Objective: This study points to build up and validate a simple methodology to quantify the most used drug sofosbuvir for the treatment of hepatitis C virus (HCV) infection, in human plasma by using atazanavir as an Internal Standard (IS) for preclinical studies and validate as per USFDA guidelines.Methods: Sofosbuvir was isolated from plasma samples by liquid-liquid extraction method using acetonitrile; good chromatographic separation was achieved on Kromasil Column (250 mm ×4.6 mm, 5 µm). The

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... obile phase consisted of 0.1 % orthophosphoric acid (OPA) buffer pH 2 and acetonitrile in the ratio of (68:32, v/v), respectively. The analysis time was 7 min at a flow rate 1 ml/min. The photodiode array detector (PDA) detection was carried out at 228 nm. The suggested method was validated by performing linearity, system suitability, specificity and sensitivity, accuracy and precision, recovery, ruggedness, stability studies. The method was validated as per USFDA guidelines.Results: The developed method resulted in retention times of sofosbuvir and IS were found out to be 4.7 and 4.2 min respectively. The calibration curves are linear (r2 = 0.999) over the concentration range of 0.050-2.0 µg/ml of plasma analytes concentration. LOQ value was found to be 0.050 µg/ml with precision and accuracy. Within-batch % mean accuracy of the method ranged between 96.00% and 109.09%, and within-batch and total precision, expressed as the coefficient of variation, was 1.40–10.33%. Overall percentage mean recovery of sofosbuvir from spiked plasma was 84.14%. All the validated parameters were found to be within the limit.Conclusion: A simple, accurate, precise, linear, rugged and rapid RP-HPLC method was developed for quantitative estimation of sofosbuvir in human plasma and should be suitable for conducting pharmacokinetics studies and therapeutic drug monitoring.