1. A syringe useful for injecting an aspirated therapeutic fluid, the syringe comprising in combination:a barrel having an inside wall;
a plunger disposed in coaxial sliding relationship to the inside wall;
a needle assembly further comprising a rearwardly biased needle holder and a forwardly-projecting needle and needle tip that is are retractable into the barrel following injection of the therapeutic fluid; and
a needle cap further comprising a hollow body and tapered nose tube with oppositely disposed proximal and distal open ends;
wherein the needle cap is configured to be selectively moveable between a pre-use position in which a portion of the needle cap releasably engages the barrel and extends forwardly past and circumferentially surrounds the forwardly projecting needle tip, an intermediate position in which the needle cap is moved rearwardly relative to the barrel to expose the needle tip and a forwardly extending portion of the needle sufficiently to allow the therapeutic fluid to be aspirated from a vial into the barrel by moving the plunger rearwardly inside the barrel after inserting the needle tip into the vial; and
wherein the needle cap is configured to be selectively moveable forwardly from the intermediate position back to the pre-use position following aspiration to recap and protect the needle and needle tip pending injection of the therapeutic fluid; and
wherein the needle cap is configured to be moveable forwardly from the pre-use position to a final position in which the needle cap is completely released and removed from the barrel to fully expose the needle forwardly of the barrel prior to injecting the aspirated therapeutic fluid by expelling the therapeutic fluid from the barrel.