Thesis (M.Sc. in Pharm)--Chulalongkorn University, 2004

The purpose of the study was to develop monoglyceride-based drug delivery systems containing Garcinia mangostana extract. The system is based on the ability of mixtures of monoglyceride (glyceryl monooleate) and triglycerides to form liquid crystals upon contact with water. The drug delivery systems can be administered by syringe and transformed into high-viscous liquid crystalline phases at the injection site. Ternary phase diagrams were constructed from various triglycerides: sesame oil, soybean oil and olive oil. The structure of liquid crystalline phase was investigated using polarized light microscopy. In this study, monoglyceride-based drug delivery systems were prepared in the ratio of triglycerides: glyceryl monooleate: water as 8:62:30 and 12:58:30. These systems could sustain release of Garcinia mangostana extract over a period of 48 hr and followed square root of time kinetics during the initial 24 hr of the release phase indicating that the rate of release was diffusion controlled. The system containing sesame oil showed the highest drug release. Increasing triglyceride content did not affect the release profiles. Differential scanning calorimetry results demonstrated that Garcinia mangostana extract can be incorporated into drug delivery systems without causing phase transition. In the in vitro test, monoglyceride-based drug delivery systems containing Garcinia mangostana extract did not show the antimicrobial activity probably due to the high lipophilicity of the extract therefore it did not diffuse into the medium. Additionally, the drug delivery systems containing Garcinia mangostana extract showed good stability under the stress condition.