Resettable Auto-Injector

Abstract

The present invention relates to an auto-injector (1) for automatic dispensing of a liquid product through a needle (21) of a pre-filled syringe (20). The auto-injector (1) comprises a syringe unit (2) including a syringe holder (12), a needle cover sleeve (13), and a syringe chassis (10) for supporting the syringe holder (12) and guiding movement of the needle cover sleeve (13). The auto-injector (1) further comprises a resettable drive unit (3) including 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) 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 medication delivery device for injecting, delivering, administering, infusing, or dispensing substances and / or liquids, such as insulin, hormone preparations, or vaccines. The present invention is derived from an auto-injector for automatic dispensing of liquid products through the needle of a pre-filled syringe. The auto-injector comprises a syringe unit including a syringe holder and a needle cover sleeve. The auto-injector further comprises a drive unit including a plunger rod, a drive spring for emptying the entire volume of the syringe, and a drive chassis releasably mountable to the syringe holder. [Background technology]

[0002] There are various diseases that require regular treatment by subcutaneous administration of medication, and several drug delivery devices have been developed to assist patients in accurately and controllably delivering a predetermined amount of medication in the self-administration process. Delivery devices include injection devices that are removed from the injection site after each dosing event or drug delivery process, as well as infusion devices with a cannula or needle that remain in the patient's skin for an extended period of time.

[0003] As an example, diabetes can be treated by self-administration of insulin or its derivatives with the aid of a multi-dose insulin injection pen. Injection pen devices generally have an elongated device body defining a longitudinal major device axis. Automatic injection devices have a motor or drive spring to bias a plunger rod and shift a piston within a reservoir barrel, and the drive spring may need to be manually loaded or tensioned prior to injection of a dose. Manually driven delivery drives require the user to manually provide energy to move the piston, for example, by applying a distal force to the injection device.

[0004] The drug dose to be injected can be manually selected by turning the dosage knob and observing the actual dialed dose from the insulin pen's dose window or display. The dose is dispensed by inserting the needle into the appropriate area of ​​the person's skin and manually moving the plunger or by pressing the release button of the automatic injection device. The automatic injection device can be equipped with an electronic dose dial mechanism to automatically set the dose.

[0005] Also known is the use of an auto-injector with a pre-filled syringe. An auto-injector typically includes a body for housing the syringe and an automatic drive mechanism for moving the syringe plunger upon actuation of the automatic injection. The drive mechanism of an auto-injector typically includes a drive source, such as a motor or a strong spring, for moving a transfer element, e.g., a rod, that acts against the syringe plunger. A pre-filled syringe has a needle or cannula permanently attached to one end of a syringe barrel or reservoir, which is sealed at the other end by a plunger.

[0006] For safety reasons, it is desirable that the needle not protrude from the housing of the auto-injector except when the needle is being used to inject medication. Thus, the auto-injector either moves the needle out of the housing for injection and returns it to the housing after injection, or the auto-injector provides a needle cover or needle guard that can be moved to withdraw the needle for injection and returned to a needle-covering position after injection.

[0007] Most auto-injectors are configured as single-use devices that incorporate both the syringe and the drive mechanism within the same housing. Such devices are typically disposable for ease of use.

[0008] From an environmental perspective, it is desirable to reduce waste and reuse devices as much as possible. To take into account both environmental responsibility and medical and safety standards, devices are developed as two-part, or semi-disposable, or semi-reusable, auto-injectors. Such auto-injectors include a part containing a syringe or reservoir with a drug that can be separated from and disposed of separately from other parts, such as a drive unit containing the drive mechanism of the auto-injector.

[0009] WO2017 / 033193 A1 discloses an automatic injection device including a disposable medication module with a prefilled syringe and a reusable drive module. The drive module includes a compressible drive spring. Upon activation by a user, medication is dispensed from the medication module using the drive spring of the drive module. When the medication module is manually removed from the drive module by a user, the plunger rod is retained within the housing of the drive module by a retaining element. The retaining element engages the plunger rod at an intermediate portion of the plunger rod. The retaining element is movable relative to the housing and can engage the housing by a retaining arm.

[0010] EP2 468 337 A1 discloses an automatic injector including a disposable syringe unit that holds a syringe and a reusable drive unit with a torsion spring. The drive unit is releasably attachable to the syringe unit via a bayonet coupling. After pressing the automatic injector against the injection site and pressing the release button, the support sleeve is moved distally, thereby moving the syringe distally and inserting the needle into the user via the force of the torsion spring. When the cam surface on the rotating sleeve is disengaged by the moving plunger follower, the rotating sleeve is released and begins to rotate via the spring force, moving the plunger rod toward the distal end position and dispensing the medication. When the cam surface abuts the plunger follower, the plunger rod is retracted by the spring force and returned proximally. The spring in the syringe unit is then released, returning the support sleeve with the syringe away from the injection site. Summary of the Invention

[0011] A first object of the present invention is to provide a reliable dispense-driven reset mechanism for a reconfigurable auto-injector. A second object of the present invention is to conceal the internal interface between the disposable and reusable portions of the reconfigurable auto-injector while allowing for a customized look and feel.

