Syringe assembly having disabling mechanism

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-1 DESCRIPTION Background of the invention

The present invention relates to syringe assemblies and in particular to syringe assemblies having an automatic disabling mechanism.

Throughout the world the multiple use of hypodermic syringe products that are intended for a single use, is essential for the abuse of drugs and in the transmission of contagious diseases. Intravenous drug users who routinely share and reuse syringes are a high-risk group for the AIDS virus. In addition, the effects of multiple use are a major concern in some countries where repeated use of syringe products during large-scale immunization programs may be responsible for the spread of many diseases. The reuse of single-use hypodermic syringe assemblies is also critical in the spread of drug abuse, even in the absence of infection or disease.

Many attempts have been made to remedy this problem. Most notable are the initial contributions that were based on a specific action to destroy the syringe after use either by using a destructive device or by providing a syringe assembly with frangible zones, such that the syringe can be rendered useless by the application of force. Other attempts involve the inclusion of a structure that allows the destruction or suppression of the function of the syringe in a conscious act on the part of the user of the syringe. Although many of these devices work quite well, they require the specific intention of the user followed by actual action to destroy or render the syringe inoperative. These devices are not effective with a user who has the specific intention of reusing the hypodermic syringe. Consequently, a single-use hypodermic syringe was required which after use automatically becomes inoperative or can no longer be used without further action on the part of the user. The automatic function is much more difficult to provide because the means of rendering the syringe inoperative must not prevent its filling or use under normal conditions.

A single-use syringe that is automatically rendered useless after injection is taught in US Patent No.^s 4,973,310 to Kosinski. This syringe contains a locking element located on the syringe barrel between the plunger rod and the inner surface of the barrel. During use, the syringe allows the user to attract a preselected amount of medication into the cylinder chamber and deliver this medication, such as by injection, into the patient.

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-2 Any attempt to withdraw the plunger to use the syringe a second time will cause the locking element itself to embed itself into the inner surface of the syringe barrel to prevent proximal movement of the plunger rod.

The first part of claim 1 relates to an operative syringe assembly as described in DE 89 14 128 U. This one-way injection syringe comprises an elongated hollow plunger rod which forms a hollow plunger part. comprising an H-shaped component with two spring tabs extending from both sides of a base portion in opposite directions. The spring tabs engage in coupling rings of the hollow plunger part. The component connects to a plunger plate through a plunger rod. When the syringe assembly is used to draw liquid into the syringe barrel, the spring arms of the H-shaped component disengage from the ring portions of the hollow plunger rod, moving inward and outward. H-shaped component is released from the piston rod. This allows a single syringe attraction operation. Thereafter, the H-shaped component is at both ends released from the hollow plunger rod, so that the plunger plate is no longer connected with the plunger rod.

WO 94/13336 describes a non-reusable syringe with a needle opening. The syringe comprises a piston releasably connected to a plunger so that it becomes inoperative after a single use. The piston has a plurality of rearwardly projecting lock arms that can be engaged with a retaining ring disposed at the forward end of the plunger. A retaining collar is provided to lock the locking arms in the engaged position. When the liquid is drawn into the syringe barrel, the retaining collar remains in the locked position. Thereafter, the liquid is expelled from the barrel of the syringe, whereby the locking arms are released from the retaining collar so that the piston is no longer connected to the piston rod.

US 5,222,942 A describes a syringe having a locking means associated with a plunger or plunger rod, which can be used to deliver the maximum volume of the syringe only once. The plunger rod has a serrated edge of a saw tooth design in cooperation with a stop collar. The action of the stop collar produces the consequence that although the piston rod can be pushed into the cylinder, it is no longer possible

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-3 repeat the extraction in the direction of movement since this extraction is prevented by means of fasteners that rest against a tooth flank. Therefore, an empty stroke is still possible, but the repetition of a suction stroke is avoided. These provisions ensure that a syringe can be used for a single intended application.

There is still a need for a single use syringe that allows a preselected number of plunger rod strokes before the automatic disable mechanism is activated. For example, four strokes of the plunger may be necessary to complete the injection process. As when the syringe assembly is used to draw a diluent into the syringe barrel, dispense the diluent into a vial containing the substances to be reconstituted, draw the reconstituted medication back into the syringe, and then dispense the contents of the syringe to the patient.

