Resettable autoinjector

Abstract

The invention relates to an autoinjector (1) for automatically dispensing a liquid product by means of a needle (21) of a pre-filled syringe (20). An autoinjector (1) comprises a syringe unit (2) comprising a syringe holder (12), a needle cover sleeve (13) and a syringe chassis (10) for supporting the syringe holder (12) and guiding the movement of the needle cover sleeve (13). The autoinjector (1) further comprises a resettable drive unit (3) comprising a plunger rod (60), a drive spring (63), a retaining element (51) for retaining the plunger rod (60) in a proximal position prior to dispensing activation, and a drive chassis (50) for supporting the drive spring and releasably attachable to the syringe holder (12). The plunger rod (60) comprises a retaining element (65) for retaining the plunger rod within the drive unit (3).

Description

TECHNICAL FIELD

[0001] The present invention relates to a drug delivery device or medicament delivery device for injecting, delivering, administering, infusing or dispensing a substance and / or a liquid such as insulin, a hormone preparation or a vaccine. It differs from a self-injector for automatic dispensing of a liquid product through a needle of a pre-filled syringe. The self-injector comprises a syringe unit including a syringe holder and a needle cover sleeve. Further, the self-injector comprises a drive unit including a plunger rod, a drive spring for emptying the entire volume of the syringe and a drive chassis which can be releasably attached to the syringe holder. BACKGROUND

[0002] There are a variety of diseases which require regular treatment by subcutaneous administration of a medicament and a variety of drug delivery devices have been developed to support patients in accurately and controllably delivering a certain amount of a drug in a self-administration process. Delivery devices include injection devices which are removed from the injection site after each drug treatment event or drug delivery process and infusion devices whose cannula or needle remains in the patient's skin for an extended period of time.

[0003] For example, diabetes can be treated by self-administration of insulin or a derivative thereof by means of a multi-dose insulin injection pen. The injection pen device usually has an elongated device body defining a longitudinal main device axis. Automatic injection devices have a motor or a drive spring for biasing the plunger rod and displacing the piston in the container barrel, wherein the drive spring can have to be manually pressurized or tensioned before a dose is injected. Manually powered delivery drives require the user to manually provide energy to move the piston, for example by applying a distal force component to the injection device.

[0004] The dose of medicament to be injected can be manually selected by turning a dose knob and observing the actual dialled dose from a dose window or display of the insulin pen. The dose is dispensed by inserting the needle into a suitable portion of the human skin and by manually moving the piston or by pressing a release button of the automatic injection device. Automatic injection devices can comprise an electronic dose dial mechanism to automatically set the dose.

[0005] It is also known to use a self-injector with a pre-filled syringe. The self-injector usually comprises a body for accommodating the syringe and an automatic drive mechanism to move the plunger of the syringe upon actuation of the self-injector. The drive mechanism of the self-injector typically comprises a drive source such as a motor or a powerful spring for moving a transmission element such as a rod acting on the plunger of the syringe. The pre-filled syringe has a needle or cannula permanently attached to a first end of a syringe barrel or reservoir which is sealed at the opposite end by the plunger.

[0006] For safety reasons, it is desirable that the needle does not protrude from the housing of the auto-injector other than when the needle is used to inject a medicament. Therefore, the auto-injector either moves the needle out of the housing for injection and back into the housing after injection, or the auto-injector provides a needle cover or needle guard which can be moved to withdraw the needle for injection and which can be moved back over the needle after injection.

[0007] Most auto-injectors are configured as single-use devices which incorporate both the syringe and the drive mechanism in the same housing. For ease of use, such devices are usually disposable.

[0008] From an ecological point of view, it is desirable to reduce waste and to reuse devices as long as possible. In order to take both ecological responsibility and medical and safety standards into account, devices are developed as two-part or semi-disposable or semi-reusable auto-injectors. Such auto-injectors comprise a part which comprises a syringe or reservoir with a medicament and which can be separated from another part, e.g. from a drive unit comprising the drive mechanism of the auto-injector, and which can be disposed of separately.

[0009] WO 2017 / 033193 A1 discloses an automatic injection device comprising a disposable medicament module with a pre-filled syringe and a reusable drive module. The drive module comprises a compressible drive spring. Upon activation by a user, the medicament is dispensed from the medicament module by means of the drive spring of the drive module. If the user manually removes the medicament module from the drive module, the plunger rod is held within the housing of the drive module by a holding element. The holding element engages the plunger rod at an intermediate portion of the plunger rod. The holding element is movable relative to the housing and can engage the housing by a holding arm.

[0010] EP 2 468 337 A1 discloses an auto-injector comprising a disposable syringe unit holding a syringe and a reusable drive unit with a torsion spring. The drive unit is releasably attachable to the syringe unit by a bayonet coupling. After pressing the auto-injector against an injection site and pressing a release button, a support sleeve is moved distally, thereby moving the syringe distally and inserting the injection needle into the user by the force of the torsion spring. When a cam surface on a rotating sleeve disengages from a moving plunger follower, the rotating sleeve is released and starts to rotate by spring force and moves the plunger rod towards a distal end position to dispense the medicament. When the cam surface abuts the plunger follower, the plunger rod is withdrawn by spring force and moves back in proximal direction. Then, a spring in the syringe unit is released and the support sleeve with the syringe is moved away from the injection site. SUMMARY

[0011] A first object of the present invention is to provide a reliable dispensing drive reset mechanism for a resettable auto-injector. A second object of the present invention is to achieve a customized look and feel while hiding the internal interface between the disposable part and the reusable part of the resettable auto-injector.

[0012] This object is achieved by the auto-injector or method according to the independent claims. Preferred embodiments are evident from the dependent claims.

[0013] The present invention relates to an auto-injector for automatic dispensing of a liquid product (a drug or a medicament) through a needle of a pre-filled syringe (PFS) of the auto-injector. The auto-injector comprises a syringe unit and a resettable drive unit releasably attachable to the syringe unit. The syringe unit comprises • a syringe holder for holding the pre-filled syringe, and preferably the syringe holder is adapted to support a distal shoulder of the syringe; • a needle cover sleeve for shielding the needle in an extended position or distal end position of the needle cover sleeve; • a syringe chassis for mechanically supporting the syringe holder and guiding movement of the needle cover sleeve from the extended position to a retracted position or proximal end position of the needle cover sleeve in which the needle is exposed.

