Safety Device and a Drug Delivery System Mounted on Said Safety Device

The safety device includes a tubular body configured to receive a barrel, a head arrangement configured to abut against the flange and to lock into a flange, at least two actuation arms connecting the tubular body and the head arrangement, said actuation arms having a proximal link connected to the head arrangement by a proximal hinge and a distal link connected to the tubular body by a distal hinge. The proximal link and the distal link are connected by an intermediate hinge. The actuation arm is movable between a collapsed position in which the tubular body is maintained in a position proximally close to the flange uncovering the needle and an extended position in which the tubular body is maintained in a position distally distant from the head arrangement shielding the needle; a locking means for maintaining the actuation arms in a collapsed position and a locking means for maintaining the actuation arms in an extended position.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to European Patent Application No. 22306631.7 filed Oct. 28, 2022, the disclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a safety device for mounting onto a drug delivery device such as a prefilled or pre-fillable syringe in order to protect a user from needle stick injuries after injection of a medical product. The invention also relates to a drug delivery device including this safety device.

Description of Related Art

In this application, the distal end of a component or of a device is to be understood as meaning the end furthest from the user's hand and the proximal end is to be understood as meaning the end closest to the user's hand. Likewise, in this application, the “distal direction” is to be understood as meaning the direction of injection, with respect to the safety device or drug delivery device of the invention and the “proximal direction” is to be understood as meaning the opposite direction to said direction of injection, that is to say the direction towards the user's hand.

Drug delivery devices, such as pre-fillable or prefilled syringes, usually comprise a hollow body or barrel forming a container for a medical product. This body comprises a distal end in the form of a longitudinal tip defining an axial passageway through which the medical product is expelled from the container. The distal end is equipped with a needle for injection of the medical product into an injection site.

It is of great importance that the patients and users are protected from any risk of needle stick injuries, particularly between the moment that injection is finished and the discarding of the drug delivery device.

In order to minimize the risks of needle stick injuries, drug delivery devices may be equipped with a safety device that protects the needle after injection. Safety devices usually comprise a tubular body for receiving the syringe barrel, and a needle cover, in the form of a protective sleeve, that slides relative to the tubular body. The needle cover has a retracted position in which the needle cover is substantially contained inside the tubular body to allow a user to carry out an injection, and an extended position in which the needle cover moves distally from the retracted position to cover the needle once the injection is completed.

Although known injection systems are generally satisfactory, they do not always meet all of the user's expectations and they can include a number of components. Therefore, they can be expensive to manufacture and thus this can limit the widespread use of safety devises at the expense of the security of medical users and patients.

They also tend to include components made of various materials which can be complex and expensive to recycle

SUMMARY OF THE INVENTION

A need exists for an improved safety that provides a user with more convenient safety device that is also cost effective and easy to manufacture.

In one aspect, the invention is directed to a safety device for mounting onto a drug delivery device having a barrel including with a flange at its proximal end and an injection needle at its distal end, and a piston rod including a piston flange, the safety device including:a tubular body extending along a longitudinal axis (A), the tubular body being configured to receive the barrel,a head arrangement configured to abut against the flange and to lock into the flange,at least two actuation arms connecting the tubular body and the head arrangement, said actuation arms having a proximal link connected to the head arrangement by a proximal hinge and a distal link connected to the tubular body by a distal hinge, the proximal link and the distal link being connected by an intermediate hinge, the actuation arm being movable between a collapsed position in which the tubular body is maintained in a position proximally close to the flange uncovering the needle and an extended position in which the tubular body is maintained in a position distally distant from the head arrangement shielding the needle,a locking means for maintaining the actuation arms in a collapsed position and a locking means for maintaining the actuation arms in an extended position.

At least one the hinge cab be a living hinge.

The safety device is formed in a single shot injection molding process.

The safety device has a relaxed state in which the arms returns from being in the collapsed position or from being in the extended position.

The proximal link and the distal link form an angle between 75° and 105° in the relaxed position.

The proximal links can include at least one locking hooks configured and sized to enter into resilient snap fit engagement with at least one wings protruding from the annular head to maintain the actuation arm in the extended position.

The head arrangement includes an annular head comprising a locking member which includes a radially oriented wall and two wings extending laterally from the wall.

The annular head includes a longitudinal tongue which extends distally from the locking member and is configured and sized to engage into a channel defined by two guiding walls provided on the tubular body.

