Patent ID: 8403905

Claim:
A method for retaining aerosols when accessing a vial having a pierceable seal located over an opening of the vial, the method comprising the steps of: piercing the vial seal with a sharp cannula having a medicament lumen and a vent lumen separate from each other; conducting non-dispersed liquid through the medicament lumen of the cannula into the vial; conducting gas out of the vial through the vent lumen and through a vent port in fluid communication with the vent lumen to an atmosphere outside the vial; blocking the passage of non-dispersed liquid out the vent lumen to the outside atmosphere at a first filter device comprising pores having a diameter in the range of 0.2-3.0 microns; absorbing liquid dispersed in gas at a second filter device disposed between the first filter device and the vent port; and inhibiting the passage of bacteria at a third filter device disposed between the second filter device and the vent port, the third filter device having a pore diameter smaller than 0.2 microns.