[0012] This object is achieved by an 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 (drug or medication) through the needle of a pre-filled syringe (PFS) of the auto-injector. The auto-injector includes a syringe unit and a resettable drive unit releasably attachable to the syringe unit. The syringe unit includes: a syringe holder for holding a pre-filled syringe, preferably the syringe holder is adapted to support a distal shoulder of the syringe; a needle cover sleeve for shielding the needle in its extended or distal position; a syringe chassis for mechanically supporting the syringe holder and guiding movement of the needle cover sleeve from an extended position to a retracted or proximal end position of the needle cover sleeve in which the needle is exposed; Includes:

[0014] Reconfigurable drive units are a plunger rod movable from a proximal position to a distal position thereof for driving a stopper in the barrel of the prefilled syringe toward the needle to dispense the liquid product; a mechanically driven spring for emptying the entire volume of the barrel in a single dispensing event; a retaining element for holding the plunger rod or drive spring in a pretensioned state prior to 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 mounted or releasably mountable to the syringe chassis for mounting of the syringe unit to the drive unit.

[0015] The plunger rod includes a retaining element for retaining the plunger rod within the drive unit upon separation of the drive unit and syringe unit after product dispensing. The retaining element is provided at the proximal end, at the proximal end portion, or at the proximal half of the plunger rod. In the initial state and in the dispensing state, the retaining element is located proximal to the distal end of the drive spring. Furthermore, the retaining element includes a (preferably flat or planar) distal stop surface, and the drive unit includes a (preferably flat or planar) proximal stop surface, and after product dispensing, the distal stop surface is preferably pressed against the proximal stop surface by the force of the drive spring so that the plunger rod remains in a stable distal end position even when the syringe unit is removed from the drive unit. The plunger rod is not retracted or returned by the drive spring force.

[0016] After tool-by-tool separation of the autoinjector into the syringe unit and drive unit, the plunger rod is no longer guided inside the syringe barrel or by elements of the syringe unit. In such a detached state, the retaining element reliably prevents the plunger rod from separating from the drive unit, and in particular from the drive chassis. Because the retaining element is located at the proximal end of the plunger rod, a compact and space-saving design is provided. Furthermore, due to the proximally located retaining element, the plunger rod does not need to be retracted from a distal position to a proximal position before separation of the syringe unit and drive unit. Furthermore, the plunger rod does not need to be retracted by a drive spring, which requires a complex retraction mechanism. Instead, the plunger rod can be retracted or reset / reloaded by an external force.

[0017] The retaining element holds the plunger rod to the drive unit (especially after separation of the syringe unit and drive unit), but allows the plunger rod to move relative to the drive chassis. Specifically, the plunger rod may be rotatable or linearly movable relative to the drive chassis. However, due to a flat distal stop surface pressing against a flat proximal stop surface of the drive unit, the plunger rod is stable and remains in its distal end position after dispensing.

[0018] The retaining element may be, for example, a knob, protrusion, recess, hook, or screw on the plunger rod. The drive chassis, or any other component of the drive unit, includes a proximal stop surface that engages a distal stop surface at a distal position on the plunger rod. The proximal stop surface may be located on, for example, a cam, slot, protrusion, or recess.

[0019] The proximal stop surface may be rigid or may be resiliently attached to a component of the drive unit to engage the distal stop surface and securely retain the plunger rod when the syringe unit is separated from the drive unit.

[0020] The auto-injector according to the present invention is reconfigurable, which means that after use, the auto-injector can be returned to the manufacturer or a reprocessing location to be reconfigured and prepared for reuse. For this purpose, the auto-injector is separated into a syringe unit and a drive unit. Specialized tools may be required for disassembly of the auto-injector and for separation of the drive unit and syringe unit.

[0021] The syringe unit and drive unit may then be subjected to functional testing, in particular a drive spring test may be performed to assess whether the drive spring meets predetermined requirements, such as a minimum drive force. In a further step, the syringe unit and drive unit may be cleaned or sterilized in an industrial manner. If the drive spring test is passed, and if the drive spring meets the requirements for it to be reset, for example, a mechanical spring is tensioned or an elastic material is compressed to prepare the drive unit for reuse.

[0022] During these preparation steps, the retention element, and particularly the proximal and distal stop surfaces, securely retain the plunger rod within the drive unit, thus preventing removal of the plunger rod, which results in efficient handling and assembly of the drive unit during the reset procedure.

[0023] After loading the syringe unit with a new pre-filled syringe, the syringe unit and drive unit are reconnected and, after quality control, the auto-injector is ready for use for a new injection.

[0024] In contrast to known semi-reusable auto-injector concepts with user-operated syringe cassettes, the syringe unit of an auto-injector according to the present invention is not completely discarded; only the empty syringe is replaced. The syringe chassis is reused and reconnected to the drive chassis when a new, pre-filled syringe is loaded, which reduces waste compared to semi-reusable auto-injectors with syringe units that are completely discarded after use.

[0025] Furthermore, the present invention provides an auto-injector drive unit that can be reset or reloaded, preferably manually, by the manufacturer or by a human at a reprocessing location, thus also allowing the drive unit to be reused. A resettable auto-injector according to the present invention therefore contributes to a reduced carbon footprint per injection.

