Sequential drug delivery syringe

A sequential drug delivery syringe, comprising:

• a hollow syringe barrel defining an inner wall, a proximal barrel end and a distal barrel end, the distal end of the barrel including a connector defining an outlet lumen therethrough, the outlet lumen in fluid communication with an interior of the barrel, the barrel interior defined by the proximal barrel end, the distal end, and the inner side wall;
• a plunger disposed with the barrel interior, having a proximal end extending outside of the proximal end of the barrel and a distal end;
• a secondary stopper disposed within the barrel interior, having:
• a proximal axial end coupled to the distal end of the plunger, and a distal axial end defining a distal cavity therein;
• a primary stopper disposed within the barrel interior between the secondary stopper and the distal end of the barrel, having:
• a proximal axial end defining a proximal cavity, a distal axial end defining a distal cavity with a seating surface, and a defining a through-passage in fluid communication with both of the proximal and distal cavities thereof;
• a telescoping actuator assembly oriented with the respective cavities of the primary and secondary stoppers, having:
• plural nested tubes in sliding, friction engagement with each other, each nested tube respectively having an outer circumferential surface and an inner wall, an outer circumferential surface of a most proximally oriented one of which being coupled to and within the distal cavity of the secondary stopper, with its inner wall in sliding, friction engagement with the outer circumferential surface of an adjoining tube captured therein, and
• a reciprocating actuator oriented within the through-passage of the primary stopper, the actuator including a collet bushing having an annular bushing rim, a radially projecting, proximal axial face thereof in opposed orientation with a mating, annular-shaped seating surface of the primary stopper, a plurality of collet bushing fingers projecting away from the proximal axial face of the annular bushing rim, in friction contact with the surface defining the through-passage, a distal tip of each bushing finger projecting into the proximal cavity of the primary stopper, the distal tips of the collet bushing fingers coupled to a platform oriented on a distal end of an actuator shaft, an outer surface of a proximal end of the actuator shaft in sliding friction engagement with the inner wall of the distal-most oriented tube, the seating surface of the primary stopper captured between the collet bushing and the platform;
• a primary fluid chamber within the barrel interior, defined between a distal end surface of the primary stopper and outlet lumen at the distal end of the barrel, volume of the primary fluid chamber being selectively variable by translation of the plunger;
• and
• a secondary fluid chamber, within the barrel interior, defined between a distal end surface of the secondary stopper and the through-passage of the primary stopper, volume of the secondary fluid chamber being selectively variable by translation of the plunger when the proximal axial face of the annular bushing rim is spaced away from the seating surface of the primary stopper;
• wherein the secondary fluid chamber is in fluid communication with the primary fluid chamber and the outlet lumen of the syringe when the proximal axial face of the annular bushing rim is spaced away from the seating surface of the primary stopper, and the secondary fluid chamber is isolated from the primary fluid chamber when the proximal axial face of the annular bushing rim is in abutting contact with the seating surface of the primary stopper;
• wherein withdrawal of the plunger tensions the telescoping actuator assembly, reciprocates the proximal axial face of the of the annular bushing rim into abutting contact with the seating surface of the primary stopper, and withdraws said primary stopper;
• and
• wherein advancement of the plunger alone at a first axial pressure advances the primary stopper, advancement of the plunger at a axial second pressure greater than the first axial pressure reciprocates the proximal axial face of the annular bushing rim away from abutting contact with the seating surface of the primary stopper, which establishes fluid communication among the secondary and primary fluid chambers and the outlet lumen and advances the secondary stopper;
• and advancement of the plunger at a third axial pressure greater than the second axial pressure collapses the telescoping actuator assembly within the respective distal cavity of the secondary stopper and the proximal cavity of the primary stopper.