Abstract: A device for the introduction of liquid medication into a flexible bag for the administration of intravenous solutions. The device comprises an elongated generally cylindrical hollow tubular member having an open end and a closed end, a boss extending from the closed end carried by the boss a cannula having a sharpened outer end, and a rigid sheath surrounding the cannula and carried by the boss. The sheath serves to limit the advancement of the cannula into an orifice having a diameter greater than that of said cannula. A thrust portion is provided within the tubular member and a fluid passage extends longitudinally through the center of the thrust portion. The lower end of the fluid passage communicates with the upper end of the cannula. A cylindrical vial having a resilient stopper in its open end seals on the inside walls of the vial. There are threads on the thrust portion and cooperating threads on the stopper adapted to be interlocked, whereby the plug can be interlocked with the thrust portion.