In Vitro Nail Penetration of Tavaborole Topical Solution, 5%, Through Nail Polish on Ex Vivo Human Fingernails.

Background: Onychomycosis is a common infection of the toenails that causes nail thickening and discoloration. The physical appearance of the infected nail can diminish self-image and negatively impact quality of life. Patients may use nail polish to mask the appearance of infected nails.

Objective: To evaluate the in vitro nail penetration properties of tavaborole topical solution, 5%, through nail polish using ex vivo, non-diseased human fingernails.

Methods: In study 1, tavaborole penetration was evaluated over 20 days of dosing using the Franz finite dose technique and modified Franz diffusion cells. Nails received either 1 coat of over-the-counter (OTC) typical polish or were left unpolished (controls). In study 2, tavaborole penetration was measured over 14 days of dosing using the finite dose technique and vertical diffusion cells. Nails were polished with either 4 coats or 1 coat of salon typical polish or with 2 coats or 1 coat of OTC typical polish, or they were left unpolished.

Results: In study 1, the mean ± standard deviation (SD) cumulative tavaborole penetration at day 21 was numerically higher, though not statistically significant, through polished nails (3,526 ± 1,433 μg/cm(2))vs unpolished nails (2,661 ± 1,319 μg/cm(2)).In study 2, the mean cumulative tavaborole penetration was also numerically higher (statistical significance not assessed) through all nails that received polish vs unpolished nails. At day 15, mean ± SD cumulative tavaborole nail penetration was 1,179 ± 554 μg/cm(2) through 4 coats of salon typical polish, 1,227 ± 974 μg/cm(2) through 1 coat of salon typical polish, 1,493 ± 1,322 μg/cm(2) through 2 coats of OTC typical polish, 1,428 ± 841 μg/cm(2) through 1 coat of OTC typical polish, and 566 ± 318 μg/cm(2) through unpolished nails.

Conclusion: Results from these in vitro studies demonstrated that tavaborole penetrated through human nails with up to 4 layers of nail polish.