Liquid chromatography-tandem mass spectrometry method for the determination of propranolol in human plasma and its application to a bioequivalence study

A rapid, sensitive, and specific method based on liquid chromatography/tandem mass spectrometry (LC-MS/MS) was developed and validated for the determination of propranolol in human plasma using metoprolol as internal standard. The drugs were extracted from plasma by liquid-liquid extraction and separated isocratically on a Phenomenex Synergi Fusion-RP C-18 analytical column, 4m (150mm4.6mm i.d.) maintained at 30 degrees C, with acetonitrile/water (95/5, v/v): 100mM ammonium acetate: 100mM acetic acid (65:15:20 v/v/v) as mobile phase, run at a flow rate of 1mL min(-1) (split 1:3). Detection was carried out by positive electrospray ionization (ESI+) in selected reaction monitoring (SRM) mode. The chromatographic separation was obtained within 3.0min and was linear in the concentration range of 2-150 ng mL(-1) (r(2) = 0.9969). The method was successfully applied for the bioequivalence study of two tablet formulations (test and reference) of propranolol 80mg after single oral dose administration to 36 healthy human volunteers, using an open, randomized, two period crossover design with one week wash out interval.The geometric means ratios of Cmax and AUC(0-) were 99.77 and 103.70%, respectively, with both the confidence intervals between 90.12-112.92% demonstrating the bioequivalence of the two formulations.