Abstract: A system for controlling flow through a line during intravenous drug delivery. The system is capable of use in conjunction with a bedside-pharmacy system for the preparation and delivery of intravenous drugs. The system includes a disposable cassette with first and second valve chambers and a control unit into which the cassette is capable of being received. The control unit has a cam and first and second actuators. The bedside-pharmacy system may include a liquid inlet for connection to a liquid supply, vial receptacles, and a liquid outlet for providing the intravenous drug in mixed, liquid form to the patient. That system may include a chamber having a variable volume, and a valve mechanism, which may be actuated to control flow between the liquid outlet, the variable-volume chamber, the vial receptacles and the liquid inlet.