[0026] The drive unit preferably comprises a mechanical drive spring, preferably a compression spring of the helical type, which is preferably manually resettable and reloadable.

[0027] The drive unit or syringe unit preferably further includes a lockout element for locking the needle cover sleeve in an extended position against proximal movement relative to the syringe chassis, meaning that after an injection, when the user removes the auto-injector from the injection site, the lockout element locks the needle cover sleeve in an extended or distal position to cover the needle and prevent injury. During the reset procedure, the lockout element is also preferably reset to allow the needle cover to be pushed proximally again during a new injection.

[0028] The drive unit further includes a retaining element for retaining the plunger rod in a compressively stressed proximal position. The retaining element is released upon actuation, preferably upon retraction of the cover sleeve from the extended position to the retracted position, to allow the plunger rod to move freely in a distal direction to dispense the liquid product. Examples of retaining elements are resilient and / or flexible arms, snap elements, or movable cams or stoppers.

[0029] In this context, the terms "substance," "drug," "medication," and "pharmaceutical" should be understood to include any flowable pharmaceutical formulation suitable for controlled administration, for example, through a cannula or hollow needle, including liquids, solutions, gels, or fine suspensions containing one or more pharmaceutically active ingredients. A medicament can be a composition containing a single active ingredient, or a premixed or co-formulated composition in which two or more active ingredients are present in a single container. Pharmaceuticals include drugs such as peptides (e.g., insulin, insulin-containing drugs, GLP-1-containing drugs, or derivative or similar preparations), proteins and hormones, active ingredients derived from or collected by biological sources, hormonal or gene-based active ingredients, nutrients, enzymes, and other substances in both solid (suspended) or liquid form, but also polysaccharides, vaccines, DNA, RNA, oligonucleotides, antibodies or antibody portions, as well as suitable basic substances, auxiliary substances, and carrier substances.

[0030] The term "distal" is meant to refer to the direction or end of the auto-injector that carries the injection needle or injection cannula, while the term "proximal" is meant to refer to the opposite direction or end that points away from the needle or cannula.

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

[0032] Preferably, the proximal and distal stop surfaces are oriented perpendicular to the longitudinal direction. This provides a simple design and secure support and engagement of the distal and proximal stop surfaces. Alternatively, the proximal stop surface may be angled or oblique, and the distal stop surface may have a corresponding angled or oblique configuration.

[0033] Preferably, the proximal stop surface is integrally formed within the drive chassis and is therefore monolithically formed in one piece. The drive chassis may be an injection molded plastic part with the proximal stop surface integrated into it.

[0034] In a preferred embodiment, the drive unit includes two holding elements oriented opposite each other and each including a proximal stop surface. In this case, the drive unit includes two corresponding distal stop surfaces. The two stop surfaces provide a more stable support for the plunger rod at 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. The drive chassis, or any component of the drive unit, preferably includes a mating element adapted to engage the protrusion or recess to retain the plunger rod. The protrusion or recess on the plunger rod and the mating element thus form a snug connection. Examples of mating elements are notches, slots, stops, hooks, or mating protrusions.

[0036] The snug connection provides a simple and secure engagement of the plunger rod with the chassis or any other drive unit component. The plunger rod is held in its distal end position by the connection between the protrusion or recess and the mating element, allowing the plunger rod to move relative to the drive chassis but preventing it from being ejected from the drive unit.

[0037] Alternatively, the retaining element may be a screw that couples the plunger rod to the drive chassis or to any other drive unit component.

[0038] The present invention further relates to an auto-injector for automatic dispensing of a liquid product through the needle of a pre-filled syringe, the auto-injector comprising a syringe unit, the syringe unit comprising: A syringe holder for holding pre-filled syringes, a needle cover sleeve for shielding the needle in the extended position of the needle cover sleeve; A syringe chassis for supporting the syringe holder and guiding movement of the needle cover sleeve from the extended position to the retracted position. Including, The auto-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 for driving a stopper in the barrel of the prefilled syringe toward the needle to dispense the liquid product; A resettable or rechargeable drive spring to empty the entire volume of the barrel in a single dispensing event; a drive chassis that supports a drive spring and that is releasably attached or releasably attachable to a syringe holder or syringe chassis; Equipped with.

[0039] The auto-injector may include a shroud extending longitudinally between the distal and proximal ends of the auto-injector, the shroud covering at least half of the syringe unit and being the auto-injector's outermost covering that also covers the drive unit when the syringe unit is attached to the drive unit. The shroud thus encases the drive unit and syringe unit, thus providing an outermost covering for the syringe unit and drive unit. In a preferred embodiment, the shroud is sleeve-shaped extending along the longitudinal axes of the syringe unit and drive unit.

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

[0041] The shroud preferably does not support or guide internal elements or components, and therefore does not hold the drive mechanism or syringe. The shroud is therefore not part of the support housing. Instead, the shroud is mounted solely to the outside of the drive chassis and syringe chassis, which means that the shroud is mounted to the support structure of the drive chassis or syringe chassis and preferably lacks any support capability for the auto-injector components enclosed by the shroud.

