Improvement in oral bioavailability and dissolution of tanshinone IIA by preparation of solid dispersions with porous silica

Abstract

Objectives This study aims to evaluate the oral bioavailability and dissolution of tanshinone IIA (tanIIA) by preparation of solid dispersions (SDs) with porous silica. Methods SDs of tanIIA were prepared using a solvent method. The physicochemical properties, dissolution property, drug stability and in-vivo performance of the SDs prepared were all evaluated. Key findings Compared with tanIIA alone and corresponding physical mixtures, tanIIA from SDs showed remarkably improved in-vitro dissolution rate. After forming the SDs, tanIIA changed into an amorphous state, which can infer from differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD). Fourier transform infrared spectroscopy (FTIR) also revealed the presence of interactions between tanIIA and porous silica in SDs. During the stability study, there is no significant decreasing in either the in-vitro dissolution or the drug content, which was observed following storage at room temperature for 12 months. The results of a pharmacokinetic study in rats showed the areas under the concentration-time curve from 0h to 24h (AUC0-24h) for the SDs and tanIIA were 1019.87±161.819mg/h per litre and 343.70±75.628mg/h per litre, respectively. Conclusions SDs with porous silica as carrier could achieve superior oral bioavailability by improving drug dissolution, whereas drug stability could be maintained.