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Syringe assembly having disabling mechanism with tamper resistance features

  • US 7,399,293 B2
  • Filed: 03/05/2007
  • Issued: 07/15/2008
  • Est. Priority Date: 07/30/2003
  • Status: Active Grant
First Claim
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1. An operable syringe assembly having passive disabling structure comprising:

  • a barrel including a cylindrical side wall having an inside surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall having a passageway therethrough in fluid communication with said chamber;

    an elongate plunger rod having a proximal end, an open distal end including a side wall having an interior surface, at least one detent on said interior surface, said side wall having an axial opening and a positioning lug projecting into said opening, said lug having a distal face and a proximal face;

    a stopper including a circular shaped sealing element having a peripheral surface forming a seal with said inside surface of said barrel, a boss member projecting proximally from said sealing element, at least one boss detent on said boss, a retaining element connected to said stopper by a frangible connection and defining an axial recess having a proximal ledge for accepting said positioning lug of said plunger and for limiting the axial motion of said positioning lug in said axial recess,a locking element including a central body portion having an aperture therethrough, at least one cantilevered leg extending distally outwardly from said body portion, and at least one finger element extending proximally inwardly from said aperture, said at least one leg having a sharp free end directed outwardly for engaging said inside surface of said barrel;

    said locking element being positioned with said sharp free end contacting said interior surface of said plunger rod proximally of said at least one detent, said boss member being positioned in said aperture of said locking element wherein said at least one finger element is contacting said boss proximally of said at least one boss detent, so that applying a proximally directed force to said plunger rod while holding said barrel causes said plunger rod to move proximally with respect to said stopper until said free end of said cantilevered leg moves distally along said inner surface of said plunger rod to said at least one detent and said proximal face of said positioning lug contacts said proximal ledge of said retaining element to move said stopper in a proximal direction for a selected distance, and subsequently applying a distally directed force to said plunger rod to discharge fluid from said chamber through said passageway causes said plunger rod to move in a distal direction along with said locking element due to its engagement with said at least one detent until said finger element of said locking element rides over said at least one boss detent and into contact with said at least one boss detent and said plunger rod contacts said stopper to move said stopper distally to discharge fluid from said chamber, after which applying a proximally directed force to said plunger rod will causes said plunger rod to move proximally until said free end of said cantilevered leg moves distally along said interior surface past said distal end of said plunger rod so that said sharp end of said at least one cantilever leg engages said inside surface of said barrel to help prevent proximal movement of said stopper to render said syringe assembly unusable.

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