Patent Description:
Needle retraction features have been incorporated into syringe assemblies to protect users from needle stick injuries. In conventional assemblies, the needle hub assemblies, including a needle cannula, are attached to the syringe barrel and must be withdrawn into the syringe barrel by a user or by a retraction feature. Alternatively, a needle shield may be placed over the needle cannula by the user or otherwise.

In conventional syringe assemblies in which the needle hub assemblies are retracted into the syringe barrel by a retraction feature, the retraction feature is often provided within the syringe barrel and/or the plunger rod disposed within the syringe barrel. Specifically, the plunger rod may include a chamber that houses the needle hub after it is retracted. The retraction feature typically includes a cutting element disposed between the plunger rod and the stopper that is used to open the stopper after the contents of the syringe barrel are expelled, to expose the chamber of the plunger rod to receive the retracted needle • hub. A spring is often incorporated in the needle hub assemblies to drive the retraction of the needle hub into the plunger rod.

Accordingly, such retraction features require cutting, breaking, piercing or other force-intensive mechanical action for activation and, thus, increased complexity to enable the sealed plunger and stopper to be breached during activation. Further, as most conventionally designed retractable needles are activated after dosing by continued pressure on the rear of the plunger rod, inadvertent activation of the retraction feature may occur since the same forces must be applied when expelling the contents of the syringe barrel. Moreover, some devices may be inadvertently activated during dosing if sufficient pressure is generated during expulsion of the contents of the syringe, for example, when the medication is viscous and requires the user to apply additional pressure or force to the plunger rod, which exceeds the force required to activate the retraction feature. Premature activation is especially problematic in applications where high forces are applied to the plunger rod, for example, during high speed injections.

The retraction features of conventional syringe barrels that are plunger-activated must withstand increased syringe pressures and associated increase in force applied to the plunger rod, as described above. These increased forces and pressure lead to a requirement for large activation forces which could exceed the operational forces in order to prevent premature activation. Since most conventional syringe barrels employ an additional plunger motion after full dispensing, and in the same manner as the dispensing motion, a threshold force must be used to allow the user to differentiate between a fully bottomed plunger and the activation of the retraction feature. The threshold force may be difficult to ascertain and maintain separately from the force applied to the plunger rod to expel the contents of the syringe barrel. Further, proper application of the threshold force may require a user to position the syringe barrel and the needle cannula at an increased angle to the patient's skin, instead of positioning the syringe barrel and needle cannula substantially parallel to the patient's skin. The additional force required to activate the retraction feature may cause additional pressure to be generated at the stopper or other removable opening in the plunger rod, which may be sufficient to cause the stopper and/or plunger rod to malfunction.

In conventional retractable syringe assemblies where the retraction feature and the subsequent housing of the needle hub are contained within the fluid path, the retraction feature and housing may cause a volume of medication to become trapped within the syringe barrel, thereby increasing waste and potentially affecting dosing accuracy. Further, a portion of the trapped medication may be expelled during the activation of the retraction feature causing splatter, if the retraction feature is activated when the needle cannula is outside of the patient, or an unintended increase in the dose administered to the patient, if the retraction feature is activated when the needle cannula is in the patient. Placement of the retraction feature within the syringe barrel may also cause trapped air to remain in the syringe barrel when purging or priming the syringe. This can lead to the possibility of injected air. The size of the syringe barrel must also accommodate the retraction feature and the needle hub assembly that will be housed therein after retraction.

In syringe assemblies which do not house the retraction feature within the fluid path, the retraction feature is often disposed at a location that requires the user to change their grip of the syringe assembly to activate the retraction feature. Such designs may not be ergonomically acceptable to certain users of these syringe assemblies.

Conventional retraction syringe assemblies often do not incorporate reuse prevention features, and thus, the retraction mechanism may be reset so the syringe barrel may be reused. The reuse of syringe assemblies without sterilization or sufficient sterilization is believed to facilitate the transfer of contagious diseases.

Accordingly, it would be desirable to provide a retractable syringe assembly with a retraction feature that does not interfere with normal operation of the syringe assembly and reduces the risk of premature activation or the retraction mechanism. It would also be desirable to provide a retractable syringe assembly which incorporates a reuse prevention feature.

<CIT> discloses a disposable safety syringe, which comprises a reservoir and a tubular sheath.

The subject-matter of the invention is defined by independent claim <NUM>.

In this disclosure, a convention is followed wherein the distal end of the device is the end closest to a patient and the proximal end of the device is the end away from the patient and closest to a practitioner.

Aspects of the disclosure pertain to retractable syringe assemblies and methods of aspirating and expelling a liquid from a syringe assembly.

A first aspect of the present disclosure pertains to a retractable syringe assembly having a retraction feature that is activated by the user to retract a needle hub assembly, which includes a needle cannula, into the syringe assembly.

In the embodiment shown in <FIG>, the retractable syringe assembly includes a dual syringe barrel <NUM> that includes fluid barrel <NUM> and a retraction barrel <NUM>. The retractable syringe also includes a needle hub assembly <NUM>, a plunger rod <NUM>, stopper <NUM> and a trigger element <NUM>. The fluid barrel shown in <FIG>, includes a distal end <NUM>, a open proximal end <NUM>, a sidewall <NUM> extending from the distal end <NUM> and the proximal end <NUM> including an inside surface <NUM> defining a chamber <NUM>. The inside surface <NUM> defines a cross-sectional width and may include a reuse prevention feature, that will be discussed in greater detail below. The distal end <NUM>, includes a distal wall <NUM> that encloses the distal end <NUM>. In the embodiment shown, the sidewall <NUM> includes a first aperture <NUM> for permitting fluid communication between the fluid barrel and the retraction barrel. As will be discussed in greater detail below, the first aperture <NUM> also permits fluid communication between a needle cannula disposed within the retraction barrel <NUM> and the retraction barrel <NUM> and the fluid barrel <NUM>.

The fluid barrels shown in <FIG> may include a reuse prevention feature. Specifically, the fluid barrel <NUM> may include a retaining element <NUM>. that extends around the entire circumference of the inside surface <NUM> of the fluid barrel <NUM> at a location adjacent to the proximal end <NUM> of the fluid barrel. The cross-sectional width of the inside surface <NUM> at the retaining element is less than the first cross-sectional width or the cross-sectional width of the inside surface <NUM> at the remaining locations along the length of the fluid barrel. In one or more embodiments, optional tabs or detents can be used to create a region of the fluid barrel <NUM> having a cross-sectional width that is less than the first cross-sectional width of the fluid barrel <NUM>. The retaining element may also be shaped to facilitate activation of the reuse prevention feature. For example, the fluid barrel <NUM> may also include a diameter transition region disposed proximally adjacent to the retaining element at the proximal end <NUM> of the fluid barrel <NUM>. The cross-sectional width of the inside surface <NUM> of the fluid barrel,at the diameter transition region increases from the distal end <NUM> to the proximal end <NUM> of the fluid barrel <NUM>. As will be described in greater detail below, in embodiments of the retractable syringe assembly that utilize a reuse prevention feature, the reuse prevention feature of the fluid barrel <NUM> cooperates with corresponding reuse prevention features on plunger rod <NUM> to lock the plunger rod <NUM> within the fluid barrel <NUM> and/or to disable the plunger rod <NUM> from further use.

An alternative embodiment is shown in <FIG>, wherein the retractable syringe assembly may include a single barrel <NUM>. In such embodiments, a portion of the barrel is divided by a dividing wall <NUM> into a fluid barrel <NUM> and the remaining portion of the barrel houses the retraction feature and the needle hub assembly and is referred to as the retraction barrel <NUM>. The dividing wall <NUM> may include an aperture <NUM> for permitting fluid communication between the fluid barrel <NUM> and the retraction barrel <NUM>. The single barrel <NUM> of <FIG> provides an ergonomic design which improves grip by providing a large diameter for small syringe sizes.

