Single-injection device

Claim 1

A single-injection syringe, comprising a container for a medicament; said container having first and second open end positions; said first end portion of the container having a penetrable seal mounted therein for sealing said first end portion, and said second end portion having a piston inserted therein to define with said seal a chamber for containing the medicament; a syringe body mounted on and surrounding said first end portion of the container; said syringe body having a penetrable end wall extending across said first end portion of the container and an elongated generally cylindrical sleeve integrally formed with and extending from said wall; said sleeve having an elongated bore formed therein extending from said end wall to an open end located in spaced relation from said end wall and a threaded external periphery; a needle support mounted in said bore for movement between first and second positions therein; said needle support having a diameter which is slightly less than the diameter of said bore and including an annular projection formed thereon and at least four stabilizing fins extending perpendicularly thereto into engagement with the bore; a needle mounted in said support having an end portion located within said bore in the first position of the needle support and piercing said end wall and said seal as it is moved to its second position; said bore of said sleeve having a pair of spaced annular grooves formed therein respectively defining the first and second positions of said needle, said groove receiving and cooperating with said annular projection on the needle support to hold the needle support in its respective positions against inadvertent movement in the sleeve; and a hollow plunger including a first end portion threadably engaged with said threaded sleeve and operatively engaged in bearing engagement with said support, and a second end portion having means formed on the exterior thereof for engaging said piston when the plunger is removed from the sleeve; said needle support also including an annular shoulder formed thereon; and said plunger having an annular socket formed therein at its first end portion operatively engaging said annular shoulder in bearing engagement to urge said support towards the syringe body to cause the needle to pierce the end wall and seal upon rotation of the plunger on the sleeve when the plunger is rotated on the sleeve in a direction to move it towards the syringe body, said plunger having an elongated chamber formed therein receiving said needle, whereby said needle support forms, with the end wall of said syringe body an enclosed sterile chamber for the needle and is moved from its first to its second position to cause said needle to pierce said end wall and said seal when said plunger is threaded on the sleeve in a direction to move it towards the syringe body.