NZ614086B2 - Auto-injector - Google Patents

Abstract

auto-injector (1) for administering a dose of a liquid medicament (M) is disclosed. The auto-injector including a tubular chassis (2) and a carrier subassembly comprising a tubular carrier (7) slidably arranged partially inside the chassis (2). The carrier (7) is adapted to contain a syringe (3) with a hollow injection needle (4), a drive spring (8) and a plunger (9) for forwarding load of the drive spring (8) to a stopper (6) of the syringe (3). The syringe (3) is lockable for joint axial translation with the carrier (7). A control spring (19) is arranged around the carrier (7). A needle insertion control mechanism (24) couples a proximal end of the control spring (19) to either the carrier (7) for advancing it for needle insertion or to the chassis (2) for needle retraction depending on the relative axial position of the carrier (7) and the chassis (2). The needle insertion control mechanism (24) comprises a first collar (20) biased by the control spring in a proximal direction (P), whereon at least one resilient beam is proximally arranged. Respective recesses are arranged in the carrier (7) and case (2), wherein a transversal extension of a head of the resilient beam (20. 1) is wider than a gap between the carrier (7) and the chassis (2), causing the head of the resilient beam to abut a distal face on the recess in the chassis (2) while being prevented from deflecting in an inward direction (I) by the carrier (7) or to abut a distal face on the recess in the carrier (7) while being prevented from deflecting in an outward direction (O) by the chassis (2) thereby forwarding load from the control spring (19) to the carrier (7) for needle insertion. The resilient beam is arranged to be switched between the chassis (2) and the carrier (7) by ramped engagement of the head to the distal faces under load of the control spring (19) depending on the relative longitudinal position between the chassis (2) and the carrier (7). with a hollow injection needle (4), a drive spring (8) and a plunger (9) for forwarding load of the drive spring (8) to a stopper (6) of the syringe (3). The syringe (3) is lockable for joint axial translation with the carrier (7). A control spring (19) is arranged around the carrier (7). A needle insertion control mechanism (24) couples a proximal end of the control spring (19) to either the carrier (7) for advancing it for needle insertion or to the chassis (2) for needle retraction depending on the relative axial position of the carrier (7) and the chassis (2). The needle insertion control mechanism (24) comprises a first collar (20) biased by the control spring in a proximal direction (P), whereon at least one resilient beam is proximally arranged. Respective recesses are arranged in the carrier (7) and case (2), wherein a transversal extension of a head of the resilient beam (20. 1) is wider than a gap between the carrier (7) and the chassis (2), causing the head of the resilient beam to abut a distal face on the recess in the chassis (2) while being prevented from deflecting in an inward direction (I) by the carrier (7) or to abut a distal face on the recess in the carrier (7) while being prevented from deflecting in an outward direction (O) by the chassis (2) thereby forwarding load from the control spring (19) to the carrier (7) for needle insertion. The resilient beam is arranged to be switched between the chassis (2) and the carrier (7) by ramped engagement of the head to the distal faces under load of the control spring (19) depending on the relative longitudinal position between the chassis (2) and the carrier (7).

Description

njector Technical Field The invention relates to an auto-injector for stering a dose of a liquid medicament according to the preamble of claim 1.

Background of the invention Administering an injection is a s which presents a number of risks and challenges for users and healthcare professionals, both mental and al. injection s (i.e. devices capable of delivering medicaments from a medication container) typically fall into two categories — manual devices and auto-injectors.

In a manual device — the user must provide the mechanical energy to drive the fluid through the . This is typically done by some form of button / plungerthat has to be continuously pressed by the user during the injection. There are numerous disadvantages to the user from this approach. if the user stops pressing the button / r then the injection will also stop. This means that the user can deliver an underdose it the device is not used properly (Le. the plunger is not fully pressed to its end position). Injection forces may be too high forthe user, in particular ifthe patient is elderly or has dexterity problems.

The extension of the button/plunger may be too great. Thus it can be inconvenient for the user to reach a fully extended button. The combination of injection force and button extension can cause trembling / shaking of the hand which in turn increases discomfort as the inserted needle moves.

Auto-injector devices aim to make self-administration of injected therapies easier for ts. Current therapies delivered by means of self-administered injections include drugs for diabetes (both insulin and newer GLP-i class drugs), migraine, hormone therapies, anticoagulants etc.

Auto-injectors are devices which completely or partially replace activities involved in parenteral drug delivery from standard syringes. These activities may include removal of a protective syringe cap, insertion of a needle into a patient’s skin, injection of the medicament. removal of the needle, shielding of the needle and preventing reuse of the device. This overcomes many of the disadvantages of manual s. Injection forces / button ion, haking and the likelihood of delivering an incomplete dose are reduced. Triggering may be performed by numerous means, for e a trigger button or the action of the needle reaching its injection depth. in some devices the energy to r the fluid is provided by a spring.

US 2002/0095120 A1 discloses an automatic injection device which automatically injects i5 a asured ty of fluid medicine when a tension spring is released. The tension spring moves an ampoule and the injection needle from a storage position to a deployed position when it is released. The content of the ampoule is thereafter expelled by the tension spring forcing a piston forward inside the ampoule. After the fluid ne has been injected, torsion stored in the tension spring is released and the injection needle is automatically retracted back to its original storage position.

High viscosity medicaments e high forces for expeiling them h the relativeiy thin injection needle. To achieve these forces strong drive springs are needed. This can lead to a high impact felt by the user when inserting the needle into the skin and to high forces felt by the user when triggering the injection. y of the invention It is an object of the present ion to provide an improved njector, or to at least provide the public with a useful choice.

The object is achieved by an auto~injector according to claim 1. Preferred embodiments of the invention are given in the dependent claims.

In the context of this specification the term proximal refers to the direction pointing towards the patient during an injection while the term distal refers to the opposite direction ng away from the patient. The term inwards refers to a radial direction ng towards a longitudinal axis of the auto-injector whereas the term outwards refers to the opposite direction radially pointing away from the longitudinal axis. ing to the invention an auto-injector for administering a close of a liquid medicament comprises: a tubular chassis, a carrier subassembly comprising a tubular carrier siidably arranged partially inside the s, the carrier d to contain a syringe with a hollow injection needle, a drive spring and a plunger for fonivarding load of the drive spring to a stopper of the syringe, wherein the syringe is lockable for joint axial ation with the carrier, 3 control spring arranged around the carrier, a needle insertion control mechanism for coupling a proximal end of the l spring to either the carrier for advancing it for needle ion or to the chassis for needle retraction depending on the relative axial position of the carrier and the chassis.

The needle insertion control mechanism comprises a first collar biased by the l spring in a proximal direction, wherein at least one resilient beam is proximally arranged on the first coliar, wherein respective recesses are arranged in the carrier and chassis, wherein a transversal extension of a head of the resilient beam is wider than a gap between the carrier and the chassis causing the head of the resilient beam to abut a distal face on the recess in the chassis while being ted from deflecting in an inward direction by the carrier or to abut a distal face on the recess in the carrier white being prevented from deflecting in an outward direction by the chassis thereby forwarding load from the control spring to the carrier for needle insertion, wherein the resilient beam is arranged to be switched between the chassis and the carrier by ramped engagement of the head to the distal faces under load of the control spring depending on the relative longitudinal position between the chassis and the carrier. As the head of the ent beam may be inwardly and outwardly ramped it may be referred to as an arrowhead. In an initial state the resilient beam is coupled to the chassis and prevented from inward tion by the carrier. In order to start an injection cycle the carrier is translated in the proximal ion by a small distance which may be achieved by a trigger button being depressed, the trigger button coupled to the carrier in a mannertranslating it. The small distance translation moves the recess in the carrier inwardly behind the resilient beam thus allowing the resilient beam to be deflected s due to its ramped engagement to the s under load of the control spring so as to engage the resilient beam to the carrier y releasing the control spring for advancing the carrier for needle insertion. Hence, the control spring continues moving the carrier in the proximal direction from this point. Whilst the user advances the needle by a proportion of its travel, the control spring takes over insertion before the needle protrudes from the proximal end. Therefore the user experience is that of pressing a button, rather than manually inserting a needle.

In the context of this specification the chassis is generally considered as being fixed in position so motion of other components is described relative to the chassis.

The distal face on the recess in the chassis may be shaped as a distal seventh ramp and/or the distal face on the recess in the carrier may be shaped as a distal tenth ramp. it goes without saying that in the ramped engagements between the resilient beam on the first collar and the faces on the recesses there may be respectivelyjust one ramp on one or the other component or there may be ramps on both components without significantly influencing the effect of the ramped engagement.

The gap between the carrier and the s may be wider than a shaft of the resilient beam between the first collar and the head ng the shaft to pass between the carrier and the chassis without ering. An aperture is arranged proximally from the recess in the chassis ng the head of the resilient beam to disengage from the carrier by ramped action and to deflect into the aperture when the r has been sufficiently ated relative to the s in the proximal direction thus switching the proximal end of the control spring to the chassis for allowing needle retraction. The carrier and hence the needle cannot be retracted as long as the carrier is biased in the al direction by the control spring. The proximal end of the control spring must therefore be decoupled from the carrier. The r can then be retracted by another spring or by the control spring provided its distal end is switched to the carrier subsequently.

The resilient beam may be connected to the first collar by a living hinge. A living hinge being a reduced diameter n of material in the resilient beam defines the position where the resilient beam is bent when deflected. This avoids g the shaft of the resilient beam over a more significant length which could result in undesirable interference with the chassis or carrier so as to affect the reliability of the switching.

The resilient beam may be initially coupled to the chassis, wherein the auto-injector is arranged to be actuated by translating the r in the proximal direction until the resilient beam switches to the carrier translating it further under load of the controi spring for needle insertion.

An elongate tubular case may be arranged, wherein the chassis and the carrier are oped within the case, wherein the case is biased in the distal direction and arranged to translate in the proximai direction against the bias when the chassis is pressed against an injection site, wherein a first rib on the case is arranged to t the head of the resilient beam from entering the aperture when the chassis is pressed against the injection site, wherein on l from the injection site and subsequent translation of the case in the distal direction the first rib is moved so as to allow the head of the resilient beam to disengage from the carrier and t into the aperture. This ensures that the carrier is being kept pressed against the injection site by the control spring as long as the user keeps the case against the injection site. If the user attempts to remove the auto-injector from the injection site they will reduce force on the case which will thus translate in the distal direction. The proximal end of the control spring is immediately decoupled from the carrier allowing the njector to retract the carrier and the needle.