In the embodiments shown in <FIG>, the retraction barrel <NUM> is disposed adjacent to the sidewall <NUM> of the fluid barrel <NUM> in the embodiment shown in <FIG>. The retraction barrel <NUM> is configured to house a needle hub assembly <NUM> therein and the retraction feature. The retraction barrel <NUM> includes an open distal end <NUM> and an open proximal end <NUM>. A wall <NUM> having an interior surface <NUM> defining the needle chamber <NUM> extends from the distal end <NUM> to an open proximal end <NUM>. The wall <NUM> of the retraction chamber is adjacent to the sidewall <NUM> of the fluid barrel <NUM>. In one or more embodiments, the wall <NUM> may extend around the portions of the retraction barrel <NUM> that are not in direct contact with fluid barrel <NUM> and the sidewall <NUM> may form the barrier between the retraction barrel <NUM> and the fluid barrel <NUM>. In other words, the outside surface of the sidewall <NUM> may form the interior surface <NUM> of the retraction barrel <NUM> along the portion of the retraction barrel <NUM> that is in direct contact with the fluid barrel <NUM>.

The size of the needle chamber <NUM> may be modified to accommodate the needle hub assembly <NUM> and/or the retraction feature. According to one or more embodiments, the interior surface <NUM> of the retraction barrel <NUM> has a cross-sectional width that is smaller than the first cross-sectional width of the fluid barrel <NUM>. In specific embodiments, the cross-sectional width of the interior surface <NUM> of the retraction barrel is less than about <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% of the cross-sectional width of the inside surface <NUM> of the fluid barrel. Such designs in which the cross-sectional width of the interior surface <NUM> of the retraction barrel is less than the cross-sectional width of the inside surface <NUM> of the fluid barrel, provides ergonomic and functional advantages. For example, the overall appearance and handling of the dual barrel syringe is more appealing to the user. In certain embodiments, the retraction barrel can be nested within the fluid barrel. For example, both the retraction barrel and the fluid barrel may both be bounded or circumscribed by a common wall, and the retraction barrel may be partially or fully disposed within the fluid barrel, or alternatively, a dividing wall may separate a single barrel into two separate barrels, a fluid barrel and a retraction barrel.

The open distal end <NUM> of the retraction barrel <NUM> in the embodiment may be fully open or partially enclosed by, for example, a barrier wall (not shown) that partially encloses the open distal end <NUM>. The open distal end <NUM> may be free of a barrier wall and may be fully open. In such embodiments, the needle hub assembly forms a closure around the open distal end <NUM> such that there is fluid communication between the needle cannula and the aperture <NUM> that permits fluid communication between the fluid barrel <NUM> and the retraction barrel <NUM>. In one embodiment, as shown in <FIG>, the wall <NUM> may include a second aperture (not shown) that permits fluid communication with the fluid chamber <NUM> and the needle chamber <NUM>. The second aperture of the wall may also allow fluid communication between the fluid chamber <NUM>, needle chamber <NUM> and the needle cannula. The fluid communication between the fluid barrel <NUM> and retraction barrel <NUM> may be provided by a first conduit (not shown) that extends from a first aperture (not shown) of the fluid barrel <NUM> and the second aperture (not shown) of the retraction barrel.

According to one or more embodiments, the retraction barrel has a cross-sectional dimension that is smaller than the cross-sectional dimension of the fluid barrel. In specific embodiments, the cross sectional dimension of the retraction barrel is less than about <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% of the cross-sectional dimension of the fluid barrel. Such designs in which the cross-sectional dimension of the retraction barrel is less than the cross-sectional dimension of the fluid barrel, provides ergonomic and functional advantages. For example, the overall appearance and handling of the dual barrel syringe is more pleasing to the user.

The needle hub assembly may include a second conduit (not shown) that extends from an open end of the needle cannula to second aperture (not shown) of the retraction barrel. The second conduit may include an opening (not shown) that must be aligned with the second aperture to permit fluid communication between the needle cannula and the fluid barrel.

The needle hub assembly <NUM> is disposed within the retraction barrel <NUM> and includes a needle hub <NUM> and a needle cannula <NUM> attached to the needle hub <NUM>. The needle hub <NUM> includes a distal end <NUM> and a proximal end <NUM>. The needle cannula <NUM> includes a free and open distal end <NUM> end and an open proximal end <NUM> that is attached to the distal end <NUM> of the needle hub. The needle hub <NUM>, shown in <FIG> and <FIG>, includes a needle hub body <NUM> and a needle cannula support <NUM> disposed distally within the needle hub body <NUM>. The needle cannula support <NUM> includes a recessed portion (not shown) for partially housing one end of the needle cannula. The recessed portion may include a portion of the second conduit (not shown) that extends through the needle hub <NUM> to the second aperture (not shown) of the retraction barrel to permit fluid communication between the needle cannula <NUM> and the fluid barrel <NUM>.

The needle cannula <NUM> of the needle hub assembly <NUM> is biased to move in the proximal direction. In the embodiment shown, the needle hub assembly <NUM> is biased to move in the proximal direction, thereby biasing the attached needle cannula <NUM>. In the embodiment shown, the needle hub assembly <NUM> is biased to move in the proximal direction by a biasing element <NUM> disposed between the needle hub body <NUM> and the needle cannula support <NUM>. As shown more fully in <FIG>, the biasing element <NUM> is shown as surrounding the needle cannula support <NUM>. To assemble the needle hub assembly <NUM> with the biasing element <NUM>, the biasing element <NUM> is initially placed over the needle cannula support <NUM> and compressed, as shown in <FIG>. The needle hub body <NUM> includes a distal end <NUM>, a proximal end <NUM>, distal portion <NUM> disposed adjacent to the distal end and proximal portion <NUM> disposed adjacent to the proximal end. The distal portion <NUM> may include a conical fitting with an opening (not shown) therethrough for receiving the needle cannula <NUM>. The proximal end <NUM> includes two hinged enclosing walls <NUM>, <NUM>. The enclosing walls <NUM>, <NUM> surround the needle cannula support and the biasing element <NUM> as they are assembled with the needle hub body <NUM>. Specifically, the needle cannula <NUM> is inserted into the opening of the distal portion <NUM> as shown in <FIG>. The cross-sectional width of the opening increases from the proximal end of the distal portion <NUM> to the distal end of the distal portion <NUM> so that the needle cannula <NUM> extends through the opening, while the needle cannula support <NUM> remains within the distal portion <NUM>. The two hinged enclosing walls <NUM>, <NUM> of <FIG> are moved inwardly until they surround the needle cannula support <NUM> and the biasing element <NUM>, as shown in <FIG>.

In the embodiment shown, the biasing element <NUM> engages the needle cannula support <NUM>. The biasing element <NUM> may include a spring, which may be a compression spring that applies a constant force on the needle hub body <NUM> in the proximal direction. In alternative embodiments, the biasing element <NUM> may be provided in another form, for example, a lever arm (not shown) may be disposed between the needle hub and the barrier wall. The needle hub body <NUM> includes a frangible element <NUM> that supports biasing element <NUM>, the needle cannula support <NUM> and the needle cannula <NUM> from moving in the proximal direction. As will be explained in greater detail below, breaking the frangible element <NUM> will allow the biased needle hub <NUM> and the needle cannula <NUM> attached thereto to retract into the retraction barrel <NUM>.

In one or more variants, the entire needle hub assembly <NUM> may be biased. For example, the needle hub body <NUM>, needle cannula support <NUM> and the needle cannula <NUM> may be provided as an integral unit that is biased and the retraction barrel may include a support element (not shown) that is frangible and applies a force on the needle hub assembly <NUM> in the distal direction. The biasing element <NUM> may be located between the needle hub assembly <NUM> and the distal end <NUM> of the retraction barrel <NUM>. The force applied by the support element to the needle hub assembly <NUM> in the distal direction counteracts the force applied to the needle hub assembly <NUM> by the biasing element <NUM> in the proximal direction. Once the support element is broken, the needle hub assembly <NUM> may be retracted into the retraction barrel <NUM>.

The frangible element <NUM> is shown in <FIG> as a partially extending shelf wall <NUM> that is disposed along portions of the inside surface of the needle hub body <NUM>. The shelf wall <NUM> extends radially inwardly to form a supporting barrier that is positioned adjacent to the biasing element <NUM> that surrounds the needle cannula support, which prevents movement or expansion of the biasing element <NUM>. Once the frangible element <NUM> is broken, for example, by the movement of the trigger element <NUM> in the distal direction, the engagement between the biasing element <NUM> and the needle cannula support <NUM> cause the biasing element <NUM> to move the needle cannula support <NUM> and the needle cannula <NUM> attached thereto into the trigger element <NUM> and/or the retraction barrel <NUM>. Specifically, the expansion of the biasing element <NUM> drives the needle cannula support <NUM> and the needle cannula <NUM> into the trigger element <NUM> and/or the retraction barrel <NUM>.

