Donepezil and Quercetin Simultaneous Estimation in Rat Plasma Using Developed Bioanalytical HPLC Method: Relevance in Pharmacokinetic Studies

Abstract

The objective of this investigation was to create and apply a reliable reverse phase high performance liquid chromatography (RP-HPLC) technique for the concurrent measurement of donepezil (DPZ) and quercetin (QT) in rat blood samples for pharmacokinetic research. This is the first publication that introduces a method for DPZ and QT simultaneous determination in rat plasma by high-performance liquid chromatography (HPLC). Using a mobile phase of methanol and HPLC grade water (pH 2.8; adjusted with 0.05% v/v orthophosphoric acid) 45:55 v/v with 2-3 drops of triethylamine (TEA) in an isocratic elution mode at flow rate of 1.0ml/min, DPZ and QT were successfully separated chromatographically on a Hypersil gold C-18 column (250 mm × 4.6 mm, 5μm). The retention time for DPZ and QT was observed to be 6.3 and 12.3 minutes and was detected at an isobestic wavelength of 273 nm using a UV detector. The method was shown to be precise (%RSD < 2%), accurate (96–100%), and specific for the simultaneous detection of DPZ and QT. Several freeze-thaw cycles of the treated plasma samples did not significantly affect the analyte’s stability. The method’s applicability was subsequently confirmed through an oral pharmacokinetic investigation in rats. Since the results were deemed trustworthy, the validated RP-HPLC method may be used to simultaneously detect and quantify both drugs. The method worked well for evaluating the pharmacokinetic characteristics in wistar rats following a single oral dose of 5 mg/kg of QT and 10 mg/kg of DPZ. It is well acknowledged that the chromatographic process is straightforward, robust, accurate, exact, and repeatable.