Preparation Of Capsaicin/SiO₂Microspheres And Its Drug Release Study

Capsaicin is a vanilla amide alkaloid isolated from red pepper. It has been extensivelyconcerned by scholars in the field of biomedical, food preservation, marine pollutionprevention because of its anti-inflammatory, analgesia, antipruritic, antibacterial, insect andother biological functions. But its pungent odor, skin irritation and short half-life limit itsapplication greatly. Capsaicin/SiO₂microspheres can cover up the pungent odor as well asextend the effective duration time of the drugs thus effectively expand its application fields.In our article, Tetraethyl orthosilicate（TEOS） was used as silica source, capsaicin/SiO₂microspheres were prepared by oil/water/oil（O/W/O） multiple emulsion. By usingsingle-factor test and L9（34） orthognal test, the preparation parameters were optimized, andthe drug release of capsaicin/SiO₂were alse studied. The results were as follows:1. Preparation method of Capsaicin/SiO₂microspheres and its single-factor testTake capsaicin as encapsulation drug, TEOS as silica source, an appropriate preparationmethod of capsaicin/SiO₂microspheres was selected on the basis of emulsion method, and thepreparation parameters of the microspheres were determined by single-factor test. The resultsshowed that, O/W/O multiple emulsion method can been uesed to prepare capsaicin/SiO₂microspheres. The preparation parameters determined by the single factor test were as follows:HPC was added in the external oil phase as stabilizer, the original emulsion was prepared byhomogenizer, the stirring speed of multiple emulsion was660rpm/min and the reaction timeof TEOS was16h.2. Optimization for process parameters of Capsaicin/SiO₂MicrospheresCapsaicin/SiO₂microspheres were prepared by O/W/O multiple emulsion. Themorphology and size were characterized by SEM and optical microscopy, the encapsulationefficiency were determined by UV spectrophotometry and the effect of different factors onencapsulation efficiency was studied by L9（34） orthogonal method. Most of the capsaicin/SiO₂microspheres had spherical hollow structure, with the average diameter of4.62μm. If there isno cross-interaction, the optimal process parameters should be HPC and Span80contents were1.5%and0.5%mass percentage of the external oil phase, PEG and Tween20contentswere4.0%and0.5%mass percentage of the water phase.3. The Drug Release of Capsaicin/SiO₂MicrospheresCapsaicin/SiO₂microspheres with different drug loading were prepared by changing thedosage using O/W/O multiple emulsion. The average particle size was4.49μm, in vitro drugrelease study showed that the microspheres had a slow-release effect in the water-ethanolmixture. With the increase of drug loading, the release rate increased and release timeprolonged. The drug release curve of sample C5was estimated, and was found to be in agreewith diffusion-erosion model, which means the drug release was determined by diffusion ofcapsaicin and dissolution of SiO₂skeleton in the water-ethanol mixture.