A liquid drug transfer device for use with an injection vial which includes a vial adapter having a puncturing cannula for puncturing a vial stopper and a fluid transfer port in flow communication with the puncturing cannula. The vial adapter includes set-up vial retention flex members for vial retention purposes in a set-up position without puncturing an injection vial and activation vial retention flex members for vial retention purposes in an activation position puncturing the injection vial.
