Determination of 3,7-dimethyl-1-(5-oxohexyl)-xanthine (pentoxifylline) and its 3,7-dimethyl-1-(5-hydroxyhexyl)-xanthine metabolite in the plasma of patients with multiple diseases using high-performance liquid chromatography

Pharmacokinetic studies of pentoxifylline in elderly patients with multiple diseases are described. Because of the low plasma levels of pentoxifylline and its hydroxy metabolite a new high-performance liquid chromatographic method was established. Under our chromatographic conditions, piracetam, a nootropic drug, can be easily separated from simultaneously applied pentoxifylline and its metabolite. Piracetam shows no appreciable ultraviolet absorption above 230 nm and cannot be detected at 268 nm.