Safety reservoir snap on overcap for parenteral drug container

Claim 1

Safety reservoir cap for application over the closure and finish of a parenteral drug container to prevent outflow to the environment of said drug upon reconstitution of the drug by injection into the drug container of diluent with a hypodermic syringe and needle and withdrawal of reconstituted drug into the syringe and withdrawal of the needle from the container, said cap comprising: (a) a substantially cylindrical top portion having a vertical axis for alignment with the vertical axis of the container, (b) a skirt integral with and depending downwardly from the top portion and having an inner surface substantially conforming to the contour of the outer surface of the closure and adapted to receive and press against said outer surface, (c) a cylindrical chamber inset into the lower surface of the top portion and having a vertical axis aligned with the vertical axis of the top portion and having a volume at least sufficient to retain any drug that would normally escape during reconstitution and removal of reconstituted drug, (d) an annular shoulder defined in said top portion by the sidewall of the cylindrical chamber and having a lower surface defined by lower surface of the top portion and conformihg to the contour of the top outer portion of the closure and adapted to press against said outer portion, the ratio of the outer diameter of the shoulder to the inner diameter of the shoulder being at least 1.5:1, (e) a single inwardly extending continuous annular locking flange integral with the bottom of the skirt, said flange having an inwardly angled surface to allow the cap to be pushed down over the container closure and an upper surface adapted to engage under the container finish to retain the cap on the container, (f) an upstanding annular bead in the upper surface of said top portion axially aligned with the vertical axis of the top portion and defining a target area for the insertion through the cap of said needle, said cap being of a material having an elasticity substantially that of natural rubber so as to allow application over the closure and to provide sufficient pressure by the lower surface of the shoulder against the top outer portion of the closure and by the inner surface of th skirt against the outer surface of the closure to prevent leakage between said cap and said closure or container during reconstitution.