[0014] The resettable drive unit comprises • a plunger rod movable from a proximal position to a distal position of the plunger rod to drive a stopper in a barrel of the pre-filled syringe towards the needle for dispensing the liquid product; • a mechanical drive spring for emptying the entire volume of the barrel in a single dispensing event; • a holding element for holding the plunger rod or the drive spring in a pre-tensioned state before dispensing activation; • a drive chassis for mechanically supporting the drive spring and for supporting further internal components of the drive unit. The drive chassis is releasably attachable or can be releasably attached to the syringe chassis for attaching the syringe unit to the drive unit.

[0015] The plunger rod comprises a retaining element to hold the plunger rod within the drive unit upon separation of the drive unit and the syringe unit after product dispensing. The retaining element is provided at, in or in a proximal half of the proximal end of the plunger rod. In the initial state and in the dispensed state, the retaining element is located proximally from the distal end of the drive spring. Furthermore, the retaining element comprises a (preferably flat or planar) distal stop surface and the drive unit comprises a (preferably flat or planar) proximal stop surface, and wherein, after product dispensing, the distal stop surface is pressed by the force of the drive spring onto the proximal stop surface such that the plunger rod is held in a stable distal end position, preferably also when the syringe unit is detached from the drive unit. The drive spring force does not retract and move back the plunger rod.

[0016] After separation of the auto-injector into the syringe unit and the drive unit by means of a tool, the plunger rod is no longer inside the barrel of the syringe or guided by elements of the syringe unit. In this detached state, the retaining element reliably prevents the plunger rod from being separated from the drive unit and in particular from the drive chassis. Due to the retaining element being arranged at the proximal end of the plunger rod, a compact and space-saving design is provided. Furthermore, due to the proximally arranged retaining element, the plunger rod does not have to be retracted from a distal position to a proximal position before the syringe unit is separated from the drive unit. Furthermore, the plunger rod does not have to be retracted by the drive spring, which would require a complex retraction mechanism. Instead, the plunger rod can be retracted or re-pressurized by an external force.

[0017] The retaining element holds the plunger rod to the drive unit (in particular after separation of the syringe unit from the drive unit), but allows movement of the plunger rod relative to the drive chassis. That is, the plunger rod can be moved rotationally or linearly relative to the drive chassis. However, due to the flat distal stop surface pressing on the flat proximal stop surface of the drive unit, the plunger rod is stable and held in its distal end position after dispensing.

[0018] The retaining element can for example be a knob, a protrusion, a recess, a hook or a thread on the plunger rod. Any other component of the drive chassis or the drive unit comprises the proximal stop surface which engages the distal stop surface in the distal position of the plunger rod. The proximal stop surface can for example be arranged on a cam, a slot, a protrusion or a recess.

[0019] The proximal stop surface can be a rigid or resiliently mounted component of the drive unit to engage the distal stop surface to reliably hold the plunger rod upon separation of the syringe unit from the drive unit.

[0020] The self-injector according to the present application is re-settable. This means that after use, the self-injector can be returned to the manufacturer or a reprocessing site to re-set the self-injector and prepare it for reuse. For this purpose, the self-injector is separated into a cartridge unit and a drive unit. Specialized tools can be required to disassemble the self-injector and separate the drive unit and the cartridge unit.

[0021] Then, the cartridge unit and the drive unit are subjected to a functional test and, in particular, a drive spring test can be performed to assess whether the drive spring meets predefined requirements, such as a minimum drive force. In a further step, the cartridge unit and the drive unit can be industrially cleaned or sterilized. If the drive spring test is passed and if the drive spring meets the requirements, it is re-set, e.g. tensioned mechanical spring or compressed elastic material, to prepare the drive unit for reuse.

[0022] During these preparation steps, the retaining elements, and in particular the proximal and distal stop surfaces, securely hold the plunger rod within the drive unit and thus avoid disassembly of the plunger rod. This enables an efficient handling and assembly of the drive unit during the re-set procedure.

[0023] After loading the cartridge unit with a new prefilled cartridge, the cartridge unit and the drive unit are reconnected. After a quality check, the self-injector is ready for a new injection.

[0024] In contrast to known semi-reusable self-injectors with a user-manipulated cartridge magazine, the cartridge unit of the self-injector according to the present application is not completely discarded, but only the emptied cartridge is replaced. Once loaded with a new prefilled cartridge, the cartridge chassis can be reused and reconnected to the drive chassis. This reduces waste compared to semi-reusable self-injectors with a cartridge unit that is completely disposed of after use.

[0025] In addition to this, the present application provides a self-injector drive unit that can be re-set or re-pressurized preferably manually by a person at the manufacturer or reprocessing site and thus also allows reuse of the drive unit. Thus, the re-settable self-injector according to the present application contributes to reducing the carbon footprint per injection.

[0026] The drive unit preferably comprises a mechanical drive spring, preferably a helical compression spring, which is preferably manually re-settable and re-pressurizable.

[0027] The drive unit or the syringe unit preferably further comprises a latching element for latching the needle cover sleeve in the extended position against proximal movement relative to the syringe chassis. This means that after an injection, when the user has removed the auto-injector from the injection site, the latching element latches the needle cover sleeve in the extended or distal position to cover the needle and prevent injuries. The latching element is also preferably reset during the reset procedure to allow the needle cover to be pushed again in the proximal direction during a new injection.

[0028] The drive unit further comprises a holding element for holding the plunger rod in a pre-stressed proximal position. Upon activation, preferably upon retracting the cover sleeve from the extended position to the retracted position, the holding element is released so that the plunger rod is free to move in the distal direction to dispense the liquid product. Examples for the holding element are resilient or / and flexible arms, snap elements or movable cams or stops.

