Additive transfer unit having a slidable piercing member

Claim 1

An additive transfer unit for storing and trans-ferring of a medicament to a solution container having an exposed closure; said transfer unit comprising an additive container for storing the medicament to be transferred, said additive container having a rigid neck portion defining a finish and an opening, the opening in said container being sealed by a closure affixed thereto; said closure having a shoulder for resting against said finish of the rigid container neck, said closure including a puncturable stopper positioned in sealing engagement with the opening in the additive container and in a substantially stationary manner, and means for affixing the stopper to the additive con-tainer; said stopper including a central opening extending along the longitudinal axis thereof for slidably receiving a piercing member, the end of the stopper projecting into the con-tainer being sealed by a puncturable diaphragm; a piercing member having a passageway therethrough for the flow of said medicament and a point on both ends thereof and disposed within the central opening in said stopper, one end of the piercing member extending from said opening; said piercing member having an integral stop and being movable from a first position for entry through the closure of the solution container with said integral stop contacting said exposed closure of the solution container to a second position for puncturing of the diaphragm of the stopper in the additive container to thereby provide a pathway between the containers and permit the said medicament within the additive container to transfer into the solution container; said integral stop of the piercing member including an annular shoulder extending from the body thereof at a point in the portion of the piercing member which extends from the central opening in the stopper, said shoulder limiting penetration of the piercing member into the closure of the solution container when the piercing member is inserted in the closure of said solution container; said piercing member including an elongated body with said point on either end thereof and a projection extending from the body intermediate the ends thereof; the central opening within the stopper including an undercut to receive the projection on the piercing member when the piercing member is moved from the first position to the second position within the central opening in the stopper for puncturing of the diaphragm of the stopper whereby the projection on the piercing member will engage the undercut in the opening in the stopper to thereby retain the piercing member within the opening in the stopper when the transfer unit is withdrawn from the solution container.