Patent Description:
Patients suffering from a number of different diseases frequently must inject themselves with pharmaceuticals. A variety of devices have been proposed to facilitate these injections. One type of device is an automatic injection device. This type of device typically includes a trigger assembly that when operated by a user causes the device to automatically insert into the user a needle of a syringe that prior to triggering was disposed within the device housing, and then the device automatically injects a dose of medication through that inserted needle. The device may then automatically retract the syringe back into the device housing.

Some automatic injection devices include a syringe carrier that engages with a flange of a syringe. The syringe carrier may only support the flange or, in some cases, move the syringe between retracted and deployed positions. Some syringe carriers are of a single-piece construction. Some syringe carriers only partially surround the syringe, e.g. <NUM> degrees around the syringe, to leave an opening through which the syringe can be inserted radially.

Some automatic injection devices include retraction assemblies for auto-retraction of the syringe/needle combination. Retraction assemblies may include two components that slidably engage with one another. For example, to retract the syringe, one component rotatably slides against the other component. The inventors have recognized that such sliding contact can generate friction and/or friction variation along the sliding contact surfaces that may serve to impede retraction. Improvements to the syringe carrier and the retraction assemblies are described herein. Prior art syringe carriers are described in <CIT>, <CIT>, <CIT> and <CIT>.

Further aspects and preferred embodiments of the invention are defined in the dependent claims.

Aspects of the invention are described below with reference to the following drawings in which like numerals reference like elements, and wherein:.

Referring now to <FIG> and <FIG>, there are shown different views of a first embodiment of an automatic injection device, generally designated <NUM>, with a trigger assembly. When the trigger assembly is operated, the needled syringe of the device <NUM> is automatically driven downward such that the injection needle projects beyond the distal end of the device housing to penetrate the user. The device may then proceed to inject automatically, that is without further user action, the medication contents of the syringe through the needle, after which the syringe is retracted automatically such that the needle is returned to within the housing.

It will be appreciated from the following description that device <NUM> is conceptually similar in various aspects to the devices disclosed in <CIT>, and <CIT>.

In the illustrative embodiment shown in <FIG>, device <NUM> includes an outer housing <NUM> in which are operationally disposed working components of the device. The outer housing <NUM> may include a sleeve <NUM> and a main body <NUM> that may together form the axial height of the outer housing. Sleeve <NUM> may be rotatable relative to the main body <NUM> by the user. The sleeve may include a protruding fin <NUM> to facilitate rotation by a user. The device may include a button <NUM> that is part of the trigger assembly and that protrudes in the axial direction from the proximal end <NUM> of the housing. In some embodiments, when properly rotationally oriented by rotation of sleeve <NUM>, the button <NUM> is unlocked such that the button can be depressed in the distal direction to start the automatic injection function of device <NUM>. As used herein, distal and proximal refer to axial locations relative to an injection site when the device is oriented for use at such site, whereby, for example, distal end of the housing refers to the housing end that is closest to such injection site.

Button <NUM> may be molded as a single piece from a suitably durable material, such as Lustran ABS <NUM>. As further shown in the illustrative embodiment of <FIG>, button <NUM> may include a disc <NUM> with a skirt <NUM> extending distally from the outer periphery of disc <NUM>. End disc <NUM> may have a flat proximal face <NUM> upon which a force can be directly applied by a user to selectively plunge the button to trigger the device. A notch <NUM> may be formed in skirt <NUM> at the distal end of the skirt <NUM>, and may extend axially and form a slot which receives a rib of sleeve <NUM> so as to rotatably key together the button <NUM> and sleeve <NUM>. A set of three equally angularly spaced resilient fingers <NUM> that may each be provided with a detent on its radially inward face may be provided at the base of skirt <NUM> for locating the button <NUM> on shuttle <NUM>. Each finger <NUM> may be adjacent to one of three equally angularly spaced fingers <NUM> with inwardly angled stops <NUM> also provided in skirt <NUM> for attachment to shuttle <NUM>.

Tapered flange portion <NUM> may have a sloped surface that serves as an actuating element of the trigger which cams a prong of the trigger to unlatch it for the trigger assembly. Differently designed actuating elements, including one that is not ramp shaped, can be used to cam and thereby unlatch the prong in alternate embodiments.

