Medicament delivery device

1. A medicament delivery device, comprising:

a housing having proximal and distal end portions, with a longitudinal axis extending between and along the proximal and distal end portions;

a container holder arranged in the housing at the proximal end portion;

an axially movable plunger adapted to be displaced along the longitudinal axis into the container holder; and

an energy-accumulating member arranged inside the housing and adapted to displace the plunger along the longitudinal axis toward the proximal end portion;

wherein the container holder is adapted to accommodate a medicament container that is configured for attachment of a medicament delivery member at an end portion of the medicament container and that comprises a first piston sealingly and slidably arranged inside an opposite end portion of the medicament container and a second piston slidably arranged inside an intermediate portion of the medicament container; and

the axially movable plunger comprises an outer plunger rod, an inner plunger rod arranged at least partially inside the outer plunger rod, a biassing arrangement for actuating the inner plunger rod, and a locking arrangement that, in a first state, is arranged to lock the biassing arrangement in an energy-storing position and, in a second state, is arranged to release the biassing arrangement from the energy-storing position to displace the inner plunger rod along the longitudinal axis toward the proximal end portion into the container holder,

wherein the outer plunger rod is rotatable relative to the housing.

2. The medicament delivery device of claim 1 , wherein the biassing arrangement is inside the outer plunger rod at the distal end portion.

3. The medicament delivery device of claim 1 , wherein the inner plunger rod is adapted to engage the outer plunger rod when the inner plunger rod is positioned in an end position toward the proximal end portion.

4. The medicament delivery device of claim 3 , wherein the inner plunger rod comprises at least one resilient projection adapted to engage a recess in the outer plunger rod when the inner plunger rod is positioned in the end position.

5. The medicament delivery device of claim 4 , wherein the outer plunger rod includes a series of elevations and/or depressions, and the resilient projection is adapted to run in abutment along the series of elevations and/or depressions when the inner plunger rod is moved toward the end position, thereby producing an audible and/or tactile feedback to a user of the medicament delivery device.

6. The medicament delivery device of claim 1 , wherein the biassing arrangement comprises a compression spring that extends along the longitudinal axis and, in the energy-storing position, is subjected to an axial compression.

7. The medicament delivery device of claim 6 , wherein the locking arrangement comprises a compression rod that extends along the longitudinal axis, and when the locking arrangement is in the first state the compression rod engages the compression spring and the housing at the distal end portion, thereby generating the axial compression.

8. The medicament delivery device of claim 6 , wherein the inner plunger rod is adapted to engage the outer plunger rod when the inner plunger rod is positioned in an end position toward the proximal end portion.

9. The medicament delivery device of claim 6 , wherein the energy-accumulating member comprises a main torsion spring for transferring stored energy into rotational movement for displacing the plunger along the longitudinal axis toward the proximal end portion.

10. A medicament delivery device, comprising:

a housing having proximal and distal end portions, with a longitudinal axis extending between and along the proximal and distal end portions;

a container holder arranged in the housing at the proximal end portion;

an axially movable plunger adapted to be displaced along the longitudinal axis into the container holder; and

an energy-accumulating member arranged inside the housing and adapted to displace the plunger along the longitudinal axis toward the proximal end portion;

wherein the container holder is adapted to accommodate a medicament container that is configured for attachment of a medicament delivery member at an end portion of the medicament container and that comprises a first piston sealingly and slidably arranged inside an opposite end portion of the medicament container and a second piston slidably arranged inside an intermediate portion of the medicament container; and

the axially movable plunger comprises an outer plunger rod, an inner plunger rod arranged at least partially inside the outer plunger rod, a biassing arrangement for actuating the inner plunger rod, and a locking arrangement that, in a first state, is arranged to lock the biassing arrangement in an energy-storing position and, in a second state, is arranged to release the biassing arrangement from the energy-storing position to displace the inner plunger rod along the longitudinal axis toward the proximal end portion into the container holder,

wherein the energy-accumulating member comprises a main torsion spring for transferring stored energy into rotational movement for displacing the plunger along the longitudinal axis toward the proximal end portion.

