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.

Insight about Lines of Treatment of Onychomycosis: Review Article

“…Nails are more receptive to antifungal treatments when they are applied topically in an aqueous medium. The medicine is delivered transungually by applying a topical antifungal agent to the nail's dorsal surface (12) .…”

Contemporary Techniques and Potential Transungual Drug Delivery Nanosystems for The Treatment of Onychomycosis

“…The nail is composed mainly of protein (about 80%), water (7-12%), lipids (< 1.5%), and minute quantities of minerals and electrolytes. Keratin, as a main component of the nail plate, is linked with disulfide bonds, electrostatic bonds, and hydrogen bonds, with the presence of phospholipid in low amounts; therefore, the nail plate represents a hydrogel membrane barrier with a limited degree of permeability [3]. Hyponychium is the epithelium under the nail plate at the junction between the nail-free edge and the skin of the fingertip, which acts as a seal for the nail bed [4].…”

“…Hyponychium is the epithelium under the nail plate at the junction between the nail-free edge and the skin of the fingertip, which acts as a seal for the nail bed [4]. The mean growth rate of fingernails and toenails per month is 3 mm and 1 mm respectively, where complete regeneration of a fingernail occurs in 4-6 months and 8-12 months for a toenail [3]. More than half of the diseases that affect nails are triggered by fungi, including dermatophytes, non-dermatophytes, molds, and yeasts, where the main species belong to the genera Trichophyton, Epidermophyton, or Microsporum [5].…”