Compendium of the invention

An object of the invention is to provide an operable syringe assembly having a passive disabling structure.

The syringe assembly of the present invention is defined by claim 1.

An operational syringe assembly that has a passive disabling structure includes a barrel that has a cylindrical side wall with an inner surface that defines a chamber for retaining fluids, an open proximal end, and a distal end that includes a distal wall has a conduit to through it in fluid communication with the chamber. An elongated hollow plunger rod is provided having a proximal end, an open distal end, and an inner surface. A stop has a circular-shaped sealing member having a peripheral surface that forms a seal with the inner surface of the cylinder and a projecting member that projects proximally from the sealing member. A locking element interacts between the stopper and the piston rod. The locking member includes a central body portion having at least one cantilevered leg extending distally outward from the body portion wherein the leg includes an outwardly directed sharp free end to engage with the inner surface of the cylinder. The locking member movably engages the shoulder of the stopper and movably engages the inner surface of the plunger rod. A structure is provided to match the element of

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-4 engaging distally on the plunger rod during proximal movement of the plunger rod to draw fluid into the chamber and to engage the distal locking member on the shoulder of the stop during distally directed movement of the plunger rod to supplying fluid from the chamber through the conduit and means for engaging the locking element with the inner surface of the cylinder side wall to prevent reuse of the assembly of syringe.

A structure for engagement of the latch with the inner surface of the cylinder side wall may include an opening in the distal end of the plunger rod to shorten the axial length of the inner surface area of ​​the opening to allow the end to Sharp free protrudes outward beyond the piston rod and onto the inner surface of the cylinder.

The mating structure includes at least one pawl on the inner surface of the distal end of the plunger rod, at least one boss pawl on the boss, and at least one arm cantilevered on the abutment having a rib that it extends outward near its free end sized to engage a recess in the inner surface of the plunger rod. The mating structure further includes that the locking member has at least one finger member that extends inwardly from an opening in the central body portion of the locking member. The locking member is located with its sharp free end in contact with the inner surface of the plunger rod proximal to the at least one pawl and the projecting member is located in the opening of the locking member in which the at least A finger member is in contact with the protrusion member proximally of the at least one protrusion pawl and the outwardly extending rib is located in the recess of the plunger rod.

The syringe assembly can be configured so that at least one pawl on the plunger rod includes two axially spaced pawls and the at least one pawl on the boss includes two axially spaced boss pawls so that the piston rod can move distally once or twice before proximal movement of the plunger rod causes the locking element to engage the inner surface of the cylinder, depending on the initial position of the locking element at the time of use. The two axially spaced pawls on the plunger rod may include two axially spaced steps, each with a blunt surface at its distal end that extends inwardly from the interior surface of the plunger rod. The two guarantors of

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Axially spaced projections may both include a proximally inwardly extending inclined surface and a blunt surface at a distal end of each of the radially inwardly extending inclined surfaces.

The at least one cantilevered leg of the latch may include two cantilevered legs located on opposite sides of the central body portion. The stop may further include two radial cam protrusions positioned to contact and bias the two cantilevered legs outwardly when excessive force directed proximally to the plunger rod is applied in an attempt to overcome engagement of the locking element. with the inner surface of the cylinder.

The at least one cantilever arm of the stopper may include two cantilever arms located on opposite sides of the boss and said at least one recess on the inner surface of the plunger rod may include two recesses located on opposite sides of the plunger rod and configured to receive the outwardly extending ribs of the two cantilevered arms.

The barrel of the syringe may further include an elongated tip that extends distally from the distal wall and has a passage therethrough in fluid communication with the chamber of the syringe. The syringe assembly may also include a needle cannula with a distal end, a proximal end, and an internal passage therethrough, wherein the proximal end of the needle cannula connects to the distal end of the syringe barrel such that the internal passage is in fluid communication with the cylinder conduit. The syringe assembly can include a locking element made of sheet metal such as stainless steel. Furthermore, the stopper and all its elements can be integrally formed of thermoplastic material.

Brief description of the drawings

Fig. 1 is a side elevation view of the syringe assembly of the present invention.

Fig. 2 is a side elevation end view of the proximal end of the syringe assembly of Fig. 1.

Fig. 3 is a cross-sectional view of the syringe assembly of Fig.

taken along line 3-3.

