Injection device with withdrawal mechanism and related method

Abstract

To provide an easy-to-handle injection device whose operation is further comfortable for patients.SOLUTION: The present invention relates to an injection device (10), the injection device comprising: a needle support (24); an injection needle (22) integrated with the needle support and having a free end (28) spaced apart from the needle support; and a needle extraction mechanism (50) including a base (52) connected to a needle support and a plunger (54) movable relative to the base between a needle use position and a needle extraction position. The base (52) is movable relative to the needle support between an inactive position of the extraction mechanism and an active position of the extraction mechanism. The plunger (54) includes an outer member and an inner member movable relative to the outer member from a storage plunger configuration to a deployed plunger configuration in which the length of the plunger is greater than in the retracted configuration.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to an injection device, which comprises - a needle support, - an injection needle integrated with the needle support and having a free end disposed away from the needle support, - a mechanism for withdrawing the injection needle, comprising a base connected to the needle support and a plunger movable relative to the base between a use position of the needle and a withdrawal position of the needle, wherein the base is movable relative to the needle support between an inactive withdrawal mechanism position and an active withdrawal mechanism position, and comprises

[0002] The present invention also relates to a preparation process for such a device and an injection method. <,

Background Art

[0003] Such devices are used to treat some lesions that require regular and direct injection of a liquid drug dose into a patient's organ.

[0004] To do so, it is known to permanently implant a chamber subcutaneously in the patient's chest. This chamber extends through a support into the organ to which the drug dose is to be delivered. The implantable chamber has a reservoir in contact with the skin and provided with a pierceable cover along its surface. <0,000020>

[0005] To inject the drug dose, the needle of the device is inserted through the patient's skin into the implantable chamber, and the drug dose is injected into the chamber through the needle.

[0006] To remove the needle from the implantable chamber, the operator grasps the device holder and pulls the needle out of the chamber.

[0007] However, because the membrane of the implantable chamber is relatively strong, a considerable tensile force must be applied to the needle in order to remove it.

[0008] To prevent the patient from experiencing force applied to the skin by the implantable chamber during needle removal, it is known to use an injection device equipped with an in-situ withdrawal mechanism, as described in Patent Document 1.

[0009] Such a device features a mechanical withdrawal mechanism mounted on the needle support of the injection device, which includes a plunger that allows the operator to simply withdraw the needle in a continuous and safe manner. For this purpose, the needle, held by the holder, is gradually retracted into the plunger during withdrawal.

[0010] The extraction mechanism is hinged to the needle support so that it can extend along the patient's body when not in use, in order to reduce the size of the extraction device. To reduce the movement of the extraction mechanism, it is held in the extended position by a flexible coupling mechanism.

[0011] This device can be further improved. The extraction device has a substantial base area that should be reduced, even in its extended position. Bulky devices are more likely to cause handling errors, such as causing pain to the patient due to the needle being implanted in the patient's skin, or accidental impacts to the device.

[0012] In addition, disengaging the flexible coupling mechanism to withdraw the needle may cause an unpleasant wobble when the needle is inserted into the patient's body. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] French Patent No. 2869806 Specification [Overview of the project] [Problems that the invention aims to solve]

[0014] The objective of the present invention is therefore to provide an injection device that is easy to handle and more comfortable for the patient to operate. [Means for solving the problem]

[0015] To this end, an object of the present invention is to provide the aforementioned type of injection device, characterized in that the plunger comprises an outer portion and an inner portion that is movable relative to the outer portion from a retracted plunger configuration to an deployed plunger configuration in which the length of the plunger is greater than that in the retracted configuration.

