A device is provided for injecting fluid from a pre-filled cartridge. The device includes a needle and a hollow barrel that holds a pre-filled cartridge. A needle retainer releasably retains the needle in an extended position so the needle can be inserted into a patient. A plunger in the rear of the...http://www.google.com.au/patents/US7004929?utm_source=gb-gplus-sharePatent US7004929 - Safety pre-filled cartridge injector
