Degradation Kinetics of Olopatadine HCL Using a Validated UV-Area under Curve Method

The objectives of this investigation were to establish a validated UV-area under curve (AUC) method for assay of Olopatadine HCL and to study the degradation behaviour of the drug under different ICH-recommended stress conditions. The spectral measurements were performed using AUC; 275 ↔ 320 nm with wavelength maxima at 298 nm in 0.9% w/v sodium chloride as solvent. The method was validated for linearity, precision, accuracy, robustness, specificity, and sensitivity, using sample of the bulk drug. Linear regression analysis data for the calibration plots showed a good linear relationship between response and concentration in the range of 5-100μg/mL. The drug was subjected to mild and moderate forced degradation and the degradation constant was calculated using linear as well as non-linear fit model for all the conditions. The drug was found to be less stable in acidic and photolytic degradation conditions. Photolytic degradation constants of Olopatadine in dry and wet state were 0.002488 and 0.003583 % min-1, respectively. The effect of deliberate changes in solvent strength and upper and lower wavelength were observed on AUC using 33 fractional factorial designs. The overall % RSD for robustness studies was 1.15. The utility of the method was verified by analyzing the drug in bulk form and a marketed formulation, the assay was found to be 99.04-101.5% and 99.15-99.27%, respectively. These results indicate the method can be successfully used for routine analysis of Olopatadine HCL in the bulk drug and in pharmaceutical dosage forms.