A syringe (1) contains a liquid medical substance which has to be mixed with another substance before use. This is done by interconnecting the syringe (1) and a capsule containing the other substance by a transfer device (2) which screws into a socket (4) in the piston-seal (3) of the syringe (1) and penetrates through into the liquid. The device (2) extends slidably but non-rotatably through a screw cap (8) which fits to the rear end of a housing (13) for the syringe (1). As the cap (8) screws on, so does the transfer device (2) screw into the piston-seal (3). The relationship between the screw threads is such that, on removing the screw cap (8), the transfer device (2) disengages from the piston-seal (3) first, so that the latter cannot be inadvertently removed from the syringe.
A medical injection system includes a needle guard and an automatic injection system. The needle guard has a cartridge housing coupled with a release mechanism and configured to house a medical cartridge having a needle, a plunger and a carrier configured to carry the dose. Coupled with the cartridge housing and the release mechanism is a shield that is extendable between a retracted and an extended position that substantially covers the needle. The release mechanism is engageable and configured to maintain the shield in the retracted position and allow the shield to extend upon engagement. The automatic injection system can be configured to house the needle guard and configured to inject the dose when activated.
