Injection device with dose indicator mechanism

1. An injection device comprising:

a. a housing having a longitudinal axis;

b. a dose indicator positioned within the housing; and

c. a dose selector operatively connectable to the dose indicator, the dose selector and the dose indicator being capable of cooperating with one another to set a dose to be ejected from the injection device,

wherein the dose indicator comprises an odometer including:

i. a units wheel operatively connected to the dose selector so that rotation of the dose selector also rotates the units wheel, and

ii. a tens wheel selectively engageable with the units wheel so that rotation of the units wheel also rotates the tens wheel,

wherein the dose indicator further comprises an axially-moveable shuttle lock rotationally locked to the tens wheel and selectively engageable with the units wheel and the housing along the longitudinal axis;

wherein the tens wheel is selectively engageable with the units wheel via said shuttle lock; and

wherein, when the tens wheel is not engaged with the units wheel, the shuttle lock is rotationally locked to the housing.

2. The injection device of claim 1 wherein the shuttle lock is generally cylindrical, having a forward section and a rear section, the forward section having a greater diameter than a diameter of the rear section.

3. The injection device of claim 1 wherein one of the shuttle lock and tens wheel includes an axially-extending keyway and the other of the shuttle lock and tens wheel includes a radially projecting key for engaging in said keyway in order to rotationally lock the shuttle lock to the tens wheel.

4. The injection device of claim 3 wherein the shuttle lock and tens wheel are axially moveable with respect to one another when said key is engaged in said keyway.

5. The injection device of claim 1 wherein the shuttle lock includes a set of peripheral teeth arranged in one axial location on an outer surface thereof, the peripheral teeth being capable of selectively engaging one or more formations on an internal surface of the housing.

6. The injection device of claim 5 wherein the peripheral teeth are substantially equally spaced around a circumference of the shuttle lock at said axial location.

7. The injection device of claim 5 wherein the peripheral teeth each have a forward surface and a rear surface, the forward and rear surfaces being capable of engaging first and second formations respectively on the internal surface of the housing.

8. The injection device of claim 7 wherein said first formations comprise ribs for engaging the forward surface of said peripheral teeth and said second formations comprise dogs for engaging the rear surface of said peripheral teeth.

9. The injection device of claim 8 wherein, when the tens wheel is not engaged with the units wheel, the shuttle lock is rotationally locked to the housing by said ribs engaging the forward surface of said peripheral teeth.

10. The injection device of claim 1 wherein said units wheel includes a drive dog having a cam surface capable of selectively engaging a dog on said shuttle lock to effect axial movement of said shuttle lock.

11. The injection device of claim 1 wherein said units wheel includes an axially-extending spline capable of engaging teeth on an end surface of said shuttle lock so as to selectively rotationally lock the units wheel and shuttle lock together.

12. The injection device of claim 1 wherein the units wheel and tens wheel are each marked with a sequence of numbers or symbols, at least one of the numbers or symbols being visible through an aperture or window in the housing.

13. The injection device of claim 1 further comprising a medicament container.

14. The injection device of claim 13 wherein the medicament container comprises a pre-filled syringe or cartridge.

15. The injection device of claim 13 further comprising a medicament contained in the medicament container.

16. The injection device of claim 15 wherein the medicament is selected from the group comprising: antipsychotic substances including risperidone, hormones, antitoxins, substances for the control of pain, immunosuppressives, substances for the control of thrombosis, substances for the control or elimination of infection, peptides, proteins, human insulin or a human insulin analogue or derivative, polysaccharide, DNA, RNA, enzymes, antibodies, oligonucleotide, antiallergics, antihistamines, anti-inflammatories, corticosteroids, disease modifying anti-rheumatic drugs, erythropoietin, or vaccines, for use in the treatment or prevention of rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, ulcerative colitis, hormone deficiency, toxicity, pain, thrombosis, infection, diabetes mellitus, diabetic retinopathy, acute coronary syndrome, angina, myocardial infarction, atherosclerosis, cancer, macular degeneration, allergy, hay fever, inflammation, anaemia, or myelodysplasia, or in the expression of protective immunity.

17. An injection device comprising:

a. a housing;

b. a dose indicator positioned within the housing; and

c. a dose selector operatively connectable to the dose indicator, the dose selector and the dose indicator being capable of cooperating with one another to set a dose to be ejected from the injection device,

wherein the dose indicator comprises an odometer including:

i. a units wheel operatively connected to the dose selector so that rotation of the dose selector also rotates the units wheel, and

ii. a tens wheel selectively engageable with the units wheel so that rotation of the units wheel also rotates the tens wheel,

wherein the dose indicator further comprises an axially-moveable shuttle lock rotationally locked to the tens wheel and selectively engageable with the units wheel and the housing;

wherein the tens wheel is selectively engageable with the units wheel via said shuttle lock; and

wherein, when the tens wheel is not engaged with the units wheel, the shuttle lock is rotationally locked to the housing,

wherein the internal surface of the housing further comprises an axially-extending rib for limiting rotation of the tens wheel.

18. The injection device of claim 17 wherein said tens wheel includes a rotary endstop feature for engaging said axially-extending rib.

19. The injection device of claim 18 wherein said tens wheel includes two of said rotary endstop features, for maximum and minimum dose limiting respectively.

20. The injection device of claim 19 wherein each of said rotary endstop features are capable of engaging said axially-extending rib.