Shielded needle unit with lock indicator

Abstract

A needle unit adapted to be mounted on a drug delivery device, comprising a needle hub with a mounting coupling, and a shield in which the needle hub is arranged. The shield is axially moveable relative to the needle hub between an initial extended position in which the shield axially covers the needle distal end, a retracted proximal position in which the needle distal end protrudes from the shield, and a locked extended position in which the shield covers the needle distal end. The shield comprises an indicator window, and the needle hub comprises an indicator marker. The shield comprises guide means allowing it to be mounted axially moveable but non-rotatable on the drug delivery device. The indicator marker is not visible through the indicator window when the shield is in the initial extended position, but visible through the window when the shield is in the locked extended position.

Description

[0001] SHIELDED NEEDLE UNIT WITH LOCK INDICATOR

[0002] The present invention generally relates to a shielded needle unit adapted to be used in combination with a drug delivery device intended for subcutaneous introduction of a fluid drug formulation, the device comprising a drive spring adapted to expel one or more predetermined dose volumes of the fluid drug formulation.

[0003] BACKGROUND OF THE INVENTION

[0004] In the disclosure of the present invention reference is mostly made to hypodermic needles intended for use by a patient for subcutaneous administration of a fluid drug formulation, e.g. in the treatment of diabetes by delivery of insulin or a GLP-1 type drug, or in the treatment of growth disorders by delivery of growth hormone, however, these are only exemplary uses of the present invention.

[0005] To administer such drugs a great number of different drug delivery systems have been developed over the last 30 years. The drug delivery system is commonly in the form of a “pen” device (due to its form) comprising a cartridge containing the liquid drug to be injected. The pen device may be of the durable type adapted to receive a user-replaceable drug cartridge or it may be a “prefilled” disposable provided with a cartridge not intended to be replaced by the user. The pen device may be adapted to expel a single or a number of drug doses, the size of the dose being either user-settable or pre-set and thus not adjustable by the user. The expelling mechanism for driving the fluid drug out of the cartridge may be “manual” with the force applied to the pen device as the drug is being expelled. Alternatively, the pen device may be “automatic” in which case a strained spring will provide the energy forthe expelling mechanism. The spring may be strained during dose-setting, e.g. as in a FlexTouch® pen provided by Novo Nordisk A / S, or the spring may be provided pre-strained to the user with sufficient energy to expel one or more pre-set or user-set doses. As a further alternative the pen device may be motor-driven.

[0006] Common to all these different types of drug delivery devices is that an injection needle has to be provided allowing the drug to be administered subcutaneously. The needle may come preattached which is common for single-dose devices, however, it has also been proposed to provide multi-dose devices with a pre-mounted needle adapted for repeated use.

[0007] This said, for multi-dose pen devices the most common solution is to provide single-use needle units intended to be mounted by the user on the pen device prior to use and then discarded after use. The needle unit (also referred to as a “needle module”) typically comprises a hub member adapted to be releasably mounted on the cartridge distal end, the hub member carrying a subcutaneous needle with a pointed distal end adapted to be inserted subcutaneously and a pointed proximal end adapted to be inserted through a needle-pierceable septum into the