In some embodiments, device <NUM> includes a medication-filled syringe. As shown in <FIG>, the syringe, generally designated <NUM>, includes a barrel <NUM> with a flange <NUM>, and an injection needle <NUM> mounted at the distal end of the barrel and in fluid communication with the medication contents of the barrel. Although needle <NUM> is shown as a single needle and is generally expected to be sized for subcutaneous delivery, with adaptions the device could be equipped with a needle of various sizes or types known in the art, including, but not limited to, a needle formed of one or more shortened injection needles, including microneedle arrays, and which needle allows for injection at different depths, such as intradermal.

Device <NUM> in general, and more particularly the technology claimed in this application, may be utilized in injecting a variety of medications or therapeutics into a person in need thereof. Syringes of the devices or claimed technology can be filled with any of a number of therapeutics. Device <NUM> may further comprise a medication, such as for example, within a reservoir within barrel <NUM> of syringe body or cartridge. In another embodiment, a system may comprise one or more devices including device and a medication. The term "medication" refers to one or more therapeutic agents including but not limited to insulins, insulin analogs such as insulin lispro or insulin glargine, insulin derivatives, GLP-<NUM> receptor agonists such as dulaglutide or liraglutide , glucagon, glucagon analogs, glucagon derivatives, gastric inhibitory polypeptide (GIP), GIP analogs, GIP derivatives, oxyntomodulin analogs, oxyntomodulin derivatives, therapeutic antibodies, such as, for example, but not limited to treatment of psoriasis, ulcerative colitis, Chrohn's disease, pain, migraine, and any therapeutic agent that is capable of delivery by the above device. The medication as used in the device may be formulated with one or more excipients. The device is operated in a manner generally as described above by a patient, caregiver or healthcare professional to deliver medication to a person. The device, or claimed technology of this application, may then be operated in a manner generally as described above with respect to device <NUM> to inject a person with such therapeutic in the syringe.

The plunger mechanism may include a plunger element, generally designated <NUM>, and an elastomeric sealing member or piston <NUM> that seals the medication within barrel <NUM>.

Plunger element <NUM> may be molded as a single piece of a lightweight but sturdy and sufficiently resilient material, such as DELRIN 311DP from Dupont Engineering Polymers. As further shown in <FIG>, plunger element <NUM> includes a cylindrical foot <NUM> which may be hollowed so as to have a cruciform center <NUM>. The distal face <NUM> of foot <NUM> operationally abuts piston <NUM> during plunger advancement. A ribbed bar <NUM> may rigidly or inflexibly extend axially upward from the top of foot <NUM> to a disc-shaped flange <NUM> that has a larger diameter than foot <NUM>. A plunger arm <NUM> may be formed on the outer radial periphery of flange <NUM> and may extend axially and distally from flange <NUM> in spaced relationship with plunger bar <NUM>.

Four equally angularly spaced bosses <NUM> may upwardly project from the flange <NUM>. Bosses <NUM> may aid in centering the drive coil spring <NUM> shown in <FIG> that acts on flange <NUM> to bias plunger element <NUM> distally within device <NUM>.

Plunger element <NUM> may include a resilient prong, generally designated <NUM>, that serves as part of the trigger assembly. The single prong <NUM> may latchably engage a shuttle in the shown embodiment until released by the plunging of button <NUM>, which release allows the spring <NUM> to bias the plunger element <NUM> distally to result in needle insertion and injection. In some embodiments, the plunger includes one and only one resilient prong. In other embodiments, however, the plunger may include more than one resilient prong.

Prong <NUM> may include an upstanding, tapering finger <NUM> that projects axially from the center of flange <NUM> so as to be centered on the axis of the housing <NUM>. Finger <NUM> may be flexible due to its construction to allow its bending movement when the prong is acted on for its release. As shown in <FIG>, prong <NUM> may include a triangular projection <NUM> centered on the side to side width of finger <NUM>. Projection <NUM> may include a ramp surface <NUM> extending proximally and at an angle inward from the tip <NUM> of the projection <NUM> to form an outward facing ramp used in camming of the prong for release. Ramp surface <NUM> extends from tip <NUM> to a proximal end <NUM>. The distal face <NUM> of projection <NUM>, which face does not serve a latching function, is transverse to the axial direction.

