The present invention provides an improved cannula that can be used to reconstitute powdered drugs in a drug delivery system. Furthermore, the present invention provides a cannula and drug delivery system incorporating same. To this end, the present invention provides a cannula structure for use in a reconstitution device for reconstituting a powdered drug comprising a cannula having a first end and a second end, and defining a channel in an interior thereof between the first and second ends. The first end is closed and includes a member for piercing a septum. The cannula includes at least two slots providing fluid communication between the channel and an exterior of the cannula. The slots are located in juxtaposition to the first end and have a width, as measured along a length of the cannula, that is less than a length, as measured around the cannula. The slots also have a minimum projected area equal to or greater than the cross-sectional area of the channel.