Dissolving microneedle to improve transdermal delivery of terbinafine for treatment of onychomycosis

The topical formulation of antifungal agents has demonstrated prominent success in treating fungal infection. However, traditional topical cream or solution limited ability to penetrate the nail plate and target the infected area contributes to the inefficacy of antifungals in the treatment of onychomycosis. In this work, the problem of topical administration reaching only the skin's surface was addressed by dissolving microneedles (MN) to pierce the skin and deliver drugs directly to the site of infection. Terbinafine (TH) was encapsulated into polydopamine (PDA) nanoparticles (TH@PDA) to increase the antifungal efficacy of TH. The results of checkerboard microdilution assays showed that the antifungal efficacy of TH@PDA was increased up to 2–8 times in comparison to free TH. In animal experiment, TH@PDA was incorporated into MN to target the infected site and increase the therapeutic effect. Our results demonstrated TH@PDA MN significantly decreased the fungal burden in the nails and relieved inflammation at the site of infection when compared to TH MN, TH cream, and oral TH. These results suggested that the TH@PDA MN exhibited enhanced antifungal effects and can serve as a potentially promising approach for onychomycosis treatment.