Universal plunger rod and method for connecting and disconnecting plunger rod and plunger stopper

Abstract

The invention relates to a plunger rod (1) to be connected to a plunger stopper (100), comprising:-a rod (2),-a sleeve (9) having a movable portion (16) movable from a first radial position to a second radial position under the action of a centrifugal force exerted thereon, -said rod (2) being translationally slidable within said cannula (9) from a first axial position to a second axial position under the effect of a distal pressure exerted on its proximal end (3),-a releasable locking member (7, 14) configured for temporarily locking said rod (2) in its second axial position. The invention also relates to a method for connecting / disconnecting a plunger rod and a plunger stopper.

Description

Technical Field

[0001] The present invention relates to a plunger rod intended to be connected to a plunger stopper in order to expel or reconstitute a product (eg a drug) within a container of an injection device. Background Art

[0002] In this application, when a component or device is in the use position, the distal end of the component or device refers to the end farthest from the user's hand, and the proximal end refers to the end closest to the user's hand. Similarly, in this application, the terms "along the distal direction" and "distal" refer to the injection direction, and the terms "along the proximal direction" and "proximally" refer to the direction opposite to the injection direction.

[0003] Injection devices (e.g., syringes) are well known. Many different types of injection devices have been designed for administration. Injection devices generally include a container intended to receive a drug or product to be injected and a plunger rod intended to move a plunger stopper in the container. During injection, the plunger stopper can be moved in a distal direction to discharge the product. Alternatively, the plunger stopper can be moved in a proximal direction to extract a product from, for example, a separate vial and transfer the product to the container of the injection device. There are empty and pre-filled disposable injection devices on the market that are convenient, safe, and efficient and can be used directly in emergency situations.

[0004] Prefilled injection devices are filled with drugs (e.g., medicines packaged for use), which are then typically stored in a doctor's office, hospital, etc. until they are needed. In order to ensure that the product present in the container does not leak outward during storage, the distal end of the container is closed with a rubber cap, and the proximal end thereof is closed with a plunger stopper.

[0005] In some cases, the plunger rod is connected to the plunger stopper of the prefilled injection device. However, in this case, the prefilled injection device will occupy a large amount of storage space. The required storage space is an important feature of prefilled injection devices. This may be particularly important when the drugs contained in these devices must be stored and transported at low temperatures.

[0006] In hospitals and pharmacies, storage space for drugs is limited. Therefore, it is desirable that the prefilled injection device takes up as little volume as possible during transportation and / or storage.

[0007] In view of this, prefilled injection devices are increasingly not provided with any plunger rod, the proximal end of the injection device being sealed solely by a plunger stopper. In this case, a separate plunger rod is provided, and the plunger stopper is usually provided with a connecting member intended to cooperate with a complementary connecting member located on the plunger rod to connect the plunger stopper and the plunger rod together when the time for injection has arrived. Traditionally, these connecting members are mating threads or hooks: the proximal end of the plunger stopper is provided with a cavity with an internal thread, and the distal end of the plunger rod is provided with an external thread capable of cooperating with the internal thread of the cavity of the plunger stopper to screw the plunger rod into the plunger stopper.

[0008] In any case, as manufacturers of drugs and injection devices around the world develop, the design and size of the internal threads of the plunger stopper and the materials forming the plunger stopper may vary, and some plunger rods may be incompatible with the plunger stopper sealing the proximal end of the prefilled injection device. The incompatibility between the plunger rod and the plunger stopper may cause the plunger rod to bend and / or break during the screwing step of screwing the plunger rod into the plunger stopper, and / or may affect the integrity of the container closure and make it impossible to inject the product in a safe manner. In addition, with two incompatible plunger stoppers and plunger rods, extraction may not be possible and reconstitution may not be performed correctly.

[0009] Therefore, there is a need for a plunger rod that is compatible with any plunger stopper so that, regardless of the specific features, design and / or dimensions of the connecting components (e.g., internal threads or hook space) of the plunger stopper's cavity, and regardless of the material the plunger stopper is made of, the user can be confident that the connection between the plunger rod and the plunger stopper is effective and reliable.

[0010] In addition, plunger rods are often made of plastic. Plunger rods are usually single-use and discarded with the prefilled injection device after the injection is completed. Plastic plunger rods are part of the global plastic waste generated by the medical device industry.

[0011] Therefore, there is also a need for a plunger rod that can not only achieve a secure connection with any plunger stopper of an injection device, regardless of the design and / or material of such plunger stopper, but can also be removed from the plunger stopper and reused as many times as possible with plunger stoppers of other prefilled injection devices. Summary of the invention

[0012] A first aspect of the invention is a plunger rod intended to be connected to a proximal cavity of a plunger stopper of an injection device, the plunger rod comprising:

[0013] - a rod having a proximal end and a distal end,

[0014] a sleeve configured to receive at least the distal end of the rod, the distal portion of said sleeve being provided with at least one movable portion capable of moving from a first radial position to a second radial position under the effect of a force exerted on said movable portion,

[0015] - the rod is capable of sliding in translation within the sleeve from a first axial position to a second axial position, in which the distal end of the rod is not in contact with the movable part, the movable part is in its first radial position, and the distal part of the sleeve can freely enter and leave the proximal cavity of the plunger stopper, in which the distal end of the rod has exerted a force on the movable part to move the movable part to its second radial position, and the movable part is capable of forking the inner wall of the proximal cavity of the plunger stopper so that the plunger rod is connected to the plunger stopper, the rod being configured to translate from its first axial position to its second axial position under the action of a distal pressure exerted on its proximal end,

[0016] - a releasable locking member configured for temporarily locking the rod in its second axial position.

