DRUG DELIVERY DEVICE WITH DOSE COUNTING MECHANISM

A drug delivery device includes a dose counting mechanism and an end-of-content or remaining-dose indication. For example, a dose expelling mechanism is coupled to a reciprocating element configured to undergo a predefined motion during each dose expelling action to allow a dose to be expelled. The predefined motion includes displacement in a first axial direction from a first position to a second position followed by displacement in a second axial direction from the second position to the first position, with a counter element being movable in the first axial direction. First and second unidirectional ratchet mechanisms prevent motion in the first axial direction and allow motion in the second axial direction of the reciprocating element relative to the counter element, and vice versa, respectively.