Microemulsion based Hydrogel of Mycophenolate Mofetil for the Treatment of Psoriasis

Mycophenolate mofetil (MMF), the morpholinoethyl ester of mycophenolic acid is an immunosuppressive agent used to prevent organ rejection after kidney and heart transplant. The drug seem to be effective in dermal diseases mainly psoriasis. However, till date it can be only be administered using systemic route which is often associated with side effects such as nausea, leucopenia, sepsis and diarrheoa. The aim of the present study was to develop microemulsion based hydrogel for topical delivery of mycophenolate mofetil and to investigate its in vitro release and its potential in treating psoriatic inflammation using imiquimod induced skin inflammation animal model. Pseudoternary phase diagrams were constructed and on the basis of microemulsion existence range, various formulations were developed using oleic acid, Tween80, propylene glycol and distilled water as oil phase, surfactant, cosurfactant and aqueous phase, respectively. The selected formulations were subjected to physical stability studies and consequently to various physicochemical characterization. The optimized formulation (F2) consisting of 6.06% v/v of oleic acid 36.36% v/v of Tween80 and 18.18% v/v of propylene glycol has shown a globule size of 124 nm, refractive index 1.421, zeta potential -34.35 ±0.051 mV, pH 5.9 and conductivity value of 10⁴ μS cm⁻¹. The permeability of drug from microemulsion after 24 h was observed to be 69.52%. Carbopol 940 was used to convert microemulsion into microemulsion based hydrogel to improve its viscosity for topical administration and was characterized. The histopathological studies performed on mice skin revealed that the treated skin showed complete clearance of hyperkeratotic plaques and a significant reduction in the area of perakeratosis. The results indicated that the formulated gel may be a promising vehicle for topical delivery of mycophenolate mofetil for the treatment of psoriasis.