Micellar spectrofluorimetric protocol for the innovative determination of HCV antiviral (daclatasvir) with enhanced sensitivity: Application to human plasma and stability study.

Daclatasvir dihydrochloride (DAC) is a new, direct-acting antiviral drug with powerful inhibitory effect against all hepatitis C virus (HCV) genotypes. A sensitive, simple, fast and specific fluorometric method for estimation of DAC in the presence of sofosbuvir was developed and validated. The method is based on reinforcement the fluorescence intensity of DAC by 170% of its original value in an aqueous solution of hexadecyl trimethyl ammonium bromide (pH 5.5, Teorell and Stenhagen buffer). The fluorescence intensity measurements were accomplished at 387 nm with 328 nm for excitation wavelength. A linear relationship was achieved between the DAC concentration and the fluorescence intensity in a range of 50.0-2000.0 ng ml-1 with 0.9998 and 0.9999 for the determination and correlation coefficients, respectively. The detection and quantitation limits were 13.4, 40.8 ng ml-1, respectively. The excellent sensitivity and specificity of the proposed method allowed the efficient estimation of DAC in real human plasma with adequate recovery (81.78 ± 1.57), and the selective determination for DAC in its commercial dosage form without interference from tablet excipient. Moreover, the proposed method was expanded to examine the stability of DAC by determination the parent drug of DAC in the presence of its oxidative, alkaline, acidic, UV, daylight and sunlight degradations products in agreement with ICH guidelines. Furthermore, the kinetic study of acidic and oxidative degradations of DAC was inspected. In addition, the half-life times of the reaction (t1/2) and the first-order reaction rate constants were estimated. Moreover, a suggestion for the degradation pathway was supposed.