Simple spectrophotometric determination of acyclovir in bulk drug and formulations

Abstract

A simple and cost effective spectrophotometric method is described for the determination of acyclovir in bulk drug and in formulations. The method is based on the formation of blue coloured chromogen when the drug reacts with Folin–Ciocalteu (F–C) reagent in alkaline medium. The coloured species has an absorption maximum at 760 nm and obeys Beer's law in the concentration range 50–450 μg ml −1. The absorbance was found to increase linearly with increasing concentration of acyclovir, which is corroborated by the calculated correlation coefficient value of 0.9998 ( n=9). The apparent molar absorptivity and Sandell sensitivity were 1.65×10 2 l mol −1 cm −1 and 1.36 μg cm −2, respectively. The slope and intercept of the equation of the regression line are 6.87×10 −4 and 8.33×10 −3, respectively. The limit of detection was 5.68 μg ml −1 and the limit of quantification was 18.95 μg ml −1. The proposed method was successfully applied to the determination of acyclovir in pharmaceutical formulations. The reliability of the assay method was established by parallel determination by standard-addition method, and by recovery studies. The results demonstrated and the procedure is at least as accurate, precise and reproducible (RSD<2%) as the official method, while being simple and less time consuming. A statistical analysis indicated that there was no significant difference between the results obtained by the proposed procedure and those of the official method.