[0042] While the drive chassis and syringe chassis provide a support structure or framework for the auto-injector components, they do not cover or encase the components, and neither should be construed as a housing. The drive chassis and syringe chassis are preferably merely support structures and include several openings and breakouts that allow direct access to components such as the drive spring reset mechanism. The internal components are preferably shielded from the user and covered by a dedicated attached shroud.

[0043] In the assembled state, the syringe unit and the drive unit are coaxially disposed inside the shroud. The shroud is preferably connected to at least one of the syringe unit and the drive unit, preferably on a tool-by-tool basis, by a snap-fit ​​connection between the shroud and the syringe chassis or the drive chassis. In a preferred embodiment, the shroud can be disassembled at the reprocessing site (e.g., not by the user) exclusively with dedicated tools and personnel. This means that the user cannot disassemble the auto-injector, thus preventing unintended use or injury.

[0044] The shroud allows for customization of the auto-injector by providing specific visual elements (such as a label, trademark, non-electronic identifier, or electronic identifier such as an RFID tag) or by providing a dedicated exterior form or geometry, e.g., a user grip portion.

[0045] The shroud is preferably disposable, meaning that it is discarded during the auto-injector reset procedure, so that a new shroud can be installed during reset of the auto-injector.

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

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

[0048] Biopolymers can be biodegradable or non-biodegradable, examples of the latter being polypropylene (bio-PP), polyethylene (bio-PE), bio-polyesters such as polyethylene terephthalate (bio-PET), polyethylene 2,5-furandicarboxylate (bio-PEF), polyamide (bio-PA), polyoxymethylene (bio-POM), polycarbonate (bio-PC), polyacrylonitrile-butadiene-styrene copolymer (bio-ABS), and 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 organisms, particularly microorganisms, that digest, metabolize, and convert biodegradable plastics into energy and non-plastic waste.

[0050] Biodegradable polymers include not only biopolymers (e.g., polylactic acid PLA, starch blends, lignin-based polymer composites) but also biodegradable petroleum-based polymers (e.g., polyglycolic acid PGA, polybutylene succinate PBS, polycaprolactone PCL).

[0051] To further reduce waste and to respect the needs of environmental protection, 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 not only biopolymers but also non-biopolymers.

[0052] As an alternative to polymers, the shroud can be made of recyclable cardboard or wood veneer. Wood veneer shrouds include thin slices or sheets of wood and / or bark that are glued or adhered together in a continuous manner to produce a sleeve-shaped shroud. Wood veneer shrouds offer the benefit of lower overall energy use, greenhouse gas emissions, and air and water pollution impacts compared to plastic shrouds.

[0053] If the shroud is made of any type of plastic, it is preferably manufactured using one or multiple component injection molding, which allows for efficient and cost-effective high volume manufacturing.

[0054] In a preferred embodiment, the syringe holder is adapted to hold the syringe fixedly and immovably relative to the drive chassis in the longitudinal direction of the syringe, and to that end, the syringe holder may include a stop or contact surface that supports the distal shoulder of the syringe barrel.

[0055] That means that the syringe is not displaced during the injection process, in contrast to, for example, an auto-injector, which provides syringe motion to displace the syringe distally and automatically insert the injection needle into the injection site.

[0056] Additionally, the syringe chassis is adapted to mechanically support the syringe holder and to guide 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 toward the extended position by a needle cover sleeve spring.

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

[0058] In a preferred embodiment, the drive chassis or the syringe chassis includes a snapper, and the other of the drive chassis or the syringe chassis includes a recess or mating element adapted to engage the snapper to form a snap-fit ​​connection between the syringe unit and the drive unit. Examples of mating elements are notches, protrusions, or hook-shaped elements.

[0059] Thus, the syringe unit and the drive unit can be securely connected to one another. The snap-fit ​​connection can include one or more snappers and correspondingly one or more mating elements.

[0060] In a preferred embodiment, the snap-fit ​​connection is releasable, meaning that the syringe chassis and drive chassis can be disconnected and reconnected several times, allowing the auto-injector to be refilled and reused several times. In a preferred embodiment, the snap-fit ​​connection is releasable exclusively 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 shroud, which extends longitudinally between the distal and proximal ends of the auto-injector and at least partially covers the syringe unit and the drive unit as described above.

[0062] The snapper preferably comprises a release surface, which can be deflected radially by pressing on the release surface, thereby releasing and separating the snap-fit ​​connection between the syringe unit and the drive unit, which means that the snapper can be deflected by pressing on the release surface, thus disengaging the snapper from the notch or mating element.

[0063] A device-specific tool or dedicated key may be required to reach the release surface and deflect the snapper through the release surface. This avoids unintentional deflection and therefore unintentional detachment of the syringe unit from the drive unit. In particular, the snap-fit ​​connection may be designed such that the connection can be detached exclusively at the manufacturing or reprocessing site by an auto-injector-specific disassembly tool.

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

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

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

[0067] In the first position, the plunger rod is preferably prevented from being returned proximally or to the retracted position. This can be achieved, for example, by an element or intermediate member (e.g., sawtooth) of the locking member that abuts the plunger rod and thus blocks plunger rod movement toward the retracted position. In the second position, the element preferably does not hold the plunger rod, and the plunger rod is therefore free to be pushed back to the retracted position. Thus, in the second position of the locking member, the plunger rod's travel path is free, and therefore, plunger rod movement is permitted.