The needle hub assembly is sized moveable within the needle chamber. The size and shape of the needle hub assembly may be modified to permit movement in needle chambers having different sizes. In the assembled state, prior to use, the needle hub assembly is positioned at the open distal end of the retraction barrel.

A plunger rod <NUM> is disposed within the fluid barrel <NUM> and includes a stopper <NUM> attached thereto for forming a fluid-tight seal with the inside surface <NUM> of the fluid barrel <NUM>. The plunger rod <NUM> may include a reuse prevention feature that locks the plunger rod <NUM> within the fluid barrel <NUM> or otherwise disables the plunger rod <NUM>. The plunger rod may include a reuse prevention feature that cooperates with a reuse prevention feature disposed on the fluid barrel <NUM>. In one or more embodiments, the plunger rod may include a protrusion <NUM> that has a cross-sectional width that is greater than the cross-sectional width of the inside surface <NUM> of the fluid barrel <NUM> at the retaining element <NUM>. As discussed above, the retaining element forms a smaller cross-sectional width than at other locations along the length of the fluid barrel <NUM>. Accordingly, when the protrusion of the plunger rod advances distally past the retaining element of the fluid barrel <NUM>, the smaller cross-sectional width of the retaining element prevents movement of the protrusion in the proximal direction. Accordingly, the plunger rod <NUM> is locked within the fluid barrel <NUM> by the retaining element. In one or more embodiments, the stopper <NUM> and/or the plunger rod <NUM> may have a structure to permit relative movement of the plunger rod <NUM> with respect to the stopper <NUM>. For example, the stopper <NUM> may have an interior recess that allows the distal end of the plunger rod <NUM> to move in the distal and proximal directions within the interior recess, thus elongating and shortening the length of the plunger rod and the stopper. Exemplary plunger rods and stoppers which permit relative movement of the plunger rod with respect to the stopper are disclosed in <CIT> (published as <CIT>) and <CIT> (published as <CIT>).

The stopper <NUM> may also include reuse prevention features that also cooperates with reuse prevention features disposed on the fluid barrel <NUM>. For example, the stopper <NUM> may include a sealing portion (not shown) that has a cross-sectional width that is greater than the cross-sectional width of the inside surface <NUM> of the fluid barrel <NUM> at the retaining element. In such embodiments, removal of the stopper <NUM> is prevented because the smaller cross-sectional width of the retaining ring of the fluid barrel <NUM> prevents the stopper <NUM> from being removed. The plunger rod <NUM> and the stopper <NUM> may be joined by a frangible connection <NUM> that may cause the plunger rod <NUM> to become disconnected from the stopper <NUM>, while the stopper <NUM> remains locked within the fluid barrel <NUM> by the retaining element. Exemplary stoppers which include a reuse prevention feature and plunger rods and stoppers joined by a frangible connection are disclosed in <CIT> and <CIT>, referred to above.

The retractable syringe assembly <NUM> also includes a trigger element <NUM> that includes a distal end <NUM> and a proximal end <NUM>. The trigger element <NUM> is moveable independently of the plunger rod <NUM> and extends into the needle chamber <NUM> of the retraction barrel <NUM>. In the embodiment shown in <FIG>, the trigger element <NUM> includes a trigger pad <NUM> on which the user applies a force in the distal direction to activate the retraction mechanism of the syringe assembly.

The trigger element <NUM> is sized, shaped and positioned to provide a trigger force on the frangible element <NUM> of the needle hub body <NUM> to release the biasing element <NUM> so the needle cannula <NUM> retracts and is housed into the retraction barrel. The trigger element <NUM> includes a trigger element body <NUM> that extends from the distal end <NUM> to the proximal end <NUM>. The trigger element body <NUM> is shaped to have a cylindrical shape and is elongate. In the embodiment shown, the trigger element <NUM> has an open distal end <NUM> and the trigger element body <NUM> has a hollow interior <NUM> to house the needle hub <NUM> and the needle cannula <NUM>. The proximal end <NUM> of the trigger element is closed and may be tapered to retain the needle hub <NUM> within the hollow interior <NUM> after the needle hub <NUM> and the needle cannula <NUM> is retracted into retraction barrel. The needle cannula support <NUM> may also include structure to retain the retracted needle cannula support <NUM> and the needle cannula <NUM> within the trigger element <NUM>.

The open distal end <NUM> of the trigger element may have a beveled edge that breaks the frangible element <NUM> more efficiently by concentrating the force applied to the frangible element <NUM>. The breaking of the frangible element <NUM> releases the force applied to the biasing element <NUM> and the needle cannula support <NUM> in the distal direction. After the release of this distally direction force, the force applied on the needle cannula support <NUM> by the biasing element <NUM> in the proximal direction remains due to the compression of the biasing element <NUM>. The expansion of the biasing element <NUM> or the presence of the proximally directed force on the needle cannula support <NUM> by the biasing element <NUM> causes the needle hub <NUM> to retract or move into the retraction barrel <NUM> or specifically, the hollow interior <NUM> of the trigger element.

In use, as shown in <FIG>, the user is free to aspirate fluid or liquid into the fluid barrel <NUM> and expel the fluid without inadvertently activating the retraction mechanism and retracting the needle cannula. After the user aspirated and expelled the liquid as desired, the user may activate the retraction mechanism by applying a force on the trigger element <NUM> in the distal direction. The separate retraction barrel <NUM> and the needle chamber <NUM> allows the use of a reliable or constant activation force to activate the retraction mechanism. Specifically, the activation force is no longer dependent on the viscosity of the liquid filled within the fluid chamber <NUM>. In addition, the activation force no longer has to compensate for the risk of accidental activation during normal operation of the syringe assembly, and, therefore, the activation force may be set at a low level. Moreover, because the retraction feature no longer has to cut through a stopper, as required by some retractable syringe assemblies, the activation force can be optimized to solely activate the retraction feature, instead of also being optimized to penetrate stoppers.

In addition, the separation of the retraction mechanism from the fluid barrel <NUM> also reduces the risk of accidental activation because it is no longer coupled with the aspiration and injection of the fluid using the plunger rod. Accordingly, there is no risk of premature activation of the retraction mechanism by applying high force during high speed injections. In use, after the finger or thumb is used to apply a force on the plunger rod <NUM> to expel the contents of the fluid barrel <NUM>, the user simply shifts the finger or thumb to the trigger pad <NUM> disposed adjacent to the thumb press <NUM> at the proximal end of the retraction barrel <NUM>. The user does not need to modify their grip or utilize two hands to activate the retraction mechanism, as is required in known embodiments of retractable syringe assemblies.

The separation of the retraction barrel, needle hub assemblies and the retraction feature of the syringe assemblies disclosed herein also allows the use of exchangeable needles for all dimensions of the retractable syringe. The asymmetrical orientation of the needle hub assembly, with respect to the entire syringe assembly, facilitates low angle injections (i.e. subcutaneous injections). Further, the asymmetrical orientation also allows the user to detent needle cannula orientation by simply gripping the syringe assembly.

In one or more embodiments, the needle hub assembly may be attached to the retraction barrel to provide a leak proof pathway for the liquid. In one or more embodiments, this is accomplished by utilizing a needle hub assembly that includes a sealing member, which is activated by the pressing and turning required to assemble the needle hub assembly. The pressing and turning motions are achieved by incorporating slightly wedged surfaces on the needle hub assembly which attach to corresponding structures on the retraction barrel. The needle hub assembly may also be designed to be turned and attached in one direction. This allows the needle hub assembly to be locked in a defined position, while the torque applied is turned into sealing pressure.

In the embodiment shown in <FIG>, the needle hub assembly <NUM> may be shaped and sized to cooperate with the retracting barrel <NUM> and a needle shield <NUM> to provide sealing pressure to the retraction barrel. In the embodiment shown, the retraction barrel <NUM> includes a wall <NUM> that extends from an open distal end <NUM>. The wall includes a securing element <NUM> disposed at the distal end <NUM> for securing the needle hub assembly <NUM> to the retraction barrel. The securing element <NUM> is formed integrally with the sidewall of the barrel, as shown in <FIG>. In the embodiment shown, the securing element <NUM> includes at least one indentation or opening <NUM> for receiving a corresponding finger element or other protrusion on the needle hub assembly. In the embodiment shown, the opening <NUM> extends in a distal direction from the open distal end <NUM>. The securing element also includes at least one inwardly extending protuberance <NUM> that is disposed adjacent to the opening <NUM>. The protuberance <NUM> extends inwardly into the open distal end <NUM> of the retraction barrel.

