Preparation of Evodiamine Solid Dispersions and Its Pharmacokinetics
In order to increase the dissolution rate and bioavailability, solid dispersions of evodiamine in PVP K30 with different enriched samples of evodiamine to PVP K30 ratios were prepared by solvent method. Our studies showed that the dissolution rate of evodiamine was significantly higher in the solid dispersion system in comparison with that in enriched samples of evodiamine or physical mixtures. The increase of the dissolution rate was evidently related to the ratio of evodiamine to PVP K30. The solid dispersion system (enriched samples of evodiamine/PVP K30= 1/6, w/w) gave the highest dissolution rate: about 27.7-fold higher than that of enriched samples of evodiamine in hard capsules. Powder X-ray diffraction studies showed that enriched samples of evodiamine presented a total chemical stability after its preparation as solid dispersions. In vivo administration studies indicated that solid dispersions of evodiamine in hard capsules had a higher Cmax and a shorter Tmax than those of physical mixture in hard capsules, and the differences of Cmax and Tmax between them were significant. These results suggest that solid dispersions of evodiamine in hard capsules has a notably faster and greater absorption rate than enriched samples of evodiamine in physical mixture hard capsule and corresponds with the in vitro dissolution.