Medication delivery device

1. A medication delivery device configured to contain a drug to be delivered, the medication delivery device comprising: a housing,

a cap configured to be: (i) removed from the housing and set aside during delivery of the drug and (ii) reattached to the housing after delivery of the drug, a moveable element, and

a locking portion configured to lock the cap and to function based on an amount of the drug that the medication delivery device contains when the cap is reattached, wherein the housing comprises an aperture,

wherein, in a first state in which the medication delivery device contains more than a predetermined amount of the drug, the cap is removable from the housing if the cap is reattached, and

wherein, in a second state in which the medication delivery device contains equal or less than the predetermined amount of the drug, the moveable element is configured to push the locking portion radially outward through the aperture in the housing such that the locking portion is configured to lock the cap if the cap is reattached over the locking portion.

2. The medication delivery device according to claim 1 , wherein the medication delivery device is configured to deliver a multitude of doses of the drug and, when the last dose has been delivered, the cap is configured to lock if the cap is reattached.

3. The medication delivery device according to claim 2 , wherein if the cap is reattached, the locking portion is configured to lock the cap when the moveable element is positioned in a given position, the given position being the position the moveable element reaches when a last dose is delivered, and

wherein the moveable element is configured to force the locking portion to protrude from the housing when the moveable element reaches the given position.

4. The medication delivery device according to claim 1 , wherein the cap and the housing are configured to encapsulate the drug when the cap is locked.

5. The medication delivery device according to claim 1 , wherein, if the cap is reattached, the locking portion is configured to lock the cap when the moveable element is positioned in a given position.

6. The medication delivery device according to claim 5 , wherein the moveable element is moveable translationally and/or rotationally.

7. The medication delivery device according to claim 5 , wherein the moveable element is designed as a piston rod.

8. The medication delivery device according to claim 5 , wherein the cap comprises a mating section which is engageable with the locking portion, and wherein when the moveable element is located in the given position the locking portion is configured to protrude from the housing and is configured to be coupled with the mating section so that the cap is locked.

9. The medication delivery device according to claim 1 , wherein the cap is configured to be permanently locked during the second state if the cap is reattached.

10. The medication delivery device according to claim 1 , wherein the locking portion is integrally formed with the housing.

11. The medication delivery device according to claim 1 , wherein the cap is permanently locked during the second state if the cap is reattached.

12. The medication delivery device according to claim 1 , wherein the housing is configured to contain a replaceable cartridge and, when the cartridge is removed, the locked cap is unlocked.

13. The medication delivery device according to claim 1 , wherein the housing comprises a disposable unit and, if the cap is locked, the disposable unit is removeable.

14. The medication delivery device according to claim 13 , wherein the cap and the disposable unit are configured to encapsulate a cartridge.

15. The medication delivery device according to claim 1 , wherein the medication delivery device is formed as pen-type medication delivery device.