RESUMO
AIM To prepare nanosuspensions of flavonoids from Glycyrrhizae Radix et Rhizoma and to determine the in vitro dissolution rate.METHODS Precipitation-high pressure homogenization method was adopted in the preparation of nanosuspensions.With mean particle size and polydispersity index (PDI) as evaluation indices,concentrations of flavonoids,povidone K30 (PVP K30) and polyethylene glycol 400 (PEG 400) as influencing factors,central composite design-response surface method was applied to optimizing the preparation.For the freedried powder prepared by freeze-drying method,the optimal kind and ratio of lyoprotectant were screened.Then the in vitro dissolution rates of freeze-dried powder and physical mixture were compared.RESULTS The optimal conditions were determined to be 10.00 mg/mL for flavonoids' concentration,and 2.30 mg/mL for both PVP K30 and PEG 400 concentrations,the mean particle size and PDI were (172.3 ± 1.2) nm and 0.175 ± 0.004,respectively.The optimal lyoprotectant was 5％ mannitol-lactose (3 ∶ 2),the mean particle size and PDI after redissolution were (239.7 ±2.1) nm and 0.193 ±0.032,respectively.The in vitro dissolution rate of lyoprotectant reached 87.7％ within 60 min,which was much higher than that of physical mixture (less than 30％).CONCLUSION Nanosuspension can effectively improve the in vitro dissolution rate of flavonoids from Glycyrrhizae Radix et Rhizoma.