Stability-Indicating HP TLC Method for Determination of Donepezil Hydrochloride in Bulk Drug and Pharmaceutical Dosage Form

A sensitive, selective, precise and stability-indicating high-performance thin layer chromatographic (HPTLC) method for analysis of donepezil hydrochloride (DH) as bulk drug and in formulations was developed and validated. TLC aluminum plates pre-coated with 60 F-254 silica gel (20 x 10 cm) were used as the stationary phase. The solvent system consisted of butanol water glacial acetic acid (5:4:1, v/v/v). Densitometric analysis of DH was carried out in the absorbance mode at 260 nm. This system was found to give compact spots for DH (R(F) = 0.53 +/- 0.03 for six replicates). DH was subjected to acidic and alkaline hydrolysis, oxidation, dry and wet heat treatment, and photodegradation; under all these conditions the drug underwent degradation. Degradation products had significantly different RE values and thus were well separated from the pure drug. The method was validated with respect to linearity, precision, robustness, limit of detection (LOD), limit of quantification (LOQ), ruggedness and accuracy. Linearity was observed in the range 50-1000 ng per spot with a significantly high value of the correlation coefficient r(2) = 0.9979; 95% confidence interval of r(2) was 0.9908-0.9995. The mean S.E. value of the slope was 0.1316 with respect to the peak area. LOD and LOQ were 15.40 and 50.90 rig per spot, respectively. Statistical analysis proved that the method was repeatable and specific for the estimation of the studied drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating procedure.