A pair of latching surfaces <NUM> may be provided on the proximal-most portions <NUM> of extensions <NUM> of finger <NUM>. Latching surfaces <NUM> and extensions <NUM> flank either side of projection <NUM> and are spaced radially inward from the ramp surface <NUM> at the height of the latching surfaces along prong <NUM>. Latching surfaces <NUM> are provided generally in axial alignment with finger <NUM> and each may be formed with a slight undercut so as to slope slightly distally as it extends in the radial direction toward ramp surface <NUM>. Latching surfaces <NUM> are disposed at a height between the axial extent of ramp surface <NUM>, such as near the proximal end <NUM>. In this location, the contacting forces on the ramp surface may tend to produce a translational deflection of the latching element which may have a lower and more consistent unlatching force than would a rocking or pivoting motion, caused by the latching surfaces being substantially above or below the ramp surface, that would introduce extra deformation of prong <NUM> and make the unlatching motion less smooth.

The back surface of projection <NUM> may jut rearward beyond extensions <NUM> to define a safety protuberance <NUM>. Protuberance may be backed up by safety arm <NUM> when button <NUM> is in its locked orientation.

An assembly including the plunger element <NUM>, syringe carrier <NUM>, and syringe <NUM> is shown in <FIG>. The plunger bar <NUM> of the plunger element <NUM> extends through an opening <NUM> in the syringe carrier <NUM> and into the syringe carrier. As shown in <FIG> and <FIG>, in which one part of the syringe carrier is hidden from view, the syringe carrier encloses a radial flange <NUM> of the syringe <NUM>. As also seen in <FIG> and <FIG>, the syringe carrier also encloses the foot <NUM> of the plunger element. The syringe carrier <NUM> may be configured to provide full, surrounding support of the syringe flange <NUM> of syringe <NUM>. While such syringe carrier may be desired, designs of the syringe carrier which allow for manufacturing and assembly is also desirable in high-volume manufacturing settings.

An illustrative embodiment of a fully assembled syringe carrier is shown in <FIG>. The syringe carrier may be made up of a first part <NUM> that couples with a second part <NUM>. The parts <NUM>, <NUM> may be coupled to one another by various attachment mechanisms, such as, for example, adhesives, such as bonding glue, ultrasonic welding, mechanical interlocking, and the like. An exploded view of the syringe carrier is shown in <FIG>. The two halves of the syringe carrier combine to define a cavity <NUM> that receives syringe flange <NUM> during device assembly such that the syringe carrier <NUM> surrounds the flange <NUM>.

In some embodiments, the syringe carrier <NUM> is made up of two identical, interlocking parts. One embodiment of one of the parts is shown in <FIG>. The part shown in <FIG> is the first part <NUM> of the syringe carrier, but the second part <NUM> may also be identical to what is shown in <FIG>. Having the first and second parts be identical may have the benefit of requiring manufacture of only one shape, and may facilitate assembly of the syringe carrier by avoiding the need for a particular part being oriented at a specific side of the syringe carrier. Other embodiments of the parts having at least some of the features described herein may include parts that are not identical and still provide interlocking and support to the flange.

The first part <NUM> may include a proximal flange surface <NUM>, a distal flange surface <NUM>, and a circumferential rounded wall <NUM> disposed between the proximal flange surface <NUM> and the distal flange surface <NUM>. An axial gap <NUM> is defined between the proximal flange surface <NUM> and the distal flange surface <NUM>. The gap <NUM> is sized to receive the axial thickness of flange <NUM> (see <FIG>) of the syringe. The proximal flange surface <NUM> may include a proximal flange extending from the wall, and the distal flange surface <NUM> may include a distal flange extending from the wall in parallel with the proximal flange.

