Rheological properties and microstructures of gelatin-containing microemulsion-based organogels

Gelatin-containing microemulsion-based organogels (MBGs) composed of isopropyl myristate (IPM), AOT, Tween85 and H2O, loaded with and without a model drug (butenafine hydrochloride), have been prepared and characterized by rheological measurements and environmental scanning electron microscope (ESEM). The effects of gelatin and butenafine hydrochloride on the rheological properties and microstructures of the MBGs were investigated systematically. Transparent and homogeneous MBGs could be formed when the concentration of gelatin in the selected W/O microemulsion is in the range of 7.0–12.0 wt%. The rheological properties such as the yield stresses (σy), storage and loss moduli (G′, G″) of the MBGs samples increased and the network structures of the MBGs became more compact with increasing the concentration of gelatin in the formulations. Furthermore, the addition of butenafine hydrochloride to the MBGs could weaken the interconnected network structures of the MBGs systems. Namely, when the concentration of butenafine hydrochloride was lower than 0.5 wt%, the samples are still microemulsion gels. These results show that the MBGs can be used as potentially transdermal drug delivery vehicles.