Abstract: An apparatus for separately storing a first component, such as a drug and for mixing this first component with a second component, such as a sterilized diluent, to form a beneficial agent which can be delivered to a patient from the container containing the second component. The device includes novel means for interconnecting a container, such as a glass vial containing a first component, such as a drug, with a second container such as a flexible bag containing the second component such as a parenteral liquid, and then for mixing the components under sterile conditions.