In some embodiments, the syringe carrier <NUM> may include a cushion <NUM> that defines a distal boundary for the gap <NUM>. With reference to <FIG>, the distal surface of flange <NUM> of the syringe may rest against and be supported by the proximal surface 187A of cushion <NUM> when the flange is held by the syringe carrier. In some embodiments, the rest of the syringe carrier is made of a material having a greater hardness than that of cushion <NUM>. The cushion <NUM> may provide shock absorbance or other impact attenuation to, e.g., reduce the likelihood of breakage of the syringe during actuation of the automatic injection device, and/or to soften the impact sound of the syringe against the syringe carrier during movement of the syringe. The cushion may be made by overmolding a material onto the syringe carrier. The cushion may be formed of a compressible material, such as an elastomer or a closed cell foam.

In some embodiments, the cushion may be arc-shaped to fit with the shape of the circumferential rounded wall <NUM> and/or the shape of the distal flange surface <NUM>. In some embodiments, the cushion <NUM> segments are configured and shaped, such as in a ring shape, to provide full circumferential, that is <NUM> degrees, support to the entire flange <NUM> when the parts <NUM>, <NUM> are coupled. To this end, in some embodiments, the parts are shaped around the flange so that the cushion <NUM> can provide this full support to the flange <NUM>, such as, for example, to withstand spring insertion drive forces.

In some embodiments, the syringe carrier <NUM> may include one or more protrusions extending radially inward, where the protrusions may facilitate centering of the syringe within the syringe carrier by contacting the syringe body underneath the syringe flange. In the embodiment shown in <FIG>, the syringe carrier includes a protrusion <NUM> that extends from an inner radial surface <NUM> of the cushion <NUM>. The protrusion may be made from the same cushioning material as the cushion <NUM> and may be integrally formed with the cushion <NUM> as a single component. The protrusions may be radially compressed to a greater degree relative to any radial compression of the surface <NUM> by the syringe body. In the embodiment shown, the cushion <NUM> of each of the parts includes a pair of protrusions 188a and 188b (as shown in <FIG>) so that when the parts are coupled to one another the protrusions together help centering of the syringe at four points. In one example, the coupled parts define the four protrusions that are arranged spaced equally apart from one another. When parts are coupled, the number of protrusions provided can vary between two or more. In another embodiment, the one or more protrusions may optionally include the protrusion <NUM> that can be located along the inner radial surface <NUM> in closer proximity to a latch protrusion <NUM> than a prong <NUM>, and in some embodiments, adjacent to the end of the inner radial surface <NUM> next to the latch protrusion as shown in <FIG>. In other embodiments, there may be a protrusion adjacent the end of the inner radial surface <NUM> next to the prong <NUM> in addition to, or instead of, the protrusion <NUM>. Protrusion <NUM> may be included to support the syringe during the snap engagement of the two parts of the syringe carrier together, when the portion of the part <NUM> or <NUM>, which includes the latch protrusions <NUM>, flexes radially outward when mating with the prongs <NUM> of the other part. After the snap engagement, the protrusion <NUM> may also provide additional support to the syringe at a location where when mated there may be a gap between the cushions.

The proximal flange surface <NUM> may provide supportive engagement for the proximal surface of foot <NUM> of the plunger element.

Each part of the syringe carrier may define an opening portion <NUM> defined by radial plunger facing walls that forms one part of the opening <NUM> of the fully assembled syringe carrier. Such opening portion <NUM> may be shaped and sized to receive the shape and size of the plunger element in a manner to provide sliding support to the plunger body. In the example shown, the opening portion <NUM> in each part has a U-shape with opposing parallel planar sides coupled to one another by a rounded side.

The edges <NUM>, <NUM> of the proximal flange surface of one of the parts of the syringe carrier disposed lateral relative to the opening portion <NUM> may be complementarily shaped to mate with the edges of the other of the parts, such as shown in <FIG>. The edges may have a planar shape. In the embodiment shown, each of the edges is non-linearly shaped including a protrusion and recess.

In some embodiments, each part of the syringe carrier <NUM> may include a first lateral wall end <NUM> and a second lateral wall end <NUM>, where the circumferential rounded wall <NUM> extends from the first lateral wall end <NUM> to the second lateral wall end. In the embodiment shown, the first lateral wall <NUM> is disposed recessed relative to the edge <NUM>, while the second lateral wall <NUM> is disposed protruding relative to the edge <NUM>.