[0017] In an embodiment, the plunger rod may further comprise a biasing member configured for automatically moving the rod from its second axial position to its first axial position when the releasable locking member is released.

[0018] The plunger rod of the present invention can be connected to the proximal cavity of the plunger stopper, regardless of the design of the inner wall of the cavity. In particular, the inner wall of the proximal cavity can be provided with a thread of any size or design, and the movable part of the plunger rod of the present invention will fork the inner wall of the cavity when moving from its first radial position to its second radial position, and thus the plunger rod will be attached to the plunger stopper by interference fit or by hooking rather than by screwing. Therefore, the plunger rod of the present invention is not screwed into the plunger stopper, but is fixed to the plunger stopper by the movable part forking the inner wall of the cavity. In fact, the plunger stopper is usually made of an elastomeric material (e.g., rubber), and the movable part can easily fork the wall made of such material.

[0019] Thus, the plunger rod of the present invention allows to simplify the connection step between the plunger rod and the plunger plug. In particular, due to the plunger rod of the present invention, the end user no longer needs to screw the plunger rod into the plunger plug. As a result, the risk of bending and / or breaking of the plunger rod during the connection step with the plunger plug is significantly reduced. The plunger rod of the present invention also allows to save a processing step in the case of assembling the plunger rod with a high-speed machine at the customer's site.

[0020] In addition, due to the plunger rod of the present invention, a single plunger rod can be used for injection devices having plunger stoppers made of different materials and / or provided with connecting members (e.g., internal threads) of different designs. Therefore, the plunger rod of the present invention helps to simplify the packaging, transportation and storage process of prefilled injection devices and the use of such prefilled injection devices by end users in medical places such as hospitals.

[0021] Furthermore, the plunger rod of the present invention can be easily disconnected from the plunger stopper to which it has been attached as described above. Due to the biasing member of the plunger rod of the present invention, the movable part can be easily separated from the inner wall of the cavity to which it is fixed. The movable part is allowed to move back to its first radial position, in which the rod can be easily removed from the proximal cavity of the plunger stopper. Therefore, the end user does not need to perform a loosening step to disconnect the plunger rod from the plunger stopper. Due to the plunger rod of the present invention, the disconnection step becomes very simple.

[0022] Therefore, the plunger rod of the present invention further contributes to reducing global plastic waste generated by the medical sector and is therefore environmentally friendly. In fact, thanks to the plunger rod of the present invention, the same plunger rod can be reused for multiple prefilled injection devices, saving a lot of plunger rods and avoiding unnecessary plastic waste.

[0023] In an embodiment, the proximal end of the rod is provided with a button cap, and the proximal portion of the sleeve is provided with a radial flange, and wherein the biasing member comprises a helical spring abutting on a proximal surface of the radial flange and on a distal surface of the cap, the helical spring being capable of transitioning from a rest position in which the rod is in its first axial position to a stressed state in which the rod is in its second axial position. Such an embodiment allows the connection of the plunger rod to the plunger stopper to be implemented in a simple manner, since the end user only has to push distally on the cap of the plunger rod to achieve the connection.

[0024] In an embodiment, the rod is configured to rotate relative to the sleeve, the releasable locking member comprises at least one hook extending distally from the cap and at least one partially circumferential groove located on the radial flange, the hook and the partially circumferential groove being configured to:

[0025] - when distal pressure is applied on the cap so as to place the coil spring in its stressed state and further rotate the rod relative to the sleeve in the first direction, engage each other to lock the rod in its second axial position, and

[0026] - disengage from each other to release the rod from its second axial position and automatically move it to its first axial position when the rod is rotated relative to the sleeve in a direction opposite to the first direction and the distal pressure exerted on the cap is released.

[0027] Such an embodiment allows the plunger rod to be locked in its connection configuration with the plunger stopper in a simple manner. Thus, the end user can be sure that the connection between the plunger rod and the plunger stopper is effective and reliable and can be sure that the injection step can be carried out safely. Such an embodiment also allows the plunger rod to be unlocked from the plunger stopper in a very simple manner.

[0028] In an embodiment, the distal end of the rod is provided with an extension portion, the extension portion being configured to exert a radial force on the movable portion to move the movable portion from its second radial position to its first radial position when the rod moves back from its second axial position to its first axial position. Such an extension portion may be located distal to the movable portion and may be provided with an inclined surface capable of cooperating with a complementary inclined surface located on the movable portion to move the movable portion in a centripetal direction when the extension portion moves in a proximal direction as the rod moves back from its second axial position to its first axial position.

[0029] The distal portion of the cannula may be provided with more than one movable portion; for example, the distal portion of the cannula may be provided with two, three or four movable portions, which may be regularly distributed on the circumference of the cannula. In an embodiment, the distal portion of the cannula is provided with two diametrically opposed movable portions. Since the two movable portions are anchored in the inner wall of the proximal cavity of the plunger stopper, these embodiments allow a reliable and stable connection to be obtained between the plunger rod and the plunger stopper.

