Optimization and Evaluation of Acyclovir Loaded Liquid and Solid Self Nanoemulsifying Drug Delivery System

Acyclovir has low bioavailability mainly due to low solubility. In this study, solid self-nanoemulsifying drug delivery systems (S-SNEDDS) of acyclovir were developed with the objective of improving its solubility. Initial screening was carried out to select the excipients. Ternary phase diagrams were constructed to detect the nanoemulsification region. The nanoemulsion systems selected from the phase diagram were characterized for their robustness to dilution and cloud point temperature. Box- Behnken design was then applied for further optimization. The formulations obtained were further characterized for their droplet size and entrapment efficiency. The best formulation was converted to S-SNEDDS by simple adsorption technique. The liquid SNEDDS (L-SNEDDS) was adsorbed onto microcrystalline cellulose in 1:1 ratio. Zeta potential, differential scanning calorimetry, scanning electron microscopy was then carried out. In vitro drug release was studied by comparing the S-SNEDDS with pure drug. The L-SNEDDS formulation which was converted to S-SNEDDS showed particle size of 147 nm. The formulation was found to be robust to dilution and showed cloud point at 86 ◦C. Negative zeta potential meant, there was no coalescence of globules. SEM studies of nanoemulsion demonstrated that the globules in L-SNEDDS were indeed adsorbed on the MCC. Results of DSC confirmed that the drug was incorporated in the S-SNEDDS that was formulated. The in vitro drug release from acyclovir S-SNEDDS was found to be considerably higher in comparison to that of the pure drug. Therefore, it can be concluded that acyclovir loaded S-SNEDDS improved the solubility and release characteristics of the drug.