Disclosed is an adapter configured to couple a withdrawal spike with a multidose vial for maintaining sterility of the multidose vial during and after withdrawal of a first dose. The adapter includes a hollow body defined by an outer wall having a first end and a second end. The adapter includes a first retaining member at the first end adapted to irreversibly engage a portion of the multidose vial and a second retaining member at the second end adapted to irreversibly engage a portion of the withdrawal spike. The withdrawal spike is locatable in a predetermined position with respect to the multidose vial.
