Validated liquid chromatographic–fluorescence method for the quantitation of darifenacin in mice plasma and its application to a pharmacokinetic study

A highly selective, sensitive, and rapid high-performance liquid chromatography (HPLC) method has been developed and validated for the quantification of darifenacin in mouse plasma. Bisoprolol was used as an internal standard (IS). Darifenacin and the IS were extracted using the deproteinisation technique, followed by injection of an aliquot of the supernatant into the chromatographic system. The chromatographic separation was achieved on a reversed phase C18 column with a mobile phase of acetonitrile: 0.1% diethyl amine (pH 3.5) (60:40, v/v) pumped at a flow rate of 1.0 mL min−1. The analytes were detected at 210 and 314 nm for excitation and emission, respectively. The assay exhibited a linear range of 100–3000 ng mL−1, with a lower detection limit of 35 ng mL−1. The method was statistically validated for linearity, accuracy, precision, selectivity and stability according to the FDA guidelines. The intra- and inter-assay coefficients of variation did not exceed 13.5% from the nominal concentration. The accuracy for darifenacin was within ±15% of the theoretical value. The assay was successfully applied in a pharmacokinetic study.