Preparation and in vitro and in vivo evaluation of silymarin self-microemulsifying concentrated microemulsion

Objective:To prepare silymarin self-microemulsifying concentrated microemulsion and evaluate its properties in vitro and in vivo.Methods:The compositions of SCM were determined according to previous work.The particle size and distribution of silymarin microemulsion were surveyed by means of dynamic light scattering method.The morphology of silymarin microemulsion was observed through transmission electron microscope.Accelerated tests were used to evaluate physical and chemical stability of silymarin SCM.The in vitro release of silymarin SCM was assessed by dialysis method.The bioavailability of silymarin SCM was determined by oral administration to dogs compared with commercial silymarin capsule.Results:The results of dispersion experiment indicated that the self-microemulsify of silymarin SCM was obtained within five minutes and the mean diameter of microemulsion was 21nm.The shape of silymarin microemulsion appeared spheroid or spheroid-like.The results of the accelerate test for six months showed that the clarity,the size of microemulsion and the silymarin content did not change significantly.The accumulation release percent of silymarin from SCM and conmercial capsule for 12 hours were(72.5±4.0)% and(44.0±6.9)%,respectively.The AUC of silymarin SCM and commercial silymarin capsule were(4.78±1.02)and(2.09±0.15) μg·mL-1·h,respectively.The relative bioavailability was 227.2%.Conclusion:The self-microemulsify of silymarin SCM was obtained easily,quickly and with good stability.The bioavailiablity of silymarin by oral administration to dogs was increased significantly.The SCM might be a potential effective preparation for silymarin.