The aim of this study was to investigate and evaluate a microemulsion gel-based system of babchi oil (Psoralea corylifolia) for the treatment of
psoriasis, which could provide improved permeation of the
drug through the skin and increased patient compliance. Babchi oil is used because its chief constituent
psoralen is a photoactive
furocoumarin that binds to
DNA when exposed to UV light to form photoproducts with
pyrimidine base. This action inhibits
DNA synthesis and causes decrease in cell proliferation. Moreover, babchi oil, in addition to providing
psoralen, also acts as an oily phase for microemulsion system. The presence of
surfactant and cosurfactant increases the permeation. On the basis of qualitative and quantitative estimation of all eight brands of babchi oil, Bakuchi Tail was selected for microemulsion formulation. Microemulsions were prepared by aqueous phase-titration method. Pseudoternary phase diagrams were constructed for the identification of microemulsion existence zones. Prepared microemulsions were subjected to different thermodynamic stability tests and characterized for droplet size, viscosity and refractive index. In vitro skin permeation of babchi oil through rat abdominal skin was determined by the Franz diffusion cell. The in vitro skin permeation profile of formulation F2, which consisted of 1.67% v/v of babchi oil, 8.33% v/v of
oleic acid, S(mix) 55% v/v of
Tween 80 Transcutol-P (S/Co ratio 1:1) and 35% v/v of distilled water, was significant when compared with other microemulsion formulations (p < 0.05). Formulation F2 was converted into microemulsion gel by adding 1% Carbopol-940 and coded as MGF2. Formulation MGF2 was selected for its in vivo antiinflammatory effects determined by footpad
edema. The results suggested that microemulsion gel is a potential vehicle for improved topical delivery of
psoralen and that microemulsion
gels are potential vehicles for improved topical delivery of babchi oil.