Dual drug-loaded cubic liquid crystal gels for transdermal delivery: inner structure and percutaneous mechanism evaluations

The goal of this paper was to develop and evaluate dual component-loaded with the hydrophilic sinomenine hydrochloride (SH) and lipophilic cinnamaldehyde (CA) cubic liquid crystal gels for transdermal delivery. The gels was prepared with a vortex method using phytantriol/water (70:30, w/w) and characterized by polarized light microscopy, small-angle X-ray scattering and rheology. The inner structure of the gels were Pn3m cubic phase and exhibited a pseudoplastic fluid behavior. Furthermore, the in vitro release profile showed that the release behavior of the two drugs from cubic liquid crystal gels conformed to Higuchi equation and were dominated by Fick’s diffusion (n < 0.45). The ex vivo penetration experiment indicated that dual components-loaded liquid crystal gels can enhance and extend the skin permeation of these two drugs, especially the ratio of SH to CA is 1: 0.5. Finally, transdermal mechanisms were evaluated using laser scanning confocal microscopy and attenuated total reflectance-fourier transform infrared, hinting that hydrophilic and lipophilic drugs weaken each other’s transdermal velocity at the initial stage of penetration. In short, the dual drug-loaded liquid crystal gels was a promising strategy for transdermal applications in treatment of chronic disease.