Technical field

Present invention relates to a syringe comprising a syringe plunger for preventing re-usage by retaining of said plunger which can be manufactured at a cost similar to a conventional syringe.

Background

Misusage of syringes is a common issue, of the 16 billion injections administered each year over 2 million patients and users are infected with severe blood transmittable deceases such as HIV, Hepatitis B and C. In order to prevent the emergence of decease and infection due to misusage of syringes some syringes are equipped with arrangements for preventing re-usage. This may be especially important with regards to prevent re-usage by addicts.

In some instances the prevention is achieved via an arrangement wherein the needle is retracted into the syringe barrel after one usage whereby additional injections with the syringe are made impossible. In some instances the prevention is achieved by arrangements which destroys the syringe needle after one usage.

There are also instances where the prevention is achieved via introduced weaknesses in the syringe plunger which may cause the plunger to deform or brake and thereby preventing re-usage. In further instances re-usage may be prevented by a piece of metal molded into the plunger.

One advantage with such arrangements is that the risk for injuries and decease due to contact with the syringe needle in for example the disposal process is more or less eliminated. However, the arrangements enabling the retracting or destruction of the needles are often complex and more costly to produce. Since the relatively high cost for syringes often is a driving factor for the re-usage of conventional syringes, especially in development countries, there is a need for more cost-efficient solutions for providing the prevention of re -usage.

Another issue with current arrangements for preventing re-usage of syringes is that they often require fairly complex arrangements which with the considerable volumes which drugs and syringes are produced represent a significant cost.

Hence, there is a need to provide a syringe which addresses the disadvantages and shortcomings of the prior art in general and to provide a non-reusable syringe which can be manufactured in a cost-efficient manner.

Summary of the invention

Accordingly, the present invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solves at least the above mentioned problems by providing a syringe; the syringe comprising a barrel adapted to contain a drug; the barrel having a distal end wall portion and a tubular wall extending proximally from said distal end wall portion, the barrel extending along an axis.

The distal end wall portion may have an opening extending into a syringe head adapted to receive a syringe needle. As is conventional, the syringe head may be a luer, such as a luer grip or a luer slip. Further, the syringe may comprise a plunger shaft extending along the axis; said plunger shaft being displaceable within said barrel.

A plunger in a resilient material, such as for example an elastomeric material, is attached to a distal end of said plunger shaft. The plunger is adapted to be in fluid- tight engagement with the tubular wall of the barrel, thus enabling movement of the drug towards the syringe head.

To prevent re-usage the syringe is provided with a plunger stop extending transversally from the tubular wall; said plunger stop being adapted to stop movement of the plunger solely in a direction extending proximally from the distal end wall portion. This provides a non-reusability function which does not require any complex retaining features, whereby a cost efficient non-reusable syringe is achieved to exactly the same manufacturing cost as a conventional syringe.

The plunger may comprise a first sealing surface, whereby said first sealing surface has a base extending into a circumferential groove; the circumferential groove being adapted to receive the plunger stop and thereby retain the plunger at the plunger stop, the first sealing surface being a distal sealing surface.

The plunger may further comprise a second sealing surface extending along the axis, said second sealing surface being a substantially conical surface tapered in a direction extending towards the distal end wall portion; said substantially conical section having an edge being in fluid-tight engagement with the tubular wall, said edge being adapted to deform so as to stop movement of the plunger in the direction extending proximally from the distal end wall portion upon contact with the plunger stop.

The piston may comprise both the aforementioned portions, whereby a fail-safe arrangement is achieved (with dual means to prevent re-usage).

To further ensure the non-reusability and thus provide a more robust and reliable non-reusability function, the plunger may comprise a first and second plunger member, the first plunger member being releaseably attached to the second plunger member via a locking arrangement. The second plunger member may be in a fluid-tight engagement with the tubular wall and be adapted to be stopped by the plunger stop, whereby the locking arrangement is adapted to release the first plunger member from the second plunger member when the plunger shaft is pulled in a direction away from the distal end wall portion after retaining of said second plunger member at the plunger stop.

