Results from a Phase 1/2 trial of BB2603, a terbinafine-based topical nano-formulation, in onychomycosis and tinea pedis.

BB2603 is a nano-formulation of the antifungal drug terbinafine with the polymer polyhexamethylene biguanide (PHMB) as an excipient to enhance solubility and drug delivery to skin and nails. BB2603 is delivered topically using a low-velocity spray. It is being developed in different strength formulations for the treatment of fungal infections of the nail and skin, including onychomycosis and tinea pedis, with BB2603-1 (0.01% terbinafine) tested in the present trial. The aim of this study was to assess systemic exposure, safety and tolerability of BB2603-1 compared with Lamisil AT 1% spray and BB2603-1 vehicle control in onychomycosis and tinea pedis. Preliminary mycological and clinical activity were also investigated. This was a single-centre Phase 1/2, randomised, partially blinded, active- and vehicle-controlled, parallel-group trial in 46 subjects with onychomycosis associated with tinea pedis. Part 1 investigated BB2603-1 versus Lamisil AT 1% spray and BB2603-1 vehicle (4 weeks treatment). Part 2 investigated BB2603-1 versus BB2603-1 vehicle (additional 48 weeks treatment). No measurable systemic exposure of terbinafine was shown over 52 weeks of treatment with BB2603-1. BB2603-1 had an excellent safety and tolerability profile with no drug-related safety findings and no evidence of skin sensitisation. BB2603-1 showed preliminary evidence of anti-dermatophyte activity, demonstrated by a reduction in dermatophyte positive cultures and a reduction in microscopic evidence of dermatophytes. The pharmacokinetic, safety and efficacy data from this trial support further development of the topical terbinafine-based nano-formulation BB2603 in fungal infections of the skin and nail, including onychomycosis and tinea pedis.