Syringe with needle guard injection device

The present invention provides for an injection device including a syringe with a proximal end, a distal end, a needle extending from the distal end, and a plunger inserted into the proximal end. A guard is slidable on the syringe, has a proximal end, a distal end, and is biased from a first position wherein the needle is exposed towards a second position wherein the guard covers the needle. The injection device includes first and second sets of cooperating detents for retaining the guard and syringe in the first and second positions, respectively. A latch member extends proximally from the guard that is engageable by the plunger as the plunger is depressed to release the first set of cooperating detents. Upon release, a spring element biases the guard towards the second position until the second set of cooperating detents engage and secure the guard in the second position.

FIELD OF THE INVENTION

The present invention relates generally to injection devices for administering therapeutic agents to patients, particularly to safety devices for syringes, and more particularly to syringe devices that include a needle guard slidably coupled to a syringe for covering a needle of the syringe after use.

BACKGROUND

Medication is often dispensed using a medicine cartridge, such as a syringe, having a barrel with a needle extending from one end and a plunger slidably inserted into the other end. Such cartridges are often referred to as “pre-filled syringes” because they may contain a specific dosage or volume of medication when they are initially provided, as compared to conventional syringes that are furnished empty and filled by the user before making an injection.

Alternatively, a medicine cartridge may be used, such as an ampoule or vial, that includes a penetrable seal instead of a needle on one end of the barrel, and/or a piston rather than a plunger on the other end. Such medicine cartridges are generally inserted into an adapter that includes a hollow body adapted to hold the cartridge, a plunger to engage and move the piston in the cartridge, and/or a double-ended needle to penetrate the seal and communicate with the interior of the barrel.

Because of the risk of communicable diseases, a number of syringes and adapters have been developed that are intended to prevent accidental needle sticks and/or inadvertent reuse of a syringe. Retractable needle devices have been suggested for this purpose that include a cartridge that allows a needle of the cartridge to be withdrawn into the barrel after medication is dispensed from it. For example, U.S. Pat. No. 4,973,316 issued to Dysarz discloses a syringe including a barrel having a needle assembly that is slidable within the barrel between an exposed position such that a needle on the assembly extends from the barrel and a retracted position wherein the needle assembly is withdrawn into the barrel. The needle assembly is initially locked in the exposed position, but may be disengaged upon depression of the plunger, whereupon a spring biases the assembly towards the retracted position, thereby withdrawing the needle into the barrel.

Alternatively, syringe holders have been suggested that include a body within which a conventional syringe or cartridge may be received, and a shield that is manually slidable with respect to the body to cover the needle. For example, U.S. Pat. No. 6,030,366, issued to Mitchell, which is assigned to the assignee of the present application, discloses a self-shielding guard that includes a body having an open proximal end for inserting a syringe into a cavity within the body, and a distal end with an opening through which a needle on the syringe may extend once received in the body. A shield is slidable over the body between retracted and extended positions to expose and cover the needle, respectively. With the shield in the retracted position and the needle exposed, an injection may be made, and then the shield may be manually advanced to the extended position. In the extended position, cooperating detents and detent pockets on the body and shield substantially permanently lock together, thereby preventing reuse of the needle, reducing the risk of accidental needle sticks, and/or facilitating disposal of the syringe.

As an alternative to requiring manual extension of a shield to cover a needle, spring-loaded devices have also been suggested. These devices often include a body and slidable shield, similar to the manual devices described above, but also may include a spring element to bias the shield to advance and cover the needle. An actuator, such as a button or lever, may be activated by the user to release the shield, thereby allowing the spring element to advance the shield to cover the needle. For example, U.S. Pat. No. 5,695,475 issued to Best, Jr. et al. and U.S. Pat. No. 4,923,447 issued to Morgan disclose spring-loaded syringe devices that include inner and outer sliding sleeves that include a button slidable in a longitudinal slot to selectively expose and cover a needle on the devices. A spring in the devices biases one of the sleeves to extend and cover the needle, but this bias may be manually overcome to expose the needle. Thus, these devices may not lock the extending sleeve in a covered position, and therefore may risk accidental needle exposure and/or reuse of the needle. In addition, although these devices are spring-driven, their shields may not extend unless they are manually activated by using a button, and therefore are not truly “passive,” but require an affirmative decision by a user to activate their safety feature.

Accordingly, an injection device that includes a needle shield for covering a needle after use would be useful.

SUMMARY OF THE INVENTION

The present invention is directed to injection devices incorporating both a syringe, such as a pre-filled syringe, or a medicine cartridge, and a guard that covers a needle of the syringe after a medication in the syringe is injected into a patient. The present invention is also directed to methods for making and using such injection devices.