[0016] According to a particular embodiment, the device according to the present invention comprises one or more of the following features, which can be used alone or in any technically feasible combination: - The inner member is slidably mounted within the inner passage of the outer member. - The plunger has a flexible coupling mechanism adapted to lock the inner member against the outer member when the plunger is extended. - The flexible coupling mechanism comprises at least one snap-in tab held by either an inner or outer member, and at least one recess defined by the other of the inner or outer member, wherein the snap-in tab has teeth that are received in the recess when the plunger is extended. - One or more recesses are located near the first end of the inner member or the other of the outer member to receive one of the teeth when the plunger is extended, and the snap-in mechanism further comprises at least a second recess located near the second end of the inner member or the other of the outer member to receive a tooth when the plunger is retracted. - The flexible coupling mechanism comprises at least one inclined portion extending over the inner member or the other of the outer member, the inclined portion defining a range of recesses at its upper end, and a snap-in tab compressing the inclined portion when the plunger moves from a retracted configuration to an deployed configuration. - A flexible coupling mechanism is suitable for temporarily holding the inner member relative to the outer member when the plunger is in a retracted configuration. - In the deployment configuration, the plunger defines the internal space for receiving the needle. - The device includes an assembly for temporarily fixing the base in an inactive position, the assembly being active when the plunger is in a retracted configuration and deactivating when the plunger moves from the retracted configuration to the deployed configuration. - The temporary fixing assembly comprises a first slot extending on an inner member and a second slot extending on an outer member, the first and second slots being wider than the first slot, the first and second slots being oriented toward a needle support, and the temporary fixing assembly further comprises a bar adapted to engage with the first and second slots, the bar having a length greater than the width of the first slot and less than the width of the second slot. - The inner and outer members are advantageous to have substantially rectangular cross-sections and rounded corners. - The base is mounted so as to be pivotable on the needle support around a pivot axis between the position in which the needle is in use and the position in which the needle is withdrawn. - The pivot axis is perpendicular to the longitudinal axis of the plunger, and in particular to the sliding axis of the inner member relative to the outer member. - Either the needle support or the base is provided with a pin for guiding the pivot of the base relative to the needle support, and the other of the needle support or the base defines a connection hole for receiving the pin. - In the needle withdrawal position, the main section of the needle extends completely inside the internal receiving space defined by the plunger. - The needle has its main section on the side of its free end. - The main section defines the free end of the needle. - The needle is extended on the side of the free end by a main section extending along the longitudinal axis of the plunger and forms an elbow extended on the opposite side of the free end by a connection section extending along the longitudinal axis of the plunger.

[0017] The present invention also has as its object a method carried out before removing the needle in order to prepare for removing the needle that has been previously introduced into the patient's body, the method comprising: - providing the device described above, with the extraction mechanism in its inactive position and the plunger in its retracted position; - moving the inner member relative to the outer member to move the plunger from its retracted configuration to its deployed configuration and increase the length of the plunger; - moving the base from the inactive position of the extraction mechanism to the active position; and including.

[0018] It is a further object of the present invention to provide an injection method, the method comprising: - providing the device described above; - introducing the needle into the patient's body, the tip of which pierces the cover of the implantable chamber; - injecting a drug solution through the needle into the implantable chamber; - preparing for removing the needle by the method described above; - removing the needle by moving the plunger from the needle use position to the needle removal position; and including.

[0019] The method according to the present invention can comprise one or more of the following features, used alone or in any technically possible combination. - By moving the internal member, deactivate the temporary fixing mechanism of the base and allow its movement. - The main section of the needle extends entirely inside the plunger after the needle has been removed.

[0020] The present invention will be best understood by reading the following description, which is presented only as an example and made with reference to the accompanying drawings. [Brief explanation of the drawing]

[0021] [Figure 1] This is a three-quarter perspective view of the injection device according to the present invention in a needle usage configuration. [Figure 2] This is a longitudinal cross-sectional view of the device from the side, as shown in Figure 1. [Figure 3] This is a longitudinal cross-sectional view of the device shown in Figure 1, taken from the top. [Figure 4] Figures 1 to 3 are longitudinal cross-sectional views from the side of the device, showing the plunger in its deployed configuration. [Figure 5] Figures 1 to 3 are longitudinal cross-sectional views from the top of the device, with the plunger in the deployed configuration. [Figure 6] Figures 1 to 5 show a 3 / 4 perspective view from the rear of the device, with the extraction mechanism in its active configuration. [Figure 7] Figures 1 to 5 show vertical cross-sectional views of the devices, where the extraction mechanism is in the active configuration. [Figure 8] These are vertical side cross-sectional views of the devices shown in Figures 1 to 7 in the needle extraction configuration. [Modes for carrying out the invention]

[0022] Figures 1 to 8 show the injection device 10 according to the present invention. The device 10 is connected to an implantable chamber 11 (circularly shown in Figure 1) and is intended to inject a drug solution into it.

