Matrix based system of isotretinoin as nail lacquer to enhance transungal delivery across human nail plate

Abstract

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 32 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±0.57mg/cm2) 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±0.45mg/cm2). In comparison to marketed preparation (Retino-A cream) F3M1 afforded two fold increase in CDP/A. The permeation characteristics were defined by Higuchi model (r2=0.964) and flux value of 176μg/cm2/h. Confocal laser scanning microscopy, after 72h 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.