The auto—injector may furthermore comprise: - a trigger button arranged distally or laterally in or on the case, - a plunger release mechanism arranged for releasing the plunger for injection when the r has at least almost reached an ion depth during needle insertion, - a detent mechanism arranged for coupling the chassis to the carrier forjoint axial translation relative to the case, wherein the detent mechanism is arranged to decouple the chassis from the carrier upon actuation of the trigger button thus allowing the carrier to move relative to the chassis so as to cause the needle insertion control mechanism to switch the proximal end of the control spring to the carrier for needle ion, and - a syringe retraction control mechanism arranged for coupling a distal end of the control spring to the carrier for needle retraction or to the case otherwise.

The carrier subassembly with the integrated drive spring allows for employing a strong drive spring without any impact on the user when triggering the auto-injector or during needle insertion since these s are achieved or opposed by the control spring which can be specified erably weaker than the drive spring. This allows for delivering highly viscous medicaments.

There are a number of significant benefits of separating the functions between the drive spring and the control spring in this way. The auto-injector is always needle safe, is. the needle can be ted before the injection is complete. The reliability of the auto- injector is improved as the components for needle advance and retraction are not loaded by the high impact of a freely expanding high force drive spring. The auto- 3O or is well suited to serve as a platform as the drive spring can be swapped to deliver different viscosity drugs without affecting the insertion or tion ons.

This is particularly advantageous for high viscosity fluids.

Releasing the drive spring upon the needle reaching an injection depth avoids a so called wet injection. i.e. medicament leaking out of the needle which is a problem in conventional art auto-injectors, where both needle insertion and ion are achieved by g on the stopper. The auto-injector solves the wet injection problem by the separate springs for translation of the carrier and for drug delivery.

The auto~injector has a particularly low part count compared to most tional auto— injectors thus reducing manufacturing costs. The arrangement with separate control 1O spring and drive spring for fluid injection allows for using one design for different viscosity s byjust changing the drive spring, and for different volumes just by changing the length of the plunger. This is an advantage over conventional art designs where the main spring also powers needle insertion and/or retraction.

In an initial as delivered state of the auto-injector the proximal end of the control spring is coupled to the chassis by the needle insertion control mechanism while the distal end is coupled to the case by the syringe retraction control mechanism, release of the drive spring is prevented by the plunger release mechanism, decoupling of the s from the carrier is prevented by the detent mechanism.

In order to trigger an ion the njector has to be pressed against the injection site, e.g. a patient’s skin. The user, e.g. the patient or a caregiver, grabs the case with their whole hand and pushes the chassis protruding from the proximal end t the injection site.

When pushed against the injection site, the case translates in the proximal direction relative to the chassis against the force of the control spring. When the case has at least almost reached an ed position the detent ism is unlocked thereby allowing translation of the carrier relative to the chassis.

The carrier can now be translated, preferably manually by depressing the r button forcing the carrier in the proximal direction. The carrier translates in the proximal direction relative to the case and to the chassis thereby switching the needle insertion control mechanism depending on the relative position of the carrier in the s so as to decouple the proximal end of the control spring from the chassis and coupie it to the carrier, thereby releasing the control spring for advancing the carrier for needle insertion.

Alternatively the control spring could initially be d to the carrier by the needie insertion control mechanism so that the carrier would be immediately advanced when the detent mechanism is unlocked by translation of the case into the advanced position.

As the needle translated with the carrier subassembly at ieast almost reaches an 1O injection depth the drive spring is released by the plunger release mechanism thereby allowing the drive spring to advance the plunger and the stopper for at least partialiy delivering the medicament. The release of the drive spring is preferably triggered by the carrier reaching a predefined relative position within the case.

If the auto-injector is removed from the injection site after the stopper has bottomed out in the e or mid injection, the case is translated in the distal direction under load of the control spring relative to the carrier subassembly.

As the case reaches a defined position relative to the carrier during that motion the 2O proximal end of the control spring is decoupled from the carrier and coupled to the chassis by the needie insertion control mechanism. Furthermore the distal end ofthe control spring is decoupied from the trigger sleeve and coupled to the carrier by the syringe tion control ism.

As the controi spring now pushes against the chassis in the proximal direction and against the carrier in the distal direction the r subassembly is ted into the chassis into a needle safe position by the control .

The plunger release mechanism may comprise at least one resilient arm on the r arranged to be in a ramped engagement to the plunger so as to disengage them under ioad of the drive spring, n a peg des from a distai end face of the trigger button in the proximal direction in a manner to t the resilient arm preventing disengagement of the carrier from the plunger and thus release of the drive spring when the carrier is in a distal on. The trigger button is arranged to remain in position relative to the case when the carrier is translated for advancing the . That means, the trigger button, initially coupled to the carrier, pushes the carrier in the al direction when depressed. As soon as the control spring takes over further advancing the carrier the trigger button may abut the case and decouple from the carrier, staying in position as the carrier moves on. Hence the resilient arm is pulled away from the peg thus allowing deflection of the resilient arm due to the ramped engagement under load of the drive spring for disengaging the plunger from the r and releasing the drive spring for drug delivery when the carrier has reached a predefined position during needie advancement.

The detent ism may be arranged to provide a resistive force which has to be overcome to advance the carrier in the proximal direction for needle insertion. Once the user applies a force on the trigger button which exceeds a pre-determined value the detent mechanism releases, initiating the ion cycle. If the pre-determined value is not overcome the detent mechanism pushes the carrier and trigger button back into their prior position. This s that the auto-injector is always in a defined state, either triggered or not triggered, not half triggered by the user hesitating.

The detent mechanism may also be arranged to provide a ive force resisting translation of the carrier in the distal ion relative to the s for keeping the carrier in a defined position in a transitional state with both ends of the control spring decoupled from the carrier. This transitional state may be ed for retracting the needle on removal from the injection site. As the carrier is biased against the injection site by the control spring before removal from the injection site it has to be decoupled from the proximal end of the controi spring and coupled to the distal end for retraction.

The cing of this switching is critical as retraction will fail if both ends of the control spring are attached to the carrier at the same time. This is overcome by separating the switching of the ends by a significant cement of the case, which moves in the distal direction relative to the chassis on removal of the injection site under load of the control spring. As the switching of the distal end of the control spring to the carrier depends on the relative position of the case to the carrier the carrier has to be fixed in the tional state which is achieved by the detent mechanism.

In one ment the detent mechanism ses a resilient beam on the chassis and a rhomboid ramp member on the carrier, the resilient beam being essentially straight when relaxed and having a first beam head ed to interact in a ramped engagement with a proximal fourth ramp or a distal fifth ramp on the rhomboid ramp member in such a manner that application of a translative force on the r relative to the chassis in the proximal direction with the first beam head engaged to the fourth ramp deflects the resilient beam in one transversal direction, e.g. ds when a predetermined value of the translative force, at least depending on the resilience of the ent beam, is overcome so as to allow the first beam head to travel along one transversal side of the rhomboid ramp member on continued relative translation of the components. The beam head may protrude transversaliy from the resilient beam in a manner to t the resilient beam by lever action when pushed against the rhomboid ramp member y aiso defining the predetermined value of the translative force to be overcome by the carrier. Furthermore, the contacting faces of the first beam head and the rhomboid ramp member may have their friction adapted to define the required force by appropriately choosing their shape and material properties. The resilient beam is allowed to relax when the first beam head has reached the fifth ramp y engaging it in a manner that application of a translative force on the carrier in the distal direction deflects the resilient beam in the other transversal direction, e.g. inwards when a predetermined value of the translative force, at least depending on the resilience of the resilient beam, is overcome so as to allow the first beam head to travel along the other transversal side ofthe rhomboid ramp member on continued translation of the carrier. The first beam head may also be d to relax behind the fourth ramp at the end ofthis motion for preventing the carrierfrom being advanced again, e.g. when the auto—injector is being heavily shaken after use.

It goes without saying that the positions of the resilient beam on the chassis and the rhomboid ramp member on the carrier may be switched without altering the function of the detent mechanism.

When the njector or the syringe is assembled a protective needle sheath may be ed to the needle for keeping the needle sterile and preventing both, damage to the needle during assembly and handling and access of a user to the needle for avoiding finger stick injuries. Removal of the protective needle sheath prior to an injection usually requires a vely high force for pulling the protective needle sheath off the needle and needle hub in the al direction. in order to maintain pre injection needle safety and prevent exposure of the needle translation of the syringe in the proximal direction due to this force has to be avoided. Forthis purpose the case may be arranged to lock the detent mechanism priorto being translated in the proximal direction relative to the chassis when the chassis is being pressed against the injection site so as to avoid translation of the carrier. This may be achieved by a rib in the case preventing deflection of the resilient beam of the detent mechanism by supporting it outwardly.

Translation of the case is translated into the advanced position in the proximal direction on contact to the ion site is arranged to unlock the detent mechanism rendering it operable. This may be achieved by the rib being moved with the case so as to no longer outwardly supporting the ent beam of the detent mechanism. in orderto ensure that the case is not moved in the proximal direction ing the detent mechanism before the protective needle sheath is removed a cap may be ed to the proximal end of the case so as to make the chassis inaccessible before the cap is removed. The cap preferably engages the protective needle sheath by means of a barb in a manner to remove the protective needle sheath when the cap is being pulled off the njector.

In order to facilitate removal of the cap it may have a ed surface mating with a surface on the case so that the cap is pulled off when rotated. The barb may be connected to the cap in a manner allowing them to rotate independently so as to avoid torque on the protective needle sheath when the cap is rotated in order not to distort the needle inside the protective needle sheath.

The distally arranged r button may be at least initially coupled to the carrier, wherein the case is arranged to abut the trigger button in the initial state preventing depression of the trigger button. On translation of the case into the advanced position when the chassis is being d against the injection site the trigger button remains d to the carrier thus emerging from the case which has been moved relative to the chassis, carrier and trigger button so as to allow depression of the trigger button for starting an injection cycle. Thus a sequence of ion is defined for the auto-injector to be actuated, first pressing it against the injection site and then to push the trigger button. This reduces the risk of finger stick es particularly if the user were to be confused which end of the auto—injector to apply t their skin. Without a sequence the user would risk inserting the needle into their thumb which is significantly less probable with the forced sequence. 1O The syringe retraction control mechanism may comprise a second collar bearing against the distal end of the control spring and having a resilient proximal beam with a second beam head having an inward boss. The second beam head is arranged to be in a ramped engagement with a second case detent in the case in a manner ramping the second beam head in the inward direction under load of the control spring in the distal direction. The inward boss is arranged to inwardly abut the carrier for preventing inward deflection of the second beam head and keep the second collar locked to the case. A third recess is arranged in the carrier for allowing the inward boss to be inwardly deflected on translation of the case in the distal direction relative to the carrier on removal of the auto-injector from the injection site. in an alternative embodiment the trigger button may be arranged distally, n the case is arranged as a ver sleeve trigger having a closed distal end face covering the trigger button. In an initial state a clearance is provided between the distal end face of the sleeve trigger and the trigger button ng for some travel of the sleeve trigger t the bias of the control spring in the proximal direction in a first phase before abutting the trigger button. As soon as the sleeve r has contacted the trigger button the trigger button is pushed by the sleeve trigger on further translation in a second phase. This ment allows for keeping the ty of the components of the auto~injector while only the described features need modification allowing to customize a platform device to particular requirements. An auto~injector with a sleeve trigger is particularly well suited for people with dexterity problems since, as opposed to conventional art auto-injectors, triggering does not require operation of smail buttons by single fingers. Instead, the whole hand is used.