[0030] In an embodiment, the plunger rod may further comprise a sheath, the sheath being sized to surround the sleeve except for the movable portion, the outer diameter of the sheath being substantially equal to the outer diameter of the distal portion of the sleeve when the movable portion is in its first radial position. The sheath is preferably non-translatable relative to the sleeve. In such embodiments, the outer surface of the distal portion of the sleeve is flush with the outer surface of the sheath when the one or more movable portions are in their first radial position: in this way, the one or more movable portions do not protrude radially outward from the sheath, and the sleeve is therefore protected. Such embodiments are particularly convenient and user-friendly, as the end user does not need to be careful not to touch and / or damage the sleeve when handling the plunger rod.

[0031] In an embodiment in which the plunger rod comprises a sheath, the proximal end of the rod may be provided with a cap and the proximal portion of the sheath may be provided with a radial flange, the biasing member may comprise a coil spring supported on the proximal surface of the radial flange on the one hand and on the distal surface of the cap on the other hand, the coil spring being capable of transitioning from a rest state in which the rod is in its first axial position to a stressed state in which the rod is in its second axial position.

[0032] In such an embodiment, the rod may be configured to rotate relative to the sheath, and the releasable locking member may include at least one hook extending distally from the cap and at least one partially circumferential groove located on the radial flange, the hook and the partially circumferential groove being configured to:

[0033] - when distal pressure is applied on the cap so as to place the coil spring in its stressed state and further rotate the rod relative to the sheath in the first direction, engage each other to lock the rod in its second axial position, and

[0034] - disengage from each other to release the rod from its second axial position and automatically move it to its first axial position when the rod is rotated relative to the sheath in a direction opposite to the first direction and the distal pressure exerted on the cap is released.

[0035] In an embodiment, the distal portion of the sleeve comprises at least one radially outward flexible leg, the distal end of which forms the movable portion. Alternatively, the distal portion of the sleeve may comprise two diametrically opposed radially outward flexible legs, the distal end of each radially outward flexible leg forming the movable portion. Alternatively, the distal portion of the sleeve may comprise three radially outward flexible legs regularly distributed along the circumference, the distal end of each radially outward flexible leg forming the movable portion. In such an embodiment, when the flexible legs are in their resting state, the movable portion may, for example, be in its first radial position, and when the flexible legs move in a radially outward direction under the pressure applied by the distal end of the rod, the movable portion may be in its second radial position. When the distal end of the rod moves back to its first axial position, the flexible legs naturally return to their resting state, thereby causing the movable portion to automatically move from its second radial position to its first radial position. Therefore, such an embodiment is very easy to manufacture and can be easily implemented industrially.

[0036] In an embodiment, the movable part comprises an outer radial protrusion. Such an outer radial protrusion is preferably configured to be anchored in the inner wall of the proximal cavity under the effect of the centrifugal pressure exerted on the movable part by the distal end of the rod.

[0037] Another aspect of the present invention is a method for connecting a plunger rod as described above to a proximal cavity of a plunger stopper of an injection device, the method comprising the steps of:

[0038] - providing a plunger rod, wherein the plunger rod is in its first axial position,

[0039] - inserting the distal portion of the cannula into the proximal cavity of the plunger stopper,

[0040] - applying distal pressure to the proximal end of the rod to guide the rod to its second axial position,

[0041] - Activating the locking member to temporarily lock the plunger rod in its second axial position.

[0042] Another aspect of the present invention is a method for disconnecting a plunger rod as described above which has been connected to the proximal cavity of a plunger stopper according to the above connection method, the method comprising the steps of:

[0043] - deactivate the locking member,

[0044] - releasing any distal pressure exerted on the proximal end of the rod so that the rod is in its first axial position,

[0045] -Remove the distal portion of the cannula from the proximal cavity of the plunger stopper. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention and its advantages will be clearly seen from the following detailed description given in conjunction with the accompanying drawings:

[0047] - Figure 1 is a perspective view of a first embodiment of the plunger rod of the present invention inserted into the plunger stopper of an injection device before connection,

[0048] - Figure 2 yes Figure 1 A cross-sectional view of the plunger plug and plunger rod,

[0049] - Figure 3 yes Figure 2 Detail of the plunger stopper and the distal portion of the plunger rod cannula,

[0050] - Figure 4 yes Figure 2 Detail of the proximal region of the plunger rod,

[0051] - Figure 5 yes Figure 2 A detailed perspective view of the distal portion of the cannula of the plunger rod,

[0052] - Figure 6 It is the part after the plunger rod is connected to the plunger plug. Figure 1 A perspective view of the plunger stopper and plunger rod,

[0053] - Figure 7 yes Figure 6 A cross-sectional view of the plunger plug and plunger rod,

[0054] - Figure 8 yes Figure 6 Detail of the plunger stopper and the distal portion of the plunger rod cannula,

[0055] - Fig. 9 yes Figure 6 Detail of the proximal region of the plunger rod,

[0056] - Fig.10 It is shown Figure 6 Detailed view of the locking member of the plunger rod,

[0057] - Fig.11 is a cross-sectional view of a second embodiment of the plunger rod of the present invention inserted into the plunger stopper before connection,

[0058] - Fig.12 yes Fig.11 Detail of the plunger stopper and the distal portion of the plunger rod cannula,

[0059] - Fig.13 yes Fig.12 A perspective view of the plunger stopper and the distal portion of the cannula of the plunger rod,

[0060] - Fig.14 After connecting to the plunger plug Fig.11 A cross-sectional view of the plunger rod,

[0061] - Fig.15 yes Fig.14 Detail of the plunger stopper and the distal portion of the plunger rod cannula,