11. The medicament delivery device of claim 10 , further comprising a fixed member arranged inside the housing, the fixed member having a threaded inner surface; wherein the outer plunger rod comprises a threaded outer surface; the threaded inner surface of the fixed member is configured to engage the threaded outer surface of the outer plunger rod; a first end of the main torsion spring is connected to the housing; and a second end of the main torsion spring is connected to the outer plunger rod and releasably engages the housing.

12. The medicament delivery device of claim 11 , wherein the outer plunger rod connects to the second end of the main torsion spring via a drive member, the outer plunger being slidably connected with the drive member for sliding movement of the outer plunger rod along the drive member and the longitudinal axis.

13. A medicament delivery device, comprising:

a housing having proximal and distal end portions, with a longitudinal axis extending between and along the proximal and distal end portions;

a container holder arranged in the housing at the proximal end portion;

an axially movable plunger adapted to be displaced along the longitudinal axis into the container holder; and

an energy-accumulating member arranged inside the housing and adapted to displace the plunger along the longitudinal axis toward the proximal end portion;

wherein the container holder is adapted to accommodate a medicament container that is configured for attachment of a medicament delivery member at an end portion of the medicament container and that comprises a first piston sealingly and slidably arranged inside an opposite end portion of the medicament container and a second piston slidably arranged inside an intermediate portion of the medicament container; and

the axially movable plunger comprises an outer plunger rod, an inner plunger rod arranged at least partially inside the outer plunger rod, a biassing arrangement for actuating the inner plunger rod, and a locking arrangement that, in a first state, is arranged to lock the biassing arrangement in an energy-storing position and, in a second state, is arranged to release the biassing arrangement from the energy-storing position to displace the inner plunger rod along the longitudinal axis toward the proximal end portion into the container holder,

wherein the biassing arrangement comprises a mixing torsion spring that, in the energy-storing position, is subjected to a torsional load.

14. The medicament delivery device of claim 13 , wherein the locking arrangement comprises a locking member attached to an end of the mixing torsion spring; the mixing torsion spring at an opposite end is fixed in relation to the housing; and when the locking arrangement is in the first state the locking member is fixed in relation to the housing, thereby generating the torsional load.

15. The medicament delivery device of claim 13 , wherein the inner plunger rod is adapted to engage the outer plunger rod when the inner plunger rod is positioned in an end position toward the proximal end portion.

16. The medicament delivery device of claim 15 , wherein the inner plunger rod comprises at least one resilient projection adapted to engage a recess in the outer plunger rod when the inner plunger rod is positioned in the end position.

17. The medicament delivery device of claim 16 , wherein the outer plunger rod includes a series of elevations and/or depressions, and the resilient projection is adapted to run in abutment along the series of elevations and/or depressions when the inner plunger rod is moved toward the end position, thereby producing an audible and/or tactile feedback to a user of the medicament delivery device.

18. The medicament delivery device of claim 13 , wherein the energy-accumulating member comprises a main torsion spring for transferring stored energy into rotational movement for displacing the plunger along the longitudinal axis toward the proximal end portion.

19. The medicament delivery device of claim 18 , further comprising a fixed member arranged inside the housing, the fixed member having a threaded inner surface; wherein the outer plunger rod comprises a threaded outer surface; the threaded inner surface of the fixed member is configured to engage the threaded outer surface of the outer plunger rod; a first end of the main torsion spring is connected to the housing; and a second end of the main torsion spring is connected to the outer plunger rod and releasably engages the housing.

20. The medicament delivery device of claim 19 , wherein the outer plunger rod connects to the second end of the main torsion spring via a drive member, the outer plunger being slidably connected with the drive member for sliding movement of the outer plunger rod along the drive member and the longitudinal axis.