A transfer set generally includes an outer sleeve configured for connecting an inner sleeve to a vial such that a passage of the inner sleeve is disposed above a stopper of the vial. The transfer set further includes a cap configured for insertion into the outer sleeve such that the cap is connected to the outer sleeve and is detachable from the outer sleeve via rotation of the cap relative to the outer sleeve. The cap has an interior space and a cam disposed within the interior space, wherein the inner sleeve, and a spike within the inner sleeve, extend into the interior space when the cap is connected to the outer sleeve, and wherein, as the cap rotates relative to the outer sleeve for detachment of the cap from the outer sleeve, the cam interacts with the follower to translate the spike toward the stopper for puncturing the stopper.
