The use of polymeric solid phase extraction and HPLC analysis for the determination of ranitidine in routine plasma samples obtained from paediatric patients

A sensitive HPLC method for the determination of ranitidine in small-volume (0.5 mL) paediatric plasma samples is described. Plasma samples were extra cted using a simple, rapid solid phase extraction (SPE) technique developed using disposable copolymer packed SPE cartridges. Chromatographic separati on was achieved by reverse-phase HPLC with isocratic elution using a mu Bon dapak C-18 column and a phosphate buffer (10 mM, pH 3.75)-acetonitrile (87: 13 v/v) mobile phase with UV detection at 313 nm. The HPLC system exhibited linearity in the range 8-800 ng mL(-1). Intraday % CV and % bias values we re in the range 1.28-8.09% (% bias-4.33 to -0.87) and interday % CV and % b ias values were in the range 0.73-15.28% (% bias-1.80 to +1.65). The limits of detection and quantitation obtained were 2 ng mL(-1) and 8 ng mL(-1), r espectively, and ranitidine extraction recoveries from plasma ranged from 9 2.30 to 103.88%. in this study, the developed HPLC and SPE methodologies ha ve been successfully applied to the determination of ranitidine concentrati ons in 68 paediatric plasma samples. The sampled population was drawn from patients already receiving the study drug therapeutically. Patients recruit ed had received ranitidine by two main routes-oral and intravenous. The pla sma concentrations of ranitidine encountered in paediatric samples followin g oral or intravenous administration of a range of prescribed doses are pre sented graphically. These profiles are based on analysis of the first 68 pl asma samples obtained from the first 35 patients recruited to the study rec eiving ranitidine by the oral or intravenous route.