International Journal of Pharma Research & Review, April 2013; 2(4):22-33 T Praveen Kumar et.al, IJPRR 2013; 2(4) 22 Review Article Transungual Drug Delivery: A Promising Route to Treat Nail Disorders *T. Praveen Kumar, P. Narayana Raju Department of Pharmaceutics, K. L. R. Pharmacy College, Paloncha, Khammam, Pin – 507 115, India. _____________________________________________________________________________________________________________________________________________________________________________ ABSTRACT Transungual therapy is considered to be highly desirable to treat nail disorders due to its localized effects, improved adherence which results in minimal adverse systemic events. However, the effectiveness of topical therapies is limited due to minimal drug permeability through the nail plate. Nail permeability is quite low and limits topical therapy to early/mild disease states such as Onychomycosis, Leuconychia, Onychogrypos and Onychatrophia etc. Hence the absorption of drugs into the nail unit, to the nail plate, is highly desirable to treat nail disorders. The nail plate behaves like a concentrated hydrogel to permeating molecules and diffusion of molecules through the nail plate has been compared to the diffusion of non- electrolytes through polymer gels. For optimal transungual permeation and uptake of drug, drug molecules must be small in size and should remain non-ionic form. Current review on nail permeation focuses on the anatomy of a human nail, diseases related to nail plate, altering the nail plate barrier by means of chemical treatments, penetration enhancers as well as physical and mechanical methods used to enhance the topical bioavailability of the drugs across the nail and latest trends in drug delivery across the nail. The factors, which affect uptake of drug and permeation through the nail plate such as solute molecular size, hydrophilicity/hydrophobicity, charge, and the nature of the vehicle, are discussed. Limitations of transungual drug permeability studies and available topical therapies are discussed here. Keywords: Nail, nail lacquers, onychomycosis, psoriasis, transungual delivery. Received 23 March 2013 Received in revised form 09 April 2013 Accepted 11 April 2013 *Address for correspondence: T. Praveen Kumar Department of Pharmaceutics, K. L. R. Pharmacy College, Paloncha, Khammam, Pin – 507 115, India. E-mail: praveensuri1@gmail.com _________________________________________________________________________________________________________________________ INTRODUCTION Topical therapy is highly desirable due to its localized effects, improved adherence which results in minimal adverse systemic events. Recent advances in topical transungual delivery systems have led to the development of antifungal nail lacquers. The human nail evolved as our manual skills developed and protects the delicate tips of fingers and toes against trauma. Present review on nail permeation focuses on altering the, nail plate barrier by means of chemical treatments and penetration enhancers. Physical and mechanical methods were also given adequate consideration. The most visible part of the nail apparatus is nail plate. It consists of tightly packed dead cells and is highly keratinized. It is very variable among individuals and these plates can be small, large, wide, narrow, hard, smooth, ridged, thin, etc. Disorders of the nail unit range from relatively innocuous conditions such as pigmentation in heavy smokers to painful and debilitating states where the nail unit can be dystrophied, hypertrophied, inflamed, infected etc. Such conditions affect patients physically as well as socially and psychologically and can seriously affect the quality of life. Oral therapy suffers from systemic adverse effects and drug interactions whereas topical therapy is limited by low permeability of the nail plats [1- 3]. The physiochemical properties of the nail indicate that nail behave more like a hydrophilic gel membrane. The anatomy and composition of the nail plate limits penetration of drugs, and allows only a fraction of topical drug to penetrate across