[0029] In the present context, the terms "substance", "drug", "medicament" and "medicinal product" are to be understood as including any flowable medicinal preparation suitable for controlled administration through a device such as e.g. a cannula or a hollow needle and including liquids, solutions, gels or fine suspensions containing one or more medically active ingredients. The medicament can be a composition comprising a single active ingredient or a pre-mixed or co-formulated composition with more than one active ingredient in a single container. The medicinal product includes drugs such as peptides (e.g. insulin, insulin containing drugs, GLP-1 containing drugs or derivates or similar preparations), proteins and hormones, active ingredients derived or harvested from biological sources, hormone or gene based active ingredients, nutritional formulas, enzymes and other substances in both (suspended) solid or liquid form, as well as polysaccharides, vaccines, DNA, RNA, oligonucleotides, antibodies or parts of antibodies, as well as suitable base, auxiliary and carrier substances.

[0030] The term "distal" means to refer to the direction or end of the auto-injector carrying the injection needle or injection cannula, while the term "proximal" means to refer to the opposite direction or end pointing away from the needle or cannula.

[0031] The terms "injection system", "injector" or "auto-injector" refer to a device which is removed from the injection site after each medicinal treatment event or drug delivery process. In contrast, an infusion system refers to a device whose cannula or needle remains in the patient's skin for an extended period of time, e.g. several hours.

[0032] Preferably, the proximal stop surface and the distal stop surface are oriented perpendicular to the longitudinal direction. This provides for a simple design as well as a reliable support and engagement of the distal stop surface and the proximal stop surface. Alternatively, the proximal stop surface can be angled or inclined and the distal stop surface can have a corresponding angled or inclined form.

[0033] Preferably, the proximal stop surface is integrally formed in the drive chassis and thus formed as a single piece. The drive chassis can be an injection molded plastic part which is integrated with the proximal stop surface.

[0034] In a preferred embodiment, the drive unit comprises two retaining elements which are arranged opposite to each other and each comprise a proximal stop surface. In this case, the drive unit accordingly comprises two distal stop surfaces. The two stop surfaces provide a more stable support of the plunger rod in its distal end position after dispensing.

[0035] In a preferred embodiment, the retaining element on the plunger rod is a radially extending protrusion or recess. Any component of the drive chassis or drive unit preferably comprises a counterpart element adapted to engage the protrusion or recess to retain the plunger rod. Thus, the protrusion or recess on the plunger rod and the counterpart element form a form-fit connection. Examples of counterpart elements are notches, slots, stops, hooks or counterpart protrusions.

[0036] The form-fit connection provides a simple and reliable engagement of the plunger rod with the chassis or any other drive unit component. While the plunger rod is held in its distal end position by the connection between the protrusion or recess and the counterpart element, the plunger rod is movable relative to the drive chassis but prevented from being ejected from the drive unit.

[0037] Alternatively, the retaining element can be a thread coupling the plunger rod with the drive chassis or any other drive unit component.

[0038] The present invention also relates to a self-injector for automatic dispensing of a liquid product through a needle of a pre-filled syringe, wherein the self-injector comprises a syringe unit comprising • a syringe holder for holding the pre-filled syringe; • a needle cover sleeve for shielding the needle in an extended position of the needle cover sleeve, • a syringe chassis for supporting the syringe holder and guiding the movement of the needle cover sleeve from the extended position to a retracted position, • wherein the self-injector further comprises a resettable drive unit attachable to the syringe unit, the drive unit comprising • a plunger rod movable from a proximal position to a distal position to drive the pre-filled syringe towards a stopper in a barrel of the pre-filled syringe for dispensing the liquid product; • a resettable or rechargeable drive spring for emptying the entire volume of the barrel in a single dispensing event; • a drive chassis for supporting the drive spring and releasably attached or attachable to the syringe holder or the syringe chassis.

[0039] The auto-injector can comprise a shield extending longitudinally between a distal end and a proximal end of the auto-injector, and wherein the shield is the outermost cover of the auto-injector covering at least half of the syringe unit and the drive unit when the syringe unit is attached to the drive unit. Thus, the shield encloses the drive unit and the syringe unit and thus provides the outermost cover for the syringe unit and the drive unit. In a preferred embodiment, the shield is sleeve-shaped extending along the longitudinal axis of the syringe unit and the drive unit.

[0040] The shield is preferably attached to the drive chassis or the syringe chassis or both the drive chassis and the syringe chassis by a releasable snap-fit connection.

[0041] The shield preferably does not support or guide internal elements or components and thus does not hold the drive mechanism or the syringe. Thus, the shield is not part of the support housing. Instead, the shield is merely attached outside the drive chassis and the syringe chassis. This means that the shield is attached to the support structure of the drive chassis or the syringe chassis and the shield preferably has no support capacity for the auto-injector components surrounded by the shield.

[0042] The drive chassis and the syringe chassis provide a support structure or skeleton for the auto-injector components, but the drive chassis and the syringe chassis do not enclose or cover the components and are not to be interpreted as a housing. The drive chassis and the syringe chassis are preferably pure support structures and comprise several openings and breakthroughs allowing direct access to the components, including the drive spring return mechanism. The internal components are preferably hidden from the user and are only covered by the installed shield.

[0043] In the assembled state, the syringe unit and the drive unit are arranged coaxially inside the shield. The shield is preferably connected to at least one of the syringe unit and the drive unit by a tool connection, preferably a snap-fit connection between the shield and the syringe chassis or the drive chassis. In a preferred embodiment, the shield is only disassembled by a dedicated tool and a person at a reprocessing site, not by the user. This means that the user cannot disassemble the auto-injector and thus unintentional use or harm can be prevented.

[0044] The shield allows customizing the auto-injector by providing specific visual elements (labels, branding, non-electronic or electronic identifiers such as RFID tags) or by providing a dedicated outer shape or geometry (e.g. a user grip portion).

[0045] The shield is preferably disposable. This means that the shield is discarded during the reset procedure of the auto-injector. Thus, a new shield can be installed during the reset of the auto-injector.

[0046] The shroud is preferably made of a biopolymer based on non-fossil raw materials. Biopolymers are sustainable alternatives to fossil-based plastics. Biopolymers will be understood as plastics based on biomass and not derived from petroleum-based polymers or natural gas.

[0047] Biopolymers can be obtained by direct processing from natural biopolymers and proteins, or by chemical methods from sugar derivatives, lipids, or biologically produced by fermentation of sugars or lipids. Examples of biopolymers include sugar-based, starch-based or cellulose-based polymers.

