Response Surface Optimization for Simultanous Estimation of Sofosbuvir and Velpatasvir in Human Plasma Sample

An efficient column friendly, buffer free, highly sensitive, cost effective RP-HPLC method was developed by considering the criticality of different method parameters on analytical attributes like tailing factor, resolution and retention time in preliminary risk analysis and screening designs. The Pareto analysis of screening design highlighted the need for optimization of resolution and its influencers (capacity factor and theoretical plates) for both the drugs to imbibe quality in the method. The suggested method of optimization design was developed using ZODIAC C18 ODS (250 mm x 4.6 mm, 5 mu m) column in isocratic mode using mobile phase acetonitrile : methanol : water in the ratio of 60:10:30 at a flow rate of 0.8 mUmin and UV detection wavelength of 262 nm. The retention times of drugs were found to be 3.488 min for sofosbuvir, 5.387 min for velpatasvir. The linear regression analysis data for the calibration plots showed good linear relationship with I-2=0.997 for sofosbuvir, I-2=0.988 for velpatasvir, in the working concentration range of 1000-5000 ng/mL, 250-1250 ng/mL respectively. The AQbD devised method was applied for quantification of drugs in plasma and validated as suggested in ICH M10 guidelines.