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EP-4110433-B1 - SUB-ASSEMBLY FOR MEDICAMENT DELIVERY DEVICE, AND MEDICAMENT DELIVERY DEVICE COMPRISING THE SUB-ASSEMBLY

EP4110433B1EP 4110433 B1EP4110433 B1EP 4110433B1EP-4110433-B1

Inventors

  • BOSTRÖM, Anders

Dates

Publication Date
20260506
Application Date
20201112

Claims (11)

  1. A sub-assembly (1) for a medicament delivery device, comprising: a plunger rod (11); a biasing member (13) configured to bias the plunger rod (11); a tubular main body (12) comprising a hollow cylinder (121), wherein the plunger rod (11) and the biasing member (13) are in the hollow cylinder (121), the main body (12) comprising a holding member (123) attached to the hollow cylinder (121); and a tubular coupling member (14) arranged to be rotatable relative to the main body (12), wherein the holding member (123) is configured to have, at least, a holding position in which the holding member (123) is engaged with the plunger rod (11), and a releasing position in which the holding member (123) is released from the plunger rod (11), the holding member (123) being switchable from the holding position to the releasing position depending on rotational positions of the coupling member (14) relative to the main body (12), wherein the main body (12) comprises a first axial engagement element (127) formed on an outer surface of the hollow cylinder (121); the coupling member (14) comprises a second axial engagement element (144a) formed on an inner surface of the coupling member (14); and the main body (12) and the coupling member (14) are configured such that the first and second axial engagement elements (127, 144a) are engaged with each other to restrict a movement of the coupling member (14) relative to the main body (12) in a proximal direction of the sub-assembly, wherein the first axial engagement element (127) is arranged to protrude radially outwards from the outer surface of the hollow cylinder (121); and the second axial engagement element (144a) is arranged to protrude radially inwards from the inner surface of the coupling member (14), and wherein the holding member (123) has one end which is connected to the hollow cylinder (121), and the other end which is a free end and capable of being engaged with the plunger rod (11); characterized in that the first axial engagement element (127) is disposed on an outer surface of the holding member (123).
  2. The sub-assembly (1) for a medicament delivery device according to claim 1, wherein the first axial engagement element (127) is arranged to protrude radially outwards from the outer surface of the hollow cylinder (121); and the second axial engagement element (144a) comprises a groove which is formed on the inner surface of the coupling member (14) and capable of being engaged with the first axial engagement element (127).
  3. The sub-assembly (1) for a medicament delivery device according to claim 1, wherein the first axial engagement element (127) comprises a groove which is formed on the outer surface of the hollow cylinder (121); the second axial engagement element (144a) is arranged to protrude radially inwards from the inner surface of the coupling member (14), wherein the groove of the first axial engagement element (127) is capable of being engaged with the second axial engagement element (144a).
  4. The sub-assembly (1) for a medicament delivery device according to claim 2 or 3, wherein the groove is formed to extend along a circumferential direction of the coupling member (14) or the hollow cylinder (121), such that the engagement between the first and second engagement elements (127, 144a) via the groove is maintained when the coupling member (14) is rotated relative to the main body (12) to a certain degree.
  5. The sub-assembly (1) for a medicament delivery device according to any one of claims 1 to 4, wherein the second axial engagement element (144a) is disposed between proximal and distal ends of the coupling member (14); and the coupling member (14) further comprises a proximal inner surface (144b) which is disposed more proximally than the second axial engagement element (144a), has a height difference from the second axial engagement element (144a), and is arranged to abut the first axial engagement element (127).
  6. The sub-assembly (1) for a medicament delivery device according to any one of the preceding claims, wherein the coupling member (14) has a releasing rotational position and a holding rotational position relative to the main body (12), which respectively correspond to the releasing position and the holding position of the holding member (123), and when the coupling member (14) is in the holding rotational position, the first and second axial engagement elements (127, 144a) are engaged with each other.
  7. The sub-assembly (1) for a medicament delivery device according to any one of the preceding claims, wherein the coupling member (14) comprises a central through-hole into which the main body (12) can be inserted, and a longitudinal groove (141) which can guide insertion of the main body (12) into the coupling member (14), and the coupling member (14) is rotatable relative to the main body (12) when the main body (12) is inserted into the coupling member (14) along the longitudinal groove (141) up to a pre-determined fully-inserted position.
  8. The sub-assembly (1) for a medicament delivery device according to claim 7, wherein the coupling member (14) is in the releasing rotational position when the main body (12) is inserted into the coupling member (14) up to the pre-determined fully-inserted position, and the coupling member (14) is in the holding rotational position when the coupling member (14) is rotated in a first rotational direction by a pre-set angle from the pre-determined fully-inserted position.
  9. The sub-assembly (1) for a medicament delivery device according to claim 8, wherein the first and second axial engagement elements (127, 144a) become engaged with each other when an external force is applied to the sub-assembly after the coupling member (14) is rotated by said pre-set angle relative to the main body (12).
  10. The sub-assembly (1) for a medicament delivery device according to claim 8, insofar as depending on claim 2 or 3, wherein the first and second axial engagement elements (127, 144a) are engaged with each other via the groove, when the position of the coupling member (14) is changed from the releasing rotational position to the holding rotational position, or when an external force is applied to the sub-assembly after the coupling member (14) is rotated by said pre-set angle relative to the main body (12).
  11. A medicament delivery device, comprising: a housing (2); an activation member (3) disposed in the housing (2) and linearly movable along the longitudinal direction of the housing (2); a medicament container (60) disposed inside the activation member (3), containing medicament, and comprising a slidable stopper (64) arranged to expel the medicament out of the medicament container (60), and a medicament delivery member (63) connected with a proximal end portion of the medicament container (60); a resilient member (62) arranged to apply force to move the activation member (3) in the proximal direction of the medicament delivery device; and the sub-assembly (1) of any one of the preceding claims, which is coupled to the distal end of the housing (2), arranged to push the slidable stopper (64) when the plunger rod (11) is released, and comprises a means of restricting a second movement of the activation member (3) in the distal direction of the medicament delivery device after the activation member (3) has moved in the distal direction.

