Abstract: A closure assembly for a vial for a sterile drug comprises a body fitted with a sealable tube that has a seal that hermetically closes it on one end and that is in communication with the inside of the drug vial on the other end. The sterile drug can be reconstituted and/or diluted in an IV solution by means of sterile docking in a closed system. Via the tube on this closure assembly, the vial is connected to a component with a closed sealable tube, such as an IV solution container or a syringe by unsealing and joining the outer ends of the tubes to each other in a sterile docking procedure. If the drug needs reconstitution or dilution, a sterile fluid can first be introduced into the drug vial from the flexible container or from the syringe via the joined ends of the tubes. When the drug is dissolved, the solution can be aspirated to the flexible container or to the syringe. Subsequently, the tube connecting the vial and the component can be sealed and the seal can be cut.