Simultaneous determination of paracetamol and diphenhydramine hydrochloride mixture in the presence of their degradation products

Abstract

New accurate, selective, sensitive and precise methods were developed and validated for determination of paracetamol and diphenhydramine hydrochloride in the presence of P-amino phenol, the hydrolytic degradate and the most potential impurity of paracetamol and the N oxide degradation product of diphenhydramine in bulk form and in pharmaceutical formulation.Method A uses double divisor second derivative of ratio spectrophotometric technique, at 304nm for paracetamol and 256.4nm for diphenhydramine hydrochloride. Method B utilizes Principle Component Regression (PCR) and Partial Least Squares (PLS) chemometric techniques for quantification of the four components using a UV spectrum range of 210-350 nm. The proposed methods were successfully applied to the analysis of the mentioned drugs either in bulk powder or in pharmaceutical formulation without interference from other dosage form additives, and the results were statistically compared with the pharmacopoeial method.