The retraction barrel <NUM> is attached to a fluid barrel <NUM> with a fluid chamber (not shown) that includes an aperture <NUM> for permitting fluid communication between the needle hub assembly <NUM> and the fluid chamber. The aperture <NUM> is disposed on the opposite side of the open distal end <NUM> of the retraction barrel from the protuberance <NUM>. The securing element <NUM> of the retraction barrel may include alternative structure which cooperates with the needle hub assembly <NUM> to secure the needle hub assembly <NUM> to the retraction barrel.

As shown in <FIG>, the needle hub assembly <NUM> is assembled with a needle shield <NUM> prior to attachment to the retraction barrel. As shown in <FIG>, the needle hub assembly includes a needle hub body <NUM> having a distal end <NUM> and a proximal end (not shown). The distal end <NUM> includes an opening <NUM>. A needle cannula <NUM> is disposed within the needle hub body <NUM> and extends through the opening <NUM> of the needle hub body. A biasing element (not shown) may be disposed within the needle hub body <NUM> as otherwise described herein, for example, with reference to <FIG>. The needle hub body <NUM> includes an outside surface <NUM> that includes an attachment element <NUM> that engages the securing element <NUM> of the retraction barrel <NUM>. The outside surface <NUM> has a generally rounded conical shape or a curved conical shape. In the embodiment shown, the attachment element <NUM> of the needle hub assembly includes at least one radially outwardly extending tab <NUM> disposed on the outside surface <NUM> of the needle hub body. The tab <NUM> engages the protuberance <NUM> by sliding under the protuberance <NUM> such that the protuberance <NUM> exerts a force in the proximal direction on the tab <NUM>, when the needle hub assembly <NUM> is attached to the retraction barrel.

The needle hub body <NUM> also includes an open conduit <NUM> for permitting fluid communication between the needle cannula <NUM> and the aperture <NUM> of the fluid barrel. In the embodiment shown, the position and location of the attachment element <NUM> and the securing element <NUM> permits alignment of the open conduit <NUM> and the aperture <NUM>. Moreover, proper engagement of the attachment element <NUM> and the securing element <NUM> ensures fluid communication between the fluid barrel <NUM> and the needle cannula <NUM>.

In the embodiment shown, the needle hub body <NUM> also includes at least one finger element <NUM> disposed along the outside surface <NUM>. Specifically, the finger element <NUM> has a distal end <NUM> that is attached to the outside surface <NUM> and proximal end <NUM> that is free and unattached to the outside surface <NUM> of the needle hub body <NUM>. In the embodiment shown in <FIG>, the finger element <NUM> is flexible to extend outwardly from the outside surface of the hub body. Application of a radially outwardly-directed force on the finger elements <NUM> cause the proximal end <NUM> to lift off the outside surface <NUM> of the needle hub body. The finger element <NUM> in the embodiment shown has an elongate shape that extends a distal ring <NUM> that is disposed distally adjacent to the midpoint between the distal end <NUM> and the proximal end (not shown) of the needle hub body <NUM>. The distal ring <NUM> in the embodiment shown forms an indentation on the outside surface <NUM> of the needle hub body <NUM> that extends along the perimeter of the outside surface <NUM>. In one variant, the distal ring may form a rib that extends outwardly from the outside surface <NUM>.

The finger element <NUM> has a rounded distal end <NUM> in the embodiment shown, but may include a distal end <NUM> having a different shape. The finger element <NUM> forms a raised platform with respect to the outside surface <NUM> of the needle hub body <NUM>. From the distal end <NUM> to a bent portion <NUM>, the finger element <NUM> extends substantially parallel to the conically shaped outside surface <NUM> of the needle hub body <NUM>. From the bent portion <NUM> to the proximal end <NUM>, the finger element <NUM> extends substantially parallel to the retraction barrel <NUM>. The outside surface <NUM> also includes an indented portion <NUM> adjacent to the finger element <NUM>. The indented portion <NUM> does not have a curved conical shape, like the remaining portions of the outside surface <NUM>, but instead, has a surface that is parallel to the retraction barrel or is inwardly curved with respect to the retraction barrel. The finger element <NUM> and the indented portion <NUM> are disposed adjacent to the tab <NUM>. In the embodiment shown, the needle hub body <NUM> includes two tabs <NUM> located across the needle hub body <NUM> from one another and the indented portion <NUM> and the finger element <NUM> disposed therebetween. The open conduit <NUM> is disposed on the opposite side of the tab <NUM> from the finger element <NUM> and the indented portion <NUM>.

The needle shield <NUM> is disposed over the needle hub body <NUM> such that it encloses the needle cannula <NUM>. The needle shield <NUM> provides protection to the user from the needle cannula <NUM> and prevents contamination of the needle cannula <NUM>. The needle shield <NUM> also activates the engagement of the needle hub assembly <NUM> and the securing element <NUM> of the retraction barrel. In the embodiment shown, the needle shield <NUM> has structure that engages the needle hub body <NUM> and facilitates the rotation thereof, with respect to the retraction barrel <NUM> such that the needle hub assembly <NUM> is properly attached to the retraction barrel. In the embodiment shown, the needle shield <NUM> includes a closed distal end (not shown), an open proximal end <NUM> and a hollow body <NUM> defining a cavity <NUM> for receiving the needle hub body <NUM> and the needle cannula <NUM>. The hollow body <NUM> includes an interior surface <NUM>. The interior surface <NUM> includes the structure that enables the needle shield <NUM> to engage the needle hub body <NUM> and facilitate attachment of the needle hub assembly <NUM> to the retraction barrel.

The interior surface <NUM> includes a plurality of detents <NUM> that extend inwardly and engage the at least one finger element <NUM> of the needle hub body <NUM>. The detents <NUM> engage the finger element <NUM> to rotate the needle hub body <NUM> with respect to the securing element <NUM> to attach the needle hub assembly <NUM> to the open distal end of the retraction barrel.

As shown in <FIG>, as the needle hub assembly <NUM> and the needle shield <NUM> are placed within the open distal end <NUM> of the retraction barrel, the finger element <NUM> flexes as it moves over the wall <NUM> of the retraction barrel. As the user rotates the needle shield <NUM> and needle hub assembly <NUM> attached thereto, the detents <NUM> engage the finger element <NUM> and apply a rotational force on the finger element <NUM> to rotate the needle hub body <NUM> and needle hub assembly <NUM> until the tab <NUM> engages the protuberance <NUM> of the retraction barrel and the finger element <NUM> engages the opening <NUM> of the wall <NUM> of the retraction barrel. Upon engagement of the tab <NUM> and protuberance <NUM> and the finger element <NUM> and the opening <NUM>, the aperture <NUM> is aligned with the open conduit <NUM> of the needle hub assembly. In other words, the engagement of the securing element <NUM> and the attachment element <NUM> permits fluid communication between the aperture and the needle cannula. After proper engagement of the securing element <NUM> and the attachment element <NUM>, the needle shield may be removed from the needle hub body <NUM>.

To remove the needle hub assembly <NUM> from the retraction barrel, the user places the needle shield <NUM> over the needle hub body <NUM> and the needle cannula <NUM> and applies a rotational force to the needle shield <NUM>, which in turn causes the detents <NUM> to apply a rotational force on the finger element <NUM> and cause the needle hub body <NUM> to rotate in the opposite direction to disengage that tab <NUM> from the protuberance <NUM> and the finger element <NUM> from the opening.

A second aspect of the present disclosure pertains to a retractable syringe assembly that provides for the separate containment of the retraction mechanism and the needle cannula in a needle chamber. The assembly also includes an activation button, located at the proximal end of the syringe assembly, that extends within the needle chamber and is located adjacent to the plunger rod used to aspirate and expel fluid from a separate fluid chamber disposed adjacent to the needle chamber. On activation of the button, the needle hub is released into the needle chamber.

The embodiments according to the second aspect provide an alternative mechanism to a retractable needle syringe. Typical retractable needle syringes provide a chamber within the plunger rod to house the needle cannula and other associated components after the retraction mechanism is activated. This requires increased component complexity to enable the sealed plunger and stopper to be breached during activation. The dual barrel design of the embodiments according to the second aspect moves the retraction mechanism into a dedicated region allowing a conventional plunger and stopper to be used.

