Delivery device for delivering predetermined amounts of medicament, comprising - a body having an outer housing 17 and an inner housing 18 and having a proximal and an opposite distal end, - a cartridge with medicament to be delivered arranged inside said inner housing, said cartridge comprising an opening for expelling said medicament and a stopper movable inside said cartridge, - a threaded plunger rod arranged movable inside said body in the longitudinal direction and in contact with said movable stopper, - a manually operated push means 30 movable in the longitudinal direction and capable of, upon operation, moving said plunger rod towards said movable stopper, thereby expelling medicament through said opening, and - a spring means 19 for biasing said push means towards the distal end of the device, and - a first driver 15 and a second driver 40 for transforming a generally linear movement of said push means to a rotational movement of said plunger rod, wherein said transforming means comprises a first set of protruding structures 50 arranged on said first driver cooperating with a set of inclined ledges 43, 44 arranged on said second driver rotatably locked to said plunger rod, characterized in that the device comprises a movable release member 20 having a guide member 21 adapted to interact with a guide frame 31 arranged on the outer circumferential surface of the manually operated push means and wherein said guide frame is configured to prevent the delivery of a subsequent dose before a previously initialized dose has been fully administered, and wherein said guide frame 31 comprises parallel first and second longitudinally oriented tracks 33, 34 separated by a longitudinally oriented wall element 32 and connected to each other by distal and proximal transversal tracks 35, 36, and wherein said manually operated push means 30, in cooperation with said release member 20, is movably arranged in the longitudinal direction between a depressed position in which the guide member is generally aligned with said distal transversal track 35 and a released position in which the guide member is generally aligned with said proximal transversal track 36, and wherein said release member 20, in cooperation with said push means 30, is arranged movable along a transversal direction between a first position in which the guide member 21 is generally aligned with said first track 33 and a second position in which the guide member is generally aligned with said second track 34 and wherein said first longitudinally oriented track 33 is arranged with a first transversally aligned step ramp 38 at a distal end of said wall element 32 and a second transversally aligned step ramp 39 at a proximal end of said wall element, wherein said first and second step ramps are capable of interacting with said guide member to allow movement of said manually operated push means towards the depressed position and to prevent said manually operated push means from return movement towards the released position. - a body having an outer housing 17 and an inner housing 18 and having a proximal and an opposite distal end, - a cartridge with medicament to be delivered arranged inside said inner housing, said cartridge comprising an opening for expelling said medicament and a stopper movable inside said cartridge, - a threaded plunger rod arranged movable inside said body in the longitudinal direction and in contact with said movable stopper, - a manually operated push means 30 movable in the longitudinal direction and capable of, upon operation, moving said plunger rod towards said movable stopper, thereby expelling medicament through said opening, and - a spring means 19 for biasing said push means towards the distal end of the device, and - a first driver 15 and a second driver 40 for transforming a generally linear movement of said push means to a rotational movement of said plunger rod, wherein said transforming means comprises a first set of protruding structures 50 arranged on said first driver cooperating with a set of inclined ledges 43, 44 arranged on said second driver rotatably locked to said plunger rod,