Propranolol kinetics: use of automated liquid chromatography

Concentrations of propranolol in plasma or cerebrospinal fluid can be reliably quantitated using liquid chromatography with fluorescence detection. After addition of pronethalol as internal standard, alkalinized samples are extracted with hexane:isoamyl alcohol (98:2); the organic extract is separated, evaporated to dryness, reconstituted in mobile phase (acetonitrile:water:acetic acid, 30:69:1), and chromatographed on a reverse-phase C-18 column. Effluent is monitored with fluorescence detection at excitation and emission wavelengths of 235 and 335 nm. The simplified extraction procedure plus an automatic injection system allows one person to analyze up to 100 samples per day. Sensitivity limits are .5 ng of propranolol per ml of sample, and the method is applicable to experimental and clinical pharmacokinetic studies.