The intermediate hinge inwardly overtakes the plan defined by the proximal hinge and distal hinge when the actuation arm is in its extended position.

The annular head can includes a proximal ring and a distal ring jointed by a shoulder whereon the flange abuts.

The proximal link can include two orthogonal finger plates.

The annular head comprises at least one locking tab configured to retain the flange.

The tubular body comprises a leg extending in cantilever and having a catch at its free end, the leg being configured to deflect radially outward to allow the catch to slide over the annular head during mounting and to deflect radially inward after mounting completion so that the catch axially retains the tubular body relative to annular head.

The safety device can includes at least one recess positioned at the junction between the shoulder and the distal ring.

The head arrangement can include a crown having a proximal plate configured and sized to lock onto the flange and a distal plate mounted on the tubular body, the proximal plate and the distal plate being connected by at least two actuation arms.

The proximal plate can include two symmetrical ribs, each rib having two locking teeth configured to retain the flange.

The distal link includes at least one looking hook configured and sized to engage into at least one opening provided in the proximal link when the arm is in a collapsed position.

The safety device can includes two legs having a catch, extending in cantilever from the distal plate, configured and sized to engage into a window provided in the proximal plate and to lock into the rib.

The safety device can includes at least one finger tab positioned at the junction of the distal link and the proximal link.

In a second aspect, the invention is directed to a drug delivery device having a barrel including with a flange at its proximal end and an injection needle at its distal end, and a piston rod including a piston flange fitted with a safety device as previously described, wherein the piston flange includes a ramped surface distally convergent configured to outwardly deflect the leg.

DESCRIPTION OF THE INVENTION

The different features of the embodiments can be used in combination with and used with other embodiments as long as the combined parts are not inconsistent with or interfere with the operation of the device and assembly. This invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The embodiments herein are capable of being modified, practiced or carried out in various ways. The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not limited to physical or mechanical connections or couplings. Further, terms such as distal, proximal, up, down, bottom, and top are relative, and are to aid illustration, but are not limiting. The embodiments are not intended to be mutually exclusive so that the features of one embodiment can be combined with other embodiments as long as they do not contradict each other. Terms of degree, such as “substantially”, “about” and “approximately” are understood by those skilled in the art to refer to reasonable ranges around and including the given value and ranges outside the given value, for example, general tolerances associated with manufacturing, assembly, and use of the embodiments. The term “substantially” when referring to a structure or characteristic includes the characteristic that is mostly or entirely present in the structure.

With reference to the Figures, a safety device10is configured to be mounted onto a drug delivery device100to protect an injection needle101of the drug delivery device100after an injection has been carried out.

The drug delivery device100may be a prefilled or prefillable syringe. The drug delivery device100includes a tubular barrel102defining a reservoir for containing a medical product such as a drug. The tubular barrel102may be made of a plastic or of a glass material. This barrel102has a distal shoulder103provided with a distal tip104longitudinally protruding from said shoulder103along a longitudinal axis A. The distal tip104defines an axial passageway in fluid communication with the reservoir and is equipped with the injection needle101for injecting the medical product in an injection site. The barrel102further includes an opposite opened proximal end106provided with a flange107. The opened proximal end106receives a plunger rod110for pushing a stopper112located inside the barrel102to expel the medical product from the reservoir to the injection site via the distal tip104and the injection needle101.

The drug delivery device100may be fitted with a tip cap113for protecting and sealing the injection needle101before injection. The tip cap113may be comprised of a soft inner element115and a rigid outer element116.

The piston rod110is fitted with a plunger flange114at its proximal end. In some embodiments, the plunger flange114can include a ramped surface118. The ramped surface118is conically convergent toward the distal direction.

Turning toFIG.3andFIG.4, the safety device10includes a tubular body12, which extends along the longitudinal axis A and is configured and sized to engage on the barrel102and a head arrangement which can include an annular head14configured and sized to engage on the barrel102and to lock on the flange107.

In some embodiment, two symmetrical articulated actuation arms16connect the tubular body12and the annular head14. Other embodiments may include three or four actuation arms16.

The tubular body12is a tubular element, which has an inner diameter sized and configured so that the tubular body12can axially slide relative to the barrel102. In practice, the tubular body12inner diameter slightly exceeds the external diameter of the barrel102. In some embodiments, the tubular body12can be provided with one or more windows19so that any marking or labelling applied on the barrel102and so that the drug contained in the barrel102can be visible to a user prior to injection. In the illustrated embodiments, the tubular body12is provided with two windows19spaced apart by 180°.

