The project was aimed at development of
isotretinoin nail lacquer and assessment of its penetration efficiency across human nail plate. Preliminary studies (hydration enhancement factor and SEM) aided the selection of
thioglycolic acid as permeation and
eugenol was selected as
local anesthetic in the formulation. The nail lacquer was optimized by 3(2) factorial design and a total of nine formulations were prepared and screened. In vitro adhesion and ex vivo permeation (cumulative
drug permeation per unit area (
CDP/A) = 6.61 ± 0.57 mg/cm(2)) across bovine hoof guided the selection of F3 as optimized formulation that was improvised. Viscosity adjustments to improve handling characteristics were affected by incorporation of
ethyl cellulose (6%; F3M1) that scaled the viscosity to 312.681 cp and insignificantly (p > 0.05) affected
CDP/A (6.32 ± 0.45 mg/cm(2)). In comparison to marketed preparation (Retino-A cream) F3M1 afforded two fold increase in
CDP/A. The permeation characteristics were defined by Higuchi model (r(2) = 0.964) and flux value of 176 μg/cm(2)/h. Confocal
laser scanning microscopy, after 72 h of nail lacquer application, revealed extensive distribution of the fluorescent tracer across the human nail plate in comparison to control that was confined to the top layer. Conclusively, an efficacious and stable nail lacquer of
isotretinoin was developed for potential clinical topical use to target the
drug to nail bed in treatment of nail
psoriasis.