Further advantages will be apparent from the detailed description as well as the appended dependent claims. Brief description of drawings

These and other aspects, features and advantages of which the invention is capable, will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which Fig. 1 is a longitudinal section view of the syringe;

Fig. 2 is a side view of the syringe components;

Fig. 3 shows a plunger member of the syringe from a plurality of views;

Fig. 4 is a longitudinal section view of the syringe with a plunger stop according to one example;

Fig. 5 is a longitudinal section view of the syringe with a plunger stop according to one example.

Detailed description

Referring to Fig. 1 and 2, a non-reusable syringe 10 is shown. The syringe 10 comprises a barrel 11 , preferably of a cylindrical shape, which is adapted to contain a drug in liquid form to be injected into a patient. The barrel 11 has a distal end wall portion 13 and a tubular wall 12 extending proximally from the distal end wall portion 13.

As seen in Fig. 1 the syringe 10 extends along an axis 100 which defines the direction in which the barrel 11 extends, e.g. the barrel 11 extends along the axis 100. The syringe 10 has a syringe head 40 e.g. a syringe hub for receiving a syringe needle intended for injecting the drug in a patient, whereby the fluid communication to the syringe needle is enabled by the distal end wall portion 13 having an opening extending into the syringe head 40. The syringe head may be a luer, such as an exterior luer, for example a luer slip or a luer lock. As the skilled person recognizes, the syringe head may for example be cylindrical or conical.

Injection of the drug is achieved by moving of a plunger attached to a plunger shaft. Referring again to Fig. 1 a plunger shaft 96 and a plunger 30 for the syringe 10 is disclosed. The plunger shaft 96 extends along the axis 100 and further extends into a thumb rest 94. In order to move the drug, the plunger shaft 96 is displaceable along the axis 100 within said barrel 11.

The plunger 30 is attached to a distal end of the plunger shaft 96 and is adapted to be in fluid-tight engagement with the tubular wall 12 of the cylinder barrel 11.

Thereby, the drug contained inside the barrel can be injected through the syringe head 40 and through the syringe needle.

Re-usage of the syringe 10 is prevented by a plunger stop 70 which extends transversally from the tubular wall 12. The plunger stop 70 is adapted to stop movement of the plunger 30 solely in the direction extending proximally from the distal end wall portion 13. Thereby, further usage of the syringe is prevented by the plunger not being movable through a portion of the barrel after a first injection.

Referring to said figures, the plunger stop may be a substantially annularly shaped element extending radially towards the centre of tubular wall 12.

Advantageously, the syringe 10 further comprises a secondary plunger stop 14 to ensure that the plunger 30 and the plunger shaft 96 cannot be pulled out of the barrel 11. The syringe 10 may accordingly further comprise a secondary plunger stop 14 extending transversally from the tubular wall 12, said secondary plunger stop 14 being disposed after the plunger stop 70 in a direction extending proximally from the distal end wall portion 13. Preferably, the secondary plunger stop 14 and the plunger stop 70 are substantially annular elements.

Advantageously, the plunger may be in a resilient material such as an elastomeric material which enables retaining through deformation of said plunger.

The plunger 30 may be retained in a number of ways which will be described below with reference to Fig. 1-3.

Advantageously, the plunger stop 70 is a rounded, such as a radial, protrusion. A plunger stop with a non-rounded non-radial protrusion would have sharp edges which will make the plunger stop more brittle and susceptible for damage during

manufacturing. This is especially relevant if the syringe is injection molded; during injection molding there is a great risk for a plunger stop with sharp edges to be deformed or worn when the syringe is to be removed from the molding tool. Accordingly, the radial protrusion allows for a more reliable non-reusability function, since deformation of the plunger stop could negatively affect the retaining of the plunger.

As is presented in Fig. 3 the plunger 30 may comprise a first sealing surface 35. The first sealing surface 35 may have a base 39 extending into a circumferential groove 34. The circumferential groove 34 may be adapted to receive the plunger stop 70. To decrease the friction for when the first sealing surface passes the plunger stop 70 during injection, the first sealing surface 35 may have a distal rounded edge. The first sealing surface 35 may be a distal sealing surface.