[0048] Biopolymers can be biodegradable or non-biodegradable. Examples of non-biodegradable biopolymers are polypropylene (bio-PP), polyethylene (bio-PE), biopolyesters such as polyethylene terephthalate (bio-PET), polyethylene 2,5-furandicarboxylate (bio-PEF), polyamides (bio-PA), polyoxymethylene (bio-POM), polycarbonates (bio-PC), polyacrylonitrile-butadiene-styrene copolymers (bio-ABS), thermoplastic elastomers (bio-TPE).

[0049] In a preferred embodiment, the shroud is made of a biodegradable polymer. The term "biodegradable" means that the plastic can be broken down by the action of living organisms, in particular microorganisms, which consume, metabolize and convert the biodegradable plastic into energy and non-plastic waste products.

[0050] Biodegradable polymers include biopolymers (e.g. polylactic acid PLA, starch blends, lignin-based polymer composites), as well as biodegradable petroleum-based polymers (e.g. polyglycolic acid PGA, polybutylene succinate PBS, polycaprolactone PCL).

[0051] To further reduce waste and take into account ecological demands, the shroud can be made of recycled polymers. The use of recycled polymers reduces the use of new raw materials and closes the recycling loop. Recycled polymers can include biopolymers, but can also include non-biopolymers.

[0052] As an alternative to polymers, the shroud can be made of recyclable hardboard or wood-based plywood. A shroud made of wood-based plywood comprises thin slices or layers of wood and / or bark that are bound or glued together piece by piece to create a sleeve-shaped shroud. A shroud made of wood-based plywood has the benefit of having a smaller impact on total energy use, greenhouse gases, air and water pollution compared to a shroud made of plastic.

[0053] If the shield is made of any type of plastic, the shield is preferably manufactured by means of single-component injection molding or multi-component injection molding. Injection molding allows for an efficient and cost-saving mass production.

[0054] In a preferred embodiment, the syringe holder is adapted to fixedly hold the syringe and is not movable in the longitudinal direction of the syringe relative to the drive chassis. To this end, the syringe holder can comprise a stop or contact surface that supports the distal shoulder of the syringe barrel.

[0055] This means that, during the injection process, the syringe does not displace. This is in contrast to a self-injector that provides for a movement of the syringe, e.g. to displace the syringe in the distal direction to automatically insert the injection needle into the injection site.

[0056] In addition to this, the syringe chassis is further adapted to mechanically support the syringe holder and to guide the movement of the needle cover sleeve from the extended (distal) position to the retracted (proximal) position and vice versa. The needle cover sleeve is preferably biased towards the extended position by a needle cover sleeve spring.

[0057] The needle cover sleeve can trigger the activation of the drive spring. In particular, when the needle cover sleeve has reached the retracted position or proximal end position, the drive spring can be activated to drive the plunger rod to dispense the liquid product.

[0058] In a preferred embodiment, the drive chassis or the syringe chassis comprises a catch and the other one of the drive chassis or the syringe chassis comprises a recess or a counterpart element that is adapted to engage the catch to form a snap-fit connection between the syringe unit and the drive unit. Examples of counterpart elements are notches, protrusions or hook-shaped elements.

[0059] Thus, the syringe unit and the drive unit can be reliably connected to each other. The snap-fit connection can comprise one or more catches and correspondingly one or more counterpart elements.

[0060] In a preferred embodiment, the snap-fit connection is releasable. This means that the syringe chassis and the drive chassis can be disconnected and reconnected several times, allowing for several refills and re-use of the self-injector. In a preferred embodiment, the snap-fit connection is only disconnected by a tool.

[0061] In a further preferred embodiment, the snap-fit connection between the syringe chassis and the drive chassis is only accessible after removal of the shield. The shield extends longitudinally between a distal end and a proximal end of the self-injector and at least partially covers the syringe unit and the drive unit as described above.

[0062] The catch preferably comprises a release surface, wherein the catch can be deflected radially by pushing against the release surface, thereby releasing and disconnecting the catch-fit connection between the syringe unit and the drive unit. This means that the catch can be deflected by pushing against the release surface and thus disengaged from the notch or mating element.

[0063] A device-specific tool or special key can be required to reach the release surface and deflect the catch via the release surface. This avoids unintentional deflection and thus unintentional disconnection of the syringe unit from the drive unit. In particular, the catch-fit connection can be designed such that the connection is only disconnected by a self-injector-specific disassembly tool at the manufacturer's site or at a reprocessing site.

[0064] In addition to or instead of a tool-specific connection, the release surface can be covered by a removable cover member to prevent unintentional access and release of the catch. The cover can be implemented in the form of a cover plate or a sleeve-shaped member.

[0065] In a preferred embodiment, the drive unit comprises a locking member which is movable relative to the drive chassis. In a first position of the locking member, the plunger rod is prevented from retracting from the distal position to the proximal position (e.g. a reset movement) by the locking member, and in a second position of the locking member, which is different from the first position of the locking member, the plunger rod is free to move from the distal position back to the proximal position (to reset the drive unit).

[0066] The locking member thus locks and unlocks the reset movement of the plunger rod. The first position is preferably a proximal position of the locking member, and the second position is thus preferably a distal position of the locking member. Alternatively, the first position of the locking member is the distal position and the second position is the proximal position.

[0067] In the first position, the plunger rod is preferably prevented from moving back in the proximal direction or to the retracted position. This can be implemented, for example, by an element or intermediate member of the locking member (e.g. a sawtooth) which abuts the plunger rod and thus prevents the plunger rod from moving towards the retracted position. In the second position, the element preferably does not hold the plunger rod and thus the plunger rod is free to be pushed back to the retracted position. In the second position of the locking member, the travel path of the plunger rod is thus free and the movement of the plunger rod is thus allowed.

[0068] In a preferred embodiment, a proximal stop surface is arranged on an elongate element or arm which is adapted to hold the plunger rod in place before injection. The locking member can be, for example, a sleeve or ring-shaped element which is adapted to lock the arm in place and thus the plunger rod, or to release the arm so that it can be deflected or moved out of the locked position and the plunger rod is released.

