Formulation and evaluation of terbinafine hydrochloride invasomal gel for topical drug delivery

The primary goal of the research was to develop topical invasomal gel of terbinafine hydrochloride with enhanced permeation and sustained drug release. Invasomes were formulated through a mechanical dispersion technique, employing blends of terpenes (citral and d-limonene) and soya phosphatidylcholine. The optimization process involved assessing parameters such as particle size, zeta potential, poly-dispersibility index (PDI), and entrapment efficacy. The invasomal gel, which underwent optimization, was evaluated for drug content, spreadability, viscosity, in vitro and ex vivo drug release, antifungal activity, and stability in the study. Optimized invasomal batch containing d-limonene (0.3 %) and citral (0.685%) exhibited particle size (95.66 ± 0.49 nm), zeta potential (19.3 ± 0.081 mV), and polydispersity index (PDI) (0.274) and entrapment efficacy (86 ± 0.8165 %). In vitro drug release for optimized invasomes showed that 90 % of drug was released in 158 min with increased permeation of drug through skin. The invasomal gel exhibited 90 % of drug release in 557.9 min indicating sustained drug release.