Fig. 4 is a perspective view of the plunger rod of the syringe assembly viewed from its distal end.

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-6 Fig. 5 is a perspective view of the locking element of the syringe assembly seen from its distal end.

Fig. 6 is a perspective view of the locking clip seen from its proximal end.

Fig. 7 is a perspective view of the top of the syringe assembly viewed from its distal end.

Fig. 8 is a perspective view of the stop seen from its proximal end.

Fig. 9 is an exploded side elevation view of the plunger assembly.

Fig. 10 is a cross-sectional view of the plunger assembly of Fig. 9 taken along line 10-10.

Fig. 11 is an enlarged partial cross-sectional view of the syringe assembly of Fig. 1 taken along line 3-3 showing the syringe assembly prior to use.

Fig. 11A is an enlarged partial cross-sectional view similar to Fig.

11, but rotated 90 °.

Fig. 12 is an enlarged partial cross-sectional view of the syringe assembly of Fig. 1 taken along line 3-3 showing the syringe assembly after a first aspiration stroke.

Fig. 12A is an enlarged partial cross-sectional view similar to Fig.

12, but rotated 90 °.

Fig. 13 is an enlarged partial cross-sectional view of the syringe assembly of Fig. 1 taken along line 3-3 showing the syringe assembly during a first delivery stroke.

Fig. 13A is an enlarged partial cross-sectional view similar to Fig.

13, but rotated 90 °.

Fig. 14 is an enlarged partial cross-sectional view of the syringe assembly of Fig. 1 taken along line 3-3 showing the syringe assembly after the beginning of a second aspiration stroke.

Fig. 14A is an enlarged partial cross-sectional view similar to Fig.

14, but rotated 90 °.

Fig. 15 is an enlarged partial cross-sectional view of the syringe assembly of Fig. 1 taken along line 3-3 showing the syringe assembly after a second dispensing stroke.

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-7 Fig. 15A is an enlarged partial cross-sectional view similar to Fig.

15, but rotated 90 °.

Fig. 16 is an enlarged partial cross-sectional view of the syringe assembly of Fig. 1 taken along line 3-3 showing the position of the internal components in the event of an attempt to remove the plunger after of the second administration career.

Fig. 16A is an enlarged partial cross-sectional view similar to Fig.

16, but rotated 90 °.

Fig. 17 is an enlarged partial cross-sectional view similar to the syringe assembly of Fig. 16 showing the interaction of an additional structure to prevent reuse.

Fig. 17A is an enlarged partial cross-sectional view similar to Fig.

17, but rotated 90 °.

Fig. 18 is an enlarged partial cross-sectional view similar to the syringe assembly of Fig. 17 showing a discontinuity in the syringe barrel for engagement of the locking element.

Detailed description of the invention

The present invention is directed to a syringe assembly that has a passive disabling mechanism. The disablement mechanism allows variable doses through the syringe assembly and allows a set number of cycles or strokes through the plunger rod before being automatically disabled. In a preferred embodiment, the disablement mechanism provides two aspiration and two dispense cycles before being automatically disabled. The assembly allows the aspiration and dispensing of a selected volume of a diluent into a vial to reconstitute a drug, pharmaceutical agent, or other substance and then aspirate the reconstituted substance back into the syringe. A selected volume of the reconstituted substance can be injected or administered to a patient in which the volume of the substance that is delivered can be the same or different than the volume of the substance aspirated into the barrel of the syringe. The syringe is automatically rendered useless after the injection or delivery stroke by retracting the plunger rod, which activates the disabling mechanism.

The disable mechanism is actuated by axial movement of the plunger rod relative to the syringe barrel and to the stop, moving the rod

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-8 piston in the suction direction. The stopper engages the plunger rod to allow limited axial movement of the stopper relative to the plunger rod. The disabling mechanism moves through a series of stages, by reversing the direction of axial movement of the plunger rod with respect to the stop to move the mechanism in a staggered manner to the disabling position. The inoperative position of the mechanism is achieved by the relative movement between the plunger rod and the stopper and is not dependent on the position of the stopper on the syringe barrel or the length of the stopper stroke. In this way, the syringe assembly is capable of dispensing a desired volume of the drug or other substance, and the disable mechanism can be actuated after the last dispensing or injection stroke, regardless of the position of the stop on the cylinder of the injection. syringe. By actuating the disable mechanism, the stopper cannot retract to draw a substance into the syringe barrel, but allows any remaining substance in the syringe barrel to be dispensed.