In some embodiments, the tubular body12can comprise two tabs20positioned at its proximal end. The tabs20extends radially from the outer surface of the tubular body12and the tabs20can be oriented substantially perpendicular to the longitudinal axis A.

The tubular body12further comprises two legs21. The legs21extend in cantilever from each tab20in the proximal direction. In some embodiments, the legs21can have an arched shape with an inward facing concavity. The cantilevered attachment of the legs21onto the tabs20combined with its arched shape provide the legs21with elastic resilience in a radial direction relative to the tubular body12. At the end of the legs21, is a catch22, which is internally oriented. In some embodiments, the catch22has a ramped end.

Now turning toFIG.5, the annular head14comprises a distal ring23attached by a shoulder24to a proximal ring25. The distal ring23is coaxial with the tubular body12and has an inner diameter, which substantially equates the inner diameter of the tubular body12.

As can be seen onFIG.4, the proximal ring25can be provided with one or more locking tabs26, which radially protrude from the inner surface of said proximal ring25. In the illustrated embodiments, the proximal ring25includes four locking tabs26spaced apart by 90°.

In some embodiments, the annular head14further comprises two projecting locking member32. Each projecting locking member32, which extends from the shoulder24and the distal ring23, has a substantially T shaped cross section and includes a radially oriented wall34, which protrudes from the distal ring23. At its free end, the wall34is provided with two wings36, which extend from the wall34in a substantially perpendicular direction. Each projecting locking member32can further include a ramped nose38, which tapers in a distal direction. In some embodiments, each projecting locking member32includes two parallel guiding ears37. The guiding ears37protrude from the proximal ring25on the side of the wings36.

The annular head14and the tubular body12are linked by the two articulated actuation arms16, which each includes a proximal link39and a distal link40.

The proximal link39has a substantially rectangular shape and is connected to the annular head14by a first proximal hinge42. The annular head14has two spaced apart parallel arms43, which are connected to two corresponding arms44made in the proximal link39. The first proximal hinge42thus connects the two arms43and the two arms44of the proximal link39. The two arms44define a window45in the proximal link39. In the illustrated embodiment, the first proximal hinge42is a living hinge formed by a thinning of the plastic material, which the safety device10is made of. This allows the proximal link39to rotate relative to the arms43and44. The proximal links39further may comprise two locking hooks46, which protrude from its internal face. The two locking hooks46are sized and shaped to create a snap fit engagement with the wings36of the projecting locking member32. To this end, the locking hooks46can include a ramped finger48and the wings36can also have a tapered cross section. It can be envisaged to provide the proximal link39with a single locking hook46.

In some embodiments, the distal link40has a substantially rectangular shape and is connected to the tab20by a second distal hinge47which can be a living hinge made by a thinning of the plastic material which forms the safety device10. As shown more clearly onFIG.3andFIGS.4, the distal link40can include a proximal and a distal finger plates29,30which can be substantially orthogonally positioned and are linked by a longitudinal rib27which rigidly joins the two finger plates29and30.

The proximal link39and the distal link40are joined by an intermediate hinge49, which can be a living hinge made by a thinning of the plastic material which forms the safety device10.

Thus in some embodiments, the safety device10comprises two articulated actuation arm16which connect the tubular body12and the annular ring14and comprises a unitary structure integrally molded of thermoplastic material.

In some embodiments, the safety device10can be a single piece component. Further, the safety device10can be formed by a single shot molding process. The plastic polymer used in the molding process can be a suitable polymer such as thermoplastic, which provides a shape memory to the safety device10configured to recover its original shape from deformation when a force has been applied.

In some embodiments, in an initial and relaxed state, (see e.g.FIG.3), after manufacturing by injection molding, the safety device10is configured in a state wherein the annular head14and the tubular body12are axially spaced apart while the proximal link39and the distal link40form a substantially right angle. In practice, the angle between proximal link39and the distal link40can be comprised between for example 75° and 105°. When an axial force is applied to the safety device10, the actuation arms16may bend about the living hinges42,47and49and flex radially outwardly or inwardly depending on the force direction. When the force ceases to apply on the safety device10, it regains its initial and relaxed state. The actuation arms16are therefore transitionable from an initial and relaxed state where the proximal link39and distal link form a first angle—substantially right angle—to:

(i) a collapsed state where the proximal link39and the distal link40are substantially parallel to each other or at least form an acute angle, or

(ii) an extended state where the proximal link39and the distal link40form are substantially in line with each other.

