Preparation of baicalin colon-specific solid dispersion and evaluation on its in vitro release

OBJECTIVE: To prepare pH-dependent baicalin colon-specific solid dispersion, with the aim of colon-specific delivery and rapid drug release. METHOD: Baicalin-eudragit S100 solid dispersion was prepared by using the solvent method. The microscopic structure and physicochemical properties were analyzed by using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and infrared spectroscopy (IR). And its in vitro release was also investigated. RESULT: The results of DSC and XRD analysis suggested that baicalin may be dispersed in solid dispersion in the amorphous state. IR results indicated a non-covalent bond effect may exist between baicalin and eudragit S100. The results of in vitro release determination showed that very few baicalins in pH 1.2 diluted hydrochloric acid solution for 2 h at the baicalin-eudragit S100 ratio of 1 : 6. The accumulated dissolution rate was less than 15% in pH 6.8 phosphate buffer solution for 4 h, but exceeding 90% in pH 7.6 phosphate buffer solution for 1 h. CONCLUSION: The prepared baicalin-eudragit S100 solid dispersion could achieve the objective of colon-specific delivery and rapid drug release, and helps increase the concentration of baicalin in colons.