Nanogel, a versatile nanoscopic platform for the simultaneous delivery of acyclovir and lignocaine for the treatment of Herpes simplex virus infection: formulation and characterizations

This study was designed to develop a nanogel formulation incorporating acyclovir and lignocaine (ALN). Various formulations were developed in which ALN-V (formulation-V) was optimized. ALN-V had an average spreadability of 32.3 ± 2.1, a pH of 5.8 ± 0.6 and was physically stable. The droplet size was 221.5 ± 0.5 nm while the surface charge was −7.59 ± 1.8 mV and the polydispersity was 0.145. ATR-FTIR analysis confirmed no interactions. The thermal analysis showed that the melting peak of lignocaine appeared at 65 °C, while that of acyclovir appeared at 256.54 °C. ALN-V showed approximately 72% release for acyclovir and 80% for lignocaine. The Higuchi model confirmed that the release mechanism follows controlled diffusion via a semipermeable membrane. ALN-V nanogels with pure acyclovir and blank nanogel formulations were tested for cytotoxicity and antiviral activity. ALN-V was capable of reducing the cytopathic effect of Herpes simplex virus (HSV) for up to 72 h. Moreover, the ALN-V nanogel inhibited (>95%) the virus titre even after 48 h, which confirmed that the ALN-V nanogel is nontoxic to cells and can effectively inhibit HSV. It was concluded that optimized nanogels can be loaded with combination drugs (lignocaine and acyclovir) and suitable candidates for transdermal delivery of both.