Determination of sotalol in human body fluids for pharmacokinetic and toxicokinetic studies using high-performance liquid chromatography.

A sensitive, reliable and discriminating assay method is reported for the determination of sotalol (4-(1-hydroxy-2-isopropylaminoethyl)methanesulfonanilide) in human plasma and urine. The assay procedure has been successfully used during pharmacokinetic studies in healthy volunteers and patients as well as during toxicokinetic analysis. For sample preparation the internal standard atenolol was added to the specimen which was then extracted with n-pentanol-chloroform (1/3) at pH 9.0 followed by re-extraction into 0.05 mol/l sulfuric acid. Chromatography with fluorimetric detection was performed on Hypersil ODS 5 micron including the addition of heptanesulfonic acid and sodium dodecyl sulfate to the mobile phase of acetonitrile-water-acetic acid (20/79/1). Calibration was linear over the ranges of 0.1 to 5.0 micrograms/ml and 0.2 to 100 micrograms/ml for plasma and urine, respectively. Over these ranges coefficients of variation were below 10%. Recovery was between 82 and 98% from plasma and between 92 and 99% from urine.