Starting with a safety device10as shown onFIG.3, the safety device10can be moved into a collapsed position as shown onFIG.6.

To do so, the tubular body12is pushed in a proximal direction so that the legs21which extend from said tubular body12deflects against the noses38, this being made smooth by the ramped catch22deflecting against the tapered nose38. The legs21are then channeled between the guiding ears37. At the end of the push, the catch22locks against the free end of the proximal ring25achieving an appropriate retention of the tubular body12onto the annular ring14as illustrated onFIG.7. In this locked state, the actuation arms16are pushed in a collapsed state as can be seen onFIG.6. In some embodiments, the actuation arm16in its collapsed state has the proximal link39substantially perpendicular to the axis A whereas the proximal finger plate29is substantially parallel to the longitudinal axis A and the distal plate is substantially perpendicular to the longitudinal axis A.

In this collapsed configuration, the safety device is in a stable state and can be shipped and stored for later use or can be immediately engaged on a drug delivery device.

In an exemplary use, the safety device10can be engaged on a drug delivery device100, which can be a prefilled syringe as illustrated onFIG.9.

The drug delivery device distal end is inserted through the annular head14and is pushed in a distal direction (see e.g.FIG.9). The annular head14is locked onto the barrel flange107. As best seen onFIG.8, the locking tabs26deflect when the annular head14is pushed in a proximal direction so that the annular head14is retained on the barrel flange107.

The drug delivery device100is axially locked on the safety device10, however the drug delivery device100is free to rotate relative to the safety device10, which can be useful as user tend to rotate any drug delivery device before injection to visually check the drug which is about to be injected.

The drug delivery device fitted with a safety device100as illustrated onFIG.9can be stored for a later use.

When an injection of the drug contained in the drug delivery device100is required, a user may first remove the tip cap113.

The drug delivery device100is ready for injection. The user can visually check the drug through the windows19and can rotate the plunder rod110.

Administering an injection with a drug delivery device fitted with the safety device10is substantially the same as administering an injection with a drug delivery device fitted with the safety device10according to the prior art and thus is not likely to confuse a user and permits a user-friendly operation.

In an exemplary use illustrated onFIG.10, the user can apply a pushing force on the piston rod flange114typically by applying a thumb on the piston rod flange114while the user maintains one finger—typically the index—on one distal link40and one finger—typically the middle finger—on the other distal link40.

In embodiments where the distal links40include two orthogonal finger plates29,30, the distal finger plates30provide an intuitive and ergonomic surface to place fingers.

As the injection progresses, the piston rod flange114moves closer to the annular head14. At the end of the injection, the piston rod flange114abuts against the catch22. By further pushing the piston rod flange114, the ramp portion118comes in abutment with the ramp provided in the catch22of each legs21as indicated by the arrows ofFIG.11. The legs21are thus forced to deflect outwardly thereby releasing the catch22. The actuation arms16and the tubular body12are released from the annular head14and are therefore free to move axially along the barrel102.

In one or more embodiment, as they are free, the actuation arms16move toward their initial and relaxed state where the proximal link39and the distal link40form a substantially right angle depending on the material and the injection process used to manufacture the safety device10.

As the actuations arms16return to their initial and relaxed position, the tubular body12moves axially on a distal position and covers at least partially the needle101. However, in this state the tubular body12is still free to move in the proximal direction.

This is why, the safety device10is moved to a locked extended position. To achieve this, the user can exert a radial force on each actuation arms16. The user can place one finger—shown by a radial arrow onFIG.12—on the proximal finger plate29of one actuation arm16and one finger—shown by a radial arrow onFIG.12—on the other proximal finger29plate of the other actuation arm16; both proximal finger plates29are intuitive and friendly to use. The arrows ofFIG.12show where the user applies a force with the fingers of one hand and with the fingers of two hands.

By doing so, the actuation arms16move into an extended state distally pushing the tubular body12into a position where the tubular body12entirely encapsulates the needle101.

At the end of the pushing on the actuation arms16, the two locking hooks46lock into the wings36of the projecting locking member32and maintain the actuation arms16in their respective extended positions where the tubular body12is pushed distally and thus the tubular body12shields the needle101from post-injection needle stick as seen inFIGS.13to15.