Referring to the drawings, a syringe assembly 100 having an inoperative mechanism includes a syringe barrel 102 and a plunger assembly 104. The barrel 102 includes a cylindrical side wall 106 that has an interior surface 107 that defines a chamber 109 for fluid retention, an open proximal end 113 and a distal end 115 that includes a distal wall 117 having a conduit 119 therethrough in fluid communication with the chamber. In this embodiment, the distal wall of the cylinder includes an elongated tip extending distally therefrom and having a conduit in fluid communication with the conduit in the distal wall. In this embodiment cylinder 102 also includes a needle cannula 170 having a proximal end 171, a distal end 172, and an internal passage 173 therethrough. The proximal end of the needle cannula is attached to the elongated tip 103 such that the inner lumen of the needle cannula is in fluid communication with the conduit 119 in the barrel.

Plunger assembly 104 includes an elongated plunger rod 108, a stopper 128, and a locking member 130. Plunger rod 108 includes a proximal end 111, an open distal end 110, and an inner surface 116 and at least one aperture. or recess 114 in the inner surface at the distal end of the plunger rod. The recess includes a distal face 121. In this embodiment, there are two recesses 114 having distal faces 121. The inner surface at the distal end of the plunger rod includes at least one pawl. In this embodiment, the at least one pawl on the inner surface of the distal end of the plunger rod includes four

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-9 locks 118 axially spaced with two pawls on each side of the plunger rod. Each pair of pawls is configured to form axially spaced steps 120, each step having a blunt surface 122 at its distal end and extending inwardly from the interior surface of the plunger rod.

Stop 128 includes a circular-shaped sealing element 144 having a peripheral surface 145 that forms a seal with the inner surface of the cylinder. A protrusion member 134 extends proximally from the sealing member and includes at least one protrusion pawl and, in this embodiment, contains two protrusion fasteners 136. At least one cantilevered arm extends proximally from the sealing member and in this embodiment there are two cantilevered arms 140 extending proximally from the sealing member. Each of the cantilevered arms includes an outwardly extending rib 142. The rib is sized to fit within the recess 114 in the plunger rod. The axially spaced boss catches 136 include a sloped surface 137 extending proximally inward and a blunt surface 138 at a distal end of each of the sloped surfaces. The stopper is preferably integrally formed of thermoplastic material, such as polyethylene. The circular-shaped sealing member and / or the peripheral sealing surface thereof can be made of an elastomeric material, such as thermoplastic elastomers, natural rubber, synthetic rubber, and combinations thereof.

Locking member 130 includes a central body portion 148 having an opening 152 therethrough and at least one cantilevered leg 150 extending distally outward from the body portion and at least one finger element 154 extending inward from the opening. In this embodiment, at least two cantilevered legs, each of the cantilevered legs having a sharp free end 155 directed outwardly for engagement on the inner surface of the cylinder. The configuration of the sharp free end 155 can be any configuration capable of engaging the inner surface of the cylinder, such as a sharp edge or one or more pointed teeth and the like. The locking element can be made of various materials, or combinations of materials, however, it is preferred that it have the sharp free ends made of metal and it is also preferred that the entire locking element is integrally made of sheet metal, such as stainless steel.

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-10 In this preferred embodiment the plunger assembly 104 is assembled by inserting the locking element 130 into the distal end of the plunger rod 108. The protrusion 134 of the stop 128 is then inserted into the distal end of the plunger rod through the opening 152 of the locking element 130 so that the cantilevered legs 150 extend towards the circular-shaped sealing element 144 of the stop as shown in Figures 9 and 10.