Description

TECHNICAL FIELD The present invention generally relates to a sub-assembly of medicament delivery device comprising a transportation locking mechanism, and a medicament delivery device comprising the sub-assembly. BACKGROUND Many medicament delivery devices have been developed for users to perform the medicament delivery on their own. Document WO 2011/123024 (referred as "WO '024" in the following) and WO 2016/169748 (referred as "WO '748" in the following) disclose such medicament delivery devices. A medicament delivery device and a sub-assembly for the device according to WO '748 was proposed to resolve the problem that a delivery actuation means included in the sub-assembly of medicament delivery device according to WO '024 is actuated while the sub-assembly is being transported for the final assembly. Specifically, a plunger rod in WO '024 may be catapulted by disengagement between a recess on the plunger rod and a protrusion engaged with the recess during transportation (see Figs. 4C and 5 of WO '024). This disengagement may be caused by force unintentionally applied to the sub-assembly during transportation. Figs. 1 to 4 show a sub-assembly 8 including a delivery actuation means according to WO '748. Key structural elements in WO '748 for preventing the unintentional catapulting of the plunger rod are flexible tabs 825 oppositely arranged in a main body 82, and recesses 843 and protrusions 842 formed on an inner surface of a coupling member 84. Each flexible tab 825 has a cantilever structure. One end of the flexible tab 825 is fixed to the main body 82, and the other end is a free end. A proximal half of the tab 825 extends radially outwards from the longitudinal axis of the main body 82, and then extends radially inwards to form an arch 828. A distance between the arch 828 and the central axis of the main body 82 is larger than a distance between other portions of the tab 825 and the central axis, than an outer radius of the coupling member 84, and also than an inner radius of a housing 87 into which the sub-assembly is inserted for the final assembly of the medicament delivery device. When the coupling member 84 is mounted on and then rotated relative to the main body 82, the free end of the tab 825 snaps into the recess 843 along with being bent radially inwards. In this coupling state, due to the engagement between the free end of the flexible tab 825 and the recess 843, the coupling member 84 is prevented from rotating relative to the main body 82. Since the coupling member 84 is rotationally locked to the main body 82, a flexible arm 823 can be confined by the coupling member 84, and the free end of the flexible arm 823 can maintain the state of locking a plunger rod 81 by being engaged with an engagement hole 86 on the plunger rod 81. After transportation, the sub-assembly 8 is assembled with other sub-assemblies to form the final assembly of the medicament delivery device. In the final assembly, most parts of the sub-assembly 8 are inserted into a housing 87. As shown in Fig. 4, an inner surface of the housing 87 bends the flexible tab 825 radially inwards to the extent that the free end of the flexible tab 825 is totally released from the recess 843. Therefore, the coupling member 84 becomes ready to be rotated by interactions between rotation guides 846, 847 formed on an outer surface of the coupling member 84, and protrusions (not shown) formed on an element moving linearly along the housing 87 when the medicament delivery device is in the injection state. As discussed above, the coupling member 84 is rotationally locked to the main body 82 by the engagement between the flexible tab 825 and the recess 843. However, the coupling member 84 may be still moveable relative to the main body 82 in the longitudinal direction of the main body 82. Therefore, when an unintentional external axial force is applied to the coupling member 84, the coupling member 84 may be axially dislocated from its original position relative to the main body 82, and consequently the plunger rod 81 may be catapulted by disengagement between the engagement hole 86 and the free end of the flexible arm 823. To prevent this axial dislocation of the coupling member 84, there are provided at least one protrusion 824 at a proximal end portion of the main body 82. After the main body 82 is fully inserted into the coupling member 84 up to a predetermined position, the protrusions 824 are positioned to restrict a proximal movement of the coupling member 84 relative to the main body 82, and thus ensure maintaining the engagement between the free end of the flexible tab 825 and the recess 843 in the distal end portion of the coupling member 84. However, the inventor of the present invention found that the protrusions 824 are under the risk of breakage or wear, and may cause failure on the delivery of medicament. This breakage or wear of the protrusions 824 arises from interference of the protrusions 824 with the coupling member 84 an