High-performance liquid chromatographic determination of sotalol in plasma. I. Application to the disposition of sotalol enantiomers in humans.

Two high-performance liquid chromatographic analytical methods have been developed for the measurement of dl-sotalol or d-sotalol and l-sotalol in plasma, using dl-atenolol as internal standard. Quantitation of dl-sotalol was carried out, following solid-phase extraction, on a 5-microns C18 reversed-phase column, with a mobile phase containing acetonitrile, ion-pairing reagent and distilled water, using ultraviolet detection at 235 nm. Quantitation of d-sotalol and l-sotalol was based on derivatisation with the chiral agent S-(-)-alpha-methylbenzyl isocyanate, followed by chromatographic separation on a 3-microns C18 reversed-phase column, with a mobile phase containing methanol, glacial acetic acid and distilled water, with fluorimetric detection at 220 nm excitation and 300 nm emission. A preliminary application of the latter method suggests that the disposition of sotalol in humans is not enantioselective.