Fluorimetric determination of rivastigmine in rat plasma by a reverse phase--high performance liquid chromatographic method. Application to a pharmacokinetic study.

A sensitive and selective high performance liquid chromatographic (HPLC) method was developed and validated for the rapid quantification of rivastigmine (CAS 123441-03-2) in micro quantity in rat plasma samples. The chromatographic separation was achieved with a reverse phase monomeric column C18 (4.6 x 250 mm, 5 microm) and the mobile phase consisted of acetonitrile and 20 mmol/L phosphate buffer pH 3.0 (25:75) with a flow rate of 1 mL/min. The effluents were measured by fluorimetric detection with excitation and emission wavelengths at 220 nm and 293 nm, respectively. The calibration curve was linear (r2 > 0.99) ranging from 25-3000 ng/mL and the lower limit of quantification was 25 ng/mL. The method was validated with excellent sensitivity, selectivity, accuracy, precision, recovery and stability. The method has been successfully applied in a pharmacokinetic study of rivastigmine in rats.