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

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

[0070] Preferably, the plunger rod is hollow and the drive spring is at least partially disposed inside the hollow plunger rod. The spring is pre-stressed prior to 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. Because the spring is disposed inside the hollow plunger rod, a compact and space-saving design is provided. In a preferred embodiment, the spring has a coil wound around the longitudinal axis of the auto-injector.

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

[0072] The present invention further relates to a method for reconfiguring an automatic injector including a drive unit and a syringe unit, the syringe unit including a pre-filled syringe for automatic dispensing of a liquid product through the needle of the pre-filled syringe, the method comprising: a) after dispensing the liquid product, severing the connection (preferably a snap fit) between the syringe unit and the drive unit of the used auto-injector by a device specific tool and separating the auto-injector into a syringe unit and a drive unit by a human at the reprocessing location, wherein the plunger rod is retained in the drive unit by a retaining element provided at the proximal end of the plunger rod, the retaining element being located proximal to the distal end of the mechanical drive spring; b) removing the empty syringe from the syringe unit, either by a professional at the reprocessing location or automatically, and preferably reloading the syringe unit with a new syringe; c) resetting the plunger rod of the drive unit from a distal position to a proximal position, thereby pretensioning the mechanical spring of the drive unit. Includes:

[0073] In a preferred embodiment, the method may further include the step of removing an outer shroud covering the syringe unit and the drive unit before separating the syringe unit and the drive unit.

[0074] Additionally, the method preferably includes the steps of loading a new syringe into the syringe unit after the empty syringe has been removed, and reconnecting the syringe unit and drive unit after the plunger rod has been reset.

[0075] Alternatively, a cover lock can be reset within the syringe unit. The cover lock locks the cover sleeve in an extended position where it covers the needle after injection. Resetting the cover lock releases the cover sleeve, allowing it to be moved from the extended position to a retracted position where the needle is exposed and not covered by the cover sleeve.

[0076] Preferably, the method further comprises the step of industrial cleaning of the drive unit after it has been separated from the syringe unit, for example the drive unit may be washed or heat treated to prepare it for use with a new syringe unit containing a new pre-filled syringe.

[0077] The method may further include the steps of moving the locking sleeve to a release position to allow resetting of the plunger rod to a proximal position, and subsequently moving the locking sleeve to a locking position to prevent movement of the plunger rod in the distal direction before the plunger rod is released for injection.

[0078] Additionally, the method preferably includes the step of connecting a new shroud to the syringe unit, the shroud at least partially covering the syringe unit and the drive unit.

[0079] Although the above-described embodiments refer to an auto-injector for a pre-filled syringe, an auto-injector according to the invention can also be used with a cartridge. The cartridge comprises a needle mounting portion at its distal end for releasably mounting a needle assembly. Before injection, the user must mount the needle assembly on 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] In a cartridge-based embodiment, the present invention relates to an auto-injector for automatic dispensing of a liquid product from a pre-filled reservoir through a needle, the auto-injector comprising a reservoir unit, the reservoir unit comprising: A reservoir holder for holding the reservoir; optionally a needle cover sleeve for shielding the needle in the extended position of the needle cover sleeve; A reservoir chassis for supporting the reservoir holder and guiding movement of the needle cover sleeve, if present, from an extended position to a retracted position. Including, The auto-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 for driving a stopper in the barrel of the reservoir toward the needle to dispense the liquid product; A resettable or rechargeable drive spring to empty the entire volume of the barrel in a single dispensing event; a drive chassis that supports a drive spring and that is releasably attached or releasably attachable to the reservoir holder or reservoir chassis; wherein the automatic injector includes a shroud extending longitudinally between the distal end and the proximal end of the automatic injector, the shroud covering at least half of the reservoir unit and being the outermost cover of the automatic injector that covers the drive unit when the reservoir unit is attached to the drive unit.

[0081] In this embodiment, the reservoir is preferably a cartridge with a needle mounting location at its distal end for releasably mounting a needle assembly.

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

[0083] The shroud may be mounted to a support structure of the drive chassis or reservoir chassis, and the shroud lacks any support capacity for the auto-injector components enclosed by the shroud.

[0084] The subject matter of the present invention will be explained in more detail in the following text with reference to preferred exemplary embodiments illustrated in the accompanying drawings. [Brief explanation of the drawings]

[0085] [Figure 1] 1 is a schematic cross-sectional view of an auto-injector according to the present invention, with the cutout for the cross-section extending along the longitudinal axis. [Figure 2] 1 is a schematic cross-sectional view of a syringe unit of an automatic injector. [Figure 3] 1 is a schematic cross-sectional view of a drive unit of an automatic injector in an unused state. [Figure 4] FIG. 10 is a schematic cross-sectional view of the drive unit in a dispensing state. DETAILED DESCRIPTION OF THE INVENTION

[0086] The reference signs used in the drawings and their main meanings are listed in summary form in the description of the signs. As a rule, identical parts are provided with the same reference signs in the figures.