[0062] - Fig.16 yes Fig.15 A perspective view of the plunger stopper and the distal portion of the cannula of the plunger rod,

[0063] - Fig.17 is a cross-sectional view of a third embodiment of the plunger rod of the present invention inserted into the plunger stopper before connection,

[0064] - Fig.18 yes Fig.17 Detail of the proximal region of the plunger rod,

[0065] - Fig.19 yes Fig.17 A perspective view of the distal portion of the cannula and the distal region of the sheath of the plunger rod,

[0066] - Fig. 20 yes Fig.17 Detail of the distal portion of the cannula and the distal region of the sheath of the plunger rod,

[0067] - Fig.21 It is connected to the plunger plug. Fig.17 A cross-sectional view of the plunger rod,

[0068] - Fig. 22 yes Fig.17 Detail of the proximal region of the plunger rod,

[0069] - Fig.23 It shows Fig.17 Detail of the locking member of the plunger rod,

[0070] - Fig.24 yes Fig.21 Detail of the distal portion of the cannula and the distal region of the sheath of the plunger rod,

[0071] - Fig.25 yes Fig.21 A perspective view of the distal portion of the cannula and the distal region of the sheath of the plunger rod. DETAILED DESCRIPTION

[0072] refer to Figure 1 , shows a plunger rod 1 of the present invention intended to be connected to a plunger stopper 100. The plunger stopper 100 is intended to be inserted into Figure 1 The plunger stopper 100 is generally made of an elastomeric material such as rubber and is used to seal the proximal end of the container 111.

[0073] When the container 111 of the injection device contains a product to be injected, the plunger stopper 100 can be pushed distally to expel the product from the injection device 110 through the needle 112. When the container 111 is empty, such as Figure 1 As shown, plunger stopper 100 may be moved in a proximal direction to cause needle 112 to draw a product stored in a separate vial into container 111 .

[0074] The plunger rod 1 is intended to be connected to the plunger stopper 100 in a secure manner to allow the end user to confidently move the plunger stopper 100 in the distal direction and / or the proximal direction depending on the intended use.

[0075] refer to Figure 3 and Figure 8 , the plunger stopper 100 is provided with a proximal open cavity 101. Although not shown in the figure, the inner wall 102 of the proximal cavity can be provided with an internal thread, which is usually the case with commercially available plunger stoppers. In the example shown, the inner wall 102 of the proximal cavity 101 is provided with a proximal inner rib 103 forming an abutment surface 104.

[0076] refer to Figure 1-10 , the plunger rod 1 has a longitudinal axis A and comprises a rod 2 aligned on said axis. The rod 2 has a proximal end 2a and a distal end 2b. In the example shown, the proximal end 2a of the rod is provided with a cap 3 formed by a transverse wall 4, from which a tubular wall 5 extends in the distal direction. As described in the following description, the proximal side of the transverse wall 4 can form a push surface 4a so that the end user can move the plunger rod 2 in the distal direction.

[0077] The tubular wall 5 is provided with an inner edge 6 at its distal end 5b, which forms a proximal abutment surface 6a. The distal end 5b of the tubular wall 5 is also provided with two (see Figure 1 ) A diametrically opposed distal hook 7, the function of which will be explained later.

[0078] In the example shown, the distal end 2b of the rod 2 is provided with an end portion 8 showing an outer diameter dimension that is larger than the outer diameter dimension of the rest of the rod 2. In an embodiment not shown, the distal end 2b of the rod 2 can have the same outer dimensions as the rest of the rod, as long as the outer dimensions of the distal end 2b of the rod 2 allow the outer protrusions 16 of the flexible legs 15 of the sleeve 9 (see Figure 7 ) can be moved in the centrifugal direction.

[0079] The plunger rod 2 further comprises a sleeve 9 having a proximal portion 9a and a distal portion 9b. The sleeve 9 is shaped and dimensioned to receive the distal region of the rod 2 and at least the distal end 2b of said rod 2. The proximal portion 9a of the sleeve 9 is provided with a radial flange 10 from which a tubular wall 11 extends in the proximal direction. The proximal end of the tubular wall 11 is provided with an outer rim 12 forming a distal abutment surface 12a.

[0080] The radial flange 10 is provided with two ( Fig.10 Diametrically opposed through holes 13 (only one visible) are sized to allow the distal hook 7 to pass therethrough and are provided with two adjacent part-circumferential grooves 14 forming a distal abutment surface 14a.

[0081] In the example shown, the distal portion 9b of the sleeve 9 is provided with three flexible legs 15, which can be deflected in a radially outward direction under the action of a centrifugal force applied thereto. The flexible legs 15 are regularly distributed along the circumference of the sleeve 9. In an embodiment not shown, the number of flexible legs 15 can be less than three, such as one or two, or alternatively more than two, such as four. The distal end of each flexible leg 15 is provided with an outer protrusion 16. Therefore, each outer protrusion 16 forms a movable part, which can move from a first radial position to a second radial position when a centrifugal force is applied to the flexible leg 15.

[0082] The plunger rod 2 is also provided with a helical spring 17 which is stored between the radial flange 10 and the transverse wall 4 of the cap 3 : the proximal end of the helical spring 17 bears on the distal side of the transverse wall 4 and the distal end of the helical spring 17 bears on the proximal side of the radial flange 10 .