[0023] As is known, the implantable chamber 11 is placed beneath the patient's skin 12. The chamber 11 has a generally cylindrical reservoir 13, which is bounded by a punctureable membrane 14 on its surface that is in contact with the inner surface of the skin. The reservoir is connected to a tube (not shown) for delivering the drug solution to the organ to which the drug dose should be delivered.

[0024] The injection device 10 comprises a needle 22 integrated with the needle support 24, which is extended by a tube connected to the needle and is particularly adhered to and fixed to the needle support 24. The injection device 10 comprises a needle 22 withdrawal mechanism 50 supported by the needle support 24 according to the present invention.

[0025] The needle 22 extends substantially along the vertical axis ZZ, as shown in Figure 2.

[0026] The needle 22 has a free end 28 of a curved tip that opens laterally with respect to the vertical axis ZZ.

[0027] The support 24 has an elongated central core 30 along a longitudinal axis YY perpendicular to the vertical axis ZZ. The central core 30 is substantially a parallelepiped. It has a conduit 31 extending along the longitudinal axis YY, traversing from one side to the other for carrying liquid to a needle 22. The needle 22 is attached to one end of the central core 30, which forms a head 32.

[0028] The needle 22 forms an elbow portion 34 (see Figure 2) extending on the side of the free end 28 by a main section 35 extending along the vertical axis ZZ and by a connecting section 36 extending along the longitudinal axis YY on the opposite side of the free end 28. The connecting section 36 engages with an axial duct that passes from the head 32 through the central core 30.

[0029] The support 24 is equipped with two hinge pins 38, which can be seen in Figure 1, and which protrude laterally on both sides of the central core 30 near the head 32. The hinge pins 38 extend along the transverse axis XX, which is perpendicular to the longitudinal axis ZZ and the longitudinal axis YY.

[0030] The support 24 further comprises two lower retaining pins 39 (one of which can be seen in Figure 6) and two upper retaining pins 40 (one of which can be seen in Figure 1), the lower retaining pins 39 and the upper retaining pins 40 protruding laterally from the central core 30 parallel to the horizontal axis XX.

[0031] The lower retaining pin 39 extends from the portion of the central core 30 furthest from the head 32 along the longitudinal axis YY, and along the vertical axis ZZ at the same level as the hinge pin 38.

[0032] The upper retaining pin 40 extends below the hinge pin 38 along the vertical axis ZZ.

[0033] The lower retaining pin 39 and the upper retaining pin 40 have a smaller lateral range along the transverse axis XX than the hinge pin 38.

[0034] On the side of the support 24 facing the needle 22, the support 24 has a support plate 42 that extends along the length of the support 24. The head 32 protrudes from this support plate 42 along the longitudinal axis YY.

[0035] On the side of the support 24 opposite the needle 22, the support 24 has a bar 44 for locking the extraction mechanism 50. The bar 44 extends on the central core 30 on the opposite side of the head 32 along the longitudinal axis YY. It protrudes laterally from both sides of the central core 30 in a direction parallel to the transverse axis XX.

[0036] The injection device 10 according to the present invention includes a needle 22 withdrawal mechanism 50 that is permanently connected to a needle support 24 and movable between an inactive withdrawal mechanism position shown in Figures 1 to 5 and an active withdrawal mechanism 50 position shown in Figures 6 to 8.

[0037] The extraction mechanism 50 includes a base 52 and a plunger 54 slidably mounted to the base 52. The base 52 is movable relative to the support 24 and is articulated relative to the support 24, in particular, around an articulating pin 38.

[0038] The base 52 includes a sleeve 56 that defines the range of the circulation passage 58 of the plunger 54.

[0039] When the withdrawal mechanism 50 is in an inactive position, the sleeve 56 extends substantially in a direction parallel to the longitudinal axis YY.

[0040] When the withdrawal mechanism 50 is tilted to the active position, the sleeve 56 extends substantially in a direction parallel to the vertical axis ZZ.

[0041] The sleeve 56 is laterally open over a width corresponding to the width of the central core 30 of the support. The sleeve 56 also defines a retaining cavity 59 that opens on its upper surface into the internal passage 58.

[0042] The base 52 also has two sides 60 that extend the sleeve 56 on either side of this opening, which are suitable for engaging around the central core 30. The sides 60 have two articulation holes 62 into which articulation pins 38 are received to perform articulation of the base 52 on the central core 30.

