Abstract: The present invention provides in part an improved drug injection system, comprising novel self-aspirating syringes, drug cartridge and novel needle assemblies. It is primarily intended for administering of local anesthetic by dentists, but it can be used equally well in medical and veterinary applications. In one aspect, the novel syringe is made lightweight, comfortable to hold and corrosion resistant. In another aspect, some novel changes in the design of the syringe reduce the possibility of transmitting an infection from the blood of one patient into the blood of another. Additionally, innovation in the design of needle assembly makes the syringe safe to use even without prior sterilization and at the same time eliminating the possibility of transmitting infection as the result of human error.