Preparation,characterization,and in vitro evaluation of geniposide cubic liquid crystal gel
Objective To prepare geniposide cubic liquid crystal gel(GE-CLC-G)and characterize and evaluate it in vitro,so as to enhance the transdermal performance of the water-soluble geniposide(GE).Methods Glyceryl monooleate(GMO)was used as the substrate material to prepare GE-CLC-G by injection method;the blank cubic crystal area was screened out by ternary phase diagram;the prescription and process conditions of GE-CLC-G were optimized by single factor method;the HPLC method for the determination of GE content was established.The product was characterized by polarizing microscope(PLM)and small angle X diffraction(SAXS).Modified Franz diffusion cell was used to compare the in vitro transdermal properties of GE-CLC-G and GE ointment,and DHR-2 rheometer was adopted to compare the rheological properties of GE-CLC-G and GE ointment.Results The optimal prescription and process of GE-CLC-G were as follows:GMO:anhydrous ethanol∶ water=64∶3∶33,1%GE dosage,1%penetration enhancer(azone∶ propylene glycol=1∶1),vortex at 60℃for 3 min,sealed and avoiding light in a constant temperature box at 25℃for 3 d.The obtained GE-CLC-G was colorless and clarified gel-like semi-solid;it was a cubic phase and its internal structure was a double diamond(Pn3m)lattice;the content of GE in the measured product was(9.94±0.02)mg/g,with a large drug load,which corresponded with the characteristics of cubic liquid crystal.The 24 h cumulative transdermal rate Q(%)and transdermal rate constant Js of GE-CLC-G containing 1%penetration enhancer were significantly higher than those of GE ointment and GE-CLC-G without penetration enhancer.Rheological studies showed that GE-CLC-G was a non-Newtonian fluid,with good bioadhesion and more stable structure.Conclusion The preparation process of GE-CLC-G is simple,the product appearance is fine;PLM and SAXS can be used to characterize cubic liquid crystal gel,and the content determination method is easy to operate,with good exclusiveness;the in vitro transdermal performance and rheological properties of GE-CLC-G are significantly better than GE ointment.