The syringe carrier <NUM> may include interlocking components that interlock to form the fully assembled syringe carrier. In some embodiments, the interlocking components extend from the lateral wall ends of each part of the syringe carrier. In the embodiment shown in <FIG>, the interlocking components comprise prongs <NUM>, each having an indentation <NUM>, and latch protrusions <NUM>, each having an accompanying slot <NUM>. The prongs <NUM> may extend from one of the lateral walls, shown as the first lateral wall end <NUM>, and the protrusions <NUM> extend from the other of the lateral walls, shown as the second lateral wall end <NUM>. Each of the prong <NUM> and indentation <NUM> of the first part <NUM> of the syringe carrier are complementarily shaped and sized to mate with a corresponding protrusion <NUM> and slot <NUM> of the second part <NUM> of the syringe carrier to interlock the two parts of the syringe carrier together.

As seen from the top view in <FIG> and the bottom view in <FIG>, each part of the syringe carrier may be approximately C-shaped. As seen from the front view in <FIG> and the front view in <FIG>, the syringe carrier may include a window <NUM> that passes completely through the circumferential rounded wall <NUM> of the syringe carrier.

As best seen in <FIG>, the syringe carrier <NUM> may fully surround an outer perimeter of the syringe body, i.e. <NUM> degrees around the syringe body. The proximal and distal flange surfaces <NUM>, <NUM> of each of the parts together fully overlap the proximal surface 133A and/or the distal surface 133B of the syringe flange <NUM>, as shown in <FIG>. This configuration of a syringe carrier completely surrounding and/or overlapping the syringe flange may be advantageous when higher spring forces for driving the plunger are used by the delivery device, such as, for example, due to larger volume of medication, such as <NUM> to <NUM>, and/or higher viscous medications. Such configuration can allow for distribution of the drive force over a greater area of the syringe flange, which may help to reduce the likelihood of breakage of the syringe flange that are typically made of glass.

It should be understood, however, that other configurations for the syringe carrier are possible. One alternative embodiment is shown in <FIG>. In <FIG>, one part of the syringe carrier <NUM>' is removed to better see the flange <NUM>' of the syringe interacting with the syringe carrier. The proximal flange surface <NUM>' and the distal flange surface <NUM>'of both parts of the syringe carrier <NUM>' together may be configured to provide full <NUM> degree support to the syringe flange <NUM>'. The syringe carrier may also include the cushion <NUM>, shown disposed along the proximal surface of the distal flange surface <NUM>'. When employed, the flange <NUM>' would rest along the cushion in a position in between the cushion and the proximal flange surface <NUM>'.

As seen in <FIG>, in this embodiment, the syringe carrier <NUM>' has a wall <NUM>' that does not extend laterally side to side as far as the embodiment shown in <FIG>. This shortened wall <NUM>', relative to the longer circumferential extension of the proximal and distal flange surfaces <NUM>', <NUM>', allows for lateral spaces <NUM>, <NUM> flanking the lateral ends of the wall <NUM>'. In some embodiments, these spaces <NUM>, <NUM> may be used to accommodate syringes having flanges with different shapes, such as the cut flange syringe shown in <FIG>.

The syringe carrier may have interlocking components in the form of protrusions <NUM> and indentations <NUM>. The protrusions <NUM> of the first part of the syringe carrier interlock with the indentations <NUM> of the second part. These interlocking components may have other snap-fit configurations. Due to the shortened wall <NUM>', the interlocking features are shown defined by the respective flange surfaces <NUM>', <NUM>'. Indeed, the protrusions <NUM> and indentations <NUM> are shown defined by the radially inward edges <NUM>', <NUM>'of the corresponding flange surfaces <NUM>' <NUM>'. In one embodiment, the circumferential rounded wall <NUM>' partially surrounds an outer perimeter of the syringe flange <NUM>', and the proximal flange surface <NUM>'of each of the parts together fully overlap a proximal surface 133A' of the syringe flange <NUM>'. As shown in <FIG>, the distal flange surface <NUM>' of each of the parts together fully overlap the proximal surface 133B' of the syringe flange <NUM>', with the cushion <NUM> disposed therebetween.

