Objective: The aim of the present investigation was to develop microemulsionbased
hydrogel of tacrolimus for topical application for the treatment of atopic dermatitis.
Methods: Microemulsion containing tacrolimus was developed by water titration method
and was successfully incorporated into freshly prepared 1% carbopol 940 gels. Preformulation
studies such as preparation of standard curve by HPLC, solubility studies and
construction of phase diagrams were carried out. Lauroglycol was selected as oil, Labrasol
and Tween 80 (1:1) as surfactant blend and Transcutol P as co-surfactant, on the basis of solubility of tacrolimus
in the above constituents. The optimized microemulsion formulation and microemulsion based hydrogel
were characterized for various parameters and were evaluated for the efficiency to treat atopic dermatitis
induced by 2,4-dinitrochlorobenzene in BALB/c mice.
Results: The pH value and percent transmittance of microemulsion formulation were found to be 5.9 and
99.2%, respectively. Microemulsion did not show phase separation in centrifugation study. Transmission
Electron Microscopy illustrated that the droplets of the microemulsion possessed spherical shape. The microemulsion
based gel system possessed good spreadability and 83.31±1.148 % drug content. In vitro permeation
studies showed that the permeation rate of both tacrolimus loaded microemulsions as well as microemulsion
based hydrogel was observed to be higher than the drug solution and marketed ointment formulation. Histopathological
analysis revealed that the microemulsion based hydrogel was more effective than the microemulsion
and marketed ointment.
Conclusion: The results indicated that the formulated microemulsion based hydrogel is promising vehicle for
topical delivery of tacrolimus for the treatment of atopic dermatitis.