The influence of plasticizer in nail lacquer formulations on fluconazole permeability through the bovine hoof membrane

Abstract

Medicinal nail lacquers are the most effective topical treatment of nail diseases. These formulations generally are organic solutions of the active substance as well as film-forming polymer and plasticizer, which affects the characteristics of the film formed after application and solvent evaporation. The aim of this work was to test the effects of plasticizer present in nail lacquer formulations on permeation kinetics of fluconazole through the bovine hoof membrane in a novel in vitro test. The formulations contained Eudragit RS100 dissolved in acetone, and dibutyl-phthalate, PEG 400 or propylene glycol as plasticizers present in two different concentrations. Permeation studies were carried out during the 7-day period, and the obtained permeability profiles analyzed using similarity and difference factors, and by model-dependent permeation kinetics. When analyzed within the same strength, the highest extent of fluconazole permeation was obtained from the formulation with a lower concentration of propylene glycol at 0.9% fluconazole concentration, while for formulations with 1.8% and 2.7% of fluconazole, the highest permeation was achieved from the formulation with the higher content of PEG400. The permeation profiles showed a greater difference within one formulation of different fluconazole content than with the same plasticizer present in different concentrations, when using dibutylphthalate and PEG400. The permeation profiles were similar when using propylene glycol. When comparing formulations with the same concentrations of plasticizers, there were differences in formulations with the higher fluconazole concentrations. Permeation kinetics depended on fluconazole concentration as well as the path length the active substance had to pass to reach the receptor solution.