Most conventionally designed retractable needles (single barrel designs with plunger activated retraction) are activated after dosing by a continued pressure on the rear of the plunger rod. As these are the same forces that must be applied during dispensing of the medication, inadvertent activation can occur. Specifically, such devices may be inadvertently activated during dosing if sufficient pressure is generated, i.e., during the expulsion of a viscous medication from the barrel, which requires higher forces to be applied and such forces may exceed the forces needed to activate the retraction mechanism. In other known devices, the pressure generated at the stopper may be sufficient to cause failure of the stopper or any removable opening into the plunger rod.

The retraction mechanisms of conventional type, plunger-activated safety syringes must withstand increased syringe pressures and the associated large plunger forces as described above. This leads to a requirement for large activation forces which exceed the operational forces by some safety margin in order to prevent premature retraction. Additionally, since most devices of this type employ an additional plunger motion after full dispensing, and in the same direction as the dispensing motion, a threshold force must be employed to allow the user to differentiate between a fully bottomed plunger and the activation operation.

By incorporating a separate release mechanism, distinct from the plunger rod, this limitation is removed in the dual barrel design, and the release activation force can be arbitrarily specified based on user requirements, ergonomics and safety considerations. Further, decoupling the retraction activation from the plunger rod allows for a separate and distinct control to be utilized for the needle retraction affording the operator greater control over when needle retraction occurs and removing the possibility of inadvertent actuation. Moreover, since the plunger rod and the stopper are no longer utilized with the retraction mechanism, existing plunger rods and stoppers from existing devices may be utilized with embodiments described herein.

A retractable syringe assembly <NUM> according to one or more embodiments of the second aspect is shown in <FIG>. The syringe assembly <NUM> includes a dual syringe barrel that includes fluid barrel <NUM> and a retraction barrel <NUM>. The retractable syringe also includes a needle hub assembly <NUM>, a plunger rod <NUM>, stopper <NUM> and a trigger element <NUM>. The fluid barrel shown in <FIG> includes a distal end <NUM>, a open proximal end <NUM>, a sidewall <NUM> extending from the distal end <NUM> and the proximal end <NUM> including an inside surface <NUM> defining a chamber <NUM>. The inside surface <NUM> defines a cross-sectional width and may include a reuse prevention feature, that will be discussed in greater detail below. The distal end <NUM> includes a distal wall <NUM> that encloses the distal end <NUM>. In the embodiment shown, the sidewall <NUM> includes a first aperture <NUM> for permitting fluid communication between the fluid barrel and the retraction barrel. As will be discussed in greater detail below, the first aperture <NUM> also permits fluid communication between a needle cannula disposed within the retraction barrel <NUM> and the fluid barrel <NUM>.

The fluid barrels shown in <FIG> may include a reuse prevention feature. Specifically, the fluid barrel <NUM> may include a retaining element <NUM> that extends around the entire circumference of the inside surface <NUM> of the fluid barrel <NUM> at a location adjacent to the proximal end <NUM> of the fluid barrel. The cross-sectional width of the inside surface <NUM> at the retaining element is less than the first cross-sectional width or the cross-sectional width of the inside surface <NUM> at the remaining locations along the length of the fluid barrel. In one or more embodiments, optional tabs or detents can be used to create a region of the fluid barrel <NUM> having a cross-sectional width that is less than the first cross-sectional width of the fluid barrel <NUM>. The retaining element may also be shaped to facilitate activation of the reuse prevention feature. For example, the fluid barrel <NUM> may also include a diameter transition region disposed proximally adjacent to the retaining element at the proximal end <NUM> of the fluid barrel <NUM>. The cross-sectional width of the inside surface <NUM> of the fluid barrel at the diameter transition region increases from the distal end <NUM> to the proximal end <NUM> of the fluid barrel <NUM>. As will be described in greater detail below, in embodiments of the retractable syringe assembly that utilize a reuse prevention feature, the reuse prevention feature of the fluid barrel <NUM> cooperates with corresponding reuse prevention features on the plunger rod <NUM> to lock the plunger rod <NUM> within the fluid barrel <NUM> and/or to disable the plunger rod <NUM> from further use.

As more clearly shown in <FIG>, the retraction barrel <NUM> is disposed adjacent to the sidewall <NUM> of the fluid barrel <NUM>. The retraction barrel <NUM> is configured to house a needle hub assembly <NUM> therein and the retraction feature. The retraction barrel <NUM> includes distal end <NUM> and an open proximal end <NUM>. The distal end includes a tapered wall segment <NUM> that houses the needle hub assembly <NUM> therein. A wall <NUM> having an interior surface <NUM> defining the needle chamber <NUM> extends from the open distal end <NUM> to the open proximal end <NUM>. The wall <NUM> of the retraction chamber is adjacent to the sidewall <NUM> of the fluid barrel <NUM>. In one or more embodiments, the wall <NUM> may extend around the portions of the retraction barrel <NUM> that are not in direct contact with fluid barrel <NUM> and the sidewall <NUM> may form the barrier between the retraction barrel <NUM> and the fluid barrel <NUM>. In other words, the outside surface of the sidewall <NUM> may form the interior surface <NUM> of the retraction barrel <NUM> along the portion of the retraction barrel <NUM> that is in direct contact with the fluid barrel <NUM>.

The wall <NUM> may include a second aperture <NUM> that permits fluid communication with the fluid chamber <NUM> and the needle chamber <NUM>. The second aperture of the wall may also allow fluid communication between the fluid chamber <NUM>, needle chamber <NUM> and the needle cannula.

According to one or more embodiments, the retraction barrel a cross-sectional dimension that is smaller than the cross-sectional dimension of the fluid barrel. In specific embodiments, the cross sectional dimension of the retraction barrel is less than about <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% of the cross-sectional dimension of the fluid barrel. Such designs in which the cross-sectional dimension of the retraction barrel is less than the cross-sectional dimension of the fluid barrel, provides ergonomic and functional advantages. For example, the overall appearance and handling of the dual barrel syringe is more pleasing to the user.

The needle hub assembly may include a fluid path <NUM> that extends from an open end of the needle cannula to second aperture <NUM> of the retraction barrel. The second conduit may include an opening (not shown) that must be aligned with the second aperture to permit fluid communication between the needle cannula and the fluid barrel.

Referring to <FIG>, the needle hub assembly <NUM> disposed within the retraction barrel <NUM> and includes a needle hub <NUM> and a needle cannula <NUM> attached to the needle hub <NUM>. The needle hub <NUM> includes a distal end <NUM> and a proximal end <NUM>. The needle cannula <NUM> includes a free and open distal end <NUM> end and an open proximal end <NUM> that is attached to the distal end <NUM> of the needle hub. The needle hub <NUM> shown in <FIG> includes a recessed portion <NUM> for partially housing one end of the needle cannula. The recessed portion <NUM> is in fluid communication with the fluid path <NUM> to permit fluid communication between the needle cannula <NUM> and the fluid barrel <NUM>.

The needle cannula <NUM> of the needle hub assembly <NUM> is biased to move in the proximal direction. In the embodiment shown, the needle hub assembly <NUM> is biased to move in the proximal direction, thereby biasing the attached needle cannula <NUM>. The needle hub assembly <NUM> is biased to move in the proximal direction by a biasing element <NUM> disposed between the needle cannula <NUM> and the tapered wall segment <NUM> of the retraction barrel. As shown more fully in <FIG>, the biasing element <NUM> is shown as surrounding the needle cannula <NUM>.

In the embodiment shown, the biasing element <NUM> engages the needle cannula <NUM>. The biasing element <NUM> may include a spring, which may be a compression spring that applies a constant force on the needle hub <NUM> in the proximal direction. In alternative embodiments, the biasing element <NUM> may be provided in another form, for example, a lever arm (not shown) may be disposed between the needle hub and the barrier wall. The needle hub <NUM> includes at least one hub seal <NUM> disposed along the outside surface of the needle hub <NUM> for forming a fluid tight seal with the tapered wall segment <NUM> of the retraction barrel. As will be described in greater detail below, the trigger element <NUM> supports the needle hub <NUM> and prevents biasing element <NUM> from moving in the proximal direction. The needle hub <NUM> includes at least one detent <NUM> that receives and engages the corresponding structure on the trigger element <NUM> that supports the needle hub <NUM>. As will be explained in greater detail below, disengaging the detent <NUM> from the corresponding structure on the trigger element will allow the biased needle hub <NUM> and the needle cannula <NUM> attached thereto to retract into the retraction barrel <NUM>.

