A method and system for preventing delivery of less than a predetermined minimum dose of a medicament by providing a dose setting mechanism having a spindle nut and a sprung lock nut. The mechanism includes a housing and a dose dial component positioned in the housing. The dose dial component is rotatable during a dose setting step. The mechanism further includes a drive sleeve positioned within the dose dial component. The drive sleeve is configured to drive a rotatable spindle during a dose administration step. The spindle nut is coupled to the spindle and the sprung lock nut is removably coupled to the drive sleeve and rotationally fixed to the housing. In one arrangement, when the dose dial component is rotated to select a dose less than a preselected minimum dose, the sprung lock nut allows the spindle nut to rotate thereby preventing the dose from being administered.