[0083] As will be seen from the following description, the rod 2 is received in translation in the sleeve 9 and can be moved from a first axial position (eg, Figure 1-5) to a second axial position (as shown) spaced distally from the first axial position. Figure 6-10 shown).

[0084] Now refer to Figure 1-10 The connection between the plunger rod 1 and the plunger stopper 100 is described.

[0085] refer to Figure 1-5 , the plunger rod 1 is not connected to the plunger stopper 100, and the rod 2 is in its first axial position. In such a position, the coil spring 17 is in a resting state, the distal end of the tubular wall 5 of the cap 3 is not in contact with the proximal side of the radial flange 10, and the coil spring 17 connects the rod 2 to the sleeve 9 via the distal abutment surface 12a of the outer edge 12 of the tubular wall 11 of the radial flange 10, which rests on the proximal abutment surface 6a of the inner edge 6 of the tubular wall 5 of the cap 3 (see Figure 4 ). In this position, the distal end 2b of the rod 2 is not in contact with the distal ends of the flexible legs 15, and these flexible legs 15 are in a resting state. As a result, the outer protrusion 16 is in its first radial position. Therefore, the outer dimensions of the distal portion 9b of the sleeve 9 are smaller than the inner dimensions of the inner wall 102 of the proximal open cavity 101 of the plunger stopper 100. Therefore, the distal portion 9b of the sleeve 9 is easily inserted into the proximal open cavity 101 of the plunger stopper 100, as shown in FIG. Figure 2 and Figure 3 shown.

[0086] Once the distal portion 9b of the sleeve 9 is inserted into the proximal open cavity 101 of the plunger stopper 100, an end user who wishes to connect the plunger rod 1 to the plunger stopper 100 only needs to apply distal pressure to the push surface 4a of the transverse wall 4 of the cap 3 of the plunger rod 2. Under this distal pressure, the distal end of the tubular wall 5 of the cap 3 comes into contact with the proximal side of the radial flange 10, and the helical spring 17 transitions to its stressed state. The distal movement of the rod 2 has moved the rod 2 from its first axial position to its second axial position, as shown in FIG. Figure 6-10 As shown. The end portion 8 of the distal end 2b of the rod 2 has contacted the distal ends of the flexible legs 15 and has exerted a centrifugal force on the distal ends of these flexible legs 15, causing these flexible legs 15 to deflect radially outward. This causes the outer protrusion 16 to move from its first radial position to its second radial position, as shown in FIG. Figure 8As shown. In this second radial position, each outer protrusion 16 forks over the inner wall 102 of the proximal open cavity 101 of the plunger stopper 100, thereby achieving a safe connection between the plunger rod 2 and the plunger stopper 100. Thanks to the centrifugal pressure exerted by the end portion 8 on the outer protrusions 16, the outer protrusions 16 are anchored in the inner wall 102 of the proximal open cavity 101, regardless of the design of this inner wall 102, and in particular regardless of any internal threads that may be present on said inner wall 102. The efficiency of the connection can be enhanced by the presence of the abutment surface 104 of the inner edge 103 of the plunger stopper 100, which prevents the outer protrusions 16 from moving in the proximal direction.

[0087] When the distal end of the tubular wall 5 of the cap 3 is in contact with the proximal side of the radial flange 10, each distal hook 7 passes through the corresponding through hole 13. As a result, in order to lock the rod 2 in its second axial position, the end user only needs to rotate the cap 3 relative to the sleeve 9 in the first direction so that the distal hook 7 is in contact with the abutment surface 14a of the partial circumferential groove 14, as shown in FIG. Fig.10 As shown. The helical spring 17 in its stressed state and the distal hook 7 engaged in the abutment surface 14a of the partial circumferential groove 14 form a releasable locking member of the rod 2 in its second axial position. The end user can be sure that the connection between the plunger rod 1 and the plunger stopper 100 is effective and reliable, and he can safely manipulate the plunger rod 1 to move the plunger stopper 100 within the container 111 of the injection device 110.

[0088] When the end user wishes to disconnect the plunger rod 1 from the plunger stopper 100, he simply rotates the cap 3 relative to the sleeve 9 in a direction opposite to the first direction previously used, so that the distal hook 7 disengages from the portion of the circumferential groove 14. The end user then releases the distal pressure exerted on the pushing surface 4a of the cap 3, and the rod 2 automatically returns to its first axial position under the action of the helical spring 17 naturally transitioning to its rest state, as shown in FIG. Figure 2 During this operation, the end portion 8 of the distal end 2b of the rod 2 has left the distal end of the flexible leg 15, which has returned to its resting state. As a result, the outer protrusion 16 moves from its second radial position to its first radial position, as shown in FIG. Figure 3 As shown, the plunger rod 1 can be easily disconnected from the plunger stopper 100 by simply removing the distal portion 9 b of the sleeve 9 from the proximal open cavity 101 of the plunger stopper 100 .

[0089] Figure 11-16 A second embodiment of the plunger rod 1 of the present invention is concerned, wherein the flexible legs and the outer protrusions are replaced by a non-flexible movable portion; Figure 1-10 The same elements of the plunger rod 1 are denoted by the same reference numerals.