In some embodiments, the engagement of the locking hooks46on the wings36produces an audible and/or a tactile signal indicating that locking is positively achieved.

In some embodiments, the actuation arms16are in a state where the intermediate hinge49inwardly overtakes the plan defined by the proximal hinge42and distal hinge47as it can be best seen onFIG.15. Thus, a force applied longitudinally on the tubular body12aiming at un-shielding the needle tip101cannot release the actuation arm16from its extended state. The tubular body12is locked in an extended state by the locking hooks46; locking is further achieved by the proximal link39and distal link40which are arranged as a toggle mechanism.

The protective device10accordingly achieves a substantially permanent locking of the tubular body12over the needle tip101.

In an embodiment of the invention illustrated onFIG.16, the annular head12includes two longitudinal tongues55, which each extends distally from the locking member32. The longitudinal tongue55has a substantially flat cross section and includes a corrugation52at its distal end.

The tubular body12is further provided with two parallel guiding walls59, which extend from each tab20in a distal direction. Each pair of guiding walls59define a channel60, configured and sized to receive the tongue55. In the illustrated embodiment, each the tab20includes a window61to allow the tongue55insertion between the two guiding walls59. At the distal end of each pair of the guiding walls59, the tubular body includes a transverse rib53.

While not shown, the tubular body12may be held in its collapsed state via one of the corrugation52being engaged on the transverse rib53while the tongue55is engaged between the two guiding walls59thereby increasing the overall rigidity of the safety device10when in collapsed state. The elastic snap fit of the corrugation52on the rib53can provide an audible and/or tactile feedback to a user.

In one embodiment shown onFIG.17, the annular head12includes a tab75, which extends distally from the locking member32. The tab75includes a transverse corrugation76which is sized and configured to engage on a rib77provided on the annular body12. The corrugation76being engaged on the rib77provides an axially locking force when the actuation arm16is in its collapsed state.

In one embodiment shown onFIG.18, the safety device10includes two hooks46a, which protrude from the inner face of the two proximal link39. The hooks46ahave a curved free end configured and sized to enter into snap fit engagement with a wing36.FIG.18further shows where the finger plates protrude from each distal plates. The curved shaped hooks and the finger plates protruding from the distal link tend to make the safety device easier to manufacture by injection molding.

In some embodiments shown onFIG.19, the safety device10can include one or more recesses configured to reduce the gross weight of the safety device10. Reducing the gross weight further means that less raw plastic injection material is needed. Manufacturing cycles can be reduced as less material is required and cooling time is improved. In the illustrated embodiment ofFIG.19, two recesses90are provided in the annular ring14. The recesses90can be positioned at the junction between the shoulder24and the distal ring23. In one or more embodiments, the recesses90can be located above the projecting locking member32.

Turning toFIG.20toFIG.24, the safety device210includes a tubular body212, and is configured and sized to engage on the barrel102of a drug delivery device such as a prefilled syringe and a head arrangement which can include a crown213designed and configured to axially move between a locked collapsed position (FIG.20) and a locked extended position (FIG.21).

The tubular body212is a tubular element, which has an inner diameter sized and configured so that the tubular body212can axially slide relative to the barrel102. In practice, the tubular body212inner diameter slightly exceeds the external diameter of the barrel102. In some embodiments, the tubular body212can be provided with one or more windows219so that any marking or labelling applied on the barrel102and so that the drug contained in the barrel102can be visible to a user prior to injection. In the illustrated embodiments, the tubular body212is provided with two windows219spaced apart by 180°.

The crown213includes a distal plate214which is positioned at the proximal end of the tubular body212. In the illustrated embodiment, the distal plate214has a quadrangular shape. As it can be seen onFIG.22andFIG.23, the distal plate214includes two symmetrical legs221. The legs221extend in cantilever the distal plate214in the proximal direction. The cantilevered attachment of the legs221onto the distal plate214provides the legs21with elastic resilience in a radial direction relative to the tubular body212. At the end of the legs221, is a catch222, which is internally oriented. In some embodiments, the catch222has a ramped end.

The crown213includes a proximal plate215which can have a quadrangular shape. On its proximal face, the proximal plate215is provided with locking elements where the flange107can engage the locking elements.

The proximal plate215and the distal plate214are provided with two coaxial circular openings223and224.

In some embodiments, the proximal plate215can include two symmetrical ribs218. Each ribs218can be provided with two cantilevered locking tooth219.

