Understanding the drug delivery through nails: a comprehensive review

Abstract

The nail unit is the largest cutaneous musculo-skeletal appendage. The management of nail disorders is an onerous task owing to the disease manifestations and anatomical structure of the nail plate. The topical treatment of nail infections/disorders has been a centerpiece of nail research in the past few decades as it offers a much safer and focused alternative to conventional oral therapy. However, transungual delivery had its challenges. This necessitated a lookout for novel approaches that enhanced treatment efficacy and reduced treatment time. Moreover, curing the nail condition using topical delivery has been challenging due to the lack of a validated animal model to determine the efficacy of the formulation and to establish a mathematical model that can help in predicting the desirable attributes of the formulation and permeation of various molecules through the nail plate. This review is based on publications retrieved by a selective search in PubMed. The purpose of this review is to provide an overview of nail anatomy and its disorders, factors affecting nail delivery, diagnostic procedures, current approaches, and promising approaches to treat nail infections/disorders including nail lacquers and the role of permeation enhancers, in-vitro models. This review also covers current available treatments and treatments under clinical trial. Keywords: Musculo-skeletal, Nail infection, Transungual, Mathematical model, In-vitro models.