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, pharmaceutical product or other injectable agent. The device is initially provided in a pre-armed state in a first engagement configuration wherein the needle is separated from the septum of a cartridge. To arm the injection device, the professional urges the device from the first engagement or pre-armed configuration to a second engagement or aimed configuration wherein the needle pierces the septum and provides a sterile fluid path to the drug, pharmaceutical product or other injectable agent contained within the cartridge. The disclosed embodiment is particularly adaptable to dental anesthetic applications, as well as other medical and veterinary applications.