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Controlled delivery device

  • US 4,793,997 A
  • Filed: 06/29/1987
  • Issued: 12/27/1988
  • Est. Priority Date: 03/28/1985
  • Status: Expired due to Fees
First Claim
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1. A device for the timed release of an active material into an aqueous medium, the device comprising a sealed container having a wall consisting of a water soluble glass and in which container the active material is encapsulated, wherein a minor proportion of container wall consists of a region of reduced resistance to solution attack whereby, when the device is contacted by the aqueous medium, that region is dissolved over a predetermined time period to provide an opening in the container wall so as to release the active material whilst the remainder of the glass container wall is only partially dissolved so as to prevent collapse of the container.

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