Retraction of the needle requires the user to lift the njector far enough from the injection site to allow the case or sleeve trigger to translate back in the distal direction to switch the control spring. As it may be difficult for the user to know if the injection is finished or not a releasable noise component may be provided, capable of, upon e, generating an audible and/or e feedback to the user, wherein the noise component is arranged to be released when the plunger reaches a position relative to 1O the syringe in which the stopper is located in proximity of a proximal end of the syringe, is. when the injection is at least almost finished. The released noise ent then impacts on a housing component, such as the case, sleeve trigger or trigger button indicating the end of the injection. Impacting a ly accessible component allows for high perceptibility of the noise and direct access to the user's hand or finger for generating the tactile feedback. Preferably the noise component may impact the trigger button which may be shaped as a drum for providing a loud noise.

The needle ion depth is preferably defined by the carrier ve to the chassis not relative to the case, so if the user flinches or fails to hold the auto-injector hard against the injection site, only the case will move in the distal direction while the injection depth remains constant. As long as this case motion does not exceed a set distance the case does not yet switch the control spring for needle retraction.

The auto-injector may be operated by a number of key mechanical ions: ~ The case is advanced relative to the chassis compressing the control spring giving the userthe impression of sing a skin interlock sleeve. All other components remain in the same place during case advance resulting in the trigger button appearing from the distal end of the case.

~ The user pushes the trigger button which can now be ed. Button sion directly moves the carrier and hence the drive sub—assembly in the proximal direction a set distance until the control spring takes over via the first collar and inserts the needle into the injection site.

- The trigger button stops on the distal end of the case as the carrier continues translating in the al direction. The motion of the carrier relative to the trigger button is used to release the drive spring just before full insertion depth is reached, e.g. by pulling a peg on the trigger button out of the carrierthus allowing the plunger to move. The drive spring drives the r down the e barrel expelling the medicament.

- The noise mechanism is released when the plunger is near the end of travel shortly before the r bottoms out in the syringe, indicating the end of injection to the user.

- The needle remains fully inserted until the user moves the case back a set distance at which point the second collar decouples from the case and s to the carrier while the first collar decouples from the carrier and couples to the chassis thus allowing the control spring to retract the carrier and hence the .

The auto-injector may preferably be used for subcutaneous or intramuscular injection, particularly for delivering one of an analgetic, an anticoagulant, insulin, an insulin derivate, n, Lovenox, a vaccine, a growth hormone, a peptide hormone, a proteins, antibodies and complex carbohydrates.

The term medicament“, as used herein, means a ceutical formulation containing at least one pharmaceutically active compound, wherein in one embodiment the pharmaceutically active compound has a molecular weight up to 1500 Da and/or is a peptide, a proteine, a polysaccharide, a vaccine, a DNA, a RNA, a antibody, an enzyme, an antibody, a hormone or an oligonucleotide, or a mixture of the above-mentioned pharmaceutically active compound, wherein in a further embodiment the pharmaceutically active compound is useful for the ent and/or prophylaxis of diabetes mellitus or complications associated with diabetes mellitus such as ic retinopathy, oembolism disorders such as deep vein or pulmonary thromboemboiism, acute coronary syndrome (ACS), angina, myocardial infarction, cancer, macuiar degeneration, ation, hay fever, atherosclerosis and/or rheumatoid arthritis, wherein in a further embodiment the pharmaceuticaliy active compound comprises at least one peptide for the treatment and/or laxis of diabetes mellitus or complications associated with diabetes mellitus such as diabetic retinopathy, wherein in a further embodiment the pharmaceutically active compound comprises at least one human insulin or a human insulin analogue or derivative, glucagon-like peptide (GLP~1) or an analogue or derivative f, or exedin-3 or exedin-4 or an analogue or derivative of exedin—S or exedin-4. insulin anaiogues are for example Gly(A21), Arg(B31), 2) human insulin; Lys(B3), Giu(829) human insuiin; Lys(828), Pro(829) human insulin; Asp(828) human insulin; ’15 human insulin, wherein e in position 328 is replaced by Asp, Lys, Leu. Val or Ala and wherein in position 829 Lys may be replaced by Pro; 6) human insulin; Des(828-BBO) human insulin; Des(827) human insulin and O) human insulin. insulin derivates are for example BZQ-N-myristoyl-des(830) human insulin; BZQ-N- palmitoyl~des(B30) human insulin; BZQ-N-myristoyl human insulin; BZQ-N-paimitoyi human insulin; BZB-N-myristoyl LysBZSProB29 human insulin; BZ8-N—paimitoyl— LysBZBProBZQ human insulin; BSO~N~myristoyI-ThrBZQLysB3O human insulin; BSO-N- oyl— ThrB29LysB30 human n; 829~N~(N-pa|mitoyluY~g|utamyl)-des(BSO) human insulin; BZQ~N~(N~iithocholyl-Y-glutamyl)—des(BSO) human insulin; BZQ-N-(w- carboxyheptadecanoyl)-des(BBO) human insulin and 829-N-(w-carboxyheptadecanoyl) human n.

Exendin~4 for example means Exendin~4(1-39), a peptide of the ce H-His-Gly— Glu-Gly-Thr-Phe-Thr—Ser—Asp-Leu-Ser—Lys-Gln-Met-G|u~Glu~Giu-Ala-Val-Arg-Leu-Phe~ |ie-Glu—Trp—Leu-Lys-Asn-Gly—Gly—Pro~Ser—Ser—Gly—Aia-Pro-Pro-Pro—Ser—NHZ.

Exendin—4 derivatives are for example selected from the following iist of compounds: )4—des Pro36, des Pr037 Exendin~4(1-39)-NH2, H-(Lys)5~des Pro36, des Pro37 Exendin—4(1-39)—NH2, des Pro36 [Asp28] Exendin-4(1~39), des Pr036 [IsoAsp281 Exendin-4(1-39), des Pro36 [Met(O)‘i4, Asp28] Exendin~4(1-39), des Pr036 )14, 28] Exendin-4(1-39), des Pr036 [Trp(02)25, Asp28] Exendin—4(1-39), des Pr036 [Trp(02)25, lsoAsp28] Exendin-4(1—39), 1O des Pr036 [Met(O)14 Trp(O2)25, Asp28] Exendin-4(1-39), des Pr036 [Met(O)14 Trp(02)25, isoAsp28] Exendin-4(1-39); or des Pr036 [Asp28] Exendin-4(1-39), des Pr036 [IsoAsp28] Exendin-4(1-39), des Pr036 )‘i 4, Asp28] Exendin-4(1-39), des Pro36 [Met(O)14, |soAsp28] Exendin-4(1-39), des Pr036 [Trp(02)25, Asp28] Exendin-4(1-39), des Pr036 [Trp(02)25, 28] Exendin-4(1-39), des Pr036 [Met(O)14 Trp(02)25, Asp28] n-4(1-39), des Pr036 [Met(O)14 Trp(02)25, lsoAsp28] Exendin-4(1-39), wherein the group -Ly86-NH2 may be bound to the C-terminus of the Exendin-4 derivative; or an Exendin-4 derivative of the sequence H-(Lys)6~des Pr036 [Asp28] Exendin-4(1-39)-Lys6-NH2, des Asp28 Pr036, Pr037, Pr038Exendin~4(1—39)—NH2, H-(Lys)6~des Pr036, Pro38 [Asp28] Exendin-4(1—39)-NH2, H~Asn-(Giu)5des Pr036, Pr037, Pr038 [Asp28] Exendin-4(1-39)-NH2, des Pr036, Pr037, Pr038 [Asp28] n-4(1-39)—(Lys)6~NH2, H-(Lys)6-des Pr036, Pr037, Pr038 [Asp28] Exendin~4(1—39)—(Lys)6—NH2, H~Asn-(G|u)5-des Pr036, Pr037, Pro38 [Asp28} Exendin~4(1~39)—(Lys)6—NH2, H-(Lys)6-des Pro36 [Trp(02)25, Asp28] Exendin-4(1-39)-Lys6-NH2, H-des Asp28 Pr036, Pro37, Pro38 [Trp(02)25] Exendin-4(1-39)—NH2, H-(Lys)6-des Pr036, Pr037, Pr038 [Trp(02)25, Asp28] Exendin-4(1-39)-NH2, H-Asn-(GIu)5-des Pr036, Pr037, Pr038 [Trp(02)25, Asp28] Exendin-4(‘l-39)-NH2, des Pr036, Pr037, Pr038 [Trp(02)25, Asp28] Exendin-4(1~39)-(Lys)6-NH2, H-(Lys)6-des Pr036, Pro37, Pr038 [Trp(02)25, Asp28] Exendin-4(1-39)—(Lys)6-NH2, H-Asn—(Glu)5-des Pr036, Pr037, Pr038 [Trp(02)25, Asp28] Exendin~4(1-39)-(1_ys)6-NH2, H-(Lys)6-des Pr036 [Met(O)14, Asp28] Exendin~4(1-39)-Lys6-NH2, des Met(O)14 Asp28 Pr036, Pr037, Pro38 Exendin-4(1-39)-NH2, H-(Lys)6-desPr036, Pro37, Pro38 [Met(O)14, Asp28] Exendin—4(1~39)~NH2, 1O H~Asn-(Glu)5-des Pr036, Pr037, Pr038 [Met(O)14, Asp28] Exendin-4(1-39)~NH2, des Pr036, Pro37, Pr038 [Met(O)14, Asp28] Exendin-4(1~39)—(Lys)6—NH2, H-(Lys)6-des Pr036, Pro37, Pr038 [Met(O)14, Asp28] Exendin-4(1-39)-(Lys)6-NH2, H-Asn-(Glu)5 des Pro36, Pr037, Pr038 [Met(0)14, Asp28] Exendin-4(1-39)—(Lys)6-NH2, H-LysG-des Pr036 [Met(O)14, )25, Asp28] Exendin-4(’l~39)~LysB-NH2, ‘15 H-des Asp28 Pr036, Pr037, Pr038 [Met(O)14, Trp(02)25] Exendin-4(1-39)—NH2, H-(Lys)6-des Pro36, Pr037, Pr038 [lVlet(O)14, Asp28] Exendin-4(‘l-39)-NH2, H-Asn-(Glu)5-des Pro36, Pr037, Pr038 [Met(O)14, Trp(02)25, Asp28] Exendin-4(1-39)— NH2, des Pr036, Pr037, Pr038 )14, Trp(02)25, Asp28} Exendin~4(1~39)-(Lys)6~NH2, H—(Lys)6-des Pro36, Pr037, Pro38 [Met(O)14, )25, Asp28] Exendin-4(S1-39)- (Lys)6-NH2, (Glu)5~des Pr036, Pro37, Pr038 )14, Trp(02)25, Asp28] Exendin-4(1-39)- (Lys)6-NH2; or a pharmaceutically acceptable salt or solvate of any one of the afore-mentioned Exedin-4 derivative.