In the embodiment shown, for example in <FIG>, <FIG>, the needle hub <NUM> includes a first attachment portion. In the embodiment shown, the first attachment portion is provided in the form of at least two detents <NUM> or grooves <NUM> disposed on opposite ends of the needle hub <NUM>. The grooves <NUM> are disposed adjacent to the proximal end <NUM> of the needle hub assembly. The grooves are shown as including a first portion inclined radially inwardly into the needle hub <NUM>, a second portion that has no incline and is substantially parallel to the axis along which the needle hub is disposed, and a third portion that inclines sharply radially outwardly. The first attachment portion facilitates engagement of the trigger element <NUM> with the grooves <NUM>. The third portion <NUM> prevents disengagement of the trigger element <NUM> until a sufficient force is applied to the trigger element <NUM>. Specifically, the sharp incline of the third portion <NUM> prevents the trigger element from sliding over and out of the detent <NUM>, when engaged with the detent <NUM>. Once a sufficient force is applied to the trigger rod <NUM> to overcome the third portion <NUM> of the detent <NUM>, referred herein as the trigger force, the disengagement of the trigger element <NUM> from the needle hub <NUM> permits the biasing element <NUM> to move the needle cannula <NUM> and the needle hub <NUM> attached thereto into the trigger element <NUM> and/or the retraction barrel <NUM>. Specifically, the expansion of the biasing element <NUM> drives the needle cannula <NUM> and the needle hub <NUM> into the trigger element <NUM> and/or the retraction barrel <NUM>.

A plunger rod <NUM> is disposed within the fluid barrel <NUM> and includes a stopper <NUM> attached thereto for forming a fluid-tight seal with the inside surface <NUM> of the fluid barrel <NUM>. The plunger rod <NUM> may include a reuse prevention feature that locks the plunger rod <NUM> within the fluid barrel <NUM> or otherwise disables the plunger rod <NUM>. The plunger rod may include a reuse prevention feature that cooperates with a reuse prevention feature disposed on the fluid barrel <NUM>. In one or more embodiments, the plunger rod may include a protrusion <NUM> that has a cross-sectional width that is greater than the cross-sectional width of the inside surface <NUM> of the fluid barrel <NUM> at the retaining element <NUM>. As discussed above, the retaining element form a smaller cross-sectional width than at other locations along the length of the fluid barrel <NUM>. Accordingly, when the protrusion of the plunger rod advances distally past the retaining element of the fluid barrel <NUM>, the smaller cross-sectional width of the retaining element prevents movement of the protrusion in the proximal direction. Accordingly, the plunger rod <NUM> is locked within the fluid barrel <NUM> by the retaining element. In one or more embodiments, the stopper <NUM> and/or the plunger rod <NUM> may have a structure to permit relative movement of the plunger rod <NUM> with respect to the stopper <NUM>. For example, the stopper <NUM> may have an interior recess that allows the distal end of the plunger rod <NUM> to move in the distal and proximal directions within the interior recess, thus elongating and shortening the length of the plunger rod and the stopper. Exemplary plunger rods and stoppers which permit relative movement of the plunger rod with respect to the stopper are disclosed in <CIT> and <CIT> referred to above.

The stopper <NUM> may also include reuse prevention features that also cooperates with reuse prevention features disposed on the fluid barrel <NUM>. For example, the stopper <NUM> may include a sealing portion (not shown) that has a cross-sectional width that is greater than the cross-sectional width of the inside surface <NUM> of the fluid barrel <NUM> at the retaining element. In such embodiments, removal of the stopper <NUM> is prevented because the smaller cross-sectional width of the retaining element of the fluid barrel <NUM> prevents the stopper <NUM> from being removed. The plunger rod <NUM> and the stopper <NUM> may be joined by a frangible connection <NUM> that may cause the plunger rod <NUM> to become disconnected from the stopper <NUM>, while the stopper <NUM> remains locked within the fluid barrel <NUM> by the retaining ring. Exemplary stoppers which include a reuse prevention feature and plunger rods and stoppers joined by a frangible connection are disclosed in <CIT> and <CIT>.

The retractable syringe assembly <NUM> also includes a trigger element <NUM> that includes a distal end <NUM> and a proximal end <NUM>. The trigger element <NUM> is moveable independently of the plunger rod <NUM> and extends into the needle chamber <NUM> of the retraction barrel <NUM>. In the embodiment shown, the trigger element <NUM> includes a trigger pad <NUM> on which the user applies a force in the distal direction to activate the retraction mechanism of the syringe assembly.

The trigger element <NUM> includes a trigger element body <NUM> that extends from the distal end <NUM> to the proximal end <NUM>. The trigger element body <NUM> is shaped to have a cylindrical shape and is elongate. In the embodiment shown, the trigger element <NUM> has an open distal end <NUM> and the trigger element body <NUM> has a hollow interior <NUM> to house the needle hub <NUM> and the needle cannula <NUM>. The proximal end <NUM> of the trigger element is closed and may be tapered to retain the needle hub <NUM> within the hollow interior <NUM> after the needle hub <NUM> and the needle cannula <NUM> is retracted into retraction barrel. The needle cannula <NUM> may also include structure to retain the retracted needle cannula <NUM> within the trigger element <NUM>.

The distal end <NUM> of the trigger element <NUM> includes a second attachment portion <NUM> for engaging the first attachment portion. In the embodiment shown, the second attachment portion includes at least one flexible arm <NUM> that extends distally from the trigger element body <NUM>. The flexible arm <NUM> includes a release member <NUM> that is shaped, sized and positioned to engage the grooves <NUM> of the needle hub <NUM>. Specifically, the detent includes a first segment <NUM> that is inclined radially inwardly, a second portion that has no incline and is substantially parallel to the axis along which the trigger element <NUM> is disposed, and a third segment <NUM> that inclines sharply radially outwardly. It will be understood that the release member <NUM> may have another shape or size that does not replicate the shape and size of the grooves <NUM>.

The interior surface <NUM> of the retraction barrel may include a capture rib <NUM> for capturing or retaining the flexible arm <NUM> of the trigger element <NUM> upon application of the trigger force. Specifically, the capture rib <NUM> is disposed adjacent to the tapered wall segment <NUM> and extends into the needle chamber <NUM>. The capture rib has a distal end that is attached to the interior surface of the retraction barrel and a free proximal end that extends into the needle chamber <NUM>. The capture rib <NUM> is contoured to facilitate the distal end <NUM> of the trigger element <NUM> to slide over or ride over the capture rib <NUM> upon application of a trigger force that permits the release member <NUM> to disengage from the grooves <NUM> and the trigger rod moves in the distal direction. As shown more clearly in <FIG>, as the flexible arm <NUM> of the trigger element <NUM> slides over the capture rib <NUM>, the flexible arm <NUM> flexes or moves outwardly. The capture rib <NUM> holds the flexible arm <NUM> in the flexed position and permits the needle hub <NUM>, the needle cannula <NUM> and the biasing element <NUM> to move proximally past the release member <NUM> into the hollow interior <NUM> of the trigger element.

The retraction barrel <NUM> includes a release opening <NUM> disposed adjacent to the proximal end of the retraction barrel. The release opening <NUM> may be enclosed to form an indentation in the wall <NUM> of the retraction barrel. The trigger element <NUM> includes a release detent <NUM> disposed on the trigger element body <NUM> that engages the release opening <NUM>. The release opening <NUM> and the release detent <NUM> provide an indication to the user for how much force is sufficient to overcome the grooves <NUM> of the needle hub <NUM>. This indication can be a visual indication, a tactile indication, or a combination of visual and tactile indication. Specifically, the force required to disengage the release detent <NUM> from the release opening <NUM> is the same or substantially the same as the trigger force. The height of the release detent <NUM> may be modified to require more or less force to disengage the release detent <NUM> from the release opening <NUM>. In addition, the release opening <NUM> may be modified to have curved entrances to decrease the angle between the interior surface of the wall <NUM> and the release opening <NUM>. In embodiments where the release opening <NUM> is open and not enclosed, the release opening <NUM> and the release detent <NUM> provide visual indication whether the trigger force has been applied. Specifically, the user can see whether the release detent <NUM> is engaged with the release opening <NUM> and know whether the trigger force has been applied.