With its shape, the plunger will be compressed in relation to the tubular wall 12 so as to allow for passage over the plunger stop 70 with the circumferential groove 34 when the plunger 30 is moved in a direction towards the distal end wall portion 13. However, when moved in a direction away from the distal end wall portion 13 said plunger 30 will be expanded towards the tubular wall 12 when coming into contact with the plunger stop 70. Thus, further movement is prohibited since the user will not be able to pull the groove 34 out of the engagement with the plunger stop 70, whereby the non- reusability function is provided.

Advantageously, the plunger stop 70 has a substantially larger circumference than the circumferential groove 34. Thereby, less force is required for the plunger to pass the plunger stop 70 in the "allowed" direction making the syringe easier to use.

Referring again to Fig. 1 and 3 an alternative retaining arrangement is shown. Said alternative retaining arrangement may either be implemented as a sole retaining arrangement or in combination with the circumferential groove arrangement described above, whereby a fail-safe is achieved (since the plunger stop can be retained in two separate ways). In some instances the plunger 30 may comprise a second sealing surface 33 extending along the axis 100, said second sealing surface 33 being tapered in a direction extending towards the distal end wall portion 13. The sealing surface may be a substantially conical surface having an edge 38 being in fluid-tight engagement with the tubular wall 12: the edge 38 being adapted to deform so as to stop movement of the plunger 30 in the direction extending proximally from the distal end wall portion 13 upon contact with the plunger stop 70. Preferably, the plunger 30 is in a resilient material allowing for said deformation.

The second sealing surface 33 preferably has a taper angle between 5 to 40 degrees, such as, 5 to 30 degrees, such as 10-15 degrees, i.e. in relation to a central axis of the barrel 11. Expressed in another way the sealing surface 33 has a taper angle of 50 to 85 degrees, such as 60 to 85 degrees, such as 75 to 80 degrees, in relation to a transversal plane of the plunger 30. The plunger 30 is preferably in a resilient material which allows for the edge to be deformed towards the center of the barrel 11, e.g. compressing of the plunger 30, in a radial direction when coming into contact with the plunger stop 70 when the plunger 30 is moved towards the distal end wall portion 13. Thereby, the plunger 30 is allowed to pass the plunger stop 70, thus allowing injection. However, when the plunger 30 is moved away from the distal end wall portion 13, the edge 38 will be deformed so as to expand towards the tubular wall 12 e.g. expand in a radial direction. Thus, the plunger 30 will be unable to pass said plunger stop 70 after passing it a first time. Consequently, the non-reusability function is achieved.

Preferably, the barrel has a length / and the plunger stop 30 is disposed at a distance d from the first barrel end wall portion, whereby 0,05 / < d < 0,2 /. Thereby, possible waste associated with a user attempting to draw in a liquid drug while being prevented to inject said drug can be reduced. Hence, a more cost-efficient syringe is achieved.

As presented in Fig. 1 the syringe 10 may further comprise a locking arrangement 50 which is adapted to be released when the plunger 30 is pulled in a direction away from the distal end wall portion 13 after retaining of the plunger 30 at the plunger stop 70. This is possible by the retaining force either between the edge of the plunger 38 and plunger stop 70 or the circumferential groove 34 and the plunger stop 70 being substantially larger than the force required to release i.e. unlock the locking arrangement 50 . Accordingly, any attempted re-usage of the syringe will result in the plunger shaft being separated from the plunger whereby further injections are made impossible.

Further referring to Fig. 1 the aforementioned functionality is provided by the plunger 30 comprising a first plunger member 31 and a second plunger member 32, the first plunger member 31 being releasably attached to the second plunger member 32 via the locking arrangement 50. The first plunger member 31 may be attached to the distal end of the plunger shaft 96, while the second plunger member 32 preferably comprises the aforementioned non-reusability features and further being adapted to be in fluid- tight engagement with the tubular wall.

Preferably, the second plunger member 32 is adapted to be stopped by the plunger stop 70, whereby the locking arrangement 50 is adapted to release the first plunger member 31 from the second plunger member 32 when the plunger shaft 96 is pulled in a direction away from the distal end wall portion 13 after retaining of said second plunger member 32 at the plunger stop 70.

