An assay is described for the simultaneous determination of propranolol and its active metabolite, 4‐hydroxypropranolol, in human plasma. Both compounds were separated from an ethereal extract by high‐performance liquid chromatography employing a C18 bonded‐phase column. Detection of the effluent was by fluorescence. Suitable fluorescent spectrometers and wavelength settings that allow optimum detection of both compounds have been described. The limit of sensitivity was 2 ng/ml for both propranolol and 4‐hydroxypropranolol. Mean peak plasma levels of propranolol and 4‐hydroxypropranolol in six patients receiving a single dose of a slow‐release 160‐mg formulation of propranolol were 28 and 6 ng/ml, respectively. These levels were about one‐tenth the level obtained following a single conventionally prepared dose of propranolol (160 mg). Peak levels were delayed and plasma levels of propranolol persisted for a longer period with the slow‐release formulation. Area under the curve estimates suggested that the bioavailability of the slow‐release formulation following single‐dose administration was about one‐third that of the conventional preparation.
- Bioavailability—propranolol, conventional and slow‐release formulations compared
- High‐performance liquid chromatography—simultaneous assay of propranolol and 4‐hydroxypropranolol, conventional and slow‐release formulations compared
- Pharmacokinetics—propranolol, conventional and slow‐release formulations compared
- Propranolol—high‐performance liquid chromatographic assay with 4‐hydroxypropranolol, conventional and slow‐release formulations compared