Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-03-20
2001-08-21
Nguyen, Anhtuan T. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S195000
Reexamination Certificate
active
06277097
ABSTRACT:
The invention relates to an injection system for preparing a mixture of a solvent and a medicament and for subsequent dosed injection of the mixture, the system comprising:
a syringe from which set doses are apportioned from a cylinder ampoule having a first end closed by a pierceable membrane and a second end closed by a piston which can by a piston rod, which is successively advanced in a distal direction by the injection of set doses, be forced into the ampoule to press out a dose of a medicament stored in the ampoule between the membrane and the piston through an injection needle piercing the rubber membrane,
an ampoule with a solvent fitting into the syringe, and
a needle mounted in a needle hub and having an injection part projecting from a distal side of the hub and a back needle piercing the membrane of an ampoule when the needle hub is mounted on the syringe.
Whereas many medicaments are supplied as a solution or a suspension in pre-filled cylinder ampoules of the kind mentioned above, some kinds of medicine have a low storability once they are dissolved. Therefore these types of medicine are mainly stored in a vial as a lyophilised powder which is dissolved in a solvent which is injected in the vial by the user immediately before he is going to load his syringe with a new ampoule. The solution obtained in the vial is transmitted to a cylinder ampoule which is then ready to be mounted in a syringe of the above mentioned kind.
By the mixing it is important that a precisely measured amount of solvent is used for dissolving the powder in the vial as else the concentration of the mixture in the ampoule will be wrong so that the user loses control of his medication. A precise mixing may be obtained by storing the solvent in the cylinder ampoule which is going to be used for the mixture. From the manufacturer the ampoule may contain a very precise amount of solvent which may be injected into the vial through a double ended needle penetrating the closing membranes of as well the ampoule as the vial.
When the powder in the vial is dissolved in the solvent injected in the vial, mixture obtained is sucked back into the ampoule by drawing the piston of this ampoule outward. If less than the total amount of solvent was injected into the vial, the remaining solvent will be mixed up in the mixture of medicine and solvent transmitted from the vial back into the ampoule.
When the piston of the ampoule is drawn outward to suck up the mixture in the ampoule it is very important that the piston is not drawn out of the ampoule as it may be difficult to put back again an as it will inevitably cause spill and contamination of the medicament.
From WO 95/12425 is known a device for filling a cylinder ampoule for use in a syringe of the above mentioned kind. This apparatus comprises a holder in which an ampoule containing a measured amount of solvent may be mounted. At its front end the holder is equipped with a connecting device coupling the outlet end of the ampoule to a vial into which the solvent shall be injected to dissolve a lyophilised medicament. To the rear end of the holder a support is mounted In which a piston rod may be moved in the axial direction of the ampoule. The distal end of the piston rod is screwed into the piston and the proximal end of the piston rod projects from said support. The solvent in the ampoule may be pressed through a needle which from the front end of the ampoule forms a channel to the interior of the vial. The solvent is transmitted from the ampoule to the vial by pressing the projecting end of the piston rod which then presses the piston into the ampoule. The mixture obtained in the vial is thereafter sucked back into the ampoule by drawing the piston outward. This outward drawing is made possible by the fact that a rear end of the piston is provided with a hole with an inner thread which is engaged by an outer thread at the distal end of the piston rod. The piston rod support which forms a stop preventing the piston from being drawn out of the ampoule is fixed to the ampoule holder in such a way that it cannot be unfixed unless the screw connection between the piston and the piston rod is brought out of engagement. This way the risk for inadvertently drawing out the piston is eliminated.
However, the described solution implies that different devices must be carried and used. First the filling device must be taken apart and the ampoule mounted into said device. Then a filling procedure must be run through. Thereafter the device must be taken apart again to remove the filed ampoule, which must then be installed in the syringe by which a dose may be set and injected.
Consequently it is an object of the invention to provide an injection system which makes a special filling device superfluous.
This is obtained by a system of the kind mentioned in the opening of this application, which system is characterised in that the piston rod of the syringe and the piston of the ampoule has co-operating coupling means by which the piston of the ampoule is secured to the piston rod of the syringe to make said piston follow movements of the piston rod in both axial directions.
In such a syringe an ampoule with solvent may be mounted with the distal end of the piston rod engaging the piston of the ampoule, and through a needle mounted in the common way on the syringe the solvent may be injected into a vial by repetitively setting a dose and injecting this dose through the closing rubber membrane of the vial until the ampoule is emptied. An adapter may be mounted between the syringe and the vial to keep these elements in position during said operation and during the next operation which is to draw the piston rod in a proximal direction whereby it due to its engagement with the piston in the ampoule will draw this piston outward in the ampoule. Thereby the mixture prepared in the vial by the injection of the solvent will be sucked into the ampoule from where it may now be apportioned in doses which may be individually set by the dose setting mechanism.
The coupling means of the piston rod and the piston may appropriately be parts of which one carries an outer thread which can engage an inner thread in the other part. However other kinds couplings allowing transmission of axial movements in both axial direction may be used so as snap couplings or bayonet couplings. In some syringes the piston may be moved in both axial directions against the resistance of friction in a piston rod guidance whereas other syringes are provided with a unidirectional coupling which allows only a movement of the piston rod and the piston in a distal direction when an ampoule is mounted in the syringe. When the ampoule is dismounted the unidirectional coupling is released and the piston rod may be moved in the proximal direction to a retracted position which it takes up when a full ampoule is mounted. In such syringes means may be provided which even when an ampoule is mounted in the syringe can be operated to set the piston free to be moved in a proximal direction.
According to a preferred embodiment of the invention he dosing mechanism of the syringe comprises a dose setting and injecting member which to set a dose is rotated from a stop an angle which is proportional with the set dose and which to inject the set dose is rotated back to the stop, an inner thread in a tubular housing of the syringe, an outer thread provided on elements forming a part of a piston rod assembly, which outer thread is in engagement with the inner thread of the housing, a unidirectional coupling between the dose setting and injecting member which only by injecting transmits the rotation to the piston rod to screw this rod in a distal direction through the housing, which syringe may according to the invention be characterised in that the means setting the piston rod free are means drawing the elements carrying the external thread out of engagement with the inner thread of the housing. In such a syringe the means setting the piston rod free may be means drawing the elements carrying the external thread of the piston rod
Klitmose Lars Peter
Larsen Andre
Mikkelsen Soren
Nguyen Anhtuan T.
Novo Nordisk A S
Sirmons Kevin C.
Skadden, Arps Slate Meagher & Flom LLP
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