The proximal plate215can include two windows217which are each adjacent a ribs218. The windows217are configured and sized to receive a leg221. In other words, the legs221can engage the windows217and the catches222can lock onto the ribs218when the safety device210is in a collapsed position.

The crown213further includes two arms216which connect the distal plate214to the proximal plate215. Each arm216includes a proximal link239and a distal link240.

The proximal links239have a substantially rectangular shape and are each connected to proximal plate216by a first proximal hinge242. In the illustrated embodiment, the first proximal hinges242are living hinges formed by a thinning of the plastic material, which the safety device210is made of. This allows the proximal links239to rotate relative to proximal plate215. The proximal links239can be provided with two openings250.

The distal links240have a substantially rectangular shape and are each connected to the distal plate214by a distal hinge247which can be a living hinge made by a thinning of the plastic material which forms the safety device10.

The proximal link239and the distal link240can be joined by an intermediate hinge249, which can be a living hinge made by a thinning of the plastic material which forms the safety device10.

The distal links240can each include two locking hooks246, which protrude from its internal face. The locking hooks246are sized and shaped to create (i) a snap fit engagement with the openings250provided in the proximal links239where the proximal links239and the distal links240are substantially parallel seeFIG.24and (ii) a snap fit engagement with the legs221where the proximal links239and the distal links240are in line with each other substantially seeFIG.22andFIG.23.

In some embodiments, the arms216can be each provided with finger tabs252. The finger tabs252can be positioned at the intermediate hinges249.

The actuation arms216are therefore transitionable between:(i) a collapsed state where the proximal link239and the distal link240are substantially parallel to each other, or(ii) an extended state where the proximal link239and the distal link240form are substantially in line with each other.

In some embodiments, the safety device210can be a single piece component. Further, the safety device210can be formed by a single shot molding process.

In its collapsed position shown onFIG.24, the proximal link239and the distal link240are parallel and are maintained against each other by the locking hooks246which engage into the openings250. Further, the legs221engage the windows217and lock into the ribs218.

In its extended position shown onFIGS.23and24, the proximal link239and the distal link240are in line with each other and the locking hooks246retain the legs221.

FIG.20shows the safety device210fitted on a drug delivery device100which can be a prefilled syringe.

In this collapsed position, the crown213is locked onto the drug delivery device100. To do so, the barrel flange107locks onto the ribs108. The barrel flange107snaps fit onto the locking tooth219.

The drug delivery device100is axially locked on the safety device210, however the drug delivery device100is free to rotate relative to the safety device10, which can be useful as user tend to rotate any drug delivery device before injection to visually check the drug which is about to be injected.

The drug delivery device fitted with a safety device100as illustrated onFIG.20can be stored for a later use.

When an injection of the drug contained in the drug delivery device100is required, a user may first remove the tip cap113.

The drug delivery device100is ready for injection. The user can visually check the drug through the windows19and can rotate the plunder rod110.

Administering an injection with a drug delivery device fitted with the safety device210is substantially the same as administering an injection with a drug delivery device fitted with the safety device10according to the prior art and thus is not likely to confuse a user and permits a user-friendly operation.

In an exemplary use illustrated onFIG.10, the user can apply a pushing force on the piston rod flange114typically by applying a thumb on the piston rod flange114while the user maintains one finger—typically the index—on one distal link240and one finger—typically the middle finger—on the other distal link240.

As the injection progresses, the piston rod flange114moves closer to the crown214. At the end of the injection, the piston rod flange114abuts against the catches222. By further pushing the piston rod flange114, the ramp portion118comes in abutment with the ramp provided in the catch222of each legs221as indicated by the arrows ofFIG.20. The legs221are thus forced to deflect outwardly thereby releasing the catches222from the ribs218. The actuation arms216and the tubular body212are released from the proximal plate215and are therefore free to move axially along the barrel102.

The user can exert a radial force on each actuation arms216. To do so, the user can place one finger on one finger tab252and another finger on the other finger tab252.

At the end of the pushing on the actuation arms216, the two locking hooks246lock into the legs221and maintain the actuation arms216in their respective extended positions where the tubular body212is pushed distally and thus the tubular body212shields the needle101from post-injection needle stick as seen onFIG.21.

In some embodiments, the engagement of the locking hooks246on the legs221produces an audible and/or a tactile signal indicating that locking is positively achieved.

It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that changes and modifications may be made within the scope of the appended claims.