Multi-use drug-delivery device

A drug-delivery device is provided including a drug reservoir configured to contain a fluid drug, a needle cartridge comprising a plurality of needle assemblies, a drive member, a pump, one or more springs, a loading button and a dosing button. The device is configured to use work done by the user in actuating the loading button to load the one or more springs. When the user actuates the dosing button after actuating the loading button, the device is configured to (i) release the one or more loaded springs to operate the drive member to drive a needle assembly that is in operational alignment with the drive member from a retracted position to an injection position, (ii) drive the pump to pump fluid drug from the drug reservoir through the driven needle assembly, and (iii) retract the driven needle assembly from the injection position to the retracted position.