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

Abstract

Background: 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.

Objective: 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.

Method: 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.

Results: 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.

Conclusions: 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.

Highlights: 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.