Patent ID: 8206361
Filing Date: 2012-06-26
Classification: A61M

Abstract:
1. A method for expelling medication from a cartridge of medication having a moveable piston in an injection device having a rack and pinion transmission that couples an injection button with a piston driver; the method comprising the steps of: moving a first rack rearward during setting of a dose, the rack remaining in continuous meshed engagement with a first pinion causing the first pinion to rotate during setting of a dose; moving the first rack forward during injection of a dose and causing the first pinion to rotate in an opposite direction; rotating a second pinion, which has a different diameter than the first pinion, in unison with the first pinion when the first rack is moved forward, wherein the second pinion remains in continuous meshed engagement with a second rack, driving the piston driver forward during forward motion of the first rack thereby causing medication to be expelled from the injection device, wherein the first rack moves longitudinally in unison with the injection button and wherein when the injection button is pressed to move the first rack forward, the first and second pinion move longitudinally in a forward direction; and expelling medication from the cartridge contained in the device.