INVESTIGATION OF OLOPATADINE HYDROCHLORIDE UNDER STRESS CONDITIONS BY HYDROPHILIC INTERACTION LIQUID CHROMATOGRAPHY

The purpose of the present research was to conduct stress degradation studies on the olopatadine hydrochloride, an antiallergic drug, using the hydrophilic interaction liquid chromatography (HILIC). HILIC requires the utilization of polar and moderately polar stationary phases and aqueous-organic mobile phase usually containing more than 70% of organic solvent. In this study, olopatadine hydrochloride was subjected to acid and base hydrolysis, oxidation and thermolytic degradation in order to estimate its stability under different stress conditions recommended by ICHQ1A (R2) guideline. Degree of degradation was followed by HILIC method. The chromatographic conditions were: column Betasil Cyano (100 mmx4.6 mm, 5 mu m particle size), mobile phase consisted of acetonitrile and ammonium acetate 5 mM (pH adjusted to 4.50) in ratio 85: 15 V/V, flow rate was 1 mL min(-1), column temperature was set at 30 degrees C and detection was performed at 257 nm. Results obtained for stress studies indicated that olopatadine hydrochloride underwent transformation under acidic and oxidative (30% hydrogen peroxyde) conditions showing high degree of degradation. Furthermore, it was found that olopatadine hydrochloride is relatively stable when exposed to thermal (60 degrees C) and basic (1 M NaOH) conditions. Therewith, kinetics of degradation reaction was determined with an aim to define the corresponding reaction rate constants and half-lives. Firstly, the order of the reaction was evaluated experimentally using the integral method. Based on the calculated values of the correlation coefficients, it was shown that the acidic, basic and oxidative degradation are the second-order reaction. High stability under basic conditions was achieved on the basis of the great degradation half-life values. Also, it has been verified that acidic degradation is the fastest reaction.