An automatic injector (50) includes a housing (52, 236) having a guide (158), a drive control mechanism, a transmission assembly (110), a motor (106), and an energy source. The housing (52, 236) may further include a cartridge cover (72). A drive control mechanism includes a drive screw (114), a cartridge carrier (126, 202), a plunger carrier (138, 194, 226, 242), and one or more control transfer instruments (150, 204), such as a puck or cylinder. The drive screw (114) interfaces and connects with the plunger carrier (138, 194, 226, 242). The automatic injector (50) is configured to accept a variety of syringes as cartridges (54, 224) for drug delivery. The cartridges (54, 224) may be ejected from the injector (50) and safely disposed after use, making the injector a reusable automatic injector (50). The reusable automatic injector (50) may further include one or more sensors (160, 165), such as a cartridge sensor (160) and a patient sensor (165). The novel incorporation of the drive control mechanisms into the automatic injectors (50) of the present invention enables a single motor (106) and transmission assembly (110) to drive the function of multiple components, which may include the steps of: preparation and alignment of a cartridge (54, 224) for injection, removal of a safety cap or needle shield (60), needle injection, drug dose delivery, and syringe and/or needle (58) retraction. Methods of manufacture and methods of use are also disclosed.
