The present invention relates to a medicament injector including an applicatorwith acartridge-accepting receptacle. The medicament injector includesinterchangeable, pre-filledmedicament-containing cartridges. Each cartridge includes at least one barriermember having a closed positionin which access to the medicament is inhibited. The barrier member is moveablefrom the closedposition to an open position, in which the medicament is accessible via theapplicator, when thecartridge is inserted into the cartridge-accepting receptacle. The barriermember is moves back tothe closed position when the cartridge is removed from the cartridge-acceptingreceptacle. Thisallows for plurality of pre-filled medicament cartridges to be selected ondemand via a need-basedscenario for quick assembly with the medicament injector for use in variousclinical scenarios toreduce the bulk, errors, complexity, and steps in medicament delivery whileincreasing theversatility, safety, and speed of medicament delivery in time criticalsituations.
