Pen cap

1. A drug delivery device and pen cap combination comprising:

a housing having an attached cartridge holder that contains a cartridge of medicinal product; and

a pen cap having an open proximal end and a closed distal end, the pen cap configured for attachment to the drug delivery device,

wherein an outer needle cap is configured for attachment to a distal end of the cartridge holder, wherein the outer needle cap completely covers a needle and provides a protective casing for the needle in a non-use condition, where the outer needle cap includes a rim having a radially outward facing surface and a distal surface, an outer diameter of the rim defining a maximum outer diameter of the outer needle cap,

wherein the pen cap has an inner diameter defined by an inner wall at the open proximal end of the pen cap, wherein the pen cap comprises at least one protruding element located inside the pen cap that protrudes from the inner wall, wherein the at least one protruding element is elongate, has a proximal end and a distal end, and has a proximal end surface that faces the open proximal end of the pen cap, the proximal end surface of the at least one protruding element being oriented perpendicular to a longitudinal axis of the pen cap, and being recessed from a proximal end of the inner wall of the open proximal end of the pen cap, wherein the proximal end of the at least one protruding element results in a first diameter of the pen cap that is smaller than the maximum outer diameter of the outer needle cap,

wherein the first diameter is narrower than the inner diameter of the pen cap,

wherein the distal surface of the rim of the outer needle cap abuts the proximal end surface of the at least one protruding element of the pen cap when the outer needle cap is inserted into the pen cap, and wherein at least a portion of the radially outward facing surface of the rim is covered by the pen cap when the distal surface of the rim abuts the proximal end surface of the at least one protruding element, and

wherein the abutment of the distal surface of the rim and the proximal end surface of the at least one protruding element blocks the distal surface of the rim from being advanced into the pen cap beyond the proximal end surface of the at least one protruding element and prevents the outer needle cap attached to the drug delivery device from being advanced sufficiently distally into the pen cap such that the outer needle cap becomes stuck within the pen cap when a user mounts the pen cap on the drug delivery device.

2. The drug delivery device and pen cap combination according to claim 1 , wherein the at least one protruding element extends along the longitudinal axis of the pen cap.

3. The drug delivery device and pen cap combination according to claim 1 , wherein the at least one protruding element includes at least one inwardly directed step along the length of the at least one protruding element, the at least one inwardly directed step provided between the proximal end and the distal end of the at least one protruding element.

4. The drug delivery device and pen cap combination according to claim 1 , wherein the at least one protruding element is a bar.

5. The drug delivery device and pen cap combination according to claim 1 , wherein the at least one protruding element is a ring.

6. The drug delivery device and pen cap combination according to claim 1 , wherein the at least one protruding element comprises two protruding elements, and wherein the two protruding elements are located at opposite sides of the pen cap.

7. The drug delivery device and pen cap combination according to claim 1 , wherein the at least one protruding element is made of plastic.

8. The drug delivery device and pen cap combination cap according to claim 1 , wherein the at least one protruding element is made of metal.

9. The drug delivery device and pen cap combination according to claim 1 , wherein the at least one protruding element is molded into the pen cap.

10. The drug delivery device and pen cap combination according to claim 1 , wherein the medicinal product is a pharmaceutical formulation containing a pharmaceutically active compound, the pharmaceutically active compound comprising at least one human insulin or a human insulin analogue or derivative, glucagon-like peptide (GLP-1) or an analogue or derivative thereof, or exedin-3 or exedin-4 or an analogue or derivative of exedin-3 or exedin-4.

11. The drug delivery device and pen cap combination according to claim 1 , wherein the at least one protruding element extends from the recessed proximal end surface to the closed distal end of the pen cap.

12. The drug delivery device and pen cap combination according to claim 1 , wherein a cross-sectional area of the proximal end of the at least one protruding element is greater than a cross-sectional area of the distal end of the at least one protruding element.

13. The drug delivery device and pen cap combination according to claim 1 , wherein the at least one protruding element of the pen cap comprises three protruding elements, and wherein the three protruding elements are circumferentially spaced approximately equidistantly from one another along the inner wall of the pen cap.

14. The drug delivery device and pen cap combination according to claim 1 , the proximal end surface of the at least one protruding element being located longitudinally at a most proximal location of the at least one at least one protruding element.