Abstract An improved osmotic pressure actuated injection device for long term continuous injection which has a chamber filled with the medicament to be injected and a suitable injection orifice, with a piston or similar device, the other side of he piston being a concentrated solution, such as a saturated solution, caPped with a semipermeable membrane and exposed to a second chamber having the solvent for the solution, and a freely movable piston exposed on its other side to atmospheric pressure or similar source so that the solvent moves through the semipermeable membrane increasing the osmotic pressure and so forcing the piston in the first chamber to discharge a small amount of medicament. The pressure in the solvent chamber is maIntained constant, thus preventing formation of air pockets therein.
In a continuous, long-term injector device, which comprises a hollow member with injection orifice at one end adapted for connection with body tissue, a slidable piston in the member dividing it into first and second chambers and a semipermeable membrane across the end of said second chamber, the second chamber being filled with an osmotic pressure developing solution and the 69 chamber containing a medicament, the improvement which comprises, a. a second hollow member serving as a reservoir for osmotic pressure solvent and provided with a freely sliding piston, b. screw-threaded means securing the reservoir onto the hollow member of the injector device to maintain continuous contact of the osmotic pressure solvent with the semipermeable membrane, and c, means for exposing the side of the sliding piston in the reservoir out of contact with solvent to a source of at least ambient pressure.
Claim 2
Dependent Claim
143 words
In a continuous, long-term injector device, which comprises a hollow member with injection orifice at one end adapted for connection with body tissue, a slidable piston in the member dividing it into first and second chambers and a semipermeable membrane across the end of said second chamber, the second chamber being filled with an osmotic pressure developing solution and the 69 chamber containing a medicament, the improvement which comprises, a. a second hollow member serving as a reservoir for osmotic pressure solvent and provided with a freely sliding piston, b. screw-threaded means securing the reservoir onto the hollow member of the injector device to maintain continuous contact of the osmotic pressure solvent with the semipermeable membrane, and c, means for exposing the side of the sliding piston in the reservoir out of contact with solvent to a source of at least ambient pressure.
Claim 3
Dependent Claim
19 words
A injector device according to claim 1 in which the source of at least ambient pressure is the atmosphere.