[0069] The locking member can selectively lock or release the plunger rod. Preferably, the proximal stop surface can be on an end portion of the elongated element or arm, in particular on a knob-shaped end portion.

[0070] Preferably, the plunger rod is hollow and the drive spring is at least partially arranged inside the hollow plunger rod. The spring is pre-stressed before injection and, upon activation by the user, the spring is released to move the plunger rod distally in the dispensing direction to dispense the product from the syringe. Since the spring is arranged inside the hollow plunger rod, a compact and space-saving design is provided. In a preferred embodiment, the spring has a coil that is wound around the longitudinal axis of the auto-injector.

[0071] The spring can be adapted to linearly move the plunger rod without rotation. Alternatively, the drive spring can be a pre-stressed coil spring that, upon activation, starts to rotate the plunger rod directly or via a drive member that in turn is adapted to advance the plunger rod in the dispensing direction.

[0072] The present invention also relates to a method for resetting an auto-injector comprising a drive unit and a syringe unit. The auto-injector comprises a pre-filled syringe for automatic dispensing of a liquid product through a needle of the pre-filled syringe. The method comprises the following steps: a) after dispensing the liquid product, disconnecting, preferably by a device-specific tool, a connection, preferably a snap-fit connection, between the syringe unit and the drive unit of the used auto-injector and separating the auto-injector into the syringe unit and the drive unit by a person at a reprocessing site, wherein the plunger rod is held within the drive unit by a holding element provided at a proximal end of the plunger rod and wherein the holding element is positioned proximally from a distal end of the mechanical drive spring; b) removing the emptied syringe from the syringe unit by an expert of the reprocessing site or automatically and preferably reloading a new syringe into the syringe unit; c) resetting the plunger rod of the drive unit from a distal position to a proximal position and thereby pre-tensioning the mechanical spring of the drive unit.

[0073] In a preferred embodiment, the method can further comprise the step of removing an outer shroud covering the syringe unit and the drive unit before disconnecting the syringe unit from the drive unit.

[0074] Further, the method preferably comprises the steps of loading a new syringe into the syringe unit after removing the emptied syringe and reconnecting the syringe unit and the drive unit after resetting the plunger rod.

[0075] In addition to this, the cap lock can also reset in the syringe unit. The cap lock locks the cap sleeve in an extended position in which the cap sleeve covers the needle after injection. The reset of the cap lock releases the cap sleeve and allows the cap sleeve to move from the extended position to a retracted position in which the needle is exposed and not covered by the cap sleeve.

[0076] Preferably, the method further comprises the step of industrially cleaning the drive unit after disconnection from the syringe unit. The drive unit can for example be washed or heat treated to prepare the drive unit for use with a new syringe unit comprising a new pre-filled syringe.

[0077] The method can further comprise the steps of moving the locking sleeve to the release position to allow the plunger rod to reset to the proximal position and subsequently moving the locking sleeve to the locking position to prevent the plunger rod from moving in the distal direction before the plunger rod is released for injection.

[0078] Furthermore, the method preferably comprises the step of connecting a new shield to the syringe unit, wherein the shield at least partially covers the syringe unit and the drive unit.

[0079] While the above embodiments relate to a self-injector for a pre-filled syringe, the self-injector according to the present application can also be used with a cartridge. The cartridge comprises a needle mounting portion on a distal end for releasably attaching a needle assembly. Before injection, the user has to attach the needle assembly to the cartridge. This means that, in contrast to a pre-filled syringe, the needle is not permanently (and non-releasably) connected to the reservoir body.

[0080] For the cartridge-based embodiments, the present application relates to a self-injector for automatic dispensing of a liquid product from a pre-filled reservoir through a needle, the self-injector comprising • a reservoir holder for holding the reservoir; • optionally, a needle cap sleeve for obscuring the needle in an extended position of the needle cap sleeve; • a reservoir chassis for supporting the reservoir holder and, if any, guiding the movement of the needle cap sleeve from the extended position to a retracted position, wherein the self-injector further comprises a resettable drive unit attachable to the reservoir unit, the drive unit comprising • a plunger rod movable from a proximal position to a distal position to drive the reservoir's barrel towards a stopper in the barrel to dispense the liquid product; • a resettable or rechargeable drive spring for emptying the entire volume of the barrel in a single dispensing event; • a drive chassis for supporting the drive spring and releasably attachable to or capable of being releasably attached to the reservoir holder or the reservoir chassis, characterized in that the auto-injector comprises a shroud extending longitudinally between a distal end and a proximal end of the auto-injector, and wherein the shroud is the outermost cover of the auto-injector covering at least half of the reservoir unit and the drive unit when the reservoir unit is attached to the drive unit.

[0081] In this embodiment, the reservoir is preferably a cartridge having a needle mounting portion on the distal end for releasable attachment of a needle assembly.

[0082] Preferably, the shroud is attached to the drive chassis or the reservoir chassis or both the drive chassis and the reservoir chassis by a releasable snap-fit connection.

[0083] The shroud can be attached to the support structure of the drive chassis or the reservoir chassis and the shroud has no support capacity for the auto-injector components surrounded by the shroud. BRIEF DESCRIPTION OF DRAWINGS

[0084] The subject matter of the present application is explained in more detail in the following text, with reference to the preferred exemplary embodiments illustrated in the drawings, in which: Figure 1 a schematic cross-sectional view of an auto-injector according to the present application is depicted, wherein the section line of the cross-sectional view runs along a longitudinal axis; Figure 2 a schematic cross-sectional view of a needle cartridge unit of an auto-injector is depicted; Figure 3 a schematic cross-sectional view of a drive unit of an auto-injector in an unused state is depicted; and Figure 4 a schematic cross-sectional view of a drive unit in a dispensing state is depicted.

[0085] In the list of reference signs used in the drawings, those that have the same reference signs have at least partially the same function and / or structure. In principle, identical parts are provided with the same reference signs. DETAILED DESCRIPTION

[0086] In the following text, the term "distal" refers to the side where the injection needle is positioned (e.g. in the left hand side in Figures 1 to 4 the following drawings). The term "proximal" refers to the opposite side furthest away from the needle (in the right hand side in Figures 1 to 4 the following drawings).

