A device for administering a fluid can include a cylinder, a piston displaceable in the cylinder and connected to a piston rod, and a tensioning device connected to the piston rod. The tensioning device includes a ramp rotatable via a motor, and a ramp track extending along a helical line. The tensioning device includes a roller which is in contact with the ramp track. To perform a tensioning procedure, the ramp track is rotated such that the roller runs on the region of inclination as far as the second plateau so the piston is moved to its rear end position. To perform a dispensing procedure, the ramp track is rotated until the roller runs over a transfer region and is accelerated toward the first plateau, thereby the piston is moved toward an open dispensing end. A control unit determines whether the tensioning procedure and/or dispensing procedure has taken place correctly.

A medical fluid injection device, a medical fluid transfer device and a method of administering and transferring a medical fluid are disclosed. The device and method may include a compressed gas canister in fluid communication with an expandable elastic bladder positioned within a vial of drug to provide a means to deliver drug through an injection cannula that is movable between a plurality of positions or through a transfer conduit.

A medical fluid injection device, a medical fluid transfer device and a method of administering and transferring a medical fluid are disclosed. The device and method may include a compressed gas canister in fluid communication with an expandable elastic bladder positioned within a vial of drug to provide a means to deliver drug through an injection cannula that is movable between a plurality of positions or through a transfer conduit.