[0087] In the following, the term "distal" refers to the side where the injection needle is located (e.g., the left-hand side in Figures 1 to 4), and the term "proximal" refers to the opposite side that is furthest from the needle (the right-hand side in Figures 1 to 4).

[0088] Figure 1 depicts a schematic cross-sectional view of a resettable auto-injector 1 according to the present invention. The cut for the cross-section extends along the longitudinal axis of the auto-injector 1. Figure 1 depicts the auto-injector 1 in an initial or delivery state.

[0089] The auto-injector 1 is cylindrical in shape and comprises a syringe unit 2 that houses a pre-filled syringe (PFS) 20 containing a liquid medication and a stopper 22. The auto-injector 1 further comprises a drive unit 3 that houses a mechanical drive spring 63 for dispensing the medication from the syringe 20. The auto-injector 1 further comprises an outer shroud 5 that covers and encloses both the syringe unit 2 and the drive unit 3. In an initial state as shown in FIG. 1 , a cap 4 is attached to the distal end of the auto-injector 1.

[0090] The syringe unit 2 and drive unit 3 are not intended to be separated by the user. However, after use and return to the manufacturer or a reprocessing location, the auto-injector 1 can be separated into the syringe unit 2 and drive unit 3 by a professional or automatically. The auto-injector can then be refilled by installing a new syringe and reconfigured for redistribution and reuse. The syringe unit 2 and drive unit 3 are described in detail below. Subsequently, the procedure for reconfiguring the auto-injector is described.

[0091] Figure 2 depicts a schematic diagram of the separate syringe unit 2 of Figure 1 in an initial or delivery state, and Figure 3 depicts a schematic diagram of the separate drive unit 3. Both units are shown without the covering shroud 5.

[0092] As shown in FIG. 2 , the syringe unit 2 includes a sleeve-shaped syringe chassis 10 and a syringe holder 12 supported and held by the syringe chassis 10. The syringe holder 12 holds a filled syringe 20 in place and 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 also supports and guides a needle cover sleeve 13 that is coaxially disposed outside the syringe chassis 10. The cover sleeve 13 is longitudinally movable relative to the syringe chassis 10 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 disposed within the syringe unit, but may alternatively be disposed within the drive unit.

[0093] At its proximal end, syringe chassis 10 includes two oppositely disposed snappers or flexible arms 15 adapted to engage and fit into recesses 54 in drive chassis 50 of drive unit 3 to connect syringe unit 2 to drive unit 3 via a snap-fit ​​connection. Each flexible arm 15 features a hook 16 or hook-shaped free end that fits within recess 54. Hook 16, in turn, includes a release surface 17 that engages arm 15 and allows arm 15 to be deflected, as described in more detail below.

[0094] The drive unit 3, as shown in FIG. 3, includes a sleeve-shaped drive chassis 50, a hollow plunger rod 60, and a pre-stressed, helical-type compression drive spring 63 coaxially disposed within an opening 62 in the hollow plunger rod 60. The proximal end of the helical spring 63 is supported by the wall of the drive chassis 50, and the distal end of the helical spring 63 abuts the inner end wall or bottom of the opening 62 in the plunger rod 60, thus biasing the plunger rod 60 distally. The plunger rod 60 is held in its biased proximal position by two oppositely disposed flexible locking arms 53 that can selectively lock or release the plunger rod 60. The arms 53 can be deflected radially outward when a coaxially disposed locking sleeve 55 is in the released position. At its free end, each arm 53 includes a cam 51 adapted to engage a notch 61 in plunger rod 60 to hold plunger rod 60 in place.

[0095] A locking sleeve 55, supported and guided by the drive chassis 50, is longitudinally movable relative to the drive chassis between its released and locked positions. In the locked position, the cam 51 is blocked by the locking sleeve 55 so that the arms 53 cannot deflect radially outward. The plunger rod 60 is then locked in its biased proximal position. In the released position, the cam 51 can deflect radially outward, so that the arms 53 do not retain the plunger rod 60, allowing the plunger rod 60 to move freely in the distal or dispensing direction.

[0096] At its proximal end, the plunger rod 60 includes two oppositely arranged radial protrusions 65, each including a distal stop surface 64 adapted to engage with a proximal stop surface 52 located on the respective cam 51. This means that when the plunger rod 60 is in the distal position after dispensing, the proximal stop surface 52 of the cam 51 abuts the distally oriented stop surface 64 of the protrusions 65. Thus, the plunger rod 60 is held within the drive chassis 50 and cannot fall out of or be separated from the drive unit 3. The protrusions 65 thus act as retaining elements to prevent separation of the plunger rod 60 from the drive chassis. The protrusions 65 are located proximal to the distal end of the drive spring 63 in the initial or unused state and in the dispensing state, as shown in FIGS. 3 and 4 . The stop surfaces 52, the cam 51, and the protrusions 65 are integrally formed within the locking arm 53. The locking arm 53 may then be integrally formed within the drive chassis, which is an injection molded plastic part.

[0097] Alternatively, the proximal stop surface is provided axially near the proximal end of the syringe on the drive chassis or by an element that is axially immovable relative to the drive chassis.

