Terbinafine-Loaded PLGA Nanoparticles Applicable to the Treatment of Tinea Fungus

Tinea is a superficial fungal infection of keratinized structures caused by specific filamentous fungi called dermatophytes. Terbinafine, a drug used to treat tinea, is poorly soluble in water, and its delivery into the skin via nanoparticle formulation usingpoly(lactic-co-glycolic acid) (PLGA) has been demonstrated. In this study, we investigated the preparation conditions for nanoparticles (NPs) to achieve efficient intradermal delivery of terbinafine. Terbinafine-loaded PLGA NPs were prepared using the nanoprecipitation method, and the particle size distribution and average particle size were measured using dynamic light scattering. Skin permeability tests were conducted using mouse dorsal skin, and the amount of terbinafine delivered into the skin was measured to evaluate the release behavior in the skin. In the preparation of terbinafine-loaded PLGA NPs, under conditions where the external solution was purified water, the mean volume diameter was 40.49 ± 15.63 nm, the terbinafine-loaded content was 3.31 ± 0.29%, and the entrapment efficiency was 55.08 ± 4.88%. Under conditions of an external solution containing 1.0 × 10−3 w/v% arginine(Arg) aq. solution, the mean volume diameter was 41.71 ± 16.08 nm, the terbinafine-loaded content was 5.17 ± 0.37%, and the entrapment efficiency was 86.48 ± 6.01%. The entrapment efficiency and content were higher under the condition using 1.0 × 10−3 w/v% Arg aq. solution compared to purified water. In addition, in the skin permeability test, no drug was detected in the receptor solution sampled from both the NPs suspension group and the simple solution group, and no drug was detected in the intradermal solution in the simple solution group. The intradermal drug concentration was 77.94 ± 10.66 µg/g under conditions where purified water was used as the dialysate, and 96.42 ± 61.62 µg/g under conditions using 1.0 × 10−3 w/v% arginine, exceeding the reported minimum inhibitory concentration (MIC) of 8.87 µg/g, suggesting the efficacy of terbinafine-loaded PLGA NPs for the treatment of tinea versicolor. Since tinea treatment is a long-term process, it is desirable to deliver a stable amount of drug to the treatment site at all times. Therefore, the nanoparticle preparation conditions using purified water as the external solution, where the intradermal drug concentration exceeded the MIC and remained stable in the skin permeability test, were suggested to be suitable for tinea treatment.