BIOAVAILABILITY AND TOXICITY STUDIES OF MICROENCAPSULATED CHEMICALS

国家毒理学计划正在探索 采用微胶囊作为替代手段， 将挥发性的、反应性的和/或不可口的化学物质掺入到 毒理学研究用动物饲料。 经口（给药-喂食）毒理学 对这些化学品进行了研究， 在微胶囊中充分稳定，但释放到 胃肠道以允许生物利用度。 的 吸收三氯乙烯（TCE），稳定在明胶中- 山梨糖醇微胶囊，相当于纯TCE 当通过管饲法给予Fischer 344时， 大鼠 在F344大鼠的14天重复给药研究中， 通过在饲料中给予微胶囊化TCE， 溶于玉米油的三氯乙烯灌胃给药。 这些研究 表明微胶囊化可以提供优异 研究口服毒理学特性的替代方法 挥发性化学物质的实验动物。 2-乙基己醇（2- EH）稳定在淀粉基质型微胶囊中。 生物等效性研究表明，2-EH与 灌胃给药玉米油混悬液后吸收 微胶囊化的2-EH或溶于玉米油中的纯2-EH。 未来的工作将涉及生物等效性研究和毒理学 其他微胶囊化化学品的特性。

The National Toxicology Program is exploring the feasibility of adopting microencapsulation as an alternative means of incorporating volatile, reactive, and/or unpalatable chemicals into animal feed for toxicologic studies. Oral (dosed-feed) toxicology studies are performed on those chemicals which are demonstrated to be adequately stabilized in the microcapsules, but released into the gastrointestinal tract to allow biological availability. The absorption of trichloroethylene (TCE), stabilized in gelatin- sorbitol microcapsules, was equivalent to that of neat TCE dissolved in corn oil when administered by gavage to Fischer 344 rats. In a 14-day repeated-dose study in F344 rats, similar toxic effects were produced by microencapsulated TCE given in feed as TCE dissolved in corn oil administered by gavage. These studies indicate that microencapsulation can provide an excellent alternative method for studying the oral toxicological properties of volatile chemicals in laboratory animals. 2-Ethylhexanol (2- EH) was stabilized in a starch matrix-type microcapsule. Bioequivalence studies have demonstrated that 2-EH is similarly absorbed after gavage administration of corn oil suspensions of microencapsulated 2-EH or neat 2-EH dissolved in corn oil. Future work will involve bioequivalence studies and toxicologic characterization of other microencapsulated chemicals.