DOSE SETTING MECHANISM AND METHOD OF SETTING A DOSE

摘要

A method and system for preventing delivery of less than a predetermined minimum dose of a medicament by providing a dose setting mechanism (104; 204) having a spindle nut (128; 228) and a sprung lock nut (130; 230). The mechanism includes a housing (120; 220) and a dose dial component (122) positioned in the housing. The dose dial component is rotatable during a dose setting step. The mechanism further includes a drive sleeve (124; 224) positioned within the dose dial component (122). The drive sleeve is configured to drive a rotatable spindle (126; 226) during a dose administration step. The spindle nut (128; 228) is coupled to the spindle (126; 226) and the sprung lock nut (130; 230) is removably coupled to the drive sleeve (124; 224) and rotationally fixed to the housing (120; 220). In one arrangement, when the dose dial component (122) is rotated to select a dose less than a preselected minimum dose, the sprung lock nut (130; 230) allows the spindle nut (128; 228) to rotate thereby preventing the dose from being administered.