Stability Indicating Assay Method Development and Validation of Simultaneous Estimation of Chlorzoxazone, Diclofenac Sodium and Paracetamol in Bulk Drug and Tablet by RP-HPLC

Abstract

A simple, accurate, specific and stability-indicating RP-HPLC method was developed for simultaneous determination of chlorzoxazone, diclofenac sodium and paracetamol, using C18 Vydac Monomeric 120A (250 × 4.6mm, 5μ) at 40ºC. The mobile phase contains a mixture of 20mM potassium dihydrogen phosphate buffer (pH 6.2 adjusted with potassium hydroxide) and acetonitrile (30:70 v/v). The flow rate was 1ml/min and detection was carried out at 275nm using PDA detector. The retention time of paracetamol, chlorzoxazone and diclofenac sodium were 3.28mins, 13.27mins and 15.61mins respectively. The analytical curve was linear over a concentration range of 0.65- 6.5μg/ml for paracetamol, 1-10μg/ml for chlorzoxazone and 0.1-1μg/ml for diclofenac sodium. The drugs in bulk and tablet were subjected to acid and alkali hydrolysis, oxidation, thermal and photolytic degradation. This method can be successfully employed for simultaneous quantitative analysis of Chlorzoxazone, Diclofenac sodium and Paracetamol in bulk drug and tablet formulation.