Design, Formulation and Evaluation of Physicochemical Properties of Valacyclovir Effervescent Tablet

Valacyclovir (VA) displays antiviral activity against Herpes simplex virus (HSV) and Varicella zoster virus (VZV). The aim of this study was to design, formulate and evaluate the physicochemical properties of effervescent tablets containing VA in order to facilitate pill swallowing for the pediatric, elderly and bed-ridden patients.

Sixteen formulations with different amounts of effervescent base were prepared by modified direct compression for the loading of 500 mg VA. The Design-Expert® software was then used to generate formulations using a full factorial design with four different variables: citric acid (A) sodium bicarbonate to citric acid molar ratio (B), PVP k30 (C) and PEG 6000 (D). The prepared tablets were assessed for weight variation, hardness, thickness, friability, drug content, CO2 content, effervescence time and pH. To improve the taste of formulations, several sweeteners and fruity essences such as raspberry and cherries were used.

F2 formulation was selected as the optimized formulation with the desirability of 72.8%. The optimized formulation had an effervescent time of 98.33 ± 3.51 seconds, friability % of 0.55, pH value of 4.67 ± 0.06, CO2 amount of 261.33 ± 20.26 mg and hardness of 77.23 ± 3.12 N.

It, therefore, seems that optimized effervescent tablets may be helpful for the delivery of VA in the treatment of herpes simplex or herpes zoster and chikenpox.