HPLC quantification of carvedilol in small plasma volumes from children

A sensitive high-performance liquid chromatographic method has been develop ed for the determination of the beta -receptor blocker carvedilol in small volumes of plasma from pediatric patients. Carvedilol and the internal stan dard naftopidil were extracted from only 300 muL plasma with solid-phase ex traction columns and eluted with a mixture of 80% (v/v) acetonitrile and 20 % (v/v) potassium acetate buffer(0.1 M, pH 5). Analysis of the extracts was performed on a Spherisorb C-6 column with a mobile phase of 65% acetonitri le, 35% potassium acetate buffer (0.25 M, pH 4) and fluorescence detection. Carvedilol and the internal standard showed recoveries of 870 +/- 13.9% an d 917 +/- 18.0%, respectively (n = 75, each; values are means +/- standard deviations). The analysis of carvedilol was linear over a range of 0.40-242 ng mL(-1), the limit of quantification was 0.40 ng mL(-1). As an applicati on of the assay, a profile of plasma concentrations versus time of a six-mo nth-old patient is reported.