Medicament delivery device

1. A drive mechanism for use in a medicament delivery device, the drive mechanism comprising:

a housing comprising an inner surface and a distal end that is covered and enclosed by an end portion that is axially and rotationally fixed relative to the housing before and after dose delivery;

a container holder coaxially arranged within the housing and configured to fixedly hold and support a medicament container, wherein both the container holder and the medicament container are rotationally and axially fixed relative to the inner surface of the housing before, during and after dose delivery;

a plunger rod having a longitudinal axis;

a spring biasing the plunger rod in a proximal direction; and

a holder axially fixed relative to the housing and comprising an annular proximal end and enclosing all but a proximal portion of the plunger rod, where the plunger rod is releasably fixed relative to the holder to maintain the spring in a pre-tensioned state,

wherein the holder has a portion that extends proximally from the annular proximal end abutting a distal projecting surface of the medicament container, and

wherein the holder and the annular proximal end are axially fixed relative to the housing during dose delivery.

2. The drive mechanism of claim 1 , wherein the portion that extends proximally comprises a cut-out.

3. The drive mechanism of claim 2 , wherein the cut-out is arc-shaped.

4. The drive mechanism of claim 1 , wherein the spring is positioned within a hollow portion of the plunger rod.

5. The drive mechanism of claim 4 , wherein the plunger rod has an open distal end and a proximal end, where the proximal end is configured to engage and move a slidable stopper in the medicament container when the drive mechanism is assembled into the medicament delivery device and when the spring changes from the pre-tensioned state to a released state.

6. The drive mechanism of claim 1 , wherein the plunger rod has an outer surface that is releasably engaged with a protrusion on a flexible tongue.

7. The drive mechanism of claim 6 , wherein the flexible tongue is biased inwardly relative to the longitudinal axis when the spring is in the pre-tensioned state.

8. The drive mechanism of claim 6 , wherein the flexible tongue is configured to flex outwardly relative to the longitudinal axis to release the spring from the pre-tensioned state when the drive mechanism is activated and to cause the plunger rod to move axially relative to the holder in a proximal direction.

9. The drive mechanism of claim 1 , further comprising a flexible tongue comprising an inwardly directed protrusion releasably engaged with a cut-out on an outer surface of the plunger rod.

10. An automatic medicament delivery device comprising:

the medicament container axially and rotationally fixed and supported within the container holder; and

the drive mechanism as claimed in claim 1 .

11. The automatic medicament delivery device of claim 10 ,

further comprising a flexible tongue that is engaged with an outside surface of the plunger rod.

12. The automatic medicament delivery device of claim 11 , wherein the flexible tongue comprises an inwardly directed protrusion that engages with a cutout on the outside surface when the flexible tongue is flexed radially inward when the spring is in the pre-tensioned state.

13. The automatic medicament delivery device of claim 12 , wherein the flexible tongue is configured to flex radially outward when an activation member slidably positioned in the housing is moved axially in the distal direction relative to the housing causing the protrusion to disengage from the cutout.

14. The automatic medicament delivery device of claim 10 , further comprising the medicament container axially fixed within the container holder and having a slidable stopper that is operatively engaged with a proximal end of the plunger rod such that a release of the pre-tensioned spring that is positioned within a hollow portion of the plunger rod causes the plunger rod and the slidable stopper to move axially relative to the housing in a proximal direction to dispense medicament from the container.

15. The automatic medicament delivery device of claim 10 , further comprising an activation member slidably positioned relative to the holder such that an axial movement of the activation member in a distal direction relative to the holder causes the holder to release the plunger rod which causes the pre-tensioned state of the spring to change to a released state such that the spring forces the plunger axially in a proximal direction.

16. The automatic medicament delivery device of claim 15 , wherein the change from the pre-tensioned state to the released state generates an audible, tactile or visible signal to a user of the medicament delivery device.

17. The automatic medicament delivery device of claim 10 , wherein the holder is rotatably fixed relative to the plunger rod and the plunger rod has a radial space defined by an inner diameter and a proximal end.

18. The automatic medicament delivery device of claim 17 , wherein the spring biases the proximal end of the plunger rod in a proximal direction during both the pre-tensioned state and a released state.