Objective: To study on the dispersion of daidzein with polyvinylpyrrolidone (PVP) and its effects on the aqueous solubility, dissolution rate and bioavailability of daidzein.
Methods: The solid dispersion of daidzein at various daidzein to PVP ratios were obtained via the solvent evaporation method and characterized by differential scanning calorimetry and fourier transform infrared spectroscopy. In addition,the bioavailability of free daidzein as well as its solid dispersion were studied in mice.
Results: It was found that the daidzein solubility in the solid dispersion form was 8 times greater than that of the free drug in water at (37 +/- 0.1) degrees C. Meanwhile,the daidzein dissolution rate was significantly increased after dispersing with PVP. The results of the bioavailability showed that both Cmax and AUC value of daidzein solid dispersion were about 5 times larger than unprocessed daidzein, implying that the rate-limiting step in daidzein absorption may be the dissolution process.
Conclusions: The results in this work reveal the substantial advantages of adopting polyvinylpyrrolidone dispersion as an oral preparation to improve daidzein bioavailability.