A simple and precise stability indicating RP-HPLC method was developed and validated for the simultaneous determination of Darunavirethanolate and Cobicistatin bulk and pharmaceutical dosage forms. Chromatography was carried out on Enable C18 (250mm x 4.6 mm, 5 μ particlesize) column using a mobile phase of water (adjusted to pH 3 with 0.1% orthophosphoric acid): Acetonitrile (55:45 % v/v) at a flow rate of 1ml/min. The analytes were monitored using PDA detector at 245 nm. The retention time was found to be 3.074min and 6.081min for Darunavirethanolate and Cobicistat respectively. The proposed method was found to be having linearity in the concentration range of 30-120 μg/ml for Darunavirethanolate and 6-50μg/ml for Cobicistat. The mean % recoveries obtained were found to be 99.99-100.00% for Darunavirethanolate and 99.85-100.08 % for Cobicistat. Stress testing which covered acid, alkali, peroxide, photolytic and thermal degradation was performed under test to prove the specificity of the method and the degradation was achieved. The developed method has been statistically validated according to ICH guidelines and found to be simple, specific, precise and accurate with the prescribed values. Thus the proposed method was successfully applied for the stability indicating simultaneous estimation of Darunavirethanolate and Cobicistatin bulk and Pharmaceutical formulations and in routine quality control analysis.