Device <NUM> may have a delay mechanism that includes a shuttle, generally designated <NUM>, a follower <NUM> that releasably latches with the shuttle <NUM>, and a dual functioning biasing member <NUM> acting between the shuttle and the follower. Shuttle <NUM> may be formed of a proximal shuttle <NUM> and a distal shuttle <NUM> further shown in <FIG> and <FIG>, respectively, that are fixedly connected during manufacturing assembly. The interaction between the proximal shuttle <NUM> and the distal shuttle <NUM>, as well as the features of the proximal shuttle <NUM> are described in greater detail in <CIT>.

Distal shuttle <NUM> includes distal region <NUM>, and the flange <NUM> that transitions from body <NUM> to region <NUM> is designed to engage syringe carrier <NUM>. When the distal shuttle <NUM> is moved proximally during retraction, the flange <NUM> abuts against a distal surface of the syringe carrier <NUM>, thus moving the syringe carrier <NUM> and syringe barrel <NUM> in the proximal direction with proximal movement of the distal shuttle <NUM>. Groove <NUM> in distal shuttle body <NUM> receives a housing key to rotatably fix shuttle <NUM> with a cavity in sleeve <NUM>. In some embodiments, the device includes a different drive system, where the syringe carrier <NUM> and syringe barrel may remain stationary (that is, is not proximally moved), and where the syringe carrier still provides a benefit to the syringe flange.

Tabs <NUM> and <NUM> radially project from distal region <NUM> and serve as latching elements or hooks to engage the follower. Notch <NUM> that leads to pocket <NUM> within tab <NUM> receives a proximal projection <NUM> of the biasing member <NUM>.

An angled, locking latch surface <NUM> is disposed distally of an opening <NUM> in line with an axially extending channel <NUM> formed in the interior surface of distal shuttle body <NUM>. Channel <NUM> accommodates plunger arm <NUM> that can project through opening <NUM> to unlock the locking mechanism described below.

Follower <NUM> is further shown in <FIG> and includes a proximal portion <NUM> with ledges <NUM> and <NUM> that serve as latching elements that engage shuttle latching tabs <NUM> and <NUM>. Channel <NUM> and opening <NUM> in proximal portion <NUM> allow axial movement of tabs <NUM> and <NUM> therein for manufacturing assembly and for shuttle release relative to the follower during device use. Opening <NUM> tapers to a slot-shaped portion <NUM> adapted to closely receive a radial projection <NUM> of biasing member <NUM>.

A radially projecting flange <NUM> may snap past snaps in the main body <NUM> during device assembly. The interior surface of follower portion <NUM> includes an inwardly projecting ring <NUM> with a spring centering lip <NUM>. A sleeve shaped distal portion <NUM> of follower <NUM> depends from follower portion <NUM> and has a lesser diameter. Slots <NUM> in the distal edge of portion <NUM> define four damping fins <NUM> of the follower. The slots <NUM> can be adjusted in size to create to differing delay times. A locking member for follower <NUM> to limit its rotation relative to the shuttle <NUM> is formed as a flexure arm <NUM> with an upwardly extending latch <NUM> at its end.

An exploded view of the distal shuttle <NUM>, biasing member <NUM>, and follower <NUM> is shown in <FIG>. Biasing member <NUM> may function as both a torsion spring and a compression spring, with torsional preloading and an axial preloading accomplished during the manufacturing assembly of device <NUM>. Biasing member <NUM> is shown as a cylindrical spring formed of a helically coiled wire <NUM>, with a shuttle engaging tip in the form of a proximal projection <NUM>, and a follow engaging tip <NUM>.

An assembly of the distal shuttle <NUM> and follower <NUM> shown in a coupled configuration is shown in <FIG> and <FIG>. In the coupled configuration, the latch <NUM> of the follower is engaged with a protrusion <NUM> on a distal surface <NUM> of the distal shuttle <NUM>.

As shown in <FIG> and <FIG>, the distal surface <NUM> of the distal shuttle <NUM> has an undercut region <NUM> adjacent to the protrusion <NUM>. The undercut region <NUM> has a curvilinear shape. In some embodiments, the trailing surface <NUM> may be curved and the undercut region <NUM> may be curvilinear to facilitate sliding engagement between both.

