Investigation of true nanoemulsions for transdermal potential of indomethacin: characterization, rheological characteristics, and ex vivo skin permeation studies

The aim of the present study was to investigate the potential of true nanoemulsions for transdermal delivery of indomethacin. Thermodynamically stable true nanoemulsions were characterized for morphology using transmission electron microscopy (TEM), droplet size, rheological characteristics, and refractive index. The rheological behavior for all true nanoemulsions was found to be Newtonian as viscosity was unchanged by increasing the rate of shear. The ex vivo skin permeation studies were performed using Franz diffusion cell with rat skin as permeation membrane. The ex vivo skin permeation profile of optimized formulation was compared with marketed Indobene gel and nanoemulsion gel. Significant increase in permeability parameters was observed in nanoemulsion formulations (P < 0.05). The steady-state flux (J(ss)) and permeability coefficient (K-p) for optimized nanoemulsion formulation were found to be 73.96+/-2.89 mu g/cm(2)/h and 1.479x10(-2) +/-0.289x10(-2)cm/h, respectively, which were significant compared with Indobene gel and nanoemulsion gel (P<0.05). Enhancement ratio (E-r) was found to be 7.88 in optimized formulation F6 compared with other formulations. These results suggested that nanoemulsions can be used as potential vehicles for improved transdermal delivery of indomethacin.