Study of plasma, urine and gastric juice concentrations of famotidine using high performance liquid chromatography.

An improved method for the high performance liquid chromatography (HPLC) determination of famotidine, a recently introduced inhibitor of histamine H2-receptors, has been devised. Plasma, urine and gastric juice concentrations of famotidine have been measured in a series of 46 patients hospitalized for gastrointestinal disorders and for other unrelated pathologies, after a single oral dose of 40 mg. Pharmacokinetic data confirmed previously described trends of distribution and metabolism of famotidine, attaining peak plasma levels 1.5-2.0 h after oral administration and high urine levels, in unmodified form, between two and twelve hours. This simple HPLC method may be adopted for monitoring plasma concentrations of famotidine in patients, for assessing patient compliance in taking the drug by measuring urine levels and for examining the relationship between plasma famotidine concentration and the antisecretory effect.