[0043] The joint axis is parallel to the transverse axis XX in the vicinity of the head 32, and therefore, in the inclined position, the head 32 extends into the passage 58, as shown in Figure 7.

[0044] The side also has two lower retaining holes 63, which can be seen in Figure 7, and two upper retaining holes 64, which can be seen in Figure 1, opening to the inner surface of the side 60.

[0045] The lower retaining hole 63 is adapted to receive the lower retaining pin 39 when the extraction mechanism 50 is in an inactive position, and thus it is possible to temporarily hold the extraction mechanism 50 in an inactive position.

[0046] Similarly, the upper retaining hole 64 is adapted to receive the upper retaining pin 40 when the extraction mechanism 50 is in the active position, and thus allows the extraction mechanism 50 to be temporarily held in the active position.

[0047] The base 52 further includes two lateral finger rests 65 protruding from the sleeve 56 at the end opposite the head 32.

[0048] The plunger 54 is received within the passage 58 and is slidable between the needle use position shown in Figures 1 to 7 and the needle withdrawal position shown in Figure 8.

[0049] The plunger 54 comprises an outer member 70 slidably mounted within the base 52, and an inner member 72 slidably mounted to the outer member 70 in an extendable manner. The plunger 54 further includes a flexible coupling mechanism.

[0050] The outer member 70 is a hollowed sleeve having a cross-section complementary to that of the internal passage 58. This cross-section is substantially rectangular with rounded corners.

[0051] The outer member 70 is open at a front end 74 located near the head 32 and at a rear end 76 located away from the head 32. The outer member 70 defines an inner passage 78 that is open at the front end 74 and the rear end 76.

[0052] The outer member 70 defines an outer shoulder portion 79 around its front end portion 74 and a retaining pin 80 protruding from the upper surface near the front end portion 74. The retaining pin 80 is suitable for insertion into the cavity 59 at the usage position of the needle 22. The outer shoulder portion 79 is fitted so as to abut against the front edge of the sleeve 56 when the retaining pin 80 is received into the cavity 59.

[0053] The outer member 70 is oriented toward the needle support 24 and defines an outer slot 90 that opens from the front end 74 to the rear end 76, into the inner passage 78. The outer slot 90 has a width greater than the length of the bar 44.

[0054] The inner member 72 is a hollowed sleeve having a cross-section complementary to that of the inner passage 78. This cross-section is substantially rectangular with rounded corners.

[0055] The inner member 72 has an open front end 92 and a rear end 94 equipped with a rear finger rest 96. The inner member 72 defines an internal space 98 that is open at the front end 92.

[0056] The inner member 72 further defines an inner slot 100 oriented toward the needle support 24. The inner slot 100 opens from the front end 92 to the rear end 94 and opens into the internal space 98. The inner slot 100 has a width less than the length of the bar.

[0057] The inner member 72 is slidably mounted in the inner passage 78 of the outer member 70 along the longitudinal axis of the plunger 54. The inner member 72 is therefore movable from the retracted plunger 54 configuration shown in Figures 1 to 3 to the deployed plunger 54 configuration shown in Figures 4 to 8, in which the length of the plunger 54 is greater than that in the retracted configuration.

[0058] When the plunger 54 is in the deployed configuration, the inner passage 78 of the outer member 70 and the internal space 98 of the inner member 72 form a continuous internal needle 22 receiving space defined by the plunger 54, as shown in Figure 8.

[0059] The bar 44, the outer slot 90, and the inner slot 100 form a temporary fixing assembly to the base 52 in an inactive position.

[0060] The temporary fixed assembly is active when the plunger 54 is in the stowed configuration, as shown in Figure 3. The bar 44 extends into the internal space 98 and engages through the outer slot 90 and the inner slot 100. Since the length of the bar 44 is greater than the width of the inner slot 100, the bar 44 prevents the plunger 54 from moving away from the support 24. The base 52 is therefore fixed in the inactive position of the extraction mechanism 50.

[0061] The temporary fixed assembly is deactivated when the plunger 54 moves from the stowed configuration to the deployed configuration, as shown in Figure 5. In this configuration, the inner member 72 moves away from the bar 44 along the longitudinal axis YY. The bar 44 is in this case only engaged with the outer slot 90, which is wider than the length of the bar 44. The base 52 can then move to the activated position of the withdrawal mechanism 50.