In accordance with one aspect of the present invention, an injection device is provided that includes a syringe having a proximal end, a distal end, and a plunger extending from the proximal end. The injection device also includes a guard having a proximal end, a distal end, and a cavity therebetween. The guard is slidably mounted to the syringe and includes a latch member that extends proximally from the guard. A needle may extend from the distal end of the syringe. The guard is biased from a first or retracted position wherein the needle of the syringe is exposed, towards a second or extended position wherein the guard covers the needle. The guard may be biased by a spring element located in the distal portion of the guard and/or coupled to the syringe.

First cooperating detents on the syringe and the guard act to retain the guard in the first position. The first cooperating detents may include a ledge on the proximal end of the syringe and a catch on the latch member extending from the guard. Here, the ledge and detent engage one another to retain the guard in the first position. As the plunger is advanced within the syringe, the plunger may engage the latch member and release the first cooperating detents, whereupon the guard may slide towards the second position. Second cooperating detents may be provided on the syringe and guard to retain the guard in the second position. The second cooperating detents may include a detent on the guard and a corresponding detent pocket on the syringe.

Optionally, the guard may also include a window or slot that extends axially along the guard. When the slot is present on the guard, the syringe may include a stop tab configured to travel within the slot. The stop tab and slot may be configured to limit the proximal and distal movement of the syringe relative to the guard. For example, the stop tab may abut the distal edge of the slot or window when the guard is in the first position to prevent further distal movement of the syringe (or proximal movement of the guard). Similarly, the stop tab may abut the proximal edge of the slot when the guard is in the second position to prevent further proximal movement of the syringe (or distal movement of the guard). In addition, the guard may also include a set of finger flanges, grips, or protrusions usable for controlling the speed of advancement or sliding of the guard between the first and second positions.

In accordance with another aspect of the present invention, an injection device includes a guard having a proximal end and a distal end. The guard may be configured for slidably engaging a syringe, and may be biased between a first or retracted position and a second or extended position relative to the syringe, e.g., by a spring element. The injection device may also include a syringe having a proximal end, a distal end including a needle, and a plunger that extends from the proximal end. The needle may be coupled to the distal end of the syringe, i.e., molded to the distal end or a hub may be provided on the distal end of the syringe to which a needle may be attached, e.g., by threads or a luer lock. A latch member extends proximally from the guard that is detachably coupled with the syringe, thereby retaining the guard in the first position. The latch member is engageable by the plunger as the plunger is depressed for decoupling the latch member from the syringe. When the latch member is decoupled, the guard may be advanced from the first position towards the second position.

In a preferred embodiment, the latch member may include an intermediate portion that is engageable with a flange on the syringe, and a proximal portion that is engageable with the plunger as the plunger is advanced into the syringe. When the plunger engages the proximal portion of the latch member, the intermediate portion of the latch member may be deflected and released from the flange of the syringe. Additionally, cooperating detents on the guard and the syringe may secure the guard once the guard is advanced to the second position.

In accordance with yet another aspect of the present invention, a method is provided for delivering a therapeutic agent using an injection device. The injection device may include a guard having a proximal end, a distal end, and a latch member extending from the proximal end. The injection device may also include a syringe received in the guard including a needle extending from a distal end thereof, and a plunger extending from a proximal end thereof. The guard may be biased from a first position, wherein the needle is exposed, towards a second position, wherein the needle is covered by the guard.

Initially, the latch member may retain the guard in the first position. The needle may be inserted into a patient's skin while the user holds a portion of the injection device. A distal force may be applied to the plunger to inject the medication into the patient until the plunger contacts the latch member. The plunger may be depressed further to deflect the latch member, whereupon the guard may be released from the first position. The plunger may then be depressed yet further to complete delivery of the therapeutic agent. The user may then withdraw the needle from the patient's skin, and release the plunger, whereupon the syringe may retract proximally with respect to the guard until the needle is disposed within the guard. When the guard attains the second position, cooperating detents on the guard and the syringe may engage one another to lock the guard in the second position and/or prevent subsequent distal movement of the syringe relative to the guard.

DETAILED DESCRIPTION

Turning toFIGS. 1A-4C, a preferred embodiment of an injection device500is shown for administering a medication, e.g., a vaccine, drug, or other therapeutic or diagnostic agent, to a patient. The device500includes a syringe550including a needle556, and a guard502slidably attached to the syringe550. The guard502is preferably biased from a first position wherein the needle556is exposed (shown inFIG. 1A) towards a second position wherein the guard502covers the needle556(shown in FIG.1B).