[0090] With reference to these figures, the distal end of the rod 2 is provided with an extension 18 having a hollow conical surface 18a extending in the proximal direction. The distal region of the rod 2 also includes an outer conical portion 19, which tapers in the distal direction and is located proximal to the extension 18. The sleeve 9 receives in its distal portion 9b two diametrically opposed mobile portions 20, each of which includes a proximal inclined surface 20a and a distal inclined surface 20b. The wall of the sleeve 9 is provided with two diametrically opposed windows 21, each of which faces the mobile portion 20. Both the mobile portion 20 and the window 21 of the sleeve 9 are axially located between the extension 18 and the outer conical portion 19 of the rod 2.

[0091] Rod 2 in Figure 11-13 is shown in its first axial position, Figure 14-16 In its second axial position.

[0092] refer to Figure 11-13 , the outer conical portion 19 of the rod 2 is not in contact with the mobile portion 20, which is completely located inside the wall of the sleeve 9. The outer dimensions of the distal portion 9b of the sleeve 9 are smaller than the inner dimensions of the proximal open cavity 101 of the plunger stopper 100.

[0093] When the end user wishes to connect the plunger rod 1 to the plunger stopper 100, he will apply pressure to the transverse wall 4 of the cap 3 of the plunger rod 1 as described above. When the rod 2 is moved to its second axial position, as Figure 14-16 As shown, the outer conical portion 19 contacts the proximal inclined surface 20a of the moving portion 20 and exerts centrifugal force on these surfaces, thereby causing the moving portion 20 to move in the centrifugal direction. Fig.12 and 13 ) moves to its second radial position (as shown Fig.15 and 16 As shown). Therefore, the moving parts 20 extend from the window 21 of the wall of the sleeve 9, and they fork the inner wall 102 of the proximal open cavity 101 of the plunger stopper, thereby achieving the connection between the plunger rod 1 and the plunger stopper 100.

[0094] In this position, the end user can lock the rod 2 in its second axial position in the same manner as described above with reference to Figure 1-10 Same as described.

[0095] When the end user wishes to disconnect the plunger rod 1 from the plunger stopper 100, the end user releases the coil spring 17, as described above with reference to Figure 1-10 described.

[0096] When the rod 2 moves proximally from its second axial position to its first axial position, the extension portion 18 also moves proximally and its hollow conical surface 18a comes into contact with the distal inclined surface 20b of the moving portion 20 (see Fig.15 ). The hollow conical surface 18a slides onto the distal inclined surface 20b of the moving part 20, thereby exerting a centripetal force on these surfaces and causing the moving part 20 to move backward in the direction of its first radial position. As a result, Fig.13 As shown, the moving portion 20 is retracted inside the sleeve 9. Therefore, the end user can easily disconnect the plunger rod 1 from the plunger stopper 100 by removing the distal portion 9b of the sleeve 9 from the proximal open cavity 101 of the plunger stopper 100.

[0097] Figure 17-25 A third embodiment of the plunger rod 1 of the present invention is similar to Figure 1-10 The embodiment of the present invention further comprises an outer sheath surrounding the sleeve. Figure 1-10 The same elements of the plunger rod 1 are denoted by the same reference numerals.

[0098] Referring to these figures, the plunger rod 1 includes Figure 1-10 The same rod 2 comprises a cap 3 and an end portion 8. The plunger rod 1 further comprises a sleeve 9, the distal portion 9b of which is provided with two diametrically opposed flexible legs 15. The distal end of each flexible leg 15 is provided with an external protrusion 16. Figure 1-10 In contrast to the embodiment of , the proximal end of the sleeve 9 is devoid of any radial flange and comprises an outer rim 9c.

[0099] Figure 17-25 The plunger rod 1 also comprises an outer sheath 22 surrounding the sleeve 9, except for the outer protrusion 16. The proximal end of the outer sheath 22 is provided with a radial flange 23, to which the outer edge 9c of the sleeve 9 is fixed. The sleeve 9 and the outer sheath 22 are fixed to each other. Fig.19 When the outer protrusion 16 is in its first radial position, the outer diameter of the outer sheath 22 is substantially equal to the outer diameter of the distal portion 9b of the cannula 9.

[0100] The radial flange 23 is similar to Figure 1-10 The radial flange 10 of the embodiment of the present invention is different in that it is arranged at the proximal end of the outer sheath 22 instead of the proximal end of the sleeve 9. Therefore, the radial flange 23 is provided with two ( Fig.23The radial flange 23 is provided with a diametrically opposed through hole 24 (only one of which is visible on the figure) which is dimensioned to allow the distal hook 7 to pass therethrough, and with two adjacent partly circumferential grooves 25 which form a distal abutment surface 25a. The radial flange 23 is also provided with a tubular wall 26 extending in the proximal direction. The proximal end of the tubular wall 26 is provided with an outer rim 27 which is intended to cooperate with the inner rim 6 of the cap 3 in order to keep the helical spring 17 in its rest state (see Fig.18 ).

[0101] Figure 17-25 The connection method of the plunger rod 1 is the same as that for Figure 1-10 The same as described in the embodiment. Figure 17-25 The advantage of the plunger rod 1 is that the sleeve 9 is protected by the outer sheath 22 during the connection and disconnection operations. In particular, Fig.19 As shown, the outer surface of the outer protrusion 16 is flush with the outer surface of the outer sheath 22. This is very convenient for the end user, because they do not need to be careful not to touch the sheath and the outer protrusion when handling the plunger rod 1.

