Implantable, self-regulating mechanochemical insulin pump

An implantable pump for the delivery of insulin to a mammal in need thereof, said pump comprising an implantable, biocompatible housing of fixed volume which supports within its walls:

• (a) a first chamber containing a pharmaceutically acceptable insulin composition and including a pressure-responsive valve means which permits the outflow of the insulin composition in response to an increase in pressure in the chamber and seals the chamber in response to a decrease in pressure in the chamber;
• and
• (b) a second chamber including a pressure-responsive valve means which seals the chamber in response to an increase in pressure in the chamber, and permits an influx of body fluids in response to a decrease in pressure in the chamber;
• (c) an aqueous-swellable hydrogel member which initiates an insulin pumping cycle by swelling in response to an increase in blood glucose level and terminates an insulin pumping cycle by deswelling in response to a decrease in blood glucose level, said member being exposed to the body fluids which surround the pump when implanted in a mammal and including a coupling means adjacent to at least one of said first and second chambers such that swelling of the hydrogel member causes an increase in pressure in both chambers.

An implantable pump for the self-regulated delivery of insulin to a mammal in need thereof, said pump comprising an implantable, biocompatible housing of fixed volume, which supports within its walls:

• (a) an aqueous-swellable hydrogel member which initiates an insulin pumping cycle by swelling in response to an increase in blood glucose level and terminates an insulin pumping cycle by deswelling in response to a decrease in blood glucose level, said member being exposed to the body fluids which surround the pump when implanted in a mammal;
• (b) a first chamber containing a pharmaceutically acceptable insulin composition and including a pressure-responsive valve means which permits the outflow of the insulin composition in response to an increase in pressure in the chamber and seals the chamber in response to a decrease in pressure in the chamber, said chamber being configured such that its internal volume is always the same as the volume of the insulin composition it contains;
• and
• (c) a second chamber in intimate contact with said first chamber and in direct or indirect contact with said aqueous-swellable hydrogel member, such that swelling of the hydrogel member due to an increase in blood glucose level causes an increase in pressure in both the first and second chambers, said second chamber including a pressure-responsive valve means which seals the chamber in response to an increase in pressure in the chamber and permits an influx of body fluids in response to a decrease in pressure in the chamber in a volume equal to the volume of insulin composition expelled during each insulin pumping cycle,
• wherein the total combined volume occupied by the first and second chambers within the housing is always approximately the same when the pressure in both chambers substantially equals the pressure of the environment external to the pump.