As explained in more detail hereinafter, the plunger assembly is then inserted into barrel 102 through the open proximal end 113 to the initial position illustrated in Figures 11 and 11A. In the initial position of the syringe member, the locking member 130 is positioned with its sharp free ends 155 in contact with the inner surface of the axial piston rod proximally of the spaced steps 120 in the axial direction. The protruding member 134 is positioned in the aperture 152 of the locking element 130 so that the finger elements 154 contact the protruding member proximally of the protrusion latches 136. The outwardly extending ribs 142 of the cantilevered arms 140 are located in the recesses 114 in the piston rod. Ribs 142 are configured to complement recesses 114 to allow limited axial movement of the stop relative to the plunger rod. Stop 128 further includes a stabilizer member 146 located proximal to seal member 144 and has an external dimension that complements the other dimension of seal member as shown in Figure 11A, Stabilizer member 146 has an outer dimension to contact the inner surface of the syringe barrel and is spaced from sealing member 144 to aid in stabilization of stop 128 to maintain stop and projecting member 134 in an orientation substantially parallel to the syringe barrel shaft. In the position illustrated in Figures 11 and 11A, the syringe assembly 100 is ready to be used to draw liquid into the cylinder chamber.

As will now be shown, the operation of the plunger assembly of this embodiment includes a first aspiration stroke followed by a first dispensing stroke, a second aspiration stroke, and a final dispensing stroke after which the syringe is rendered useless. The disabling elements prevent or inhibit the movement of the stopper 128 in the proximal aspiration direction which limits the operation of the syringe assembly to a single use. The maximum number of strokes is limited by a series of pawls located axially on the piston rod and the number of boss pawls located

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-11 axially on the stop. However, the actual number of strokes the syringe can make will be determined by the position of the locking member relative to the pawls on the plunger rod and the pawls on the stop at the time of first use. For example, a syringe with two plunger pawls and two stopper pawls can be supplied to the end user as a syringe capable of two strokes or four strokes. This is an important feature of the present invention as a single syringe assembly can be provided with different stroke limitations prior to disablement.

The syringe assembly can now be used to draw liquid, such as a sterile water diluent into the barrel chamber by applying a proximally directed force to a thumb oppressor 123 at the proximal end of the plunger rod at the same time. holding the syringe barrel. As illustrated in Figures 12 and 12A, this causes the plunger rod to move proximally with respect to the stop until the free end of the cantilevered legs 150 moves distally along the inner surface. 116 of the plunger rod and snaps past the blunt surface 122 of the more proximal steps 120 spaced axially, as best illustrated in FIG. 12. Furthermore, during this first suction stroke the outwardly extending ribs 142 engage the distal surface 121 of the recesses 114 in the plunger rod as best illustrated in FIG. 12A. When ribs 142 engage distal surface 121 the stop is attracted proximally relative to the cylinder as the plunger rod moves. The stopper is now moved proximally, through the action of the plunger rod, until the user determines the desired volume of liquid in the chamber.

The liquid diluent in the chamber can now be discharged into a dry medication vial such as lyophilized medication, for reconstitution. This first dispensing stroke is achieved by moving the plunger rod distally while holding the cylinder. A barrel flange 124 is provided at the proximal end of the barrel to help control movement of the barrel during use of the syringe assembly. As best illustrated in Figures 13 and 13A, as the plunger moves distally, the locking member 130 moves with the plunger rod pulling the locking member with it so that the finger members 154 on the latch they slide from the most proximal to the most distal overhang pawl as they rise up the inclined surface 137 and fall into the second pawl. When the plunger rod contacts the plug,

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-12 the stopper will begin to move distally, along with the plunger rod to discharge liquid diluent from the chamber into, for example, a vial of lyophilized medication.

When the diluent and lyophilized medication are mixed, the syringe assembly of the present invention can already be used to draw the reconstituted, ready-to-inject medication into the syringe barrel chamber, as best illustrated in Figures 14 and 14A, by applying a force directed proximally to the plunger rod while holding the barrel of the syringe. The proximally directed force will cause the plunger rod to move in a proximal direction at the same time that the locking member 130 remains relatively immobile due to its connection with the boss pawl on the plug. The proximal movement of the plunger causes the locking element to move distally along the inner surface of the plunger rod such that the sharp free end 155 of the cantilevered legs moves from the more proximal steps 120 axially spaced apart. on the plunger rod to axially spaced second most distal steps 120. The proximal movement of the plunger rod also causes the outwardly extending ribs 142 of the cantilever arms 140 to engage the distal surfaces 121 of the recesses 114 in the plunger rod so that the stopper now moves in proximal direction with the plunger rod drawing the reconstituted medication into the syringe barrel chamber up to a user-determined amount. An advantage of the present invention is that the amount of medication attracted to the chamber, and therefore the maximum amount of medication that can be delivered, is determined by the user at the time of use and not by the placement of the components in the time of manufacture.

