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Purpose: To assess the potential clinical value of alpha-tocopherol-loaded poly (DL-lactic-co-glycolic acid) (PLGA) microspheres, we examined the disposition kinetics of alpha-tocopherol after administration of the microspheres to apolipoprotein B (apo B) knockout mice as a model of abetalipoproteinemia., Methods: PLGA microspheres containing alpha-tocopherol were prepared by a solvent-evaporation method. The concentration of alpha-tocopherol was measured by gas chromatography-mass spectrometry., Results: The mean value of particle size of alpha-tocopherol-loaded PLGA microspheres was 108 microm. The loading and the trapping efficiency of alpha-tocopherol in PLGA microspheres were 20.8% and 86.6%, respectively. When alpha-tocopherol solution (25 mg/kg) was subcutaneously administered to apob (+/+) and apob (+/-) mice, the plasma concentrations of alpha-tocopherol reached a peak at 6 h and decreased to the endogenous level within 4 days in both types of mice. However, the area under the plasma concentration-time curve (AUC) of apob (+/-) mice was significantly smaller than that in the case of apob (+/+) mice. When alpha-tocopherol-loaded PLGA microspheres (100 mg/kg) were subcutaneously administered, the plasma concentrations of alpha-tocopherol increased slowly and remained about 2-fold higher than the endogenous level at 5 to 10 days after administration in both types of mice, and there was no significant difference between the AUC values., Conclusions: The PLGA microsphere preparation of alpha-tocopherol is expected to be a very useful drug delivery system in vitamin E supplementation therapy for abetalipoproteinemia.