As shown in <FIG>, the latch <NUM> of the follower is axially moveable relative to the follower body <NUM> due to cantilevered flexure arm <NUM>, which is able to deflect relative to the follower body. The latch <NUM> may be comprised of a leading surface <NUM> and a trailing surface <NUM>. The sliding contact between the latch surfaces and the shuttle during rotation of the follower relative to the shuttle can generate friction variability that impede consistent rotation speed of the follower. The leading surface <NUM> engages with the protrusion <NUM> when the follower is in the coupled configuration in <FIG>. The trailing surface <NUM> may slidingly engage with the undercut region <NUM> when the follower is in an uncoupled configuration and is rotating relative to the distal shuttle <NUM>. In the uncoupled configuration, the latch <NUM> is disengaged with the protrusion <NUM>. In some embodiments, the leading surface <NUM> may be a flat surface that engages in a confronting relationship a flat surface portion <NUM> of the protrusion <NUM>. At least one, or both, of the leading surface <NUM> and flat surface portion <NUM>, may be angled slightly to facilitate latching with and/or uncoupling from the protrusion <NUM>. In some embodiments, the trailing surface <NUM> may be curved to facilitate uncoupling of the latch from the protrusion, and/or facilitate sliding engagement with the undercut region <NUM>.

Distal shuttle <NUM> may include a lubricant-infused material to aide in the movement of the distal shuttle <NUM> within the device housing, particularly during the needle retraction operation. In one example, the entire distal shuttle includes lubricant-infused material. In some embodiments, at least the distal surface <NUM> of the distal shuttle is made of a lubricant-infused material. Such a material may aid in facilitating uncoupling of the latch <NUM> from the protrusion <NUM> and/or facilitating sliding engagement between the latch <NUM> and the undercut region <NUM> as the follower <NUM> rotates relative to the distal shuttle. In some embodiments, the lubricant-infused material may serve to decrease friction and/or friction variability between the distal shuttle and the latch during movement of the follower relative to the distal shuttle. The lubricant-infused material may also serve to lower friction and/or friction variability between the tabs <NUM>, <NUM> with the ledges <NUM>, <NUM>. In some embodiments, the material may be a silicone-infused material. In some embodiments, the material may be made of polycarbonate with infused silicone of <NUM>%. In some embodiments, all of or at least a portion of the follower <NUM> may be made of a copolymer to decrease friction and/or friction variability between the distal shuttle and the follower. In some embodiments, at least one of at least the distal surface <NUM> of the distal shuttle is made of a lubricant-infused material, the trailing surface <NUM> may be curved, the undercut region <NUM> may be curvilinear, copolymer follower, or any combination thereof may be employed to provide a retraction assembly for an automatic injection device which can facilitate syringe retraction by decreasing the sliding engagement friction and/or by decreasing friction variation that is generated during retraction. Such embodiments may reduce any frictional delay variability in rotational speed and timing of the follower to a position to allow for shuttle/syringe retraction and/or and more consistent retraction speed and timing at the completion of the delivery cycle, which together may avoid factors contributing to stalled retraction.

The device may include a grease collar <NUM>, further shown in <FIG>, that provides a support surface for damping fluid as the follower <NUM> rotates relative to that support surface. Collar <NUM> includes an annular body <NUM> through which fits the syringe barrel. Collar <NUM> is axially supported within the housing <NUM>. Collar body <NUM> includes a generally U-shaped wall that defines an annular hollow <NUM>.

A damping compound <NUM> (shown in <FIG>), such as a silicone grease thickened with Teflon, may fill annular hollow <NUM>. Follower fins <NUM> fit within hollow <NUM> such that compound <NUM> is disposed both radially inward and outward of such fins <NUM>, as well as between adjacent fins <NUM> and as a film between the fin undersides and the base of the collar wall, resulting in a damping or delay effect as the follower fins <NUM> try to rotate relative to the collar.

The construction of device <NUM> will be further understood in view of a description of one illustrative embodiment of its operation after the end cap is removed in preparation for an injection. To arrange device <NUM> to inject, sleeve <NUM>, and thereby button <NUM>, is manually rotated by a user to an unlocked state in which the device is ready to inject.