As best seen inFIGS. 2A-2C, the syringe550includes a barrel552, a distal end or hub554from which the needle556extends, and a plunger553inserted into a proximal end522of the barrel552. In one embodiment, the needle556is attached to the hub554during manufacturing, and the device500is provided to a user with the needle556pre-attached. In another embodiment, the hub554includes a connector, e.g., a thread or luer lock adaptor. Thus, the device500may be provided to a user without a pre-attached needle556, and the user may attach a desired needle556to the hub554before use.

Although a substantially square cross-section is shown, the barrel552may have a substantially cylindrical cross-section, rectangular cross-section, or other suitably shaped cross-section. As illustrated, one or more stop tabs538may be provided on the barrel552. The stop tabs538extend transversely outwardly, e.g., on opposite sides of the barrel552. The plunger553may include a thumb pad551on its proximal end to move the plunger553axially within the barrel552. The thumb pad551may have a diameter or other cross-section that is larger than a dimeter of the barrel552of the syringe550. In addition, or alternatively, the plunger553may include an intermediate tab (not shown) located distally to the thumb pad551.

In the illustrated embodiment, one or more sets of ledges540may be provided, e.g., molded, on or near the proximal end522and on one or more side walls of the syringe550. Preferably, each ledge540has a sloping distal edge540aand a substantially blunt proximal edge540bdefining a detent pocket adjacent the proximal edge540b.

In addition, the syringe550may include one or more sets of detent pockets542,543adjacent the ledges540. A proximal set of detent pockets543may have substantially blunt proximal edge543band sloping or substantially blunt distal edges543a. A distal set of detent pockets542may be provided at a location on the syringe550distal to the ledges540and/or adjacent the distal end554of the syringe550. Similar to the proximal detent pockets543, the distal detent pockets542may have substantially blunt proximal edges542band have sloping or substantially blunt distal edges542a.

Turning toFIGS. 3A-3E, the guard502is a tubular member having an inner crosssection configured to slidably fit on the syringe550. For example, the inner cross-section of the guard502may be substantially rectangular, square, or cylindrical in cross-section, depending upon the cross-section of the syringe550. The guard502includes one or more side walls561a,561b, an open proximal end562, and an open distal end563defining a passage therebetween. Assembly tabs572with sloping or ramped interior surfaces573may be molded into and extend proximally from the side walls561a. Optionally, at least one side wall561a, e.g., opposing walls561a, may include an elongate opening or slot564therethrough for receiving the stop tabs538and/or for facilitating observation of the syringe550received in the guard502. A pair of finger grips515may be located on the guard502, e.g., on opposite side walls561b.

One or more latch members or fingers574extend proximally from the guard502, e.g., molded to the side wall(s)561b. Each latch member574includes an inwardly disposed catch or tab576located on an intermediate portion of the latch member574between the assembly tab572and a proximal tip578of the latch member574. The catches576and the ledges540may provide a set of cooperating detents for retaining the guard502in the first position. Alternatively, in embodiments where the syringe550lacks the ledges540(not shown), the catches576may engage with a flange on the proximal end522of the syringe550, or may engage the proximal end522itself, thereby defining a proximal set of cooperating detents that retain the guard502in the first position. Preferably, the latch members574are substantially flexible or semi-rigid, and may be curved such that the intermediate portions are disposed radially outwardly further than the proximal tips578when the latch members574are in a relaxed, unstressed state. Thus, if the proximal tips578are directed distally, the latch members574may partially bend or bow, thereby directing the intermediate portions, and consequently the catches576, transversely outwardly.

A plurality of detent arms570and a plurality of detents571are provided on the guard502, preferably molded directly to the side walls561b. The detents571preferably have shapes corresponding substantially to the shapes of the distal detent pockets542in the syringe550. For example, distal edges571aof the detents571may be ramped to facilitate slidable engagement with the proximal detent pockets543in the syringe550. Proximal edges571bof the detents571are substantially blunt for positively engaging the proximal edges542bof the distal detent pockets542and locking the guard502in the second position. Together, the detents571and distal detent pockets542at least partially define a second set of cooperating detents for securing the guard502in the second position.

As best seen inFIGS. 1B,4A, and4C, the injection device500may include a spring element504for biasing the guard502towards the second position. The syringe550may include a substantially blunt distal surface525that is proximal from the hub554, and the guard502may include a substantially blunt inner collar567. The spring502may be positioned concentrically within the guard502such that respective ends of the spring504engage the distal surface525and the inner collar567. Thus, the guard502and syringe550together at least partially define an annular space within which the compression spring504may be compressed when the guard502is in the first position. Alternatively, other configurations may be provided for the spring element504, such as those shown inFIGS. 5A-7B, and described further below.

