SPECTROPHOTOMETRIC METHODS FOR DETERMINATION OF SOFOSBUVIR AND DACLATASVIR IN PURE AND DOSAGE FORMS Original Article MONIR Z. SAAD, ATEF AMER, KHALED ELGENDY, BASEM ELGENDY * Chemistry Department, Faculty of Science, Zagazig University, Zagazig, 44519, Egypt Email: beso_elgendy@yahoo.com Received: 28 Jun 2021, Revised and Accepted: 09 Aug 2021 ABSTRACT Objective: Two simple, sensitive and accurate spectrophotometric methods have been developed for the determination of sofosbuvir (SOF) and daclatasvir (DAC) in pure forms and pharmaceutical formulations. Methods: The proposed methods are based on the oxidation of SOF and DAC by a known excess of cerium(IV) ammonium nitrate in sulphuric acid medium followed by determination of unreacted cerium(IV) by adding a fixed amount of indigo carmine (IC) and alizarin red S (ARS) dyes followed by measuring the absorbance at 610 and 360 nm, respectively. The experimental conditions affecting the reaction were studied and optimized. Results: The beer’s law was obeyed in the concentration ranges of 0.2-3.0, 0.2-4.0 for SOF and 0.5-4.5 and 0.5-5.0 μg/ml for DAC using IC and ARS methods, respectively with a correlation coefficient ≥ 0.9991. The calculated molar absorptivity value s are 2.354 × 10 4 , 1.933 × 10 4 for SOF and 1.786 × 10 4 and 2.015 × 10 4 L/mol. cm for DAC using IC and ARS methods, respectively u. The limits of detection and quantification are also reported. Intra-day and inter-day precision and accuracy of the methods have been evaluated. Conclusion: The methods were successfully applied to the assay of SOF and DAC in tablets and the results were statistically compared with those of the reference method by applying Student’s t-test and F-test. No interference was observed from the common tablet excipients. The accuracy and reliability of the methods were further ascertained by performing recovery studies using the standard addition method. Keywords: Sofosbuvir, Daclatasvir, Spectrophotometry, Cerium (IV), Dyes, Method validation, Dosage forms © 2021 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/) DOI: https://dx.doi.org/10.22159/ijap.2021v13i6.42564. Journal homepage: https://innovareacademics.in/journals/index.php/ijap INTRODUCTION Sofosbuvir, (S)-Isopropyl 2-((S)-(((2R,3R,4R,5R)-5-(2,4-dioxo-3,4- dihydropyrimidin 1(2H)-yl)-4-fluoro-3-hydroxy-4-methyltetra- hydrofuran-2-yl)methoxy) (phenoxy) phosphorylamino) propanoate (SOF) (fig. 1). It is a prodrug nucleotide analog used for the treatment of chronic hepatitis C, genotypes 1, 2, 3, 4, 5, and 6, usually in combination with other medications depending on the specific genotype. Sofosbuvir, is a medication used in combination with other medications for the treatment of hepatitis C [1, 2]. Daclatasvir dihydrochloride (DAC) is methyl [(2S)-1-{(2S)-2-[4-(4- {2-[(2S)-1-{(2S)-2-[(methoxy carbonyl)amino]-3-methyl butanoyl}- 2-pyrrolidinyl]-1H-imidazol-4-yl}-4-biphenyl yl)-1H-imidazol-2-yl]- 1-pyrrolidinyl}-3-methyl-1-oxo-2-butanyl] carbamate dihydrochloride (fig. 1). DAC is an antiviral drug used to treat chronic (long-lasting) hepatitis C, a viral infection of the liver. DAC is an antiviral and acts directly against the hepatitis C virus [3]. Literature survey reveals that there is few methods have been reported for the assay of SOF and DAC in pharmaceutical dosage forms, including High-Performance Liquid Chromatography (HPLC) [4-12], upper high-performance chromatography (UHPC) [13-17] and electrochemical method [18]. These methods are complex, require long and tedious pre-treatment of the samples and laborious clean up procedures prior to analysis. O P O O NH O O H3C CH3 H3C O F OH H 3 C N NH O O N N H N H N N O HN O O N O NH O O .2HCl SOF DAC Fig. 1: Chemical structures of sofosbuvir (SOF) and daclatasvir dihydrochloride (DAC) A through literature search has revealed that only a few spectrophotometric methods have been developed for the determination of SOF and DAC in pure and dosage forms [19-26]. However, many of the above methods suffered from one or other disadvantage like poor sensitivity, require high cost solvents in addition to elaborate treatment, need tedious extraction procedures, rigid pH control, measurements done at shorter wavelengths, heating or cooling step, use of expensive chemical and/or complicated experimental set-up. In contrast, visible spectrophotometry is considered as the most convenient analytical technique in most quality control and clinical laboratories. Spectrophotometric technique, because of simplicity and low cost, sensitivity and good analytical selectivity, significant accuracy and precision and broad availability and applicability for pharmaceutical analysis. Cerium(IV) has been widely used as an effective analytical reagent in spectrophotometric methods for the determination of many pharmaceutical compounds [27-35]. Cerium(IV) is a strong oxidant, and it has not been applied for the assay of SOF and DAC in pure forms and tablets. This paper describes for the first time the application of acidic ammonium cerium(IV) nitrate to the spectrophotometric determination International Journal of Applied Pharmaceutics ISSN- 0975-7058 Vol 13, Issue 6, 2021