The invention relates to a dose setting mechanism, which is operable to be coupled to a medication cartridge and which comprises means that prevent the user from setting a dose greater than the remaining medication in the cartridge. The dose setting mechanism comprises a shaft. A helical groove having a first pitch is provided along a first portion of the shaft. The dose setting mechanism further comprises a nut member disposed on the helical groove of said shaft. During dose setting, the shaft is rotated relative to the nut member while the nut member traverses along the groove from a distal end of the shaft towards a proximal end of the shaft. The mechanism further comprises means preventing a user of said dose setting mechanism from setting a dose of said medication that is greater than said remaining medication in said cartridge, said means comprising a second pitch provided along a second portion of said shaft, wherein said first pitch is different from said second pitch, wherein said second pitch is preferably greater than said first pitch.