Hormones are for example hypophysis es or hypothalamus hormones or regulatory active es and their antagonists as listed in Rote Liste, ed. 2008, r 50, such as Gonadotropine (Follitropin, Lutropin, Choriongonadotropin, Menotropin), Somatropine (Somatropin), Desmopressin, ressin, Gonadorelin, Triptorelin, Leuprorelin, Buserelin, Nafarelin, Goserelin.

A polysaccharide is for example a glucosaminoglycane, a hyaluronic acid, a heparin, a low molecular weight heparin or an ultra low molecular weight heparin or a tive thereof, or a sulphated, e.g. a poly-sulphated form of the above-mentioned polysaccharides, and/or a pharmaceutically acceptable salt thereof. An example of a pharmaceutically acceptable salt of a poly-sulphated low molecular weight heparin is enoxaparin sodium.

Pharmaceutically acceptable salts are for example acid addition salts and basic salts. ’10 Acid addition saits are e.g. HCI or HBr salts. Basic salts are e.g. salts having a cation selected from alkali or alkaline, e.g. Na+, or K+, or Ca2+, or an ammonium ion N+(R1)(R2)(R3)(R4), wherein R1 to R4 independently of each other mean: hydrogen, an optionally tuted Ci-CB-alkyl group, an optionaily substituted CZ-Cfi-alkenyl group, an optionally tuted C6-CiO-aryl group, or an optionally substituted 06~010- heteroaryl group. Further examples of pharmaceutically acceptable salts are described in "Remington's Pharmaceutical Sciences" 17. ed. o R. Gennaro (Ed), Mark Publishing Company, Easton, Pa, USA, 1985 and in Encyclopedia of ceutical logy.

Pharmaceutically acceptable solvates are for example hydrates.

The drive spring and control spring may be compression springs. r, they may likewise be any kind of stored energy means such as torsion springs, gas springs etc.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, white ting preferred embodiments of the invention, are given by way of illustration only, since various changes and cations within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Brief Description of the Drawings The t invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present ion, and wherein: Figure 1 shows two longitudinal sections of an auto-injector in ent section planes in a state priorto use, Figure 2 shows two longitudinal sections of the auto-injector after removal of a cap and a protective needle sheath, Figure 3 shows two longitudinal sections of the auto-injector with a proximal end pressed against an injection site, Figure 4 shows two udinal sections of the auto-injector with a trigger button depressed, Figure 5 shows two longitudinal sections of the auto-injector during needle insertion into the injection site, Figure 6 shows two longitudinal sections of the auto-injector with the needle fully inserted, Figure 7 shows two longitudinal sections of the auto-injector during injection near the end of dose, Figure 8 shows two longitudinal sections of the njector at the end of dose, Figure 9 shows two longitudinal sections of the auto~injector removed from the injection site, Figure 10 shows two iongitudinal sections of the auto~injector with the needle retracted into a needle safe position, Figure 11 shows schematic views of a detent mechanism for lling movement of a carrier relative to a chassis of the auto-injector in four different states, Figure 12 shows schematic views of a needle insertion control mechanism for controlling movement of a first collar in six different states, Figure 13 shows schematic views of a syringe retraction control mechanism in three different states Figure 14 shows schematic views of a noise release ism for audibly indicating the end of injection in three different states, Figure 15 shows schematic views of a plunger release mechanism in three different , Figure 16 shows schematic views of a button release mechanism in three ent states, Figure 17 is an isometric View of an ative embodiment of the plunger release mechanism, Figure 18 is a longitudinal section of an alternative embodiment of the button release ism, Figure 19 shows longitudinal sections of an alternative embodiment of the detent mechanism, Figure 20 is a longitudinal section of a third embodiment of the detent mechanism, Figure 21 is a longitudinal section of an ative embodiment of the noise release mechanism, Figure 22 shows longitudinal sections of an alternative embodiment of the needle insertion control mechanism, also ed to perform the function of the detent mechanism on needle retraction and needle insertion, Figure 23 is an isometric view of the needle insertion control mechanism of figure Figure 24 shows longitudinal ns of a third embodiment of the needle insertion controi mechanism, also arranged to perform the functions of the detent mechanism, Figure 25 is an isometric view of the needle insertion control mechanism of figure Figure 26 shows longitudinal sections of a third embodiment of the noise release mechanism, and Figure 27 is another ment of the auto-injector having a wrap-over sleeve r instead of a trigger button.

Corresponding parts are marked with the same reference symbols in all figures.

Detaiied Description of Preferred Embodiments A ramped engagement in the terminology of this specification is an engagement between two components with at least one of them having a ramp for ng the other component in such a manner that one of the components is flexed aside when the components are axially pushed against each other provided this component is not prevented from flexing aside.

Figures 1a and 1b show two longitudinal sections of an auto-injector1 in different section planes, the different section planes approximately 90° rotated to each other, wherein the njector 1 is in an initial state prior to starting an injection. The auto- 1O injector 1 comprises a chassis 2. In the following the chassis 2 is generally considered as being fixed in position so motion of other components is described relative to the chassis 2. A syringe 3, e.g. a Hypak syringe, with a hoilow injection needle 4 is ed in a proximal part of the auto~injector1. When the auto—injector 1 or the syringe 3 is assembled a protective needle sheath 5 is attached to the needle 4. A stopper 6 is arranged for sealing the syringe 3 distally and for displacing a liquid medicament M through the hollow needle 4. The syringe 3 is held in a tubular carrier 7 and supported at its proximal end therein. The r 7 is slidably arranged in the chassis 2.

A drive spring 8 in the shape of a compression spring is arranged in a distal part of the carrier 7. A piunger 9 serves for ding the force of the drive spring 8 to the stopper 6.

The drive spring 8 is loaded between a distal carrier end face 10 of the carrier 7 and a thrust face 11 arranged distally on the plunger 9.

The r 7 is a key element housing the syringe 3, the drive spring 8 and the plunger 9, which are the components required to eject the ment M from the syringe 3.

These ents can therefore be referred to as a drive sub-assembly.

The chassis 2 and the carrier 7 are arranged within a tubular case 12. A trigger button 13 is arranged at a distal end of the case 12. In a plunger release mechanism 27 a peg 14 des from a distal end face of the trigger button 13 in the proximal direction P between two resiiient arms 15 originating from the distal carrier end face 10 thus preventing them from flexing towards each other in an initial state A illustrated in figure 15A. In figure 15A only one of the ent arms 15 is shown to illustrate the principle.

Outwardly the resilient arms 15 are caught in respective first recesses 16 in a distal plunger sleeve 17 attached distally to the thrust face 11 and arranged inside the drive spring 8. The engagement of the resilient arms 15 in the first recesses 16 prevents axial translation of the plunger 9 relative to the carrier 7. The resilient arms 15 are ramped in a manner to flex them inwards on ve motion between the plunger 9 and the carrier 1O 7 under load of the drive spring 8, which is prevented by the peg 14 in the initial state A.

The carrier 7 is locked to the chassis 2 for preventing relative translation by a detent mechanism 18 illustrated in more detail in figures 11A to 11D.

The trigger button 13 is initially d to the case 12 by a button release ism 26 and cannot be depressed. The button release mechanism 26 is illustrated in detail in figures 16A to 16C. Referring now to figure 16A the button e mechanism 26 comprises a resilient proximal beam 13.1 on the trigger button 13, the proximal beam 13.1 having an outward first ramp 13.2 and an inward second ramp 13.3. in an initial state A iilustrated in figure 16A the d first ramp 13.2 is engaged in a ramped first case detent 12.1 preventing the trigger button 13 from moving out of the distal end D.

The trigger button 13 proximally abuts both the case 12 and the carrier 7 hence being prevented from being depressed in the proximal direction P.

Referring again to figures 1A and 18 a control spring 19 in the shape of another compression spring is ed around the carrier 7 and acts between a proximal first collar 20 and a distal second coliar 21. The control spring 19 is used to move the carrier 7 and hence the drive sub-assembly in the proximal direction P for needle ion or in the distal direction D for needie retraction.

In the state as delivered as shown in figures 1a and 1b a cap 22 is attached to the al end of the case 12 and the protective needie sheath 5 is still in place over the needle 4 and the needle hub. An inner sleeve 22.1 of the cap 22 is arranged inside the chassis 2 and over the protective needle sheath 5. in the inner sleeve 22.1 a barb 23 is attached. The barb 23 is d to the protective needle sheath 5 forjoint axial translation.

A sequence of operation of the auto-injector 1 is as follows: A user pulls the cap 22 from the proximal end of the case 12. The barb 23 joins the protective needle sheath 5 to the cap 22. Hence, the protective needle sheath 5 is also 1O removed on removal of the cap 22. Figures 2a and 2b show the njector 1 with the cap 22 and needle sheath 5 removed. The carrier 7 and e 3 are prevented from moving in the proximal direction P by the detent mechanism 18 being in a state A as in figure 11A. ing now to figure 11A, the detent mechanism 18 comprises a resilient beam 2.1 on the chassis 2 with an inwardly protruding first beam head 2.2. The first beam head 2.2 has a proximal third ramp 2.3. The detent mechanism 18 further comprises a rhomboid ramp member 7.1 on the carrier 7 having a proximal fourth ramp 7.2 and a distal fifth ramp 7.3. in state A a rounded off distal side of the first beam head 2.2 abuts the ramp member 7.1 in the distal direction D resisting movement of the carrier 7 in the proximal ion P relative to the chassis 2. A rib on the case 12 is provided for preventing outward deflection of the resilient beam 2.1 y also preventing motion of the carrier 7 relative to the chassis 2.

