Osmotic dispenser with means for dispensing active agent responsive to osmotic gradient
First Claim
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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Abstract
An osmotic active agent dispenser is comprised of a chamber having controlled permeability to an external fluid, i.e., water, and containing an osmotically effective solute which, in solution, exhibits an osmotic pressure gradient against said external fluid, said chamber housing a flexible bag of relatively impervious material containing an active agent and provided with means or dispensing head for releasing said active agent to the exterior of the dispenser. The flexible bag is disposed within the said housing chamber such that as the, e.g., water permeates from the external environment through the permeable walls of the chamber and migrates or diffuses by osmosis into the solution contained therein, same increases in volume thereby generating mechanical compressing or deflating force on the flexible bag, which force in turn ejects the active agent out of the apparatus at an osmotically controlled rate over a prolonged period of time.
421 Citations
10 Claims
- 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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9. An ocular osmotic dispenser for dispensing an ophthalmic agent comprising,
a. an inner wall formed of a flexible material, relatively impervious to tear fluid, osmotic solutes and an ophthalmic agent, the wall surrounding and forming, b. a compartment defined by the wall'"'"'s inner surface which compartment contains an ophthalmic agent and is provided with a means for dispensing the agent to the exterior of the device, c. a layer of an osmotically effective solute deposited on the wall'"'"'s outer surface, said solute exhibiting an osmotic pressure gradient against tear fluid when the dispenser is placed in the environment of use, d. an outer wall intimately surrounding the layer of the solute, said wall comprised of a material having shape retaining properties, permeable to a tear fluid and substantially impermeable to the solute, and, e. wherein in operation in the environment of use the ophthalmic agent is dispensed from the device by tear fluid permeating from the exterior through the permeable outer wall producing a continuous solution of the solute in a tendency towards osmotic equilibrium with the environment thereby continually increasing the volume between the outer wall and the compartment generating a mechanical force causing the compartment to continuously collapse and dispense the ophthalmic agent from the device at a controlled rate over a prolonged period of time.
Specification