Abstract: AimTo evaluate the self-emulsifying ability and dissolution behavior of tretinoin in vitro and the pharmacokinetic behavior in beagle dogs. MethodsThe self-emulsifying rate was evaluated by determining the intensity of scattered light at different time and the particle size of resultant emulsions after self-emulsifying were observed by optical microscope. The plasma concentrations were determined by HPLC and dissolution and pharmacokinetic behavior of self-emulsifying formulations were evaluated by comparison with commercial capsules. ResultsThe area under the curve (AUC) was significantly higher in the tretinoin self-emulsifying formulation group (3 048.0 mg·h·L^-1) than that in the commercial capsule group (1 826.0 mg·h·L^-1). Also, Tmax was smaller in the self-emulsifying formulation group (1.25 h) compared with market products (2 h) and the dissolved amount from self-emulsifying formulations in water at 15 min was much higher (more than 80%) than that of the market products (less than 5%). ConclusionThe self-emulsifying drug delivery systems can increase drug dissolution in vitro and absorption in vivo significantly.