Referring again to figures 2A and 28 the user grabs the case 12 and places the s 2 protruding from the case 12 at the al end P against an injection site, e.g. a patient's skin. As the auto-injector 1 is pressed t the injection site the case 12 translates in the proximal direction P relative to the chassis 2 into an advanced position as illustrated in figures 3A and BB. The second collar 21 is locked to the case 12 and is moved with the case 12 relative to the chassis 2 and relative to nearly all other components of the auto—injector 1 thus slightly compressing the control spring 19 against the first collar 20 which is prevented from moving in the proximal direction P by the chassis 2 due to a needle insertion control mechanism 24 being in a state A illustrated in detail in figure 12A. Referring now to figure 12A, a resilient member in the shape of an arrowhead 20.1 is proximally ed on the first collar 20. The first collar with the arrowhead 20.1 is being forced in the proximal direction P under load of the compressed control spring 19. An outward sixth ramp 20.2 on the arrowhead 20.1 interacts with a second distal seventh ramp 2.4 on the chassis 2 ramping the arrowhead .1 in an inward direction I which is prevented by the arrowhead 20.1 inwardly abutting the carrier 7. Hence, the first collar 20 cannot translate in the proximal direction P. ing again to figures 3A and BB the second collar 21 is locked to the case due to a syringe retraction control mechanism 25 being in a state A illustrated in detail in figure 13A. Referring now to figure 13A, the syringe retraction control mechanism 25 comprises a resilient proximal beam 21.1 on the second collar 21, the proximal beam 21.1 having a second beam head 21.2 having an inward boss 21.3 and a distal outward eighth ramp 21.4. The distal outward eighth ramp 21.4 is engaged in a ramped second case detent 12.2 in a manner ramping the second beam head 21.1 in the inward direction 1 with the second collar 21 under load of the control spring 19 in the distal direction D which is prevented by the inward boss 21.3 inwardly abutting the carrier 7.

Referring again to figures 3A and 38, if the user was to move the case 12 away from the injection site, the control spring 19 expands returning the auto-injector 1 to the initial condition after removal of the cap 22 as illustrated in figures 2A and 28.

In the state as in figures 3A and 3B the carrier 7 continues to be prevented from moving in the proximal ion P by the detent mechanism 18, r with the case 12 in its advanced position the detent ism 18 is unlocked as the rib on the case 12 has also moved and no longer prevents outward deflection of the resilient beam 2.1. nt of the case 12 relative to the carrier 7, which is locked to the s 2 by the detent mechanism 18, causes the button release mechanism 26 to switch to a state B rated in figure 168. The trigger button 13 cannot translate with the case 12 in the proximal direction P as it is abutted against the r 7. The ramp on the first case detent 12.1 interacts with the outward first ramp 13.2 on the proximal beam 13.1 on the trigger button 13 deflecting the proximal beam 13.1 in the inward direction I thus engaging the inward second ramp 13.3 on the al beam 13.1 in a ramped carrier detent 7.4 ed in the carrier 7. As the case 12 is translated further in the proximal direction P it ts the ai beam 13.1 outwardly thus locking the trigger button 13 to the carrier 7. The trigger button 13 now des from the distal end D of the chassis 12 and is ready to be pressed.

In the state as in figures 3A and 3B the user depresses the trigger button 13 in the proximal direction P. As the trigger button 13 abuts against the carrier 7 the carrier 7 is pushing in the proximal direction P against the chassis 2, the carrier 7 and the chassis 2 interacting in the detent mechanism 18. The force exerted by the user pressing the trigger button 13 is resolved through the chassis 2 onto the injection site, not between the trigger button 13 and the case 12. The detent mechanism 18 provides a ive force when the user pushes the trigger button 13. Once the user s a force which exceeds a pre-determined value the detent mechanism 18 releases, initiating the injection cycle. Referring now to figure 11B showing the detent mechanism 18 in a state B, the resilient beam 2.1 on the chassis 2 begins to bow under load from the rhomboid ramp member 7.1 on the carrier 7, storing c energy. Despite the proximal fourth ramp 7.2 on the ramp member 7.1 friction n the contacting faces of the first beam head 2.2 and the proximal fourth ramp 7.2 prevents movement of the first beam head 2.2 in the d direction 0 until the straightening force in the resiliently deformed beam 2.1 is sufficiently large to overcome it. At this point the resilient beam 2.1 is ted in the outward direction 0 moving out of the way of the carrier 7 thus allowing the carrier 7 to translate in the proximal direction P. When the carrier 7 travels sufficiently far in the proximai ion P the rhomboid ramp member 7.1 on the carrier 7 passes under the first beam head 2.2 thus ng it to relax and move back in the inward direction l distally behind the rhomboid ramp member 7.1 in a state C illustrated in figure 110 at the same time constraining translation of the carrier 7 in the distal direction D relative to the chassis 2.

Once the carrier 7 slides far enough in the proximal direction P relative to the first collar 20 the needle insertion control mechanism 24 is switched to a state B as illustrated in figure 128. In figure 128 the carrier 7 has been translated in the proximal direction P in such a manner that the arrowhead 20.1 on the first collar 20 is no ionger inwardly supported. This may be achieved by a second recess 7.5 in the carrier 7. The arrowhead 20.1 is now ted in the inward ion i into the second recess 7.5 under load of the control spring 19 arriving at a state C as illustrated in figure 120. The first coliar 20 is now decoupled from the chassis 2. instead, the arrowhead 20.1 couples the first collar 20 to the carrier 7 by an inward ninth ramp 20.3 engaging a distal tenth ramp 7.6 on the carrier 7 at the proximal end of the second recess 7.5. Hence, the control spring 19 ues moving the carrier 7 in the al direction P from this point. Whilst the user advances the needle 4 by a proportion of its , the control spring 19 takes over insertion before the needle 4 protrudes from the proximal end P.

Therefore the user experience is that of pressing a button, ratherthan manually inserting a needle.

The detent mechanism 18 relies on the user applying a force rather than a displacement.

Once the force applied exceeds the force ed to switch the detent the user will push the trigger button 13 fully, ensuring that the first collar 20 will always switch. Ifthe user fails to pass the detent, the trigger button 13 returns to its unused state ready for use as iilustrated in figures 3A and BB. This feature avoids the auto-injector 1 arriving in an undefined state. 2O Figures 4A and 4B show the auto-injector 1 with the trigger button 13 depressed sufficiently for the control spring 19 to coupie on to the carrier 7 and continue moving the r 7 forwards, but not yet abutting the case 12.

The carrier 7 d to the first coliar 20 is translated in the proximal direction P driven by the control spring 19. As the syringe 3 is arranged forjoint axial translation with the carrier 3 the syringe 3 and needle 4 are also translated resulting in the needle 4 protruding from the proximal end P and being inserted into the ion site. The trigger button 13 returns to its initial position relative to the case 12 and latches back to the case 12 from the carrier 7 as in state A in figure 16 A. The carrier 7 translates r in the proximal direction P preventing inward deflection of the proximal beam 13.1 so the outward first ramp 13.2 cannot disengage from the first case detent 12.1.

Immediately priorto the needle 4 reaching full insertion depth as illustrated in figures 5A and 5B the peg 14 on the trigger button 13 is tely pulled out from between the resilient arms 15 on the carrier 7. Hence, the plunger release mechanism 27 arrives in a state B shown in figure 158 with the resilient arms 15 no longer inwardly supported by the peg 14. Due to the ramped engagement of the resilient arms 15 in the first recess 16 they are deflected in the inward ion I under load of the drive spring 8 arriving in a state B illustrated in figure 150. Hence, the r 9 is released from the carrier 7 and driven in the proximal direction P by the drive spring 8, ready to inject the medicament M. The force to pull the peg 14 out from between the resilient arms 15 is 1O provided by the control spring 19 while the force required to deflect the resilient arms 15 out of engagement to the plunger 9 is provided by the drive spring 8.

While the plunger 9 moves and closes a gap to the r 6 the movement of the carrier 7 in the proximal direction P is completed by the control spring 19 pushing the first collar 20. As the r 7 moves with respect to the chassis 2 during needle insertion the needle insertion mechanism 24 arrives in a state D illustrated in figure 12D.

The arrowhead 20.1 has moved with the carrier 7 and is still kept ly deflected by the chassis 2 thus preventing the first collar 20 from aging the carrier 7. The arrowhead 20.1 must be able to t in the outward direction 0 to allow retraction which will be discussed below. In order to allow outward deflection the arrowhead 20.1 travels proximally beyond the part of the chassis 2 shown in figures 12A to 12F next to an aperture 2.5 in the chassis 2. However, as long as the case 12 is being kept d against the injection site and not allowed to return in the distal direction D beyond a predefined distance under load of the control spring 19 the arrowhead 20.1 will be kept from deflecting in the outward direction 0 by a first rib 12.3 on the case 12 (not illustrated in figures 12A to F, see figures 5A to 8A) during about the second half of its motion for needle insertion.

The needle 4 is now fully inserted into the injection site as illustrated in figures 6A and 68. The time between the trigger button 13 pressed and the needle 4 being fully inserted is very short, however several mechanical operations take place in this time.

The needle insertion depth is defined by the carrier 7 ve to the chassis 2 not relative to the case 12, so if the user flinches or fails to hold the auto~injector1 hard t the skin, only the case 12 will move in the distal direction D while the injection depth remains constant.

As soon as the r 9 has closed the gap to the stopper 6 under force of the drive spring 8 the stopper 6 is pushed in the proximal direction P within the e 3 displacing the ment M through the needle 4 into the injection site.

Immediately prior to the end of injection with the stopper 6 having almost bottomed out 1O in the syringe 3 as illustrated in figures 7A and 7B a noise component 28 is released.

The stack up of tolerances, most notably due to the syringe 3 requires that the noise must always be released prior to the end of injection. Otherwise, with certain ations of parts, the noise would not always e. The noise component 28 comprises an elongate portion 28.1 arranged within the distal plunger sleeve 17 and a distal end plate 28.2 arranged between the carrier end face 10 and an end face of the trigger button 13. Two second resilient arms 30 originate from the distal carrier and face and extend in the proximal direction P. A noise spring 29 is arranged to bias the noise component 28 in the distal direction D relative to the r 7 by ally bearing against a rib on the second resilient arms 30 and distally against the noise component 28 (not rated).

