Nail penetration and predicted mycological efficacy of an innovative hydrosoluble ciclopirox nail lacquer vs. a standard amorolfine lacquer in healthy subjects

[[[ Background: ]]] In a previous study a new hydrosoluble nail lacquer (P-3051) containing 8% ciclopirox (CPX) showed higher nail penetration compared to a water-insoluble 5% amorolfine (MRF) lacquer. To our knowledge, in vivo human data on a similar topic are not available. [[[ Objectives: ]]] To compare fingernail penetration of P-3051 with that of MRF reference in humans and to evaluate their predicted efficacy against Trichophyton rubrum and Candida parapsilosis. [[[ Methods: ]]] Single centre, randomized, multiple dose, open label, within subjects study. Test and reference were self-applied to all fingernails of either hand for 28 days. At baseline and after 15 and 25 days, the nail free edge was collected for analysis. Efficiency coefficients were calculated for T. rubrum and C. parapsilosis as ratios of nail concentration/minimum inhibitory concentration. The coefficients were classified as very high, high or poor. [[[ Results: ]]] Nail concentrations after 15 days were 2.82 ± 0.58 μg/mg for CPX and 0.64 ± 0.11 μg/mg for MRF. At day 25 there was a non-significant decline (1.85 ± 0.31 μg/mg, P = 0.077) for CPX and a highly significant (0.13 ± 0.03 μg/mg, P = 0.0002) 80% decline for MRF. Efficiency coefficients were very high/high in all subjects treated with P-3051 against both T. rubrum and C. parapsilosis; they were significantly lower for MRF reference against both pathogens at both observation points. [[[ Conclusions: ]]] P-3051 exhibited better penetration and higher predicted efficacy after in vivo multiple application to human fingernails when compared to MRF reference. These in vivo data are in good agreement with our previous in vitro study.