Insights into drug delivery across the nail plate barrier

Abstract

Topical therapy is at the forefront in treating nail ailments (especially onychomycosis and nail psoriasis) due to its local effects, which circumvents systemic adverse events, improves patient compliance and reduces treatment cost. However, the success of topical therapy has been hindered due to poor penetration of topical therapeutics across densely keratinized nail plate barrier. For effective topical therapy across nail plate, ungual drug permeation must be enhanced. Present review is designed to provide an insight into prime aspects of transungual drug delivery viz. nail structure and physiology, various onychopathies, techniques of nail permeation enhancement and in vitro models for trans-nail drug permeation studies. Updated list of drug molecules studied across the nail plate and key commercial products have been furnished with sufficient depth. Patents pertinent to, and current clinical status of transungual drug delivery have also been comprehensively reviewed. This is the first systematic critique encompassing the detailed aspects of transungual drug delivery. In our opinion, transungual drug delivery is a promising avenue for researchers to develop novel formulations, augmenting pharmaceutical industries to commercialize the products for nail disorders.

In vitro evaluation of the antifungal efficacy of poloxamer 407-based formulations in an infected nail plate model

“…Since data of KF and bovine hoof plates are comparable, these results support the use of KF as artificial nail plate model. However, these promising in vitro data have to be interpreted carefully, since the nail plate models were considerably thinner in comparison to the human nail plate (250 -1000 µm) (Gupchup and Zatz, 1999;Murdan, 2008;Saner et al, 2014). Moreover, bovine hoof plates exhibit a more widely meshed keratin matrix and swell to a higher extent during incubation in water.…”

UV-curable gels as topical nail medicines:In vivo residence, anti-fungal efficacy and influence of gel components on their properties

“…However, 45 drug efficacy is far from ideal, with pooled mycological cure rates in randomised controlled 46 trials being 76 ±3% for terbinafine and 63% ±7% for itraconazole (Gupta et al, 2004) . The 47 disadvantages of oral therapy, such as the potential for adverse systemic effects and drug 48 interactions means that topical therapy is highly attractive, and a number of topical 49 formulations have been tested, patented and a few have been marketed, compiled in, for 50 example (Saner et al, 2014;Shivakumar et al, 2012) . Unfortunately, the success rates of 51 topical therapy are even lower, as indicated in the medicines' patient information leaflets, 52 and compiled in (Murdan, 2016) .…”

Transungual permeation: current insights

“…Toenails grow at a slower rate (one half to one third) compared to fingernails. A normal fingernail generally grows fully in about 6 months, whereas a toenail takes about 12 to 18 months for complete growth [17,18]. Age and environment also play a major role for the growth of nails.…”