A cross-sectional view of the device in the unlocked state is shown in <FIG>. When a user subsequently applies a distal force on button <NUM>, button <NUM> starts to move downward into sleeve <NUM>, thereby driving flange surface <NUM> against ramp surface <NUM>. As button <NUM> continues to move further distally, with flange portion <NUM> inserting further into the shuttle opening, flange surface <NUM> slides along ramp surface <NUM>. During this sliding, flange portion <NUM> cams prong <NUM> radially outward because flange portion <NUM> is prevented from bending in the opposite radially outward direction due to the contact with the supportive collar surface <NUM>. Flange portion <NUM> is prevented from twisting due to contact with supportive surfaces on the proximal shuttle <NUM>. Prong <NUM> can be cammed outward as finger <NUM> bends until latching surfaces <NUM> disengage from latch surfaces on the proximal shuttle, at which point the proximal-most portion of plunger prong <NUM> passes downward through the shuttle due to spring <NUM> directly biasing the plunger element <NUM> downward to drive the plunger element and thereby the piston <NUM> distally, which driven motion shifts syringe barrel <NUM> and syringe carrier <NUM> distally relative to the shuttle and the housing to cause the tip of needle <NUM> to project beyond the housing distal end for penetrating a user's skin, and then forces the medication contents of the syringe through that needle for an injection.

As plunger element <NUM> moves distally during medication injection, the arm <NUM> abuts against the latch <NUM> of the follower <NUM>, causing flexure arm <NUM> to deflect distally, causing the leading surface <NUM> of the latch to slide distally past the protrusion <NUM> of the distal shuttle <NUM>, thus causing the latch <NUM> to clear the protrusion <NUM>. With the latch <NUM> disengaged from the protrusion <NUM> of the distal shuttle <NUM>, the follower <NUM> is in the uncoupled configuration, and the follower <NUM> is thus unlocked for rotation relative to the distal shuttle <NUM>. <FIG> shows the arrangement of device <NUM> at this point of the use process.

Follower <NUM>, as urged by the torsional preloading of biasing member <NUM>, rotates against the damping effect of damping compound <NUM>, during which rotation remaining medication can be properly expelled from the syringe through the needle. When follower <NUM> has rotated such that shuttle tabs <NUM> and <NUM> are clear of ledges <NUM> and <NUM>, shuttle <NUM> and follower <NUM> are thereby unlatched so as to allow the compressively preloaded biasing member <NUM> to decompress, forcing shuttle <NUM> proximally to retract the syringe carrier <NUM> and the syringe barrel <NUM> along with the syringe carrier, thereby retracting the distal tip of the injection needle <NUM> to a protected, retracted position within the housing <NUM>.

While the automatic injection device described herein has been shown and described as having preferred designs, the present device may be modified within the scope of the appended claims. For example, while the biased element that the trigger assembly releases in the shown embodiment is the plunger that itself contacts the syringe piston, the trigger assembly could be used to release different biased elements in alternate embodiments, or elements that are biased with parts different than coiled springs.

Claim 1:
An automatic injection device, comprising:
a housing (<NUM>) comprising a proximal end (<NUM>) and a distal end;
a syringe (<NUM>) including a needle (<NUM>), a syringe body and a plunger (<NUM>), the plunger (<NUM>) being moveable relative to the syringe body to expel medication from the syringe body through the needle (<NUM>); and
a syringe carrier (<NUM>) fully surrounding an outer perimeter of the syringe body and including a first part (<NUM>) and a second part (<NUM>) that are discrete from one another and are interlocked together, each of the first and second parts (<NUM>, <NUM>) comprising:
a proximal flange surface (<NUM>);
a distal flange surface (<NUM>);
a circumferential rounded wall (<NUM>) between the proximal flange surface (<NUM>) and the distal flange surface (<NUM>); and
a gap (<NUM>) located between the proximal flange surface (<NUM>), the distal flange surface (<NUM>) and the circumferential rounded wall (<NUM>),
wherein the syringe body includes a syringe body flange (<NUM>) received within the gap (<NUM>); and
wherein the syringe carrier (<NUM>) includes a cushion (<NUM>) in contact with a distal surface (133B) of the syringe body flange (<NUM>) to support the syringe body flange (<NUM>), and the proximal flange surface (<NUM>) and the distal flange surface (<NUM>) have a greater material hardness than the cushion (<NUM>).