Patent ID: 8079980

Claim:
A single use syringe having a leading end, a trailing end and a longitudinal axis, said syringe comprising: a longitudinally extending hollow barrel configured to contain a volume of liquid, a plunger having a stem, a head and a needle tip, said head being longitudinally displaceable within said barrel, said stem having a first engagement formation and said head having a shoulder defining a second engagement formation, wherein said first engagement formation includes a resilient finger having a fixed base portion and a resilient tip, said finger being angularly offset relative to said longitudinal axis, and said resilient tip of said finger directed generally towards said leading end of said syringe and directed generally away from said trailing end of said syringe; and a locking bush longitudinally fixed within said barrel, said bush having an aperture adapted to receive said stem, permitting the stem to slide longitudinally relative to said bush, said bush having a third engagement formation, said bush, also having an abutment surface defining a fourth engagement formation; wherein said plunger is longitudinally displaceable in a retraction direction away from the leading end to a captive position in which said resilient tip of said first engagement formation captively engages said third engagement formation thereby preventing the stem from being longitudinally displaced in an insertion direction toward the leading end from said captive position, and wherein said fourth engagement formation is engageable with said second engagement formation if an attempt is made to longitudinally displace said stem in the retraction direction from said captive position.