Spectrophotometric assessment of the brand new antiviral combination: Sofosbuvir and velpatasvir in their pure forms and pharmaceutical formulation.

Sofosbuvir (SOF) and velpatasvir (VEL) are recently co-formulated together for the treatment of hepatitis C virus. Smart and robust spectrophotometric methods were first developed and validated for quantification of SOF and VEL in their pure forms and in their combined pharmaceutical formulation without preliminary separation. VEL has two UV maxima at 302.5 and 337.0 nm that allow its direct determination by zero-order spectrophotometric method (D°) without any interference from SOF in a linear range of 2.0-30.0 μg/mL. On the other hand, determination of SOF in presence of VEL was carried out by four smart spectrophotometric methods, developed for resolving the overlaid spectra of these binary mixture. These methods are dual wavelength (DW), ratio subtraction (RS), ratio difference (RD) and first derivative of ratio spectra method (1DD). Linearity was checked and found to be in the range of 5.0-90.0 μg/mL for SOF by all of the aforementioned spectrophotometric methods. The developed methods were optimized and validated in accordance to the ICH guidelines. They were successfully utilized for estimating both SOF and VEL in their pure forms, laboratory prepared mixtures and in their pharmaceutical formulations with good recoveries. The methods can be easily applied for the routine analysis in quality control laboratories.