simple, precise, accurate, reproducible and economical reverse phase liquid chromatography method was developed and validated for the quantitative simultaneous estimation of Atazanavir and Ritonavir in bulk and marketed formulations. Estimation of drugs in this combination was done with a C18 column Kromasil 100-5C18 column [250mm x 4.6mm].using mobile phase of composition Acetonitrile and phosphate buffer (50:50 v/v, pH 5).The flow rate was 1 ml/min and the effluents were monitored at 212nm. The retention time of Atazanavir and Ritonavir were3.3 min and 6.2 min respectively. The method was found to be linear over a concentration range of 20-100 mg/ml for both Atazanavir and Ritonavir. The established method proved as reproducible one with a %RSD value of less than 2 and having the robustness and accuracy within the specified limits. Assay of marketed formulation was determined and find with 99.48% and 98.7% for Atazanavir and Ritonavir respectively. The method was validated according to the guidelines of International Conference on Harmonization (ICH) and was successfully employed in the estimation of commercial formulations. This liquid chromatographic method can be applied for the qualitative and quantitative determination of selected drugs by the modern chemist.