The syringe assembly of the present invention is now ready for a second and final dispensing stroke, best illustrated in Figures 15-15A. Medication is delivered to the patient by applying a force directed distally to the plunger rod causing the plunger rod to move distally with respect to the cylinder. As the plunger rod advances distally, engagement of the sharp free ends 155 of the latch with the more distal blunt surfaces 122 of the axially spaced steps 120 moves the latch distally so that the latch members fingers 154 of the locking element rise over the most distally inclined surface 137 of the protrusion pawls distally beyond the pawl

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-13 136 more distal overhang. When the distally moving plunger rod contacts the stopper, both the stopper and the plunger rod move toward the distal end of the barrel to discharge the contents of the chamber through the conduit.

The syringe assembly has now been used and is ready for disposal. Any attempt to move the plunger rod in a proximal direction to refill the syringe assembly for later use will render the syringe unusable by the locking element. In particular, as best illustrated in Figures 16 and 16A, movement of the plunger rod proximally will allow the plunger rod to move a short distance until the sharp free ends 155 of the locking clip snap into place. past the end of the plunger rod and engage the inner surface 107 of the cylinder side wall. Further proximal movement of the plunger will be hampered by engagement of the locking member to the inner surface of the cylinder side wall. In addition, as illustrated in Figure 17, the cam surface 125 on the stop is positioned to force the sharp free ends 155 further toward the wall of the syringe barrel as more proximally directed force is used in an attempt to misuse the syringe. Consequently, increasing the force to draw the plunger rod out of the syringe results in an increase in the force of engagement of the sharp free ends of the locking member in the barrel. It is desirable to provide a cutout area 126 at the distal end of the plunger rod along the path of the sharp free ends of the latch to support the latch and allow it to engage the inner surface of the cylinder. In addition, the area at the end of the plunger rod in the area around the cutout can be configured to support the latch so that if the user accidentally withdraws the plunger a second time before administering the last dose of medication, the medication can still be administered even though the sharp free ends of the locking element are touching the cylinder, as long as they move distally and are not driven to engage the inner surface of the cylinder by the cutout and the plunger rod. In this case the area around the cutout supports and limits movement and helps prevent deformation of the sharp free end of the locking element.

It is also within the scope of the present invention to provide a discontinuity, such as a recess or protrusion on the inner surface of the cylinder,

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-14 as illustrated in Figure 18, to further enhance the engagement of the sharp free end of the locking member with the inner surface of the cylinder. In FIG. 18 the syringe barrel 102 includes a discontinuity in the form of an inwardly directed protrusion 127 on the inner surface 107 of the barrel. In this embodiment, the protrusion 127 is an annular ring that protrudes into the cylinder and extends 360 ° around the interior surface. The discontinuity may be in the form of an annular protrusion, an annular recess, or one or more protrusions or recesses shaped to engage the locking member, all positioned within the cylinder to engage the sharp free end 155 of the locking member 130 to further enhance plus the grip of the locking element on the cylinder and the inner surface.

The present syringe assembly provides an improvement over prior art devices by allowing a variable dose of diluent, chosen by the user at the time of use, to be drawn into the syringe, dispensing the diluent into a vial that contains a substance to be reconstituted, attracting a selected amount of the reconstituted substance back to the syringe, and then delivering the contents of the syringe. The selected amount of the reconstituted substance may be equal to or less than the total reconstituted volume at the discretion of the user. The syringe assembly is automatically disabled after the final injection stroke by reversing the direction of movement of the plunger rod from the dispensing direction to the aspiration direction. Following the injection stroke of the syringe plunger the plunger rod retracts to activate the disable mechanism to prevent axial movement of the stop towards the proximal end of the syringe barrel thereby preventing the stop from being withdrawn and preventing the reuse of the syringe.

When the present syringe assembly has two or more pawls on the stopper and on the plunger rod, the maximum number of strokes that the syringe assembly is allowed can be varied by the initial position of the locking element relative to the pawls of the stopper and piston rod pawls.

While various embodiments have been chosen to illustrate the invention, it will be appreciated that changes and modifications can be made without departing from the scope of the invention.