Management of nail psoriasis by topical drug delivery: a pharmaceutical perspective.

The management of nail psoriasis is an arduous task owing to the disease manifestations and anatomical structure of the nail plate. Although various treatment therapies are available for nail psoriasis, topical therapy is contemplated as one of the most favorable options as systemic therapies are accompanied by numerous side effects that result in patient incompliance. The topical formulations including creams, gels, ointments, and nail lacquers have been used as delivery systems for various antipsoriatic drugs. Among these, nail lacquers emerge to be promising and patient friendly formulations. However, the major defiance with topical delivery is inefficacious penetration of drug through impenetrable keratinized nail plate to reach the target sites: nail matrix and nail bed. Therefore, in order to obtain effectual drug delivery systems that can retain/remain on the nail plate for a prolonged period of time and deliver the drug across it, systematic approaches like quality by design (QbD) need to be followed so that the desired quality can be "built in" the system rather than to rely solely on retrograde evaluation. Furthermore, more advances in research are still required to develop a validated animal model so as 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.