In one or more embodiments, the trigger force, which is the force required to disengage the release detent <NUM> from the release opening <NUM> and/or to disengage the release member <NUM> from the groove <NUM> is at least about <NUM> pounds of force (Ibf). In one or more variants, the trigger force is about <NUM> lbf. In another variant, the trigger force may include <NUM> lbf, <NUM> lbf, <NUM> lbf, <NUM> lbf, or <NUM> lbf. In a more specific embodiment, the trigger force is in the range from about <NUM> lbf to about <NUM> lbf.

In the embodiment shown, the needle hub assembly is permanently attached to the retraction barrel <NUM> because it is enclosed within the retraction barrel. In one or more alternative embodiments, the needle hub assembly may be removably attached to the retraction barrel <NUM> or may be attached by the user to the open distal end <NUM> of the retraction barrel.

Referring to <FIG>, the length of the plunger rod <NUM>, the trigger element <NUM> and the syringe barrel <NUM> may be modified so that the plunger rod <NUM> aligns with the trigger element upon expulsion of all of the contents of the syringe, as shown in <FIG>. The alignment of the plunger rod <NUM> and the trigger element <NUM> provides one or more of visual indication and tactile indication that the contents of the fluid barrel <NUM> have been expelled and the needle cannula <NUM> can be retracted into the retraction barrel. Further, such alignment of the trigger element <NUM> and the plunger rod <NUM> after the stopper <NUM> is in contact with the distal wall <NUM> of the fluid barrel <NUM> requires that the trigger element <NUM> is not aligned with the plunger rod <NUM> when the fluid barrel is filled. Specifically, the trigger element <NUM> is located closer to the proximal end <NUM> of the retraction barrel and the proximal end <NUM> of the fluid barrel than the plunger rod <NUM>. This alignment, when retraction of the needle cannula is not desired, reduces the chance of inadvertent activation of the retraction mechanism.

A third aspect of the present disclosure pertains to a retractable syringe assembly that incorporates structure to prevent premature activation of the retraction mechanism. The retractable syringe assembly is shown in <FIG>. In the embodiments shown in <FIG> and <FIG>, the syringe assembly <NUM> includes a dual syringe barrel as otherwise described herein that includes a retraction barrel <NUM> and a fluid barrel <NUM>. A trigger element <NUM> is disposed within the retraction barrel <NUM> and a plunger rod <NUM> is disposed within the fluid barrel <NUM>. The plunger rod <NUM> and the trigger element <NUM> have features that prevent the plunger rod from interacting with the trigger element <NUM> and accidentally activating the trigger element <NUM>. In addition, the plunger rod <NUM> and the trigger element <NUM> have reuse prevention features that prevent the user from reusing the syringe assembly <NUM>. These premature activation prevention features and reuse prevention features of the trigger element <NUM> and the plunger rod <NUM> described with respect to the third aspect may be incorporated with other trigger elements and plunger rods described herein.

The trigger element <NUM> includes a distal end (not shown) and a proximal end <NUM> and a trigger element body <NUM> that extends from the distal end to the proximal end <NUM>. A snap <NUM> is disposed adjacent to the proximal end <NUM>. In the embodiment shown, the snap <NUM> is located between the trigger element <NUM> and the plunger rod <NUM>. The snap <NUM> engages the retraction barrel and the engagement therebetween hinders or prevents movement of the trigger element <NUM> in the distal direction. As shown in <FIG>, the snap <NUM> is shown as a radially outward extension that extends from the trigger element body <NUM>. The snap <NUM> includes a distal end <NUM> and a proximal end <NUM>. The snap <NUM> has a height that increases from the proximal end <NUM> to the distal end <NUM> to permit or facilitate movement of the plunger rod <NUM> past the snap <NUM>. The distal end <NUM> of the snap <NUM> is shown as substantially perpendicular to the trigger element body.

The snap element <NUM> is depressible upon application of a force in the distal direction. The snap element <NUM> is not depressible upon application of a force in the proximal direction. Accordingly, the engagement of the snap element <NUM> with the retraction barrel <NUM> applies a force on the snap element <NUM> in the proximal direction, which prevents the snap element from depressing and hinders movement of the trigger element <NUM> in the distal direction. When the plunger rod <NUM> is moved in the distal direction, it depresses the snap element <NUM> and permits movement of the trigger element <NUM> in the distal direction. The plunger rod <NUM> may include a contacting surface, shown in <FIG> as a flat radial ring <NUM>, that deflects the snap element <NUM> so the trigger element <NUM> may be moved in the distal direction and the activation of the retraction mechanism can proceed.

In use, as shown in <FIG>, the movement of the plunger rod in the distal direction to expel all the contents of the fluid barrel <NUM> depresses the snap element <NUM>. When the plunger rod is bottomed or when all the contents of the fluid barrel <NUM> are expelled and the stopper is in contact with the distal end of the fluid barrel, the plunger rod continues to depress the snap element <NUM>. The depression of the snap element <NUM> permits movement of the trigger element <NUM> only after the contents of the syringe are expelled. Accordingly, premature activation of the retraction mechanism is prevented.

The underlying principle of the snap element <NUM> is that the inclusion of an abrupt angled surface, which can be as much as <NUM> degrees), engages the retraction barrel and prevents distal movement of the trigger element. The snap element <NUM> may have sufficient stiffness in the axial direction but may be easily deflectable in the radial direction. This ensures smooth deflection when the plunger rod engages the snap element <NUM>.

In one or more embodiments, the snap element <NUM> may be rotatable so it may be to be turned away during transport and storage, as shown in <FIG>. Prior to use or prior to activation, as shown in <FIG>, the trigger element <NUM> may be turned or rotated such that the snap element <NUM> is positioned to prevent movement of the trigger element <NUM> in the distal direction, as shown in <FIG>. Thereafter, when activation of the retraction mechanism is desired, for example, when the contents of the fluid barrel <NUM> has been expelled, the trigger element <NUM> may be rotated such that the snap element <NUM> is positioned to permit movement of the trigger element <NUM> in the distal direction, as shown in <FIG>.

The trigger element <NUM> and the retraction barrel <NUM> include a reuse prevention feature. The retraction barrel <NUM> includes a first locking element <NUM> disposed adjacent to its proximal end which engages with a second locking element <NUM> disposed on the trigger element body <NUM>. The first locking element <NUM> is shown as an opening <NUM> on the wall <NUM> of the retraction barrel <NUM>. It will be understood that the opening may be provided in other forms. The second locking element <NUM> is shown as an outwardly extending projection <NUM> disposed on the trigger element body <NUM>. The projection <NUM> has a proximally facing stop face <NUM> that prevents movement of the trigger element <NUM> in the proximal direction and prevents disengagement of the first locking element <NUM> and the second locking element <NUM>.

The first locking element and the second locking element <NUM> are positioned on the retraction barrel <NUM> and the trigger element <NUM> so they can engage when a force is applied to the trigger rod in the distal direction to activate the retraction mechanism. As shown in <FIG>, upon application of the force on the trigger element <NUM> in the distal direction, the projection <NUM> engages the opening <NUM>.

A reuse prevention feature of the trigger element may be designed to be easily deflectable in the radial direction when the trigger element contacts the interior surface of the retraction barrel <NUM>. In the final position of the first and second locking elements <NUM>, <NUM>, the projection <NUM> of the trigger element <NUM> should reach the opening <NUM> where the projection <NUM> can re-expand and lock backward motion of the trigger element <NUM>. This will prevent the trigger element <NUM> from being pulled out of the retraction barrel <NUM> and activated for multiple activations of the retraction mechanism. By adding this reuse feature to the device, the retraction mechanism can only be activated once, thus preventing re-use after for example exchanging the refracting needle.

