Simultaneous reverse phase HPLC estimation of paracetamol and rofecoxib in tablets

A simple, fast, precise and accurate reverse phase HPLC method was developed for the simultaneous estimation of paracetamol and rofecoxib in tablets. This method is based on using a Hypersil C₁₈ column with a mobile phase of 20 mM phosphate buffer (pH 7.0±0.1) and acetonitrile in the ratio of 55:45 v/v. Valdecoxib was used as an internal standard. The retention times for paracetamol, rofecoxib and valdecoxib were 2.61, 10.09 and 12.31 min, respectively. The proposed method has also been validated. The method was found to be linear (r>0.999), precise (RSD: 0.82% for paracetamol, 0.42% for rofecoxib), accurate (mean percentage recovery yields: 99.3% for paracetamol and 98.4% for rofecoxib) and selective. Due to these attributes, the proposed method could be used for routine quality control analysis of these drugs in combined dosage forms.