[0102] refer to Figure 17-20 , the plunger rod 1 is not connected to the plunger stopper 100, and the rod 2 is in its first axial position. In such a position, the coil spring 17 is in a rest state, the distal end of the tubular wall 5 of the cap 3 is not in contact with the proximal side of the radial flange 23, and the coil spring 17 connects the rod 2 to the outer sheath 22 via the outer edge 27 of the tubular wall 26 of the radial flange 23, which rests on the inner edge 6 of the tubular wall 5 of the cap 3 (see Fig.18 ). In this position, the distal end 2b of the rod 2 is not in contact with the distal ends of the flexible legs 15, and these flexible legs 15 are in a resting state. Therefore, the outer protrusion 16 is in its first radial position, as shown in FIG. Fig.19 As shown. The outer dimensions of the distal portion 9b of the sleeve 9 and the distal portion of the outer sheath 22 are both smaller than the inner dimensions of the inner wall 102 of the proximal open cavity 101 of the plunger stopper 100. Therefore, the distal portion 9b of the sleeve 9 is easily inserted into the proximal open cavity 101 of the plunger stopper 100, as shown in FIG. Fig.17 As can be seen in .

[0103] As previously described, when the end user applies distal pressure on the cap 3, the coil spring 17 switches to its stressed state, and the end portion 8 of the distal end 2b of the rod 2 contacts the distal ends of the flexible legs 15 and applies a centrifugal force to the distal ends of these flexible legs 15, thereby causing these flexible legs 15 to deflect radially outward. The outer protrusions 16 move from their first radial position to their second radial position, in which they protrude from the outer sheath 22, as shown in FIG. Fig.25Due to the centrifugal pressure exerted by the end portion 8 on the outer protrusion 16, the outer protrusion 16 is anchored into the inner wall 102 of the proximal open cavity 101, as shown in FIG. Fig.24 As shown, regardless of the design of the inner wall 102, and in particular, regardless of any internal threads that may be present on the inner wall 102. The presence of the abutment surface 104 of the inner edge 103 of the plunger stopper 100 can enhance the efficiency of the connection, and the abutment surface 104 prevents the outer protrusion 16 from moving in the proximal direction.

[0104] The rod 2 is in the second axial position (eg Figure 21-25 The locking of Figure 1-10 To this end, the end user only needs to rotate the cap 3 relative to the outer sheath 22 in the first direction so that the distal hook 7 contacts the abutment surface 25a of the partial circumferential groove 25, such as Fig.25 The end user can be confident that the connection between the plunger rod 1 and the plunger stopper 100 is effective and reliable, and that he can safely manipulate the plunger rod 1 to move the plunger stopper 100 within the container 111 of the injection device 110 .

[0105] To disconnect the plunger rod 1 from the plunger stopper 100, the end user simply rotates the cap 3 relative to the outer sheath 22 in a direction opposite to the first direction previously used, so that the distal hook 7 disengages from the portion of the circumferential groove 25. The end user then releases the distal pressure exerted on the pushing surface 4a of the cap 3 and the helical spring 17 naturally transitions to its rest state, as shown in FIG. Fig.17 As shown, the rod 2 automatically returns to its first axial position. In this step, the flexible legs 15 have returned to their resting state, and the outer protrusions 16 have returned to their first radial position, as shown in FIG. Fig.19 Therefore, the end user can easily disconnect the plunger rod 1 from the plunger stopper 100 by removing the distal portion of the outer sheath 22 from the proximal cavity 101 of the plunger stopper 100 .

[0106] Therefore, the plunger rod of the present invention allows to simplify the connection step of the plunger rod to the plunger stopper, because the screwing step is no longer required. In addition, the plunger rod of the present invention can be safely connected to any plunger stopper, regardless of the material of the plunger stopper and the inner wall design of the cavity of the plunger stopper. A single plunger rod can be used for multiple plunger stoppers and / or injection devices, thereby contributing to reducing plastic waste generated in the field of medical devices.

Claims

1. A plunger rod (1) intended to be connected to a proximal cavity (101) of a plunger stopper (100) of an injection device (110), the plunger rod (1) comprising: - a rod (2) having a proximal end (2a) and a distal end (2b), a sleeve (9) configured to receive at least the distal end (2b) of the rod (2), the distal portion (9b) of the sleeve (9) being provided with at least one movable portion (15, 16) capable of moving from a first radial position to a second radial position under the action of a force exerted on the movable portion (15, 16), - the rod (2) is capable of translating and sliding inside the sleeve (9) from a first axial position in which the distal end (2b, 8; 19) of the rod (2) is not in contact with the movable part (15, 16; 20), the movable part (15, 16; 20) is in its first radial position, and the distal part (9b) of the sleeve is able to freely enter and exit the proximal cavity (101) of the plunger stopper (100), to a second axial position in which the distal end (2b, 8; 19) of the rod (2) is not in contact with the movable part (15, 16; 20), the movable part (15, 16; 20) is in its first radial position, and the distal part (9b) of the sleeve is able to freely enter and exit the proximal cavity (101) of the plunger stopper (100), The lateral end (2b, 8; 19) exerts a force on the movable part (15, 16; 20) to move the movable part in its second radial position, and the movable part (15, 16; 20) is capable of forking the inner wall (102) of the proximal cavity (101) of the plunger stopper (100) to connect the plunger rod (1) to the plunger stopper (100), the rod (2) being configured to translate from its first axial position to its second axial position under the action of distal pressure exerted on its proximal end (2a, 3, 4, 4a), - a releasable locking member (7, 14, 14a; 25, 25a) configured to temporarily lock the rod (2) in its second axial position.

