Dual-chamber injection cartridge

Details Dual-chamber injection cartridge Dual-chamber injection cartridge

1994-02-24

1995-12-05

Rosenbaum, C. Fred

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

604 56, 604 82, A61M 3700

Patent

active

054724228

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention refers to injection cartridges of the dual-chamber type. More specifically, it refers to improvements in injection cartridges of the dual-chamber type, whereby sterility of the components in the cartridge may be assured.


BACKGROUND OF THE INVENTION

Injection cartridges of the dual-chamber type have found a very wide use in the administering of injectable preparations which are not stable as a solution or dispersion in a liquid phase. As examples of such preparations may be mentioned certain protein compounds and hormones, such as growth hormones. These preparations are provided in a dry form, which is mixed with a liquid phase, usually water or an aqueous solution, immediately before the administering.
An injection cartridge of the dual-chamber type is generally shaped as a tubular barrel, which is divided into a front chamber and a rear chamber by means of a front piston. The front chamber contains the dry component of the injectable preparation, and is closed at its front end by a closure that permits the establishment of a liquid connection with the outside. Such a closure may be in the form of a rubber septum that may be pierced by a hollow needle for withdrawing or expelling a liquid mixture from the front chamber. The rear chamber is filled with the liquid component of the injectable preparation, usually water or an aqueous solution, and is closed at its rear end by a rear piston. When the injectable preparation is to be prepared, pressure is applied on the rear piston to move it forward. This pressure is transmitted through the essentially incompressible liquid to the front piston, such that this piston is also moved forward. By this forward movement, the front piston activates a bypass connection, such that the liquid in the rear chamber can flow over into the front chamber by the action of the forward movement of the rear piston, to be mixed with the solid component of the injectable preparation. When all of the liquid in the rear chamber has been made to flow over into-the front chamber, the front face of the rear piston will abut the rear face of the front piston. On further forward movement of the rear piston, the two pistons will act as one single piston to expel the mixed injectable preparation from the front chamber through the liquid connection mentioned above. Alternatively, the front chamber may serve as a reservoir for the mixed injectable preparation, and portions thereof may be withdrawn through the liquid connection.
The bypass connection for the liquid from the rear chamber to the front chamber may be arranged as a channel in the interior wall of the barrel of the cartridge. This channel is exposed by the front piston on its movement forward, to afford a liquid connection between the two chambers. Other arrangements are also possible.
When the injectable preparation is prepared from the two components, the injection cartridge is usually placed in a holder device provided with means for applying the pressure on the rear piston. The holder device may also be provided with means for metering and administering doses of the mixed injectable preparation.
The design and function of injection cartridges of the dual-chamber type is well-known to those skilled in the art, and need not be described here in more detail. Also, a number of the above-mentioned holder devices are well-known, and some of them are commercially available.
In the manufacture of injection cartridges of the dual-chamber type, it is, of course, of the utmost importance that sterility is maintained, so that no risk of microbial contamination of the injectable preparation will arise. However, this has been a problem with the prior art injection cartridges of the dual-chamber type.
In the prior art process for manufacture, the empty cartridges are provided with the front piston in place. The barrel of the cartridge is shaped as a cylindrical tube, which may be shaped as a bottleneck at its front end to receive the closure, and which usually consists of a rubber septum and a met

REFERENCES:
patent: 2591046 (1952-04-01), Brown
patent: 2591706 (1952-04-01), Lockhart
patent: 2665690 (1954-01-01), Lockhart
patent: 3494359 (1970-02-01), Zackheim
patent: 4439184 (1984-03-01), Wheeler
patent: 4469482 (1984-09-01), Lissenburg et al.
patent: 4613326 (1986-09-01), Szwarc

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