ABSTRACT
OBJECTIVE To prepare Angelica•Cinnamomum（Angelica sinensis-Cinnamomum cassia ）self•microemulsion drug delivery system （AC•SMEDDS），and to optimize its formulation and characterize its preparation . METHODS Using Angelica• Cinnamomum mixed volatile oil as oil phase and model drug ，on the basis of selecting emulsifier and co -emulsifier and the optimization of their mass ratio range ，the formulation was optimized with central composite design •response surface methodology using the ratio of oil phase （Angelica•Cinnamomum mixed volatile oil ），mass ratio of emulsifier and co -emulsifier as factors ，the comprehensive score of volatile oil content ，particle size and emulsifying time as index . Morphology，particle size ，drug loading ， entrapped efficiency and stability of optimized AC•SMEDDS were characterized . RESULTS The optimum formulation of AC•SMEDDS contained the ratio of oil phase was 30%，and the mass ratio of emulsifier （EL•40）and co -emulsifier（ethanol）was 9∶1. Results of validation tests showed that the average particle size of AC•SMEDDS was （148.33±1.53）nm，and emulsifying time was （18.44±0.11）s. The comprehensive score was 0.68，relative deviation of which from the predicted value （0.70）was 2.86%. AC•SMEDDS prepared by optimal formulation was faint yellow ，uniform and transparent liquid ，and spherical particals with translucent edge were observed under transmission electron microscope . Calculated by ligustilide and cinnamaldehyde ，the drug loading was （7.58±0.03） and （4.17±0.01） mg/g，and entrapped efficiency was （93.25±0.01）% and （88.89±0.02）% ， respectively. No stratification or precipitation occurred after centrifugation at the speed of 10 000 r/min or placing within 7 （No.2019-0520） days at 4 and 25 ℃ . The contents of ligustilide and cinnamaldehyde were stable . Its particle size had no significant change after 50，100 and 200 times dilution by purified water . CONCLUTIONS AC•SMEDDS is prepared successfully and its formulation is optimized . The stability of the preparation is good .