Determination of Famotidine in Plasma and Urine by High‐performance Liquid Chromatography

Abstract

Because therapeutic concentrations of famotidine are low in plasma, a sensitive method is required to determine plasma famotidine concentrations in clinical studies. A sensitive and rapid high-performance liquid chromatographic (HPLC) method was developed for the determination of famotidine in both plasma and urine samples. Ranitidine and cimetidine were used as internal standards for urine and plasma measurements. For plasma, the mobile phase was acetonitrile-water (15 : 85 v/v), 45 mM sodium dodecyl sulphate (SDS) and 20 mM disodium hydrogen phosphate adjusted to pH 3. A mixture of methanol-phosphate buffer (20 : 80 v/v) adjusted to pH 6·3 was used as the mobile phase for the determination of the compound in urine. The separation was performed on an analytical 150 · 3·9 mm i.d. reversed-phase Novapack C18 (4 μm particle size) column using UV detector (267 nm for plasma and 282 nm for urine). The detection limits for famotidine in plasma and urine were 7·5 ng ml−1 and 160 ng ml−1, respectively. The inter- and intra-assay coefficients of variation were found to be less than 10%.