[0087] Figure 1 a schematic cross-sectional view of a resettable auto-injector 1 according to the present application is depicted. The section line of the cross-sectional view runs along a longitudinal axis of the auto-injector 1. Figure 1A self-injector 1 in an initial or shipped state is illustrated.

[0088] The self-injector 1 is cylindrical and comprises a syringe unit 2 which houses a pre-filled syringe (PFS) 20 containing a liquid drug and a stopper 22. The self-injector 1 further comprises a drive unit 3 which houses a mechanical drive spring 63 for dispensing the drug from the syringe 20. The self-injector 1 further comprises an outer shroud 5 which covers and encloses both the syringe unit 2 and the drive unit 3. In the initial state as shown in Figure 1 The cap 4 is mounted on the distal end of the self-injector 1 in the initial state as shown in

[0089] The syringe unit 2 and the drive unit 3 are not intended to be disconnected by the user. However, after use and return to the manufacturer or a reprocessing site, the self-injector 1 can be separated into the syringe unit 2 and the drive unit 3 by an expert or automatically. The self-injector can then be refilled by mounting a new syringe and reset for re-issuance and reuse. In the following, the syringe unit 2 and the drive unit 3 are described in detail. Subsequently, the reset procedure of the self-injector will be described.

[0090] Figure 2 A schematic view of the separate syringe unit 2 in the initial or shipped state is illustrated, and Figure 1 A schematic view of the separate drive unit 3 is illustrated. Both units are shown without the covering shroud 5. Figure 3 As shown in

[0091] The syringe unit 2 comprises a sleeve-shaped syringe chassis 10 and a syringe holder 12 which is supported and held by the syringe chassis 10. The syringe holder 12 in turn holds the pre-filled syringe 20 in place immovably relative to the chassis. For this purpose, a distal shoulder of the syringe barrel is supported by a support surface 11 of the syringe holder 12. The syringe chassis 10 further supports and guides a needle cover sleeve 13 which is arranged coaxially outside the syringe chassis 10. The cover sleeve 13 is movable relative to the syringe chassis 10 in longitudinal direction from a distal or extended position in which the needle 21 of the syringe 20 is covered to a proximal or retracted position in which the needle 21 is exposed. The cover sleeve 13 is biased to the extended position by a cover sleeve spring (not shown). The cover spring is arranged in the syringe unit, but can alternatively be arranged in the drive unit. Figure 2

[0092] ​At the proximal end, the syringe chassis 10 comprises two oppositely arranged snap members or flexible arms 15 adapted to engage and snap into recesses 54 in the drive chassis 50 of the drive unit 3 to connect the syringe unit 2 to the drive unit 3 by a snap fit connection. Each flexible arm 15 features a hook 16 or hook-shaped free end that fits into the recess 54. The hook 16 in turn comprises a release surface 17 that allows the engagement arm 15 and deflects the arm 15 as will be described in detail below.

[0093] As shown in Figure 3 The drive unit 3 comprises a sleeve-shaped drive chassis 50, a hollow plunger rod 60 and a pre-stressed helical compression drive spring 63 coaxially arranged in an opening 62 of the hollow plunger rod 60. The proximal end of the helical spring 63 is supported by a wall of the drive chassis 50 and the distal end of the helical spring 63 abuts an inner end wall or bottom of the opening 62 of the plunger rod 60 and thus biases the plunger rod 60 in distal direction. The plunger rod 60 is held in its biased proximal position by two oppositely arranged flexible locking arms 53 that can selectively lock or release the plunger rod 60. The arms 53 can be deflected radially outward if a coaxially arranged locking sleeve 55 is in a release position. At the free end, each arm 53 comprises a cam 51 adapted to engage a notch 61 in the plunger rod 60 to hold the plunger rod 60 in place.

[0094] The locking sleeve 55 supported and guided by the drive chassis 50 is movable in longitudinal direction with respect to the drive chassis between a release position of the locking sleeve and a locking position. In the locking position, the cams 51 are blocked by the locking sleeve 55 so that the arms 53 cannot be deflected radially outward. The plunger rod 60 is then locked in its biased proximal position. In the release position, the cams 51 can be deflected radially outward and thus the arms 53 do not hold the plunger rod 60 which is then free to move in distal or dispensing direction.

[0095] The plunger rod 60 comprises at its proximal end two oppositely arranged radial protrusions 65 each comprising a distal stop surface 64 adapted to engage a proximal stop surface 52 positioned on each cam 51. This means that if the plunger rod 60 is in a distal end position after dispensing, the proximal stop surface 52 of the cam 51 abuts the distally oriented stop surface 64 of the protrusion 65. Thus, the plunger rod 60 is held within the drive chassis 50 and cannot fall off and cannot be separated from the drive unit 3. Thus, the protrusions 65 act as retaining elements to prevent the plunger rod 60 from being separated from the drive chassis. As Figure 3 and Figure 4As shown in the middle, in the initial or unused state as well as in the dispensed state, the protrusion 65 is located proximally from the distal end of the drive spring 63. The stop surface 52 is integrally formed in the locking arm 53 with the cam 51 and the protrusion 65. The locking arm 53 can in turn be integrally formed in the drive chassis, which is a plastic part injection molded.

[0096] Alternatively, a proximal stop surface is provided on the drive chassis or by an element axially immovable relative to the drive chassis at an axial position close to the proximal end of the syringe.

[0097] Turning to Figure 1 , the situation is depicted when the syringe unit 2 and the drive unit 3 are connected to each other. As shown, the flexible arms 15 of the syringe unit 2 engage the drive chassis 50 of the drive unit 3 and thus couple and hold the syringe unit 2 and the drive unit 3 together. As Figure 1 As shown in the middle, the outermost cover is provided by a thin-walled shroud 5 covering or enclosing the syringe unit 2 and the drive unit 3. The shroud 5 comprises a snap element engaging a recess in the syringe chassis to fixedly connect the shroud 5 to the syringe unit 2 (not shown). The connection element is covered by a label arranged on the outside of the shroud 5. As Figure 1 As shown in the middle, the drive unit 3 is fixedly connected to the syringe unit 2 on the distal side and is enclosed by the shroud 5 on the proximal side. The shroud 5 provides a design element for the medicament label only and / or the shroud provides a user grip portion (not shown).

