Background: The conventional acyclovir topical therapy has a low efficacy, due to the lack
of penetration of a sufficient amount of drug to the target site.
Objective: The aim of this work was to formulate and optimize organogel containing acyclovir to enhance
the penetration and retention time of acyclovir in the basal epidermis, site of Herpes simplex virus
Methods: Microemulsion based organogel containing acyclovir was developed using the combination of
surfactants, polar and nonpolar solvents. To investigate the microemulsion and gelling region, titration
was carried out and pseudoternary phase diagram was constructed. The formulation was optimized by
using 3-factor, 3-level, Box-Behnken design. Response surface plots were constructed for various response
variables, viz. % drug permeation, viscosity and spreadability. The optimized formulation was
searched utilizing overlay plots and desirability of the response. The optimized formulation was further
characterized for microscopy, pH, ex-vivo permeation etc. Ex-vivo skin permeation showed first order
drug diffusion through the skin and was found being stable upto 8 hrs.
Results: In case of developed organogel formulation, significantly higher amount of acyclovir was observed
to be retained in the skin, as compared to retention observed with the conventional cream.
Conclusion: The results show that the ACV organogel penetrates into the skin and form the reservoir
that can slowly release the drug for a longer period and may control viral growth more effectively.