Note: the noise component 28 is not illustrated in figures 16A, B and C for clarity since it does not affect the function of the button release mechanism 26. A noise release mechanism 31 for releasing the noise component 28 is schematically iliustrated in figures 14A, 14B and 14C. Referring now to figure 14A, the noise release mechanism 31 comprises the second resilient arms 30. A ramped inward boss 30.1 is arranged on each second ent arm 30 which is engaged to a respective d eleventh ramp 28.3 on the elongate portion 28.1 of the noise component 28 in such a manner that the second resiiient arm 30 is deflected in the outward direction 0 under load of the noise spring 29. in an initial state A of the noise release mechanism 31 the second resilient arms 30 are prevented from being outwardly deflected by outward support of the distal plunger sleeve 17 thus preventing translation of the noise component 28 relative to the carrier 7. The noise release mechanism 31 remains in state A until ately prior to the end of injection with the stopper 6 having almost bottomed out in the syringe 3 as illustrated in figures 7A and 78. At this point the plunger 9 has been translated in the proximal direction P relative to the carrier 7 to such an extent that the second resiiient arms 30 are no longer supported by the distal plunger sleeve 17. The noise release mechanism 31 has thus arrived in a state 8 illustrated in figure 14B. Due to the ramped engagement between the ramped inward boss 30.1 and the outward eleventh ramp 28.3 the second resilient arm 30 is outwardly deflected under load of the noise spring 29 thus disengaging the noise component 28 from the carrier 7 and allowing the noise component 28 to move in the distal direction D driven by the noise spring 29 in a state C illustrated in figure 140. Hence, the noise component 28 is rated in the distal direction D and the distal end plate 28.2 impacts on the inside of the trigger button 13 producing e and tactile feedback to the user that the injection is about finished.

Figures 8A and 8B show the auto-iniector1 with the stopper 6 having entirely bottomed out in the syringe 3.

As mentioned above the user is able to let the case 12 move by a few millimetres in the distal direction D under the force of the control spring 19 without affecting the position of the needle 4 as long as that motion is below a predefined ce. ifthe user wishes to end the injection, at any time, they must allow the case 12 to move in the distal direction D beyond that distance. Figures 9A and 9B show the njector 1 lifted from the injection site with the case 12 moved all the way in the distal direction D so that the chassis 2 protrudes from the proximal end of the case 12. As the case 12 is moved the first coilar 20 releases the carrier 7 and then the second collar 21 releases from the case 12 and pulls the carrier 7 in the distal direction D. The sequencing of this switching is al as retraction will fail if both collars 20, 21 are attached to the r 7 at the same time. This is overcome by separating the switching of the collars 20, 21 by a icant displacement of the case 12.

The switching of the first collar 20 is rated in figures 12E and F. In figure 12E the case 12 has been aliowed to move in the distal direction D under load of the control spring 19 during removal of the auto~injector1 from the injection site. The first rib 12.3 (not illustrated, see figure 9A) is removed from outwardly behind the arrowhead 20.1.

The first collar 20 is still being pushed in the proximal direction P by the control spring 19. Due to the engagement of the inward ninth ramp 20.3 on the arrowhead 20.1 with the distal tenth ramp 7.6 on the carrier 7 the arrowhead 20.1 is deflected in the outward direction 0 into the aperture 2.5 of the chassis 2 (illustrated in figures 12A to 12F), the needle ion control mechanism 24 arriving in a state E as rated in figure 12E, decoupling the first collar 20 from the carrier 7 and latching it to the chassis 2. 1O As the case 12 is moving r in the distal direction D on removal from the injection site the syringe retraction control mechanism 25 switches from its state A (cf. figure 13A) into a state B illustrated in figure 133. The case 12 and the second collar 21 locked to the case 12 move together in the distal direction D while the carrier 7 is held in place by the detent ism 18 in its state C as described above (of. figure 110).

Due to this motion the inward boss 21.3 on the second beam head 21.2 of the proximal beam 21.1 on the second collar 21 no longer inwardly abuts the carrier 7. Instead the inward boss 21.3 is deflected in the inward direction I into a third recess 7.7 in the carrier 7 due to the ramped engagement of the second beam head 21.1 to the ramped second case detent 12.2 under load of the control spring 19. The syringe retraction control mechanism 25 thus s in a state C as rated in figure 13C with the second collar 21 decoupled from the case 12 and coupled to the carrier 7. The detent mechanism 18 applies a small retarding force to the movement of the carrier 7 before the syringe tion control ism 25 switches to state C as there is a small sliding force, applied by the second collar 21, g the carrier 7 in the distal direction D on translation of the case 12 in the distal direction D when the needle insertion control mechanism 24 has already been switched into state E. It the carrier 7 moves too far in the distal direction D before the second collar 21 switches, the case 12 runs out of travel before the inward boss 21.3 can deflect into the third recess 7.7 preventing retraction.

Starting from the position C of the detent mechanism 18 (cf. fig. 110) the carrier 7 and hence the rhomboid ramp member 7.1 are translated in the distal direction D under load of the control spring 19. Hence, the distal fifth ramp 7.3 of the rhomboid ramp member 7.1 engages the proximal third ramp 2.3 on the first beam head 2.2 of the resilient beam 2.1 in a manner deflecting the resilient beam 2.1 in the inward direction I. This applies the small retarding force to the movement of the carrier 7 required for ng the switching of the second collar 21 to the carrier 7. The resilient beam 2.1 and the rhomboid ramp member 7.1 are offset sideways to allow the resilient beam 2.1 to pass without ting the rhomboid ramp member 7.1 as soon as the first beam head 2.2 is entirely inwardly from the ramp member 7.1 in a state D illustrated in figure 11D.

The l spring 19 is grounded at its proximal end in the case by the first collar 20 being abutted against the chassis 2. The distal end of the control spring 19 moves the second collar 21 in the distal direction D taking with it the carrier 7 and hence the syringe 3 with the needle 4 ming the detent mechanism 18 as illustrated in figure 11D. Note that the needle 4 is retracted out of the skin by the auto-injector 1 as soon as the user allows the case 12 to translate sufficiently far as opposed to auto- injectors with needle shields which e the user to remove the auto-injector from the injection site thereby themselves pulling the needle out of the skin for allowing the needle shield to advance.

As the movement allowed of the noise component 28 is limited relative to the r 7 it is no longer in contact with the trigger button 13 which has moved in the distal direction D with the case 12 on removal from the injection site. When the tion begins the noise spring 29 does not provide any retarding force. Once the noise component 28 hits the trigger button 13 again on retraction of the carrier 7 the noise spring 29 must be recompressed, reducing the force driving the final part of retraction. In order to ensure a reliable retraction e this reducing force the control spring 19 must be appropriately dimensioned.

The retraction ends when the distal collar 21 meets a first back stop 12.4 on the case 12 as in figures 10A and 108. The arrowhead 20.1 on the first collar 20 is inwardly supported by the carrier 7 in a state F illustrated in figure 12F and thus prevented from ting in the inward direction I. The outward sixth ramp 20.2 of the arrowhead 20.1 is engaged behind the first rib 12.3 on the case 12 preventing the case 12 from being pushed in the proximal direction P again. A clearance may be provided between the ead 20.1 and the first rib 12.3 to allow for tolerances.

The detent mechanism 18 returns to state A as in figure 11A locking the carrier 7 in position relative to the chassis 2 as it did initially, however it cannot be ed now as the case 12 cannot move relative to the chassis 2.

A tab 20.4 on the first collar 20 is now visible through an indicator window 32 in the case 12 — indicating the auto~injector 1 has been used.

Figure 17 is an isometric view of an alternative embodiment of the plunger release ism 27. The plunger release mechanism 27 prevents movement of the plunger 9 in the proximal direction P relative to the carrier 7 until the carrier 7 is moved in the proximal direction P for needle insertion. As opposed to the plunger release mechanism 27 of figure 15, where relative movement of the r 7 and r button 13 are used to trigger the release of the plunger 9, the alternative embodiment of figure 17 releases the plunger 9 by movement of the carrier 7 relative to the second collar 21. Figure 17 illustrates the plunger release mechanism 27 priorto plunger e. The second collar 21 is shown transparent to improve clarity. The plunger 9 is being pushed in the al direction P by the drive spring 8. in order for the plunger 9 to advance, it must rotate around a twelfth ramp 7.8 on the carrier 7. A ramp member 9.1 on the plunger 9 is arranged to engage this twelfth ramp 7.8. on of the ramp member 9.1 is blocked by an inward longitudinal rib 21.5 on the second collar 21 d in a longitudinal aperture 7.9 in the carrier 7. The case 12 and the second collar 21 remain in the same on, i.e. coupled to each other forjoint axial translation. On depression of the trigger button 13 the carrier 13 and the plunger 9 being part of the drive sub-assembty are moved in the proximal direction P, first by the user pressing the trigger button 13 and then by the control spring 19 taking over via the first collar 20 as described above. Once the carrier 7 moves sufficiently far in the proximal ion P 3O relative to the second collar 21 the ramp member 9.1 on the collar 9 comes clear of the longitudinal rib 21.5 on the second collar 21 and can rotate past the proximal end of the longitudinal rib 21.5 due to its ramped engagement to the twelfth ramp 7.8 under load of the drive spring 8. Hence, the drive spring 8 es the plunger 9 in the proximal direction P for injecting the medicament M.

Figure 18 is a longitudinal section of an alternative embodiment of the button release mechanism 26. Otherthan the button release mechanism 26 of figure 16 which gives the appearance of a revealing trigger button 13 on skin contact by switching the ground of the trigger button 13 n the carrier 7 and the case 12, the button release mechanism 26 of figure 18 starts with the r button 13 locked but protruding from the distal end of the case 12. Once the carrier 7 has moved in the distal direction D on skin contact of the chassis 2, it is possible to depress the trigger button 13 and activate the auto-injector 1. This ensures a ced ion.

In the embodiment offigure 18 the trigger button 13 has two proximal beams 13.1, each of them having a ramped outward boss 13.4. In the initial state shown in figure 18 the ramped outward bosses 13.4 are engaged in respective fourth recesses 12.5 in the case 12. Disengaging the ramped outward bosses 13.4 from the fourth recesses 12.5 is prevented by the r 7 inwardly supporting the proximal beams 13.1 in a mannerto keep the proximal beams 13.1 from deflecting inwardly. Inward protrusions 13.5 on the al beams 13.1 abut against a second rib 7.10 on the carrier 7 in a manner preventing the carrier 7 from moving further in the proximal direction P in the initial state.

Once the carrier 7 has moved in the distal direction D on skin t of the chassis 2 a first window 7.11 in the carrier 7 is moved behind the inward protrusion 13.5 so as to allow the proximal beams 13.1 to be inwardly deflected due to their ramped engagement in the fourth recesses 12.5 on depression of the trigger button 13. The proximal beams 13.1 are now outwardly supported by the case 12 and remain engaged to the carrier 7 even on tion of the needle 4. The trigger button 13 does therefore not return to its initial position, indicating that the auto-injector 1 has been used.