[0098] The shroud 5 is made of recycled biopolymer, in particular bio-PP and produced by injection molding. In alternative embodiments, the shroud is made of biodegradable plastic such as lignin-based polymer composite or the shroud can be made of wood plywood.

[0099] In the following, the reset procedure of the auto-injector 1 is described in detail. After use, the user returns the auto-injector 1 directly to the manufacturer site (or to an authorized reprocessing site) by mail service or brings the auto-injector back to the point of sale, e.g. a pharmacy. The packaging and the device cap are not intended to be reused and are disposed of by the user.

[0100] At the manufacturer site (or reprocessing site), an expert performs the reset procedure to make the auto-injector ready for re-issuance to a consumer.

[0101] In a first step, the auto-injector is logged by means of an electronic tag (NFC tag) or by a serial number. If the lifetime has not been exceeded, the auto-injector 1 is forwarded for reset.

[0102] In a second step, the auto-injector 1 is disassembled. For this purpose, the shield 5 is removed by releasing the snap-fit connection between the shield catch arms and the barrel chassis 10 of the barrel unit 2. A disassembly tool specific to the auto-injector is inserted from the distal side into the cover sleeve to reach and release the snap-fit connection. The barrel unit 2 and the drive unit 3 remain connected without the shield 5.

[0103] After the shield 5 has been removed and discarded, a disassembly tool with two arms can be inserted through an opening in the outer surface of the drive chassis 50 to reach and release the snap-fit connection between the barrel chassis 10 and the drive chassis 50. This means that, after insertion, the two arms of the disassembly tool contact the release surfaces 17 and further move radially outwardly pressing the release surfaces 17 and thereby causing the two flexible arms 15 to deflect outwardly. This releases the snap-fit connection between the barrel chassis 10 and the drive chassis 50 and thus the barrel unit 2 and the drive unit 3 can be separated. The plunger rod 60 is held in the drive unit and cannot fall out because the distal stop surface 64 of the plunger rod abuts the proximal stop surface 52 on the cam 51 of the drive unit. Thus, the plunger rod 60 is reliably held in the drive unit.

[0104] In a next step, the emptied barrel 20 is disposed. In a further step, the drive unit 3 is reset. For this purpose, the locking sleeve 55 is displaced from the proximal locking position to the distal release position, if it is not already in the release position. Subsequently, the plunger rod 60 is pushed proximally back to the retracted proximal end position and thereby tensions the drive spring 63. When the plunger rod 60 is in its proximal end position, the locking sleeve 55 is moved back to the locking position to hold the biased plunger rod 60 in place.

[0105] In a further step, the drive spring force is tested by releasing the plunger rod to determine whether the drive spring meets the requirements for re-filling. If the spring force does not reach a predefined threshold value or if any malfunction of the drive unit 3 is detected, the drive unit 3 is discarded and replaced with a new one.

[0106] In a further step, the barrel unit 2 and the drive unit 3 are subjected to industrial cleaning or sterilization. Furthermore, a new prefilled barrel 20 is inserted into the barrel holder 12 until the distal shoulder of the barrel barrel contacts the support surface 11 of the barrel holder 12. The lateral wall of the barrel holder 12 is slightly deformed and presses against the barrel barrel to hold the barrel 20 in place.

[0107] In the next step, the syringe unit 2 and the drive unit 3 are connected to each other. When the flexible arms 15 of the syringe chassis 10 are inserted into the drive chassis 50 along the longitudinal axis, the arms 15 are deflected and their hooks 16 snap into the recesses 54 and thus connect the syringe chassis 10 to the drive chassis 50. Then, the syringe unit 2 and the drive unit 3 are reconnected. The needle cover lock is reset by releasing the snap element that prevents the needle cover from retracting (moving in proximal direction) after the previous dispensing event. The needle cover lock can be arranged on either of the drive unit and the syringe unit. This means that the cover sleeve is then able to move from its extended position to its retracted position and thus prepares the cover sleeve for a new injection.

[0108] The drive unit 3 can further comprise a resettable click sleeve (not shown) that is adapted to generate an end click signal upon completion of a dispensing stroke. In the initial or unused state, the click sleeve is biased by a click sleeve spring and held in place by a cam (not shown) on the plunger rod. Once the plunger rod has reached its distal end position after a dispensing stroke, the cam no longer holds the click sleeve and the click sleeve spring can release. This means that the click sleeve spring moves the click sleeve a short distance proximally and the click sleeve abuts a proximal end wall of the drive unit, thereby generating a click sound to the user indicating that the injection is completed. During the reset procedure, the click sleeve moves back to its distal initial position and thereby biases the click sleeve spring. The cam of the retracted plunger rod holds the click sleeve in place.

[0109] To complete the reset, a new shield 5 is installed. The connected syringe unit 2 and drive unit 3 are inserted into the sleeve-shaped shield until the snap arms of the shield snap into notches in the syringe chassis 10, thereby securing the shield 5 to the syringe unit 2 by a snap fit. As a final assembly step, a new cap 4 is installed on the distal end of the syringe unit 2. After the assembly procedure, a quality check is performed. Subsequently, the auto-injector 1 is ready for re-issuance.

[0110] While the application has been described in detail in the drawings and foregoing description, such description is to be considered illustrative or exemplary and not restrictive. Variations and modifications to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed application, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage. In particular, any one of the features recited in any of the claims can be used in combination with features of any other claim.