A fourth aspect of the present disclosure pertains to a retractable syringe assembly <NUM> that includes an alternative retraction mechanism. The retractable syringe assembly <NUM> is shown in <FIG>. The syringe assembly <NUM> includes a dual chamber syringe barrel as otherwise described herein that includes a needle chamber and a fluid chamber. A needle hub assembly <NUM> according to the needle hub assembly described with reference to <FIG>, wherein a needle hub <NUM> encloses a needle cannula support <NUM>, a needle cannula <NUM> that is attached to the needle cannula support and a biasing element <NUM> disposed between the needle cannula support <NUM>, needle cannula <NUM> and the needle hub <NUM>. The needle hub <NUM>, as shown in <FIG>, include a distal end <NUM> and a proximal end <NUM>. The distal end <NUM> may include a body portion <NUM> having a conical shape and including an opening (not shown) therethrough for receiving the needle cannula <NUM>. The proximal end <NUM> includes a first retraction portion <NUM> that extends in the proximal direction from the body <NUM> and defines a hub cavity for housing the needle cannula support <NUM>, biasing element <NUM> and the needle cannula, as described above with reference to <FIG>. The first retraction portion <NUM> includes a distal end <NUM> attached to the body portion <NUM> and a free proximal end <NUM>. The first retraction portion <NUM> also includes at least one flexible portion <NUM> having an engaging tab <NUM> at the proximal end thereof. The engaging tab <NUM> engages the needle cannula support <NUM> and exerts a force on the needle cannula support <NUM> in the distal direction to counteract the force applied by the biasing element <NUM> in the proximal direction on the needle hub assembly <NUM>.

The trigger element <NUM> includes a distal end <NUM> and a proximal end (not shown). The trigger element <NUM> also includes a trigger element body <NUM> extending from the distal end <NUM> to the proximal end, as otherwise described herein, which may include a hollow interior <NUM> for housing the retracted needle cannula. The trigger element body <NUM> includes a rib <NUM> that extends radially outwardly for disengaging the engaging tab <NUM> from the needle cannula support <NUM> and releasing the force applied by the engaging tab <NUM> on the needle hub assembly <NUM>. The trigger element <NUM> disengages the tab <NUM> and the needle cannula support <NUM> upon application of the trigger force by the trigger element, which provides sufficient force in the distal direction on the engaging tab <NUM> and/or the flexible portion <NUM> to cause the flexible portion <NUM> to move outwardly so the engaging tab <NUM> is no longer engaged with the needle cannula support <NUM> and the force applied by the biasing element is no longer counteracted. Specifically, the removal of the force applied by the engaging tab <NUM> on the needle cannula support <NUM> in the distal direction allows the force applied by the biasing element <NUM> to move the needle cannula support <NUM> and needle cannula <NUM> into the trigger element.

The embodiments described herein may include alternative retraction mechanisms that are disclosed in U. Provisional Application Reference Number P-<NUM>, <CIT>. Specifically, the retraction mechanisms disclosed in <FIG>, <FIG> and <FIG> of U. Provisional Application Reference Number P-<NUM>.

Alternative embodiments of the trigger element are shown in <FIG>, <FIG>, <FIG> and <FIG>, which may be utilized with the syringe assemblies described herein.

In <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG>, <FIG> and <FIG>, the proximal end of the trigger element has a circular trigger pad that substantially envelopes or surrounds the plunger rod in the open proximal end of the fluid barrel. The trigger element may be coded by indicia such as one or more of indentations, markings or color coding. Upon activation of the trigger element by applying a distal force on the plunger rod, the plunger rod proximal end or thumbpress may be fully nested within the trigger pad.

<FIG> show a design in which the plunger rod engages the trigger element shaped a semicircular element or crescent-shaped element. The plunger rod thumbpress can be depressed to its distal most position, and the user can then activate the trigger element by application of force to the trigger element.

<FIG> show a design in which proximal end of the trigger element has a substantially rectangular shaped trigger pad with curved edges and the plunger rod can nest within the trigger pad. In <FIG>, the trigger pad is substantially oval in shape. In <FIG>, the trigger pad is aligned with the needle cannula: on one side of the finger flange of the syringe assembly. In <FIG>, <FIG>, <FIG>, the trigger element has a trigger pad that is aligned with the needle cannula and needle chamber, and the trigger pad extends outwardly from the body of the needle chamber. <FIG> shows a configuration in which the trigger element is a small tab at the end of the needle chamber. <FIG> shows a trigger element as a tab that can be activated by applying a force in the distal direction. The trigger element has a gripping surface in the form of a plurality of spaced ribs. <FIG> shows an alternative trigger element design in which the trigger element is in the form of a block-shaped that can be activated by the user. <FIG> shows a button embedded in the proximal end of the needle barrel that can be activated by the user by pressing or squeezing the button to cause the needle to retract.

<FIG> shows a plunger rod thumbpress that has hinged portion that can be moved by applying distal force to the hinged portion to activate the trigger element an retraction mechanism. <FIG> shows a trigger element that is somewhat similar to <FIG>, except that the trigger element is in the form of a toggle type element that can be radially moved to activate the retraction mechanism.

In another embodiment of the present disclosure a method for aspirating and expelling a liquid from a syringe assembly of the present invention is provided comprising aligning the trigger guard to prevent movement of the trigger element in the distal direction. A pre-selected amount of liquid is then aspirated into the fluid chamber by inserting the needle cannula into the liquid and applying a force on the plunger rod in a proximal direction. The liquid from the fluid chamber is expelled by applying a force on the plunger rod in the distal direction. The needle cannula is retracted into the retraction barrel by aligning the trigger guard to permit movement of the trigger element in the distal direction and applying a force on the trigger guard in the distal direction to provide the trigger force causing the needle cannula to retract into the retraction barrel.

In another embodiment of the present disclosure a method for aspirating and expelling a liquid from a syringe assembly of the present invention is provided comprising aspirating a pre-selected amount of liquid into the fluid chamber by inserting the needle cannula into the liquid and applying a force on the plunger rod in a proximal direction. The liquid from the fluid chamber is then expelled by applying a force on the plunger rod in the distal direction. The plunger rod is locked within the fluid barrel by applying a continuous force on the plunger rod in the distal direction causing the protrusion of the plunger rod to move distally past the retaining ring of the fluid barrel. The needle cannula is retracted into the retraction barrel by aligning the trigger guard to permit movement of the trigger element in the distal direction and applying a force on the trigger guard in the distal direction to provide the trigger force causing the needle cannula to retract into the retraction barrel.

In another embodiment of the present disclosure a method for aspirating and expelling a liquid from a syringe assembly of the present invention is provided comprising providing a syringe barrel including a fluid barrel and a retraction barrel in fluid communication, the fluid barrel including a plunger rod attached to a stopper for aspirating and expelling liquid from the fluid barrel and a retraction barrel including a needle hub, needle cannula with an opening and a trigger element for providing a trigger force causing the needle cannula to retract into the retraction barrel. The opening of the needle cannula is submerged in a liquid and the fluid barrel of the syringe is filled with the liquid by applying a force to the plunger rod in a proximal direction. The liquid from the fluid barrel is expelled by applying a force to the plunger rod in a distal direction. The needle cannula is then retracted into the retraction barrel by applying a force to the trigger element in the distal direction to provide the trigger force.

In another embodiment of the present disclosure, a method for aspirating and expelling a liquid from a syringe assembly of the present invention is provided further comprising locking the plunger rod in the fluid barrel after expelling the liquid from the fluid barrel.

In another embodiment of the present disclosure, a method for aspirating and expelling a liquid from a syringe assembly of the present invention is provided wherein the force applied to the plunger rod is oriented along an axis that is parallel to the axis along which the force applied to the trigger element is oriented.

Claim 1:
A syringe assembly (<NUM>) comprising:
a fluid barrel (<NUM>) including a sidewall having an inside surface defining a fluid chamber for retaining fluid and a retaining element;
a plunger rod (<NUM>) disposed within the fluid chamber comprising a distal end, a proximal end, a plunger rod body extending from the distal end to the proximal end, and a stopper disposed at the distal end of the plunger rod for forming a fluid-tight seal with the inside surface of the fluid barrel;
a retraction barrel (<NUM>) including a wall having an interior surface defining a needle chamber, an open distal end, a needle cannula attached to a needle hub, the needle cannula being biased to move in a proximal direction; and
a trigger element (<NUM>) having a distal end, a proximal end (<NUM>), and a trigger element body (<NUM>) that extends from the distal end of the trigger element to the proximal end (<NUM>) of the trigger element, the trigger element disposed within the retraction barrel being independently moveable from the plunger rod, the trigger element (<NUM>) providing a trigger force causing the needle cannula to retract into the retraction barrel; and
a snap (<NUM>) disposed adjacent to the proximal end (<NUM>) of the trigger element, wherein the snap engages the retraction barrel and wherein this engagement hinders movement of the trigger element in the distal direction,
characterized in that
the proximal end of the plunger rod (<NUM>) includes a flat radial ring to deflect the snap (<NUM>) so that the trigger element (<NUM>) may be moved in the distal direction and retraction of the needle cannula can proceed.