Ciclopirox delivery into the human nail plate using novel lipid diffusion enhancers

Abstract

Context: Onychomycosis is a common fungal infection of the nail plate and bed that affects up to 14% of the population and can have a substantial impact on the quality of life of those affected.

Objective: This study compared the onychopharmacokinetics, nail absorption, nail distribution, and nail penetration of [¹⁴C]-ciclopirox dissolved in novel lipid diffusion enhancers with that of a commercial ciclopirox nail lacquer using the in vitro finite dose model.

Materials and methods: The penetration rate of ciclopirox was determined by applying doses of topical formulation twice daily to human nail plates for 11 d. Drug absorption was then measured by monitoring its rate of appearance in each nail layer and in the cotton pad/nail supporting bed.

Results: After a multiple day treatment, cumulative concentrations of ciclopirox formulated with lipid enhancers in the deep nail layer and the nail bed were significantly greater than cumulative concentrations of the commercial ciclopirox lacquer (p < 0.001) as well as several orders of magnitude greater than the minimal inhibitory concentration (MIC) deemed necessary to inhibit the growth of the causative dermatophyte species.

Conclusion: When formulated with lipid enhancers, the amount of ciclopirox in the ventral/intermediate layer and supporting bed dramatically exceed the inhibitory concentration of ciclopirox for the most common onychomycosis organisms. These results suggest that topical ciclopirox with lipid enhancers has the potential to be an effective topical treatment for onychomycosis, and the lipidic pathway of the nail can be utilized as a means of effective transungual delivery.

• Ciclopirox
• human nail
• in vitro
• MIC, onychomycosis
• onychopharmacokinetics
• topical formulation