Selective HPLC-quantification of promethazine hydrochloride and its degradation products in presence of sodium benzoate

ABSTRACT

A selective and stability-indicating RP-HPLC method has been developed and validated for the simultaneous precise determination of promethazine [PROM] and sodium benzoate [SBENZ], even in the presence of the main oxidative degradation products of PROM. Good separation could be achieved on a C8-column by using a mobile phase composed of 0.008M ammonium acetate [pH 4.7] + methanol = 52 48, v/v by adopting isocratic programmed elution with UV-detection at 253 nm. The method was linear over the concentration ranges of 4- 60 micro g ml[-1] and 0.2-3 mg ml[-1], with accuracy of 100.68 +/- 1.49% and 101.82 +/- 0.91% and limits of quantitation [LOQ] of 0.8 micro g ml[-1] and 20 micro g ml[-1], for PROM and SBENZ, in orders. The method was successfully adopted for the stability-screening and -improvement of PROM in presence of SBENZ in their syrups