A vented vial adapter has a filter attached to a vent arm that includes at leasttwo filter media for suppressing aerosolized medicaments from leaving the vialand suppressing bacteria and other contaminants from entering the vial duringreconstitution activities of the medication in the vial. The filter media allowsthe passage of air to the atmosphere outside the vial for pressure equalization.In another aspect, a third filter medium is used in the vent of the adapter to allowgas to pass in either direction through it, but prevents bacteria and particulatematter in the atmosphere from reaching the second filter device. A first filteris hydrophobic and prevents non-dispersed liquid from reaching the second filter,while conducting liquid dispersed in gas. The second filter absorbs the liquiddispersed in gas.