[0098] Turning to FIG. 1 , the syringe unit 2 and drive unit 3 are depicted when the units are connected to one another. As shown, the flexible arm 15 of the syringe unit 2 engages the drive chassis 50 of the drive unit 3, thus coupling and holding the syringe unit 2 and drive unit 3 together. As shown in FIG. 1 , the outermost covering is provided by a thin-walled shroud 5 that covers or encases the syringe unit 2 and drive unit 3. The shroud 5 includes snap elements (not shown) that engage recesses in the syringe chassis to securely connect the shroud 5 to the syringe unit 2. The connection elements are covered by a label disposed on the outside of the shroud 5. The drive unit 3 is securely connected to the syringe unit 2 distally and is covered by the shroud 5 proximally, as shown in FIG. 1 . The shroud 5 may simply provide a design element for a medication label and / or the shroud may provide a user-grasp portion (not shown).

[0099] The shroud 5 is made of recycled biopolymers, in particular polypropylene (bio-PP), and is produced by injection molding. In alternative embodiments, the shroud is made of a biodegradable plastic, such as a lignin-based polymer composite, or the shroud can be made of wood veneer.

[0100] Below, the procedure for resetting the auto-injector 1 is described in detail. After use, the user either returns the auto-injector 1 directly to the place of manufacture (or to an authorized reprocessing location) via the postal service, or returns the auto-injector to the point of sale, e.g., a pharmacy. The packaging and device cap are not intended to be reused and are discarded by the user.

[0101] At the manufacturer's location (or reprocessing location), a professional performs a reconfiguration procedure to prepare the auto-injector for redistribution to consumers.

[0102] In a first step, the auto-injector is logged either with an electronic tag (NFC tag) or by serial number. If the lifespan is still not exceeded, the auto-injector 1 is sent for reconfiguration.

[0103] In a second step, the auto-injector 1 is disassembled. To do so, the shroud 5 is removed by releasing the snap-fit ​​connection between the shroud snap arms and the syringe chassis 10 of the syringe unit 2. An auto-injector-specific disassembly tool is inserted from the distal side into the cover sleeve to reach and release the snap-fit ​​connection. The syringe unit 2 and the drive unit 3 still remain connected without the shroud 5.

[0104] After the shroud 5 is 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 syringe chassis 10 and the drive chassis 50. After insertion, the two arms of the disassembly tool contact the release surface 17, and further movement pushes the release surface 17 radially outward, thereby deflecting the two flexible arms 15 outward. This releases the snap-fit ​​connection between the syringe chassis 10 and the drive chassis 50, and the syringe unit 2 and the drive unit 3 can then be separated. The plunger rod 60 is held within the drive unit and cannot fall out once the distal stop surface 64 of the plunger rod abuts the proximal stop surface 52 on the drive unit cam 51. The plunger rod 60 is therefore securely held within the drive unit.

[0105] In a next step, the empty syringe 20 is discarded. In a further step, the drive unit 3 is reset. For this purpose, the locking sleeve 55 can be shifted from the proximal locked position to the distal released position (if it is not already in the released position). The plunger rod 60 is then pushed proximally back to its retracted proximal end position, thereby tensioning the drive spring 63. When the plunger rod 60 is in its proximal end position, the locking sleeve 55 is returned to the locked position to hold the biased plunger rod 60 in place.

[0106] In a further step, the drive spring force is tested by releasing the plunger rod to determine whether the drive spring meets the redistribution requirements. If the spring force does not reach a predetermined threshold or if any malfunction of the drive unit 3 is detected, the drive unit 3 is discarded and replaced with a new drive unit.

[0107] In a further step, syringe unit 2 and drive unit 3 are subjected to industrial cleaning or sterilization. Furthermore, a new filled syringe 20 is inserted into syringe holder 12 until the distal shoulder of the syringe barrel contacts support surface 11 of syringe holder 12. The lateral walls of syringe holder 12 are slightly deformed and pressed firmly against the syringe barrel to hold syringe 20 in place.

[0108] 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 engage in the recesses 54, thus connecting the syringe chassis 10 to the drive chassis 50. The syringe unit 2 and the drive unit 3 are then reconnected. The needle cover lock is reset by releasing the snap element that prevented retraction (movement in the proximal direction) of the needle cover after the previous dispensing event. The needle cover lock can be located either on the drive unit or on the syringe unit. This means that the cover sleeve can then be moved from its extended position to its retracted position, thus preparing the cover sleeve for a new injection.

[0109] The drive unit 3 may additionally include a resettable click sleeve (not shown) adapted to generate an end click signal upon completion of the 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 on the plunger rod (not shown). When the plunger rod reaches its distal end position after the 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 proximally a short distance until the click sleeve abuts against the proximal end wall of the drive unit, thereby generating a click sound for the user indicating that the injection is complete. During the reset procedure, the click sleeve is returned to its distal initial position, thereby biasing the click sleeve spring. The cam on the retracted plunger rod holds the click sleeve in place.

[0110] To complete the reconfiguration, a new shroud 5 is attached. The connected syringe unit 2 and drive unit 3 are inserted into the sleeve-shaped shroud until the snap arms of the shroud snap into notches in the syringe chassis 10, thereby securing the shroud 5 to the syringe unit 2 with a snap fit. As a final assembly step, a new cap 4 is attached to the distal end of the syringe unit 2. A quality inspection follows the assembly procedure. The auto-injector 1 is then ready for redistribution.

