A connector assembly is provided for efficient flow of liquid into and/or out of a vial, such as a vial containing a lyophilized drug. The connector assembly includes a spike and a stopper sleeve, both slidably mounted in the open top of the vial. The connector assembly includes a stopper affixed to the stopper sleeve and sealingly engaged in the open top of the vial. The stopper is slidably moveable in response to axial movement of the stopper sleeve. Movement of the stopper sleeve relative to the vial will move the stopper into or out of sealing engagement with the vial. The connector assembly further includes a spring for generating a small amount of axial movement of the spike, stopper sleeve and stopper after the stopper has been moved into the opened position in the vial. Movement of the spike, stopper sleeve and stopper generated by the spring will cause a sufficient change in pressure to overcome surface tension and initiate an efficient flow of fluid into or out of the vial.