Osmotic pumps
First Claim
1. An osmotic syringe comprising a tubular housing with a delivery nozzle at one end thereof, a delivery chamber in said tubular housing adjacent said delivery nozzle, said delivery chamber having delivery material therein, an osmotic salt chamber in said tubular housing adjacent said delivery chamber and remote from said delivery nozzle, said osmotic salt chamber having osmotic salt therein, said osmotic salt chamber being isolated from said delivery chamber by a first movable piston, said first movable piston having an outside diameter which is the same as the inside diameter of the said tubular housing and said first movable piston being longitudinally displaceable in said tubular housing, an osmotic fluid chamber in said tubular housing adjacent said osmotic salt chamber and remote from said delivery chamber, said osmotic fluid chamber having osmotic fluid therein, said osmotic fluid chamber being isolated from said osmotic salt chamber by a semipermeable membrane, said semipermeable membrane being permeable to said osmotic fluid but being impermeable to said osmotic salt, a fluid barrier positioned between said semipermeable membrane and said osmotic fluid chamber, said fluid barrier being capable of inactivation, a second movable piston in said tubular housing at the end of said osmotic fluid chamber remote from said fluid barrier, said second movable piston and said fluid barrier being the ends of the said osmotic fluid chamber in the said tubular housing, said second movable piston having an outside diameter which is the same as the inside diameter of the said tubular housing and said second movable piston being longitudinally displaceable in said tubular housing, and wherein displacement of said second movable piston in longitudinal direction towards said delivery nozzle is capable of inactivating said fluid barrier, whereby, when said fluid barrier is inactivated, osmotic fluid in said osmotic fluid chamber flows through said semipermeable membrane and into said osmotic salt chamber and combines with osmotic salt in said osmotic salt chamber thereby generating osmotic pressure, said osmotic pressure causing said first movable piston to displace longitudinally toward said delivery nozzle, thereby decreasing the size of the delivery chamber and forcing the delivery material out of the delivery chamber through the said delivery nozzle.
1 Assignment
0 Petitions
Accused Products
Abstract
An osmotic pump comprises a housing (2) within which is a delivery chamber (5) separated from an osmotic salt chamber (7) by impermeable moveable pressure responsive means such as a piston (6) or a flexible membrane. The osmotic salt chamber (7) is separated from a source of osmotic fluid, e.g. an osmotic fluid chamber (12), by a semipermeable membrane (96,36), optionally mounted in a piston (9,23). A fluid barrier isolates the osmotic salt chamber (7) from the source of osmotic fluid for storage of the pump, and may be inactivated when the pump is to be used. The fluid barrier may be a foil sheet (10), inactivatable by rupture, or a piston and a fluid bypass arrangement (21,23). Activation of the osmotic pump may be effected in some embodiments by loading the discharge chamber (5) with the agent to be delivered and in other embodiments by movement of a plunger (16), under manual control or, if the plunger is pre-biassed, by release of a locking means (18) which holds it in position.
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Citations
13 Claims
- 1. An osmotic syringe comprising a tubular housing with a delivery nozzle at one end thereof, a delivery chamber in said tubular housing adjacent said delivery nozzle, said delivery chamber having delivery material therein, an osmotic salt chamber in said tubular housing adjacent said delivery chamber and remote from said delivery nozzle, said osmotic salt chamber having osmotic salt therein, said osmotic salt chamber being isolated from said delivery chamber by a first movable piston, said first movable piston having an outside diameter which is the same as the inside diameter of the said tubular housing and said first movable piston being longitudinally displaceable in said tubular housing, an osmotic fluid chamber in said tubular housing adjacent said osmotic salt chamber and remote from said delivery chamber, said osmotic fluid chamber having osmotic fluid therein, said osmotic fluid chamber being isolated from said osmotic salt chamber by a semipermeable membrane, said semipermeable membrane being permeable to said osmotic fluid but being impermeable to said osmotic salt, a fluid barrier positioned between said semipermeable membrane and said osmotic fluid chamber, said fluid barrier being capable of inactivation, a second movable piston in said tubular housing at the end of said osmotic fluid chamber remote from said fluid barrier, said second movable piston and said fluid barrier being the ends of the said osmotic fluid chamber in the said tubular housing, said second movable piston having an outside diameter which is the same as the inside diameter of the said tubular housing and said second movable piston being longitudinally displaceable in said tubular housing, and wherein displacement of said second movable piston in longitudinal direction towards said delivery nozzle is capable of inactivating said fluid barrier, whereby, when said fluid barrier is inactivated, osmotic fluid in said osmotic fluid chamber flows through said semipermeable membrane and into said osmotic salt chamber and combines with osmotic salt in said osmotic salt chamber thereby generating osmotic pressure, said osmotic pressure causing said first movable piston to displace longitudinally toward said delivery nozzle, thereby decreasing the size of the delivery chamber and forcing the delivery material out of the delivery chamber through the said delivery nozzle.
Specification