[0111] List of reference signs 1 auto-injector 2 needle cylinder unit 3 drive unit 4 cap 5 shield 10 needle cylinder chassis 11 support surface 12 needle cylinder holder 13 cover sleeve 15 flexible arm 16 hook 17 release surface 20 needle cylinder 21 needle 22 stop 50 drive chassis 51 cam 52 proximal stop surface 53 locking arm 54 recess 55 locking sleeve 60 plunger rod 61 notch 62 opening 63 drive spring 64 distal stop surface 65 protrusion

Claims

1. An autoinjector (1) for automatically dispensing a liquid product through a needle (21) of a prefilled syringe (20), said autoinjector (1) comprising a syringe unit (2), said syringe unit (2) comprising • a syringe holder (12) for holding the pre-filled syringe (20); • a needle covering sleeve (13), said needle covering sleeve (13) being adapted to shield said needle (21) in its extended position; • a syringe chassis (10) for supporting the syringe holder (12) and guiding the movement of the needle cover sleeve (13) from the extended position to the retracted position, in, The autoinjector (1) further comprises a resettable drive unit (3) attachable to the syringe unit (2), the drive unit (3) comprising • a plunger rod (60) movable from a proximal position to a distal position to drive a stopper (22) in the barrel of the pre-filled syringe toward the needle to dispense the liquid product; • a resettable or re-pressurizable drive spring (63) for evacuating the entire volume of the cartridge in a single dispensing event; • a drive chassis (50) for supporting the drive spring and being releasably attached or releasably attachable to the syringe holder (12) or the syringe chassis (10), Characterized in that the autoinjector (1) comprises a shield (5) extending longitudinally between the distal end and the proximal end of the autoinjector (1), and wherein the shield (5) is the outermost cover of the autoinjector, which covers at least half of the syringe unit (2) and covers the drive unit (3) when the syringe unit (2) is attached to the drive unit (3).

2. The autoinjector (1) according to claim 1, wherein The shield (5) is attached to the drive chassis (50) or the syringe chassis (10) or both the drive chassis (50) and the syringe chassis (10) by a releasable snap-fit ​​connection.

3. The autoinjector (1) according to claim 1 or 2, wherein The shield (5) is attached to the support structure of the drive chassis (50) or syringe chassis (10), and wherein the shield (5) does not have any supporting capability for the autoinjector components surrounded by the shield.

4. The autoinjector (1) according to claims 1 to 3, wherein The plunger rod (60) includes a retaining element (65) to retain the plunger rod in the drive unit (3) when the syringe unit (2) is separated from the drive unit (3) after product dispensing, and wherein the retaining element (65) is provided at the proximal end of the plunger rod (60) and is positioned proximally from the distal end of the drive spring (63), wherein the retaining element (65) includes a distal stop surface (64), and the drive unit includes a proximal stop surface (52), and wherein, after product dispensing, the distal stop surface (64) is pressed against the proximal stop surface (52) by the force of the drive spring so that the plunger rod (60) is maintained in a stable distal end position.

5. The autoinjector (1) according to any one of claims 1 to 4, wherein The shield (5) is made of a biopolymer based on non-fossil raw materials.

6. The autoinjector (1) according to any one of claims 1 to 4, wherein The protective cover (5) is made of a biodegradable polymer.

7. The autoinjector (1) according to any one of claims 1 to 4, wherein The shield (5) is made of recycled polymer.

8. The autoinjector (1) according to any one of claims 1 to 7, wherein The protective cover (5) is manufactured by means of single-component or multi-component injection molding.

9. An autoinjector (1) for automatically dispensing a liquid product through a needle (21) of a prefilled syringe (20), said autoinjector (1) comprising a syringe unit (2), said syringe unit (2) comprising • a syringe holder (12) for holding the pre-filled syringe (20); • a needle covering sleeve (13), said needle covering sleeve (13) being adapted to shield said needle (21) in its extended position; • a syringe chassis (10) for supporting the syringe holder (12), defining a longitudinal axis, and guiding movement of the needle cover sleeve (13) from the extended position to the retracted position, in, The autoinjector (1) further comprises a resettable drive unit (3) attachable to the syringe unit (2), the drive unit (3) comprising • a plunger rod (60) movable from a proximal position to a distal position to drive a stopper (22) in the barrel of the pre-filled syringe toward the needle to dispense the liquid product; • a resettable or re-pressurizable drive spring (63) for evacuating the entire volume of the cartridge in a single dispensing event; • a retaining element (51) for retaining the plunger rod (60) in the proximal position prior to dispensing activation; • a drive chassis (50) for supporting the drive spring and being releasably attached or releasably attachable to the syringe holder (12) or the syringe chassis (10); wherein the plunger rod (60) comprises a retaining element (65) for retaining the plunger rod in the drive unit (3) when the syringe unit (2) is separated from the drive unit (3) after the product is dispensed, Characterized in that the retaining element (65) is provided at the proximal end of the plunger rod (60), and wherein the retaining element (65) is positioned proximally from the distal end of the drive spring (63), wherein the retaining element (65) includes a distal stop surface (64), and the drive unit includes a proximal stop surface (52), and wherein, after product dispensing, the distal stop surface (64) is pressed against the proximal stop surface (52) by the force of the drive spring, so that the plunger rod (60) is maintained in a stable distal end position.

10. The autoinjector (1) according to claim 9, wherein The distal stop surface (64) and the proximal stop surface (52) are oriented perpendicular to the longitudinal direction.

11. The autoinjector (1) according to claim 9 or 10, comprising two said retaining elements (65), said retaining elements (65) being arranged opposite each other and each comprising a distal stop surface (64), and wherein, The drive unit (3) comprises two corresponding proximal stop surfaces (52).

12. The autoinjector (1) according to any one of claims 1 to 11, wherein The syringe chassis (2) or the drive chassis (3) includes a snap-fit ​​member (15), and the other of the drive chassis (3) or the syringe chassis (2) includes a recess (54) adapted to engage the snap-fit ​​member (15) when the syringe unit (2) is attached to the drive unit (3) to form a snap-fit ​​connection.

13. The autoinjector (1) according to claim 12, wherein The catch (15) comprises a release surface (17), and wherein the snap-fit ​​connection can be disconnected by an autoinjector-specific tool to separate the syringe unit (2) and the drive unit (3) by pushing against the release surface (17) and thereby deflecting the catch (15).

14. The autoinjector (1) according to claims 1 to 13, wherein The drive unit (3) comprises a locking member (55) movable relative to the drive chassis (50), wherein in a first position of the locking member (55) resetting of the plunger rod (60) is prevented, and in a second position of the locking member (55) movement of the plunger rod back to the proximal position is enabled.

15. The autoinjector (1) according to any one of claims 1 to 14, wherein The plunger rod (60) is hollow, and wherein the drive spring (63) is at least partially arranged inside the hollow plunger rod (60).

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