Abstract
A stability indicating chiral high-performance liquid chromatographic (HPLC) method was developed and subsequently validated for the separation and simultaneous determination of S-(+)-and R(-)-donepezil hydrochloride (DP) in tablet products. Baseline resolution was achieved by using Chiralcel-OJ-H column with a mobile phase consisted of ethanol-n-hexane-triethylamine (20:80:0.3, v/v/v). The detection wavelength was 268 nm. Arotinolol was chosen as internal standard to guarantee a high level of quantitative performance. Chromatographic peak purity data of DP enantiomers using photodiode array detector indicated no co-eluting peaks with the main peaks of drugs, which demonstrated the specificity of the assay method for their estimation in presence of degradation products. Denepezil enantiomers and their drug products were exposed to thermal, photolytic, hydrolytic and oxidative stress conditions and the stressed samples were analyzed by the proposed method. The described method was linear over the range of 25 - 2500 ng/ml (r=0.999) with detection limit of 10 ng/ml for both enantiomers. The recoveries of S-(+)-and R(-)-DP from tablets preparations ranged from 98.0 to 100.5 % and 98.0 to 100.8 %, respectively. The intra-day and inter-day precision and accuracy were evaluated by calculating the % RSD (n = 6) and the % error were found to be in the ranges of 0.58 - 1.29% and -1.07 -1.04% for both enantiomers, respectively. The proposed method can be useful in the quality control of drug products.