US Patent 8740856 Stoppers used in pre-filled syringes

A stopper adapted for attachment with a plunger rod for use within a syringe barrel is disclosed. The stopper includes a main body defining an open rearward end and a closed front end. The open rearward end is adapted to receive a front forward end attachment portion of the plunger rod. The stopper also includes a core member integrally formed with the main body adjacent the closed front end. The core member includes a nose portion having a conical tip configured for entering an outlet opening of the syringe barrel. The closed front end of the stopper has a profile configured to cooperate with an internal surface of the syringe barrel wall to prevent reflux and reduce dead space within the barrel.