2. The plunger rod (1) according to claim 1, further comprising a biasing member (17) configured to automatically move the rod (2) from its second axial position to its first axial position when the releasable locking member (7, 14, 14a; 25, 25a) is released.

3. The plunger rod (1) according to claim 1 or 2, wherein: The proximal end (2a) of the rod is provided with a button cap (3), and the proximal portion (9a) of the sleeve (9) is provided with a radial flange (10), and wherein the biasing member comprises a helical spring (17) abutting against both the proximal surface of the radial flange (10) and the distal surface of the button cap (3), the helical spring (17) being capable of transitioning from a rest position in which the rod (2) is in its first axial position to a stressed state in which the rod (2) is in its second axial position.

4. The plunger rod (1) according to claim 3, wherein: The rod (2) is configured to rotate relative to the sleeve (9), and the releasable locking member includes at least one hook (7) extending distally from the button cap (3) and at least one partially circumferential groove (14) located on the radial flange (10), wherein the hook (7) and the partially circumferential groove (14) are configured to: - when distal pressure is applied on the button cap (3) to place the coil spring (17) in its stressed state and further rotate the rod (2) relative to the sleeve (9) in the first direction, engage with each other to lock the rod (2) in its second axial position, and - when the rod (2) is rotated relative to the sleeve (9) in a direction opposite to the first direction and the distal pressure applied to the button cap (3) is released, they disengage from each other to release the rod (2) from its second axial position and automatically move the rod to its first axial position.

5. The plunger rod (1) according to any one of claims 1 to 4, wherein: The distal portion (9b) of the cannula (9) is provided with two diametrically opposed movable portions (20).

6. The plunger rod (1) according to any one of claims 1 to 5, wherein: The distal end (2b) of the rod (2) is provided with an extension portion (18) configured to exert a radial force on the movable portion (20) so as to move the movable portion (20) from its second radial position to its first radial position when the rod (2) moves back from its second axial position to its first axial position.

7. The plunger rod (1) according to claim 1 or 2, further comprising a sheath (22) sized to surround the sleeve (9) except for the movable portion (16), and when the movable portion (16) is in its first radial position, the sheath (22) has an outer diameter substantially equal to the outer diameter of the distal portion (9b) of the sleeve (9).

8. Plunger rod (1) according to the preceding claim, wherein The proximal end (2a) of the rod (2) is provided with a cap (3), and the proximal portion of the sheath (22) is provided with a radial flange (23), the biasing member comprising a coil spring (17) supported on the proximal surface of the radial flange (23) on the one hand and on the distal surface of the cap (3) on the other hand, the coil spring (17) being capable of transitioning from a rest state in which the rod (2) is in its first axial position to a stressed state in which the rod (2) is in its second axial position.

9. The plunger rod (1) according to the preceding claim, wherein The rod (2) is configured to rotate relative to the sheath (22), the releasable locking member comprising at least one hook (7) extending distally from the cap (3) and at least one partially circumferential groove (25) located on the radial flange (23), the hook (7) and the partially circumferential groove (25) being configured to: - when distal pressure is applied to the cap (3) to place the coil spring (17) in its stressed state and further rotate the rod (2) relative to the sheath (22) in the first direction, engage with each other to lock the rod (2) in its second axial position, and - when the rod (2) is rotated relative to the sheath (22) in a direction opposite to the first direction and the distal pressure applied to the cap (3) is released, they disengage from each other to release the rod (2) from its second axial position and automatically move the rod to its first axial position.

10. The plunger rod (1) according to any one of claims 1 to 4 and 7 to 9, wherein: The distal portion (9b) of the sleeve (9) comprises at least one radially outwardly flexible leg (15), the distal end (16) of which forms the movable portion.

11. The plunger rod (1) according to claim 10, wherein: The distal portion of the sleeve (9) comprises two diametrically opposed radially outward flexible legs (15), the distal end (16) of each radially outward flexible leg (15) forming a movable portion.

12. The plunger rod (1) according to claim 10, wherein: The distal portion (9b) of the sleeve (9) comprises three radially outward flexible legs (15) regularly distributed in the circumferential direction, and the distal end (16) of each radially outward flexible leg (15) forms a movable part.

13. The plunger rod (1) according to any one of claims 1 to 12, wherein: The movable portion comprises an outer radial protrusion (16).

14. A method for connecting a plunger rod (1) according to any one of claims 1 to 13 to a proximal cavity (101) of a plunger stopper (100) of an injection device, the method comprising the following steps: - providing said plunger rod (1), wherein said rod (2) is in its first axial position, - inserting the distal portion (9b) of the cannula (9) into the proximal cavity (101) of the plunger stopper (100), - applying distal pressure to the proximal end (2a, 3, 4, 4a) of the rod (2) in order to guide the rod (2) into its second axial position, - Activating the locking member (7, 14, 14a; 25, 25a) to temporarily lock the rod (2) in its second axial position.

15. A method for disconnecting a plunger rod (1) according to any one of claims 1 to 13 which has been connected to a proximal cavity (101) of a plunger stopper (100) according to the method of claim 13, comprising the following steps: - deactivating the locking member (7, 14, 14a; 25，25a)， - releasing any distal pressure exerted on the proximal end (2a, 3, 4, 4a) of the rod (2) so that the rod (2) is in its first axial position, - Removing the distal portion (9b) of the cannula (9) from the proximal cavity (101) of the plunger stopper (100).

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