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

To prepare pH-dependent baicalin colon-specific solid dispersion, with the aim of colon-specific delivery and rapid drug release.

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.

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.

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.