[0111] While the present invention has been described in detail in the drawings and the foregoing description, such description is intended to be illustrative or exemplary, and not restrictive. Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a perusal of the drawings, the disclosure, and the appended claims. Within the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain elements or steps are recited within a particular claim does not indicate that combinations of these elements or steps cannot be advantageously used; in particular, any further meaningful claim combinations shall be deemed to be disclosed in addition to the actual claim dependencies. [Explanation of symbols]

[0112] 1 auto-injector 2 syringe units 3 Drive unit 4 Cap 5. Shroud 10 Syringe Chassis 11 Support surface 12 Syringe holder 13 Cover Sleeve 15 Flexible Arm 16 Hook 17 Release surface 20 syringes 21 needles 22 Stopper 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 auto-injector (1) for automatic dispensing of a liquid product through a needle (21) of a pre-filled syringe (20), said auto-injector (1) comprising a syringe unit (2), said syringe unit (2) comprising: a syringe holder (12) for holding said pre-filled syringe (20); a needle cover sleeve (13) for shielding said needle (21) in its extended position; a syringe chassis (10) for supporting the syringe holder (12) and guiding movement of the needle cover sleeve (13) from the extended position to the retracted position; Including, The automatic injector (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 for driving a stopper (22) in the barrel of the pre-filled syringe towards the needle to dispense the liquid product; A resettable or rechargeable drive spring (63) for emptying the entire volume of the barrel in a single dispensing event; a drive chassis (50) that supports the drive spring and is releasably attached or releasably attachable to the syringe holder (12) or the syringe chassis (10); An automatic injector (1) comprising: The automatic injector (1) includes a shroud (5) extending longitudinally between the distal end and the proximal end of the automatic injector (1), the shroud (5) covering at least half of the syringe unit (2) and being the outermost cover of the automatic injector that covers the drive unit (3) when the syringe unit (2) is attached to the drive unit (3).

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

3. 3. The automatic injector (1) according to claim 1 or 2, wherein the shroud (5) is mounted to a support structure of the drive chassis (50) or syringe chassis (10), and the shroud (5) lacks any support capacity for the automatic injector components enclosed by the shroud.

4. 4. The automatic injector (1) according to claim 1, wherein the plunger rod (60) comprises a retaining element (65) for retaining the plunger rod (60) in the drive unit (3) upon separation of the syringe unit (2) and the drive unit (3) after product dispensing, the retaining element (65) being provided at the proximal end of the plunger rod (60) and located proximal to the distal end of the drive spring (63), the retaining element (65) comprising a distal stop surface (64), the drive unit comprising a proximal stop surface (52), and 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) remains in a stable distal end position.

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

6. 5. The automatic injector (1) according to any one of claims 1 to 4, wherein the shroud (5) is made of a biodegradable polymer.

7. 5. The automatic injector (1) according to any one of claims 1 to 4, wherein the shroud (5) is made from recycled polymers.

8. 8. The automatic injector (1) according to any one of claims 1 to 7, wherein the shroud (5) is manufactured using one or more component injection molding.

9. An auto-injector (1) for automatic dispensing of a liquid product through a needle (21) of a pre-filled syringe (20), said auto-injector (1) comprising a syringe unit (2), said syringe unit (2) comprising: a syringe holder (12) for holding said pre-filled syringe (20); a needle cover sleeve (13) for shielding said needle (21) in its extended position; a syringe chassis (10) for supporting said syringe holder (12), defining a longitudinal axis, and guiding movement of said needle cover sleeve (13) from said extended position to said retracted position; Including, The automatic injector (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 for driving a stopper (22) in the barrel of the pre-filled syringe towards the needle to dispense the liquid product; a resettable or rechargeable drive spring (63) for emptying the entire volume of the barrel in a single dispensing event; a retaining element (51) for retaining said plunger rod (60) in said proximal position prior to dispensing activation; a drive chassis (50) that supports the drive spring and is releasably attached or attachable to the syringe holder (12) or the syringe chassis (10); Equipped with 1. An automatic injector (1), wherein the plunger rod (60) comprises a retaining element (65) for retaining the plunger rod in the drive unit (3) upon separation of the syringe unit (2) and the drive unit (3) after product dispensing, the retaining element (65) is provided at the proximal end of the plunger rod (60), the retaining element (65) is located proximal to the distal end of the drive spring (63), the retaining element (65) comprises a distal stop surface (64), the drive unit comprises a proximal stop surface (52), and 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) remains in a stable distal end position.

10. 10. The automatic injector (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. 11. The automatic injector (1) according to claim 9 or 10, comprising two holding elements (65) arranged opposite each other and each comprising a distal stop surface (64), and the drive unit (3) includes two corresponding proximal stop surfaces (52).

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

13. 13. The automatic injector (1) according to claim 12, wherein the snapper (15) comprises a release surface (17), and the snap-fit ​​connection can be separated by a tool specific to the automatic injector to separate the syringe unit (2) and the drive unit (3) by pressing on the release surface (17) and thereby deflecting the snapper (15).

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

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