MICROENCAPSULATION OF UNSTABLE CHEMICALS FOR RODENT FEED

THE OVERALL OBJECTIVE OF THE PROJECT IS TO DEVELOP MICROENCAPSULATION PROCEDURES AND FORMULATIONS FOR STABILIZING THE PROPERTIES OF CHEMICALS THAT ARE UNSTABLE UNDER NORMAL ENVIRONMENTAL CONDITIONS. THE STABLE MICROCAPSULES WILL BE MIXED WITH RODENT FEED, AND THE CHRONIC TOXICITY OF THE CHEMICALS WILL BE EVALUATED. DURING PHASE I, MICROCAPSULES WILL BE PREPARED FROM VITAMIN A (RETINOL). THIS CHEMICAL WAS SELECTED AS A MODEL OF AN UNSTABLE TEST CHEMICAL THAT UNDERGOES RAPID PHOTODECOMPOSITION. A NEW, MICROFLUIDIZED BED PROCESS DEVELOPED BY BIOTEK, INC. WILL BE USED TO PRODUCE TRUE WALL/RESERVOIR MICROCAPSULES. THE MICROCAPSULES WILL BE EVALUATED FOR IN VITRO AVAILABILITY, SURFACE MORPHOLOGY, DRUG CONTENT, AND SIZE DISTRIBUTION. THEIR STABILITY WILL ALSO BE EVALUATED BY STORAGE UNDER HUMIDITY AND LIGHT CONDITIONS. THE MOST PROMISING MICROCAPSULE FORMULATION WILL BE TABLETED WITH GROUND-UP RODENT FEED AND ADMINISTEREDTO RATS TO DETERMINE TASTE ACCEPTANCE AND BIOAVAILABILITY OF THE DRUG. THE MICROENCAPSULATION PROCESS WILL BE SCALED UP BY PREPARING A 800-GRAM BATCH OF MICROCAPSULES FROM ALL-TRANSRETINOL ACETATE. THIS DRUG WAS SELECTED FOR SCALE-UP PURPOSES ONLY BECAUSE IT IS SIMILAR TO BUT SIGNIFICANTLY CHEAPER THAN VITAMIN A. THE PHASE I STUDIES WILL PROVIDE THE BASIS FOR FURTHER DEVELOPMENT OF THE PROCESS IN PHASE II AND THE MICROENCAPSULATION OF OTHER UNSTABLE CHEMICALS WHOSE CHRONICTOXICITY MUST BE DETERMINED BY NIEHS.