Agent delivery systems

Abstract From the Canadian patent

An improved bolus for releasing a biologically active substance into a liquid environment; the bolus comprise a generally elongate core surrounded by a liquid impermeable casing; in use, the casing has an opening at one or both ends of the core and is progressively shed as the core retreats, to release the active substance at a rate which varies over at least one time period; the main improvement resides in that the bolus casing is, or at least some of its components are, sufficiently strong to retain integrity without disintegrating in the absence of any support provided by the core.