The button release mechanism 26 iilustrated in figure 18 may preferably be combined with the plunger release mechanism 27 illustrated in figure 17.

Figures 19A and 19B show two longitudinal sections of an alternative embodiment of the detent mechanism 18. The detent mechanism 18 of figures 11A to 11D, which may be referred to as a “race track” ism because of the first beam head 2.2 travelling around the rhomboid ramp member 7.1 has multiple functions which control the movement of the carrier 7 relative to the chassis 2. The alternative detent mechanism 18 of figures 19A and 198 uses three clips 7.12, 7.13, 2.6 to e the same effect.

The first clip 7.12 is arranged as an outwardly biased resilient beam on the r 7 extending from the carrier 7 in the proximal direction P. the first clip 7.12 is ed to prevent the carrier 7 from being moved in the proximal direction P priorto the chassis 2 being depressed or rather the case 12 being translated on skin contact. The first clip 7.12 is composed of two sections side by side. A first section 7.14 prevents movement of the carrier 7 in the proximal direction P by ng the chassis 2 in a recess. A second section 7.15 is ed as an outwardly ding clip head arranged to be ramped inwards by a ramp feature 12.6 on the chassis 12 for releasing the first clip 7.12 thereby unlocking the carrier 7 from the chassis 2 when the case 12 is being translated in the proximal direction P on skin contact. A longitudinal slot 2.7 in the chassis 2 is arranged for allowing the second section 7.15 to slide in the proximal direction P once the lock has been released. A slight friction force between the first clip 7.12 and the chassis 2 es the retarding force required to ensure retraction.

The second clip 7.13 is arranged as a resilient beam on the carrier 7 ing in the distal direction D having an outwardly protruding third beam head 7.16 with a proximal ramp. The third beam head 7.16 serves as a back stop against a third rib 2.9 on the chassis 2 for preventing the carrier 7 moving in the distal direction D from its initial position. The carrier 7 and s 2 are assembled with the second clip 7.13 in this position prior to inserting the syringe 3 into the carrier 7 which is facilitated by the proximal ramp on the third beam head 7.16. The e 3 locks the clip in place by preventing inward tion thus creating a fixed stop.

The third clip 2.6 is a resilient beam on the chassis 2 extending in the distal direction D.

A ramped fourth beam head 2.8 on the third clip 2.6 is arranged to inwardly engage in a fifth recess 7.17 in the carrier 7. Once the first ciip 7.12 is unlocked, the user can toad the third clip 2.8 by pressing the carrier 7 in the proximal direction P on depression of the trigger button 13. The third clip 2.6 is loaded in ssion, i.e. it will bend outwards and release suddenly due to its ramped engagement to the carrier 7 providing the detent functionality similarto that illustrated in figure 118.

Figure 20 is a longitudinal section of a third embodiment of the detent mechanism 18 which is a variation on the embodiment of figures 19A and 198. In this embodiment the detent function of the third clip 2.6 has been added into the first ciip 7.12. The lock 1O between the case 12 and the r 7 is released in the same way, but the detent is provided by deflecting the first clip 7.12 inwards a second level which is achieved by the s 2 not having a slot 2.7 for the second section 7.15. Instead the second section 7.15, once ramped inwards by the ramp feature 12.6 on the case 12 has to be further ramped inwards inside the chassis 2 on axial load between the chassis 2 and the carrier 7, suddenly releasing their engagement.

Figure 21 is a iongitudinai section of an alternative embodiment of the noise reiease mechanism 31. As opposed to the noise release mechanism 31 of figure 14 where the noise spring 29 acts between the carrier 7 and the noise component 28, in the embodiment illustrated in figure 21 the noise spring 29 acts between the case 12 and the noise ent 28. During needle insertion the noise spring 29 is ssed as the noise component 28 moves with the carrier 7 relative to the case 12. When the noise component 28 is released by the plunger 9 y before the end of dose, the noise component 28 moves in the distal direction D and impacts the trigger button 13.

Other than in figure 14 the noise spring 29 is not being recompressed during needle retraction since it is grounded in the case 12 not in the carrier 7. s 22A and 228 show longitudinal sections of an alternative embodiment of the needle insertion control mechanism 24 which is aiso arranged to perform the detent function of the detent ism 18 on needle tion and needle insertion. Figure 23 shows a corresponding isometric view. A fourth clip 20.5 on the first collar 20 is arranged as a resilient beam with a beam head having an inward proximal thirteenth ramp 20.6 for engaging a fourth rib 7.18 on the carrier 7 and outwardly supported by the case 12 so as to keep the first collar 20 engaged to the carrier 7 prior to use, during needle insertion and during injection. When the user lifts the case 12 away from the injection site at the end of injection, a sixth recess 12.7 in the case 12 is moved outwardly behind the fourth clip 20.5 allowing the fourth clip 20.5 to release when the carrier 7 is pulled in the distal direction D by the second collar 21. Since the fourth clip .5 has to be ramped outwards a small force is required to release the fourth clip 20.5, providing the retraction detent.

A fifth clip 2.10 on the chassis 2 abuts a block 20.7 on the first collar 20 o use preventing the first collar 20 and hence the carrier 7 engaged to the first coliar 20 from moving in the proximal direction P. In order to reiease, the fifth clip 2.10 must be deflected outwards and over the block 207. Outward deflection of the fifth clip 2.10 is initially prevented by the case 12. Once the case 12 has moved on skin contact a second window 12.8 in the case 12 appears dly from the fifth clip 2.10 allowing outward deflection. The fifth ciip 2.10 is then deflected by a fourteenth ramp 7.19 on the carrier 7 when the carrier 7 is pushed in the proximal ion P on button depression as the fourth clip 20.5 does allow translation of the r 7 in the proximal direction P relative to the first collar 20 but not the other way round. The detent for needle insertion is provided by having to deflect the fifth clip 2.10 when it is loaded by the control spring Figures 24A and 248 show longitudinal sections of a third embodiment of the needle insertion control mechanism 24, also arranged to perform the functions of the detent mechanism 18. Figure 25 is an isometric view of the needle insertion control ism 24 of figure 24.The embodiment is similar to that rated in figures 22A, 228 and 23. The difference is that the fifth clip 2.10 is arranged on the first collar 20 and the block 20.7 is arranged on the chassis 2, Le. their position has been switched, so there are two clips 2.10 and 20.5 on the first collar 20.

The fourth clip 20.5 is cal to that in figure 228. it keeps the first collar 20 connected to the carrier 7 until the needle retraction is triggered, ng full injection depth is reached and maintained until the tion cycle is initiated by removing the auto-injector 1 from the skin.

The fifth clip 2.10 provides the detent for needle insertion and releases the first collar 20 from the chassis 2, initiating needle insertion. The fifth clip 2.10 prevents the first collar and hence the carrier 7 engaged to the first collar 20 from moving in the proximal direction P priorto use by abutting the block 20.7 on the chassis 2. in order to release, the fifth clip 2.10 must be deflected outwards and overthe block 20.7. Outward deflection of the fifth clip 2.10 is initially prevented by the case 12. Once the case 12 has moved on skin contact the second window 12.8 in the case 12 appears outwardly from the fifth clip 2.10 allowing outward deflection. The fifth clip 2.10 is then deflected by the fourteenth ramp 7.19 on the carrier 7 when the carrier 7 is pushed in the proximal ion P on button depression as the fourth clip 20.5 does allow translation of the carrier 7 in the proximal direction P relative to the first collar 20 but not the other way round. The detent for needle insertion is provided by having to deflect the fifth clip 2.10 when it is loaded by the control spring 19. s 26A and 268 show a longitudinal section of a third embodiment of the noise release mechanism 31. This embodiment works without the need for a ted noise spring. The plunger 9 comprises a proximally ramped rib 9.2 arranged to splay two seventh clips 7.21 on the carrier 7 immediatety prior to the end of dose. When the proximally ramped rib 9.2 has travelled past the seventh clips 7.21 they snap back and impact the plunger 9 generating a sound. The tubular shape of the carrier 7 helps to transmit the sound. Figure 26A shows the noise release mechanism 31 before release.

Figure 268 shows the noise release mechanism 31 after release. Proximal faces of the seventh clips 7.21 on the carrier 7 are axially offset to facilitate assembly by lifting the h clips 7.21 over the distal side of the ally ramped rib 9.2 one by one.

Figures 27A and 278 show longitudinal sections of another embodiment of the auto- or 1 in different n pianes, the different n planes approximately 90° d to each other, wherein the auto—injector 1 is in an initial state prior to starting an injection. The auto-injector 1 is essentiaily cal to the one described in figures ‘1 to 16. However, otherthan the auto-injector of figures 1 to 16 the auto-injector 1 of this embodiment has a wrap-over sleeve trigger instead of a trigger button.

The wrap-over sleeve trigger 12 is the same component as the case 12 which has a closed distal end face 12.10 other than the one in figures 1 to 16. An internai trigger button 13 is ed at the distai end inside the sleeve trigger 12. Other than in figures 1 to 16 the trigger button 13 is not visible nor does it protrude from the case 12 in any state. in the initial state a clearance 33 is provided between the distal end face 12.10 of the sleeve trigger 12 and the internal trigger button 13 allowing for some travel of the 1O sleeve trigger 12 without interfering with the trigger button 13.

As the auto-injector ‘i does not differ from the njector of figures 1 to 16 in other respects it is ially operated in the same way with the following ions: As the s 2 is placed against the injection site the sleeve trigger 12 ates in the proximal direction P reiative to the chassis 2 into the advanced position in a first phase of sleeve travel removing the ciearance 33 between the distal end face 12.10 of the sleeve trigger 12 and the internai trigger button 13. As in the ment of figures 1 to 16 this motion uniocks the detent mechanism 18 and the trigger button 13. As the user ues to depress the sleeve trigger 12 in a second phase of sleeve travel y further advancing it in the proximal direction P the distai end face 12.10 hits the internal trigger button 13 thereby depressing it until the first coilar 20 is released from the chassis 2 and the control spring force is coupled on to the carrier 7. The carrier 7 then advances until the internal trigger button 13 stops on another rib in the case 12 and the plunger release mechanism 27 is reieased (note the peg 14 is shorter in this embodiment.

From a user perspective, the detent mechanism 18 is arranged to provide a resistive force when the user reaches the second phase of sleeve travel. aily, there is no difference to the embodiment of figures 1 to 16 at this point.

Needle insertion is red by the user fully advancing the sleeve trigger 12 in the second phase of sleeve travel thereby fuliy depressing the internal trigger button 13 and overcoming the detent ism as in the embodiment of figures 1 to 16.

