A medical device for using or dispensing medical items (82, 182) in a rotary cartridge, the rotary cartridge defining a cartridge gear, the medical device comprising: a housing; an operating handle movable between first and second positions and including a grip and a gear, wherein the operating handle is translatable between the first and second positions, the first handle position being a retracted position with the grip translated in to adjacent the housing, and the second handle position being an extended position with the grip translated away from the housing.; and an advancement mechanism operable to sequentially advance the medical items (82, 182) for use or dispensing, characterized in that the advancement mechanism includes a rotary drive gear assembly, an inter-gear unidirectional rotary drive assembly, and a pinion output gear, wherein the rotary drive gear assembly includes a first rotary gear and a second rotary gear that are rotatable about a common axis, the first gear is rotationally driveable by the handle gear in a first angular direction and an opposite second angular direction dependent on the movement of the operating handle between the first and second positions, the pinion output gear is indirectly rotationally driveable by the second gear, and the cartridge gear is rotationally driveable by the pinion output gear, wherein the inter-gear unidirectional rotary drive assembly operably interconnects the first and second drive gears (41, 42) so that the second gear is driveable by and is rotatable with the first gear in the first direction but is not driveable in co-rotation by the first gear in the opposite second direction, wherein the inter-gear unidirectional rotary drive assembly includes a first catch surface defined by a first catch element, a second catch surface defined by a second catch element, and a disengagement surface, wherein the catch surfaces (44a, 45a) are engageable in order to maintain the two gears (41, 42) in co-rotation in the first angular direction, at least one of the catch surfaces (44a, 45a) moves out of engagement when the first gear rotates in the opposite second direction, and the catch surface disengagement is caused by the disengagement surface moving a movable one of the catch elements (44a, 45a), wherein an idler gear assembly is provided which includes at least one idler gear (51, 52), wherein the idler gear assembly is rotationally driveable by the second gear of the drive gear assembly, and the pinion output gear is rotationally drivable by the second gear. a housing; an operating handle movable between first and second positions and including a grip and a gear, wherein the operating handle is translatable between the first and second positions, the first handle position being a retracted position with the grip translated in to adjacent the housing, and the second handle position being an extended position with the grip translated away from the housing.; and an advancement mechanism operable to sequentially advance the medical items (82, 182) for use or dispensing, characterized in that the advancement mechanism includes a rotary drive gear assembly, an inter-gear unidirectional rotary drive assembly, and a pinion output gear, wherein the rotary drive gear assembly includes a first rotary gear and a second rotary gear that are rotatable about a common axis, the first gear is rotationally driveable by the handle gear in a first angular direction and an opposite second angular direction dependent on the movement of the operating handle between the first and second positions, the pinion output gear is indirectly rotationally driveable by the second gear, and the cartridge gear is rotationally driveable by the pinion output gear, wherein the inter-gear unidirectional rotary drive assembly operably interconnects the first and second drive gears (41, 42) so that the second gear is driveable by and is rotatable with the first gear in the first direction but is not driveable in co-rotation by the first gear in the opposite second direction, wherein the inter-gear unidirectional rotary drive assembly includes a first catch surface defined by a first catch element, a second catch surface defined by a second catch element, and a disengagement surface, wherein the catch surfaces (44a, 45a) are engageable in order to maintain the two gears (41, 42) in co-rotation in the first angular direction, at least one of the catch surfaces (44a, 45a) moves out of engagement when the first gear rotates in the opposite second direction, and the catch surface disengagement is caused by the disengagement surface moving a movable one of the catch elements (44a, 45a), wherein an idler gear assembly is provided which includes at least one idler gear (51, 52), wherein the idler gear assembly is rotationally driveable by the second gear of the drive gear assembly, and the pinion output gear is rotationally drivable by the second gear.