The injection device500is pre-assembled such that the guard502is disposed in the first position, as illustrated in FIG.1A. In the first position, the catches576on the latch members574may engage the ledges540of the syringe550to retain the guard502in the first position. Specifically, the catches576on the latch members574engage the proximal edges540bof the ledges540on the syringe550, as seen inFIG. 1A, thereby retaining the guard502in the first position. In embodiments of the injection device500that lack the ledges540, the catches576may directly engage the proximal end522of the syringe550or a flange (not shown) on the syringe550. Optionally, in the first position, stop tabs538on the syringe550may abut the distal edge568of slots or windows564in the guard502, as shown in FIG.1A. Additional information on assembling the guard502and the syringe550, may be found in co-pending application Ser. No. 09/724,657, filed Nov. 28, 2000, the disclosure of which is expressly incorporated herein by reference.

Once assembled with the guard502in the first position, the injection device500may be used to inject medication from the barrel552into a patient (not shown). A needle cover (not shown) may be removed from the needle556, and the needle556inserted into the patient. Medication may then be delivered by directing the plunger553distally with the user's thumb until the thumb pad551contacts the tips578of the latch members574. While using the injection device500, the user preferably places a finger on each finger grip515and the thumb on the thumb pad551. As the plunger553is depressed further, the thumb pad551may cause the latch members574to compress axially, thereby deflecting the intermediate portions radially outwardly until the catches576are disengaged from the ledges540on the syringe550.

With the ledges540and catches576disengaged, the spring element504automatically biases the guard502distally towards the second position, i.e., to advance the distal end563of the guard502over the needle556. The syringe550may be maintained substantially stationary relative to the patient's skin, and the plunger553may be depressed further, if necessary, to complete the injection. When the catches576are disengaged, the guard502may advance until it contacts the patient's skin, and the needle556may be withdrawn from the patient, allowing the guard502to extend entirely over the needle556. As the guard502advances, the latch members574may slide distally along the syringe550.

When the needle556is withdrawn from the patient, the guard502may advance fully to the second position such that the guard502passes over and substantially covers the needle556. In the second position, shown inFIG. 4A, the detents571of the guard502enter and substantially engage the distal detent pockets542of the syringe550, thereby preventing subsequent proximal movement of the guard502. Stop tabs538on the syringe may also abut the proximal edges566of the slots564, thereby preventing further distal movement of the guard502. Thus, the guard502may be substantially permanently locked in the second or extended position, thereby preventing reuse of the injection device500and/or facilitating safe disposal of the injection device500.

In the second position, the spring element504may remain slightly compressed to provide a distal force that may ensure that the guard502is fully advanced and the detents571are received in the distal detent pockets542.

In further alternatives, additional elements may be provided on the syringe550and/or guard502to control the speed of advancement of the guard502from its initial activation in the retracted position, but allow free advancement as the guard502approaches the extended position. For example, a frictional material (not shown) may be applied to one or more contact surfaces between the syringe550and guard502that may increase the frictional resistance in the retracted position. An adhesive tape or viscous material (not shown) may be provided that peels off of, is cut or torn, or otherwise separates from the syringe550and/or guard502after partial advancement of the guard502. One or more “speed bumps” or similar protruding structures (not shown) may be molded into or otherwise provided on the syringe550and/or guard502that may be contacted when the guard502is in or close to the retracted position. A feature on one of the syringe550or guard502may travel through a corresponding tortuous feature on the other of the syringe550or guard502to slow the guard502down initially. In a further alternative, a spring or cushioned pad (not shown) may be provided on the distal end of the guard502that may soften the force with which the guard502contacts the patient if the guard502is allowed to advance.

In the embodiment described above, the spring element504is a helical compression spring. Alternatively, one or more springs (not shown) may be provided, e.g., in one or more corners of the guard502. For example, springs may be provided in diagonally opposite corners of the guard502in order to minimize the risk of subjecting the syringe550to torque as it advances from the retracted towards the extended position as may occur if only a single off-center spring is used. In another alternative, one or more helical extension springs504amay be provided that have respective ends that are secured to the syringe550and the guard502, as is shown schematically inFIGS. 5A-5C. The extension spring504amay be provided between the guard502and the syringe550. The extension spring504amay be under tension when the guard502is disposed in the retracted position, thereby biasing the guard502towards the extended position.