As the control spring 19 takes over on button depression fully advancing the carrier 7 for needle insertion the internal trigger button 13 bottoms out on an internal fifth rib 12.11 in the sleeve trigger 12 and the internal trigger button 13 switches back to being locked to the sleeve trigger 12 as in figure 16C.

The ment of figures 27A and 278 may also be combined with the alternative features illustrated in figures 17 to 26.

It goes without saying that in aii ramped engagements between two components described in the above embodiments there may be just one ramp on one or the other component or there may be ramps on both components without significantly influencing the effect of the ramped engagement. ses/comprising and grammatical variations thereof when used in this specification are to be taken to specify the presence of stated features, integers, steps or components or groups f, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

List of References auto-injector chassis 2.1 resilient beam 2.2 first beam head 2.3 proximal third ramp 1O 2.4 distal seventh ramp 2.5 aperture 2.6 third Clip 2.7 slot 2.8 fourth beam head 2.9 third rib 2.10 fifth Clip 2.11 sixth clip synnge hollow ion needle protective needle sheath stopper carrier 7.1 ramp member 7.2 proximal fourth ramp 7.3 distal fifth ramp 7.4 carrier detent 7.5 second recess 7.6 distal tenth ramp 7.7 third recess 7.8 twelfth ramp 7.9 longitudinal aperture 7.10 second rib 7.11 first window 7.12 first clip 7.13 second clip 7.14 first section 7.15 second section 7.16 third beam head 7.17 fifth recess 7.18 fourth rib 7.19 fourteenth ramp 1O 7.20 nth ramp 7.21 seventh clips drive spring plunger 9.1 ramp member 9.2 proximally ramped rib carrier end face 11 thrust face 12 case 12.1 first case detent 12.2 second case detent 12.3 first rib 12.4 first back stop 12.5 fourth recess 12.6 ramp feature 12.7 sixth recess 12.8 second window 12.9 third window 12.10 distal end face 12.11 fifth rib 13 trigger button 13.1 proximal beam 13.2 outward first ramp 13.3 inward second ramp 13.4 ramped outward boss 13.5 inward protrusion 13.6 second back stop 14 peg resilient arm 16 first recess 17 distal r sleeve 18 detent mechanism 1O 19 control spring first collar .1 arrowhead .2 outward sixth ramp .3 inward ninth ramp 20.4 tab .5 fourth clip .6 inward proximal thirteenth ramp .7 block .8 fifth clip 21 second collar 21.1 proximal beam 21.2 second beam head 21.3 inward boss 21.4 distal outward eighth ramp 21.5 longitudinal rib 22 cap 22.1 inner sleeve 23 barb 24 needle insertion control mechanism 25 syringe retraction control ism 26 button release mechanism 27 plunger release mechanism 28 noise component 28.1 elongate portion 28.2 distal end plate 28.3 d eleventh ramp 29 noise spring second resilient arm .1 ramped inward boss 31 noise release mechanism 32 indicator window 33 clearance —C‘J distal end, distal direction inward direction medicament "00$ outward direction proximai end, proximal direction

Claims (15)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. Auto-injector for administering a dose of a liquid medicament, comprising: - a tubular chassis, - a carrier subassembly comprising a tubular carrier siidably arranged partially inside the chassis, the r adapted to contain a syringe with a hollow injection needle, a drive spring and a plunger for forwarding load of the drive spring to a stopper of the syringe, wherein the syringe is lockable for joint axial translation with the carrier, - a control spring arranged around the carrier, - a needle insertion control mechanism for ng a proximal end of the control spring 10 to either the carrier for advancing it for needle insertion or to the chassis for needle retraction depending on the relative axial position of the carrier and the chassis, wherein the needle insertion control mechanism comprises a first collar biased by the control spring in a proximal direction, wherein at least one ent beam is proximally ed on the first collar, wherein respective recesses are arranged in the carrier and 15 s, wherein a transverse] extension of a head of the resilient beam is wider than a gap between the carrier and the chassis causing the head of the resilient beam to abut a distal face on the recess in the chassis while being prevented from deflecting in an inward direction by the carrier or to abut a distal face on the recess in the carrier while being ted from deflecting in an outward direction by the chassis thereby forwarding 20 load from the l spring to the carrier for needle insertion, wherein the resilient beam is arranged to be switched between the s and the r by ramped engagement of the head to the distal faces under load of the control spring depending on the relative longitudinal position between the chassis and the carrier.

2. Auto-injector ing to claim 1, characterized in that the resilient beam is 25 shaped as an arrowhead having an outward sixth ramp and an inward ninth ramp.

3. Auto-injector according to claim 1 or 2, characterized in that the distal face on the recess in the chassis is shaped as a distal seventh ramp and/or that the distal face on the recess in the carrier is shaped as a distal tenth ramp.

4. Auto-injector according to any one of the preceding claims, characterized in that the gap between the carrier and the chassis is wider than a shaft of the resilient beam between the first collar and the head, n an aperture is arranged proximally from the recess in the chassis allowing the head of the resilient beam to disengage from the carrier and to deflect into the aperture when the r has been sufficiently translated relative to the chassis in the proximal direction thus switching the proximal end of the control spring to the chassis for ng needle retraction.

5. Auto-injector according to any one of the preceding claims, characterized in that the resilient beam is connected to the first collar by a living hinge. 10

6. Auto-injector according to any one of the preceding claims, characterized in that the resilient beam is initially coupled to the chassis, wherein the auto-injector is arranged to be actuated by translating the carrier in the proximai direction until the resilient beam switches to the carrier translating it r under load of the control spring.

7. njector according to claim 6, characterized in that an elongate tubular case 15 is arranged, wherein the s and the carrier are telescoped within the case. wherein the case is biased in the distal direction and arranged to translate in the proximal direction against the bias when the chassis is pressed against an injection site, wherein a first rib on the case is arranged to prevent the head of the resilient beam from entering the aperture when the s is pressed against the injection site, wherein on removal 20 from the injection site and subsequent translation of the case in the distal ion the first rib is moved so as to allow the head of the resilient beam to disengage from the carrier and deflect into the aperture.

8. Auto—injector according to any one of the preceding claims, characterized in: - a trigger button arranged distally or laterally in or on the case, 25 - a plunger release mechanism arranged for ing the plunger for injection when the carrier has at least almost d an injection depth during needle insertion, - a detent mechanism ed for coupling the chassis to the carrier forjoint axial translation ve to the case, wherein the detent mechanism is arranged to decoupie the chassis from the carrier upon actuation of the trigger button thus allowing the r 30 to move relative to the chassis so as to cause the needle insertion l ism to switch the proximal end of the control spring to the carrier for needie insertion, and - a syringe retraction control ism arranged for coupling a distal end of the control spring to either the r for needle retraction or to the case otherwise.

9. Auto-injector according to claim 8, characterized in that the plunger release mechanism comprises at least one resilient arm on the carrier arranged to be in a ramped engagement to the plunger so as to disengage them under load of the drive spring, wherein a peg protrudes from a distal end face of the trigger button in the proximal direction in a manner to support the resilient arm preventing disengagement of the r from the r and thus release of the drive spring when the carrier is in a distal position, wherein the trigger button is arranged to remain in position relative to the

10 case when the r is translated for advancing the needle so as to pull the resilient arm away from the peg thus allowing deflection of the resilient arm due to the ramped engagement under load of the drive spring for disengaging the plunger from the carrier and releasing the drive spring for drug delivery when the carrier has reached a predefined position during needle advancement. 15 10. Auto-injector according to claim 8 or 9, characterized in that the detent ism comprises a resilient beam on the chassis and a rhomboid ramp member on the carrier, the resilient beam being essentially straight when relaxed and having a first beam head arranged to interact in a ramped engagement with a al fourth ramp or a distal fifth ramp on the rhomboid ramp member in such a manner that application of a 20 translative force on the carrier relative to the chassis in the proximal direction with the first beam head engaged to the fourth ramp deflects the resilient beam in one transversal direction when a predetermined value of the translative force, at least ing on the resilience of the resilient beam, is overcome so as to allow the first beam head to travel along one transversal side of the rhomboid ramp member on continued relative 25 translation of the components, wherein the resilient beam is allowed to relax when the first beam head has reached the fifth ramp thereby engaging it in a manner that application of a translative force on the carrier in the distal direction deflects the ent beam in the other transversal direction when a predetermined value of the translative force. at least ing on the resilience of the resilient beam, is overcome so as to 30 allow the first beam head to travel along the other transversal side of the id ramp member on continued translation of the carrier.

11. njector according to any one of the claims 8 to 10, characterized in that the case is arranged to lock the detent mechanism prior to being transtated in the al direction ve to the s when the chassis is being pressed against an injection site, wherein the case when translated into an advanced position in the proximal direction is arranged to unlock the detent mechanism rendering it operable.

12. Auto-injector according to any one of the claims 8 to 11, characterized in that the ly ed trigger button is at least initially coupled to the carrier, wherein the case is arranged to abut the trigger button in the initial state preventing depression of the trigger button, wherein on translation of the case into the advanced position when the 10 chassis is being pressed against the injection site the trigger button remains coupled to the carrier thus emerging from the case so as to allow depression for starting an injection cycle.

13. Auto~injector according to any one of the claims 8 to 12, characterized in that the syringe retraction control mechanism comprises a second collar bearing against the 15 distal end of the l spring and having a resilient proximal beam with a second beam head having an inward boss, wherein the second beam head is arranged to be in a ramped engagement with a second case detent in the case in a manner ramping the second beam head in the inward direction under load of the control spring in the distai direction, wherein the inward boss is ed to ly abut the carrier for preventing 20 inward deflection of the second beam head and keep the second collar locked to the case, wherein a third recess is arranged in the carrier for allowing the inward boss to be inwardly deflected on translation of the case in the distal ion relative to the carrier on l of the auto-injector from the injection site.

14. Auto-injector according to any one of the claims 8 to 13, terized in that the 25 trigger button is arranged distally, wherein the case is arranged as a wrap—over sleeve trigger having a closed distal end face covering the trigger button, wherein in an initial state a clearance is provided between the distal end face of the sleeve trigger and the trigger button allowing for some travel of the sleeve trigger against the bias of the control spring in the al direction in a first phase before abutting the trigger button. 30

15. Auto—injector according to any one of the preceding claims, characterized in that a releasable noise component is provided, capable of, upon release, generating an audible and/or tactile feedback to a user, wherein the noise component is arranged to be released when the piunger reaches a position relative to the syringe in which the stopper is located in proximity of a proximal end of the syringe, and wherein the released noise component s on a housing component ting the end of the injection.