A validated stability-indicating HPLC method for determination of brimonidine tartrate in BRI/PHEMA drug delivery systems

BACKGROUND A simple, rapid and accurate stability-indicating reverse phase high performance liquid chromatography (RP-HPLC) was developed and validated for the determination of brimonidine tartrate in brimonidine tartrate/poly(2-hydroxyethyl methacrylate) (BRI/PHEMA) drug delivery contact lenses and pharmaceutical formulations. RESULTS Optimum chromatographic conditions for separating brimonidine tartrate from other impurities in the leaching liquor of BRI/PHEMA drug delivery contact lenses or pharmaceutical formulations have been achieved by using a Diamonsil C18 column (150 mm × 4.6 mm, 5 μm) as a stationary phase and a mixture solution of phosphate buffer (10 mM, pH3.5) containing 0.5% triethlamine and methanol (85:15, v/v) as a mobile phase at a flow rate of 1 mL/min. The theoretical plates for the brimonidine tartrate measurement were calculated to be 8360 when detection was performed at 246 nm using a diode array detector. The proposed method was validated in accordance with ICH guidelines with respect to linearity, accuracy, precision, robustness, specificity, limit of detection and quantitation. Regression analysis showed a good correlation (R2 > 0.999) for brimonidine tartrate in the concentration range of 0.01-50 μg/mL. The peak purity factor is ≥980 for the analyte after all types of stress tests, indicating an excellent separation of brimonidine tartrate peak from other impurities. The measurement course could be completed within 10 min, which was very quick, effective and convenient. CONCLUSIONS Overall, the proposed stability-indicating method was suitable for routine quality control and drug analysis of brimonidine tartrate in BRI/PHEMA drug delivery contact lenses and other pharmaceutical formulations.