Prefilled, vented two-compartment syringe

A prefilled, vented, readily activated syringe assembly adapted to receive a hypodermic needle comprising:

• a barrel member defining a substantially tubular chamber having a wall portion;
• a nozzle portion communicating with said tubular chamber;
• a hydrophobic filter element operatively associated with said nozzle portion of said barrel member;
• a holder member in sealing arrangement with said nozzle portion and positioned outwardly from said filter element;
• means to retain said holder member on said nozzle portion;
• passage means defined by said holder element;
• a piercing tubular member having a piercing point, slidably positioned in said passage means of said holder member and said piercing point spaced from said filter element;
• a first stopper in slidable and sealing engagement in said tubular chamber to provide a compartment for a first flowable medicinal material;
• a second stopper adapted to receive a plunger rod in slidable and sealing engagement in said tubular chamber of said barrel member and spaced from said first stopper to provide a compartment for a second flowable medicinal material;
• means constructed and arranged in combination with said first and second stoppers and said barrel member to provide upon movement of said first stopper toward said second stopper fluid communication between said compartments for said first and second medicinal materials;
• whereby upon movement of said second stopper in the direction of said first stopper, intermixing of said first and second medicinal materials will be effected with emission of air through said filter element;
• upon subsequent movement of said piercing tubular member toward said filter with a piercing thereof;
• attachment of said hypodermic needle to said piercing tubular member;
• and upon further movement of said second stopper toward said first stopper substantially;
• all of said medicinal materials will be expelled from said syringe.