The disclosed embodiment relates to an injection device that is a single patient use, disposable device containing a needle and a cartridge containing a drug or pharmaceutical product. The device is initially provided in a pre-armed configuration wherein the needle sheath maintains cantilever locking tabs on the housing in a position to the maintain the needle in a position separated from the septum of a cartridge. To arm the device, the practitioner removes the needle sheath and pushes down the plunger assembly. The cantilever locking tabs flex outwardly thereby allowing the cartridge-to-housing interface and the cartridge to move forward whereby the butt end of the needle punctures the septum of the cartridge. Additionally, the cantilever locking tabs form a stop configuration with the housing of the device. The disclosed embodiment is particularly adaptable to dental anesthetic applications, as well as other medical and veterinary applications.
