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Osmotic dispenser with means for dispensing active agent responsive to osmotic gradient

  • US 3,995,631 A
  • Filed: 09/25/1972
  • Issued: 12/07/1976
  • Est. Priority Date: 01/13/1971
  • Status: Expired due to Term
First Claim
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1. An osmotic active agent dispenser comprising a bag formed of a flexible, relatively impervious material as a means for containing an active agent and provided with a means for releasing the active agent to the exterior of the device, the bag encapsulated with a film comprised of an osmotically effective solute which solute when in solution exhibits an osmotic pressure gradient against an external fluid, the film surrounded by a wall comprised of a shape retaining material having in at least a part controlled permeability to the exterior fluid, and wherein in operation when the bag is charged with at least one active agent, the agent is dispensed from the device by fluid permeating from the external environment through the permeable wall producing a solution of the solute in a tendency towards osmotic equilibrium with said environment, same increasing the volume between the wall and the bag thereby generating mechanical deflating forces on the bag, which in turn ejects the active agent out of the dispenser at an osmotically controlled rate over a prolonged period of time.

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