Other alternative spring elements may also be provided that may be coupled to the guard502and syringe550.FIGS. 6A and 6Billustrate an embodiment of the present invention having a coil spring element504bthat has one end mounted around a hub584aon the guard502(attachment point of hub584ato the guard502not shown) and the other end secured to the syringe550. The coil spring element504bmay unwind as the guard502is retracted to the retracted position, as inFIG. 6A, but is biased to wind back around the hub584ato advance the guard502towards the extended position, which is shown in FIG.6B. In another alternative, illustrated inFIGS. 7A and 7B, a leaf spring element504cmay be provided that has ends fixed to one of the guard502and the syringe550for distally biasing a hub584bcoupled to the other of the syringe550and the guard502(attached point of hub584bto body502not shown). The guard502may be retracted, thereby deflecting the leaf spring element504c, as inFIG. 7A, but when the guard502is released, the hub584band consequently the guard502may be advanced to the extended position as the leaf spring element504cattempts to return to its relaxed, undeflected state, as in FIG.7B.

In addition, if desired, any of the spring elements504-504cmay have a nonlinear spring rate, preferably having a spring rate when the guard502is disposed in the retracted position that is substantially more or less than its spring rate when the guard502approaches the extended position. A nonlinear spring rate may be useful to provide an injection device500that is “softer” upon activation, i.e., such that the spring element (504-504c) may apply a substantially lower force to the guard502when it is initially released from the retracted position than when it approaches the final extended position. For example, the thickness of the spring material may be varied along its length, different materials may be used for different portions of the spring, and the like. This “softer” spring may minimize the force with which the guard502contacts a patient being injecting using the injection device500, and thereby reduce the discomfort or anxiety that may be experienced by the patient. For example, the guard502may be activated with a softer force, such that the guard502more gently contacts the patient, but when the needle is withdrawn from the patient, a stronger force may be applied to the guard502to ensure that it advances completely to the extended position.

Turning toFIGS. 8A-8C, another method is shown for performing an injection using an injection device500. Unlike the previous embodiments, which generally discuss a guard advancing over a syringe, this method involves holding the guard502such that the syringe550may be automatically and/or controllably directed proximally to retract the needle556into the guard502. The guard502and syringe550are slidably attached to each other, similar to the previous embodiment. The guard502includes a spring element504, similar to the previous embodiments, for biasing the syringe550towards a second position wherein the guard502substantially covers the needle556.

As best seen inFIG. 8A, a needle cover (not shown) may be removed from the needle556, and the needle556may be inserted into a patient's skin700. A user may grasp finger grips515or otherwise grip an outer surface of the guard502. Thus, the guard502may be grasped to hold the injection device500substantially stationary with respect to the skin700during the injection.

To deliver medication from the syringe550, the user may grip the finger grips515and apply a distal force to the plunger553, preferably until thumb pad551engages latch members574extending from the guard502. As the plunger553is depressed further, the thumb pad551may cause the latch members574to compress axially and thereby deflect radially outwardly until the catches576(not shown inFIGS. 8A-8C) are disengaged from the ledges540(also not shown) of the syringe550, or are disengaged from the proximal end522if the syringe550does not include the ledges540. With the catches576disengaged, the spring element504may automatically bias the syringe550towards the second or retracted position, shown in FIG.8C.

Once the ledges540or the proximal end522are disengaged from the catches576, the user may gradually remove the distal force applied to the plunger553, allowing a controlled retraction of the syringe550to the retracted position. As the syringe550retracts to the retracted position, the guard502may remain substantially stationary with respect to the patient's skin700, and the needle556may be withdrawn from the patient and into the guard502, as shown inFIGS. 8B and 8C. Once in the fully retracted position, cooperating detents571,542on the guard502and syringe550engage one another to substantially and permanently lock the guard502over the needle556. Thus, the user may hold the finger grips515to position the injection device500a predetermined distance way from the patient's skin700, thereby avoiding any sudden contact between the guard502and the patient's skin700when the ledges540, or proximal end522, of the syringe550and the catches576are disengaged.

Alternatively, as shown inFIGS. 9A-9C, the user may hold the injection device500using finger grips515, insert the needle556into the patient's skin700, and then inject medication by applying a distal force to the plunger553until the thumb pad551engages a latch member574extending from the guard502. As described above, further depression of the plunger553deflects the latch member574to disengage the catches576, and release the guard502. The guard502may then automatically advance into contact with the patient's skin700, as shown in FIG.9B. The plunger553may be further advanced to complete the injection. Preferably, because the spring element504is not fully expanded, the syringe550remains biased to retract with respect to the guard502towards the retracted position. At this point, the user may gradually remove the distal force applied to the plunger553, allowing controlled retraction of the syringe550to the retracted position, as shown in FIG.9C. Once the syringe550retracts to the retracted position, the cooperating detents571,542may engage one another to substantially permanently lock the guard502over the needle556, similar to the embodiment discussed above.