Development of solid lipid nanoparticles based controlled release system for topical delivery of terbinafine hydrochloride.

The study describes the development and evaluation of solid lipid nanoparticles (SLNs) of terbinafine hydrochloride (TH) for sustained release and skin targeting. TH-loaded SLNs were prepared by solvent-injection technique and optimized using 3(3) full-factorial design. Effect of drug:lipid ratio, surfactant concentration and volume of organic solvent were studied on % entrapment efficiency (%EE) and particle size (PS). The optimum formulation based on desirability (0.945) exhibited %EE of 73.74% and PS of 300 nm. Optimized SLNs were incorporated into Carbopol gel and evaluated for drug content, pH, in vitro release, ex vivo retention, in vivo pharmacodynamic and stability studies. Drug release from SLNs dispersion followed Korsmeyer-Peppas model, indicating Fickian drug release, while that from the gel followed Higuchi model. The ex vivo studies through rat abdominal skin indicated skin retention ability of SLNs as compared to commercial product. In vivo pharmacodynamic studies showed that the SLNs based gel reduced fungal burden of Candida albicans in rats as compared to commercial product in shorter duration of time. The SLNs dispersion and gel exhibited physicochemical stability under refrigeration upto 3 months. It was concluded that SLNs incorporated Carbopol gel had skin targeting ability and may serve as a promising carrier in treatment of fungal skin infections.