LC–ESI-MS method for the determination of bisoprolol in human plasma

A sensitive liquid chromatography–electrospray ionization-mass spectrometry (LC–ESI-MS) method has been developed and validated for the determination of bisoprolol in human plasma, using metoprolol as internal standard (I.S.). After alkalization with sodium hydroxide, the samples were extracted with ethyl acetate and separated by HPLC on a ZORBAX SB-C18 column with a mobile phase of 10 mM ammonium acetate buffer containing 0.1% formic acid–methanol (32:68, v/v) at a flow rate of 1 ml/min. The chromatographic separation was achieved in less than 5 min. The linearity was established over the concentration range of 0.05–120 ng/ml. The intra- and inter-run standard deviation was less than 3.8 and 7.5%, respectively. The method had been successfully applied to study the relative bioavailability of bisoprolol fumarate tablets in healthy Chinese volunteers. The pharmacokinetic parameters of the reference and test tablets have been compared.