Comparative Study of the Selectivity Power of Colorimetric Method Over Chromatographic Methods for the Analysis of Valaciclovir Hydrochloride.

Abstract

Valaciclovir hydrochloride (VAL) is an essential antiviral prodrug used to cure various types of herpes. Analysis of VAL by different analytical techniques demonstrates a persuasive aspect that is favorable in quality control application. This study describes a comparison between colorimetric and chromatographic (RP-high performance liquid chromatography (HPLC) and thin-layer chromatography (TLC)-densitometric) methods concerning selectivity and specificity for the determination of VAL in all possible degradation products (alkali- and acid-induced degradation products, namely aciclovir [ACI] and guanine [GUA], respectively) in their synthetic mixture and pharmaceutical formulations. The colorimetric method was accomplished by forming a highly colored complex with ferric hydroxamate reagent measured at 493 nm in the concentration range (0.20-1.60 mg/mL). Both chromatographic methods were successfully applied using ultraviolet (UV) detection at 256 nm in the concentration range (2.00-5.00 µg/mL) for the RP-HPLC method and (10.00-900.00 ng/band) for the TLC-densitometric method. The linearity studies, regression equations, assay parameters, and validation sheet of the proposed colorimetric and chromatographic methods to determine VAL were obtained with highly acceptable values. The International Council for Harmonization (ICH) guidelines were followed to validate the described methods and the statistical comparison regarding both accuracy and precision, and satisfactory results were accomplished. In this study, we configure a full comparative study between different analytical methods for the analysis of challengeable mixture containing the drug of interest, VAL, along with its degradation products, ACI and GUA.