An example of such a locking arrangement is further depicted in Fig. 1; said locking arrangement 50 comprising a locking element 51, whereby the plunger shaft 96 extends along the axis 100 into said locking element 51. Preferably, the second plunger member 32 is in a resilient material, whereby the material of the second plunger member allows for elastic deformation.

The locking element 51 is preferably adapted to be fitted into a recess 52 of the second plunger member 32. To retain the locking element 51, the recess 52 has a locking portion 53 adapted to receive the locking element, the locking portion further comprising a narrower wall section 54 which retains the locking element 41 in the locking portion 53. This is achieved by the locking element 51 comprising a first portion 31 and a second portion 32 which is wider in comparison to the first portion 31 in a direction perpendicular to the axis 100, thereby the resilient elastic second plunger member 32 can be elastically deformed so as to enable the insertion of said locking element 51 through the narrower wall section 54. Thus, the locking element 51 can revert back to its original shape inside the locking portion 53, whereby an upper surface of the second portion abuts against a lower surface of the narrower wall section retaining the locking element 51. Hence, the narrower wall section 54 may be a locking shoulder adapted to be in engagement with the locking element 51. The locking element 51 may thus be a locking arm adapted to be fitted into the locking portion 53 and being retained by said locking shoulder. Preferably, the locking element 51 may be in a rigid material, such as PE or PP. With the locking arrangement described above any re-usage may be prevented due to the locking element 51 being adapted to be released from the recess 52 when a user attempts to pull the plunger shaft 96 in the direction of the second barrel end wall portion 14. Notably, with the aforementioned embodiment of the locking arrangement 50 pushing of the plunger shaft 96 towards the distal end wall portion 13 will not cause any separation of the plunger members since it will simply cause pushing of the locking 51 element against the interior bottom of the recess 52.

The first 31 and second 32 plunger members may have circular cross-sections, whereby the second plunger member 32 may have a larger diameter than the first plunger member 31. Thus, the first plunger member 31 can freely pass the plunger member without interfering with retaining arrangement between the second plunger member 32 and the plunger stop 70.

Referring to Fig. 4 and 5 examples of a plunger stop are shown. The plunger stop 70 is adapted to angularly displace the plunger 30 inside the barrel 11 when the plunger 30 is moved in a direction away from the distal end wall portion 13 and abuts to at least a portion of the plunger stop 70. Thereby, it is ensured that the plunger 30 cannot be moved so as to allow further injections, since the orientation of the plunger 30 disallows further attempts.

The plunger 30 comprises a first and second plunger member according to aforementioned examples. Accordingly, the plunger stop 70 may be adapted to angularly displace the second plunger member 32 inside the barrel 11 when the plunger 30 is moved in a direction away from the distal end wall portion and abuts to at least a portion of the plunger stop 70, when the first 31 and second 32 plunger members are being separated at the locking arrangement 50.

Hence, re-usage by tampering after the plunger shaft has been separated from the second plunger member through for example usage of an elongated object to move the plunger to allow for further injections or attempts to re-connect the first and second plunger member are prohibited, whereby an even more safe syringe with a more efficient non-reusability function can be achieved in a cost-efficient manner.

Again referring to Fig. 4 and 5 this can be achieved by a plunger stop 70 with a shape allowing for the angular displacement. The plunger stop 70 may for example be a "ring-shaped" protrusion, extending circumferentially in a substantially inclined direction in relation to the plunger 30, i.e. a direction perpendicular to the plunger shaft 96, or in relation to the transversal plane of the barrel 11, as seen in Fig. 5. Hence, the plunger stop 70 may extend circumferentially in a substantially inclined direction in relation to a direction perpendicular to the tubular wall 12.

The plunger stop 70 may also solely extends along a portion of the tubular wall to achieve a similar effect, i.e. an angular displacement of the second plunger member 32.

As seen in Fig. 5 the plunger stop 70 is a "ring shaped" protrusion placed off- centered in the barrel 11. Hence, the plunger stop 70 is may have a tapered thickness so as to form an inclined, e.g. in relation to a circumferential direction perpendicular to the tubular wall 12, distal surface adapted to abut against the second plunger member 32.

Further, the invention has mainly been described with reference to a few embodiments. However, as is readily understood by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended claims.