chromatography

Two variations of a method for the determination of sulphinpyrazone in plasma by gas chromatography and by gas chromatography/mass spectrometry are described. Both are based upon methylation of sulphinpyrazone by phase transfer catalysis with methyl iodide as the alkylating agent. The range of plasma concentrations in patients with transient cerebral ischemia being treated with sulphinpyrazone as well as hemodialysis patients being treated for arteriovenous shunt thrombosis are described. Accumulation of sulphinpyrazone did not occur in hemodialysis patients, indicating that in these patients the drug is effectively cleared by a non-renal mechanism.