[0062] The coupling mechanism is suitable for locking the inner member 72 in its movement relative to the outer member 70 when the plunger 54 is in the deployed configuration.

[0063] The flexible coupling mechanism includes an upper snap-in tab 82 supported by the outer member 70 on the upper surface of the rear end 76. The upper snap-in tab 82 has teeth on its free end facing the inner passage 78.

[0064] The flexible coupling mechanism further comprises two lateral snap-in tabs 102 supported by the inner member 72 along two sides, each lateral snap-in tab 102 having outward-facing teeth at its free end. The coupling mechanism includes a front recess 84 and a rear recess 86 defined on the side of the outer member 70, as shown in Figures 3 and 5.

[0065] The teeth of the lateral snap-in tab 102 are asymmetrical; that is, they have a blocking side and a passing side. For example, the normal of the blocking side forms a substantially zero angle with the lateral snap-in tab 102, while the normal of the passing side forms an angle between 30° and 60° with the snap-in tab 102.

[0066] The flexible coupling mechanism also includes an inclined portion 106 extending across the upper surface of the inner member 72 and an upper recess 108, the inclined portion 106 defining the extent of the upper recess 108 at its upper end.

[0067] In the deployed configuration, as shown in Figure 5, each tooth supported by the lateral snap-in tab 102 is received by one of the posterior recesses 86, and the teeth supported by the upper snap-in tab 82 are received by the upper recess 108, as shown in Figure 4.

[0068] Advantageously, the flexible coupling mechanism is suitable for temporarily holding the inner member 72 relative to the outer member 70 when the plunger 54 is in the retracted configuration.

[0069] Temporarily holding means that the force required for the plunger 54 to leave the retracted configuration is high enough to prevent the plunger 54 from leaving the deployed configuration without user intervention, but low enough so that such user intervention does not shake the injection device 10 when the plunger leaves the retracted position. This force is preferably between 6N and 10N.

[0070] In the retracted configuration, each tooth supported by the lateral snap-in tab 102 is received by one of the front recesses 84 defined by the outer member 72. When the plunger 54 moves from the retracted configuration to the deployed configuration, the passage side of each tooth strikes the edge of the front recess 84, and when the user pulls the inner member 72, the tooth can move out of the front recess 84, reducing the effort required.

[0071] Conversely, when the plunger 54 is in the deployed configuration, each tooth supported by the lateral snap-in tab 102 is received by one of the rear recesses 86. The locking side of each tooth abuts against the edge of the rear recess 86, preventing the tooth from moving out of the rear recess 86. The flexible coupling mechanism thus resists the movement of the inner member 72 away from the deployed configuration.

[0072] The following describes a method for operating the injection device 10, and more specifically, a method for removing the needle 22.

[0073] The injection device 10 is initially configured as shown in Figures 1 to 3, with the needle 22 passing through the patient's skin 12 to the implantable chamber 11 below. The support plate 42 rests on the patient's skin.

[0074] The plunger 54 is in its retracted configuration, and the withdrawal mechanism is in an inactive position. The plunger 54 extends substantially parallel to the longitudinal axis YY.

[0075] The plunger 54 is in the position where the needle 22 is used, with the shoulder of the front end 74 of the outer member 70 near the head 32 and in contact with the front of the sleeve 56. The retaining tab 80 is engaged within the retaining cavity 59 to hold the plunger 54 in the position where the needle 22 is used.

[0076] The teeth of the lateral snap-in tab 102 engage with the front recess 84, holding the plunger 54 in its retracted configuration.

[0077] The bar 44 is located in the internal space 98 of the inner member 72 and engages with both the overlapping inner slot 100 and the outer slot 90. Since the length of the bar 44 is greater than the width of the inner slot 100, the bar 44 completely locks the plunger 54 against the central core 30 and prevents the base 52 from tilting to the active position.

[0078] The length of the plunger 54 is minimized in the stowed position to ensure that the device 10 does not interfere with the patient.

[0079] In the first step, the user pulls the inner member 72 with the rear finger rest 96 to move the plunger 54 from its stored configuration to its deployed configuration shown in Figures 4 through 8.

[0080] The inner member 72 slides into the outer member 70 along axis YY. The length of the plunger 54 increases, and therefore, in the deployed configuration, it exceeds 120%, preferably 125%, of the length in the stored configuration.

[0081] The teeth of the lateral snap-in tab 102 extend from the front recess 84 and then engage with the rear recess 86 in the deployed configuration. The locking teeth move along the inclined portion 106 and engage with the upper recess 108 in the deployed configuration. The coupling mechanism then locks the plunger 54 into the deployed configuration.

[0082] The bar 44 is released from the inner slot 100 and engages only with the outer slot 90. It no longer locks the plunger 54 to the central core 30. The bottom retaining pin 39 engages with the bottom retaining hole 63 and holds the base 52 in an inactive position.

[0083] In the second step, the user tilts the base 52 around the retaining pin from the inactive position to the active position. In the active position shown in Figures 6 to 8, the plunger 54 extends substantially parallel to the vertical axis ZZ.

[0084] The head 32 is then received into the inner passage 78. The upper retaining pin 40 engages with the upper retaining hole 64 to fix the base 52 in the working position.

[0085] In the third step, the user pushes the rear finger rest 96 with their thumb and holds the lateral finger rests 65 with their other two fingers in order to slide the plunger 54 within the passage 58. The plunger 54 is then moved from the needle 22 in-use position shown in Figures 6 and 7 to the needle 22 withdrawn position shown in Figure 8.

[0086] When the needle 22 moves from the use position to the withdrawal position, the retaining pin 80 is pushed out of the retaining cavity 59 by the user.

[0087] The shoulder portion of the front end 74 of the outer member 70 then contacts the patient's skin, providing a sufficient receiving surface, and when the user presses the plunger 54, the base 52 moves the plunger 54 upward, causing the needle 22 to be withdrawn from the patient's body. The plunger 54 gradually encloses the needle 22.

[0088] In the withdrawn position of the needle 22, the main section 35 of the needle 22 is fully extended within the plunger 54 receiving space, and the front end 74 extends beyond the free end 28. This protects the user by preventing any accidental puncture.

[0089] The withdrawal mechanism 50 is designed to minimize the space occupied by such an injection device 10, especially when the plunger 54 is in its retracted position and has a short length. This reduces the space occupied by the injection device on the patient's skin and thus lowers the risk of operational errors during drug solution injection, as well as the risk of tipping caused by the swaying action of the plunger 54. The reduced dimensions of the injection device 10 also improve patient comfort.

[0090] In addition, device 10 includes a flexible coupling mechanism consisting of multiple snap-in tabs and associated recesses, which ensures that the plunger is securely locked in the deployed configuration to allow for reliable and efficient withdrawal.

[0091] Finally, temporarily fixing the base 52 in the inactive position, combined with temporarily holding the plunger in its stowed configuration by a flexible coupling mechanism, ensures that the base 52 and plunger 54 remain inactive without external intervention by the operator. This further reduces the risk of operator error. [Explanation of Symbols]

[0092] 10 Injection devices 11. Plantable chamber 12. Patient's skin 13 Storage containers 14 membrane 22 Syringe needle 22 needles 24 Needle support 28 Free end 30 central core 31 Conduit 32 heads 34 Elbow 35 Main Section 36 Connection Sections 38. Hinge pins, articulated pins 39 Lower retaining pin, bottom retaining pin 40 Upper retaining pin 42 Support plate 44 Bar 50 Extraction mechanism 52 base 54 Plungers 56 sleeves 58 Internal passage, circulation passage 59 Retaining Cavity 60 Side view 62 joint foramen 63 Lower holding hole, bottom holding hole 64 Upper holding hole 65. Lateral finger rest 70 Outer member 72 Inner component 74 Front end 76 Rear end 78 Inner passage 79 Lateral shoulder 80 retaining pins, retaining tabs 82 Upper snap-in tab 84 Front depression 86 Rear dent 90 outer slots 92 Front end 94 Rear end 96 Rear finger rest 98 Interior space 100 inner slots 102 Lateral snap-in tabs, side snap-in tabs 106 Inclined section 108 Upper indentation XX horizontal axis YY Longitudinal axis ZZ Vertical axis

Claims

1. - Needle support (24) and, - An injection needle (22) having a free end (28) that is integrated with the needle support (24) and positioned away from the needle support (24), - A withdrawal mechanism (50) for withdrawing the injection needle (22), comprising a base (52) connected to the needle support (24), and a plunger (54) movable relative to the base (52) between the use position of the injection needle (22) and the withdrawal position of the injection needle (22), wherein the base (52) is movable relative to the needle support (24) between the inactive position of the withdrawal mechanism (50) and the active position of the withdrawal mechanism (50), and the injection needle (22) is configured to be removed by moving the plunger (54) from the use position of the injection needle to the withdrawal position of the injection needle, An injection device (10) comprising, The injection device (10) comprises an outer member (70) and an inner member (72) that, in the inactive position of the withdrawal mechanism (50), is movable relative to the outer member (70) from a retracted configuration of the plunger (54) to an unfolded configuration of the plunger (54) in which the length of the plunger (54) is greater than that of the retracted configuration, and the plunger (54) defines an internal space for receiving the injection needle (22) in the unfolded configuration.

2. The injection device (10) according to claim 1, wherein the inner member (72) is slidably mounted within the inner passage (78) of the outer member (70).

3. The injection device (10) according to claim 1 or 2, wherein the plunger (54) comprises a flexible coupling mechanism adapted to lock the inner member (72) against the outer member (70) when the plunger (54) is in an extended configuration.

4. The injection device (10) according to claim 3, wherein the flexible coupling mechanism comprises at least one snap-in tab (82, 102) held by either the inner member (72) or the outer member (70), and at least one recess (86, 108) defined by the other of the inner member (72) and the outer member (70), the snap-in tab (82, 102) having teeth that are received in the recess (86, 108) when the plunger (54) is in its deployed configuration.

5. The injection device (10) according to claim 4, wherein one or more of the recesses (86, 108) are located near the first end (76) of the inner member (72) or the other outer member (70) to receive one of the teeth when the plunger (54) is in its deployed configuration, and the flexible coupling mechanism further comprises at least a second recess (84) located near the second end (74) of the inner member (72) or the other outer member (70) to receive the tooth when the plunger (54) is in its retracted configuration.

6. The injection device (10) according to claim 4 or 5, wherein the flexible coupling mechanism comprises at least one inclined portion (106) extending over the other of the inner member (72) and the outer member (70), the inclined portion (106) defining one range of the recess (108) at its upper end, and the snap-in tab (82) compresses the inclined portion (106) when the plunger (54) moves from the retracted configuration to the deployed configuration.

7. The injection device (10) according to any one of claims 3 to 6, wherein the flexible coupling mechanism is adapted to temporarily hold the inner member (72) relative to the outer member (70) when the plunger (54) is in the storage configuration.

8. The injection device (10) according to any one of claims 1 to 7, wherein the injection device (10) includes a temporary fixing assembly for temporarily fixing the base (52) in the inactive position, the temporary fixing assembly being active when the plunger (54) is in the retracted configuration and being deactivated when the plunger (54) moves from the retracted configuration to the deployed configuration.

9. The temporary fixing assembly includes a first slot (100) extending on the inner member (72) and a second slot (90) extending on the outer member (70) having a width greater than that of the first slot (100), wherein the first slot (100) and the second slot (90) are oriented toward the needle support, and the temporary fixing assembly further comprises a bar (44) fitted to engage with the first slot (100) and the second slot (90), wherein the bar (44) has a length greater than the width of the first slot (100) and less than the width of the second slot (90), the injection device (10) according to claim 8.

10. The injection device (10) according to any one of claims 1 to 8, wherein the inner member (72) and the outer member (70) have substantially rectangular cross-sections with rounded corners.

11. A method for preparing to remove the injection needle (22) that has been previously inserted into the patient's body, which is performed before removing the injection needle (22), - A step of providing an injection device (10) according to any one of claims 1 to 10, wherein the withdrawal mechanism (50) occupies its inactive position and the plunger (54) is in the storage configuration, - A step of moving the inner member (72) relative to the outer member (70) to move the plunger (54) from its storage configuration to its deployed configuration, thereby increasing the length of the plunger (54), wherein the plunger (54) defines an internal space for receiving the injection needle (22) in the deployed configuration. - A step of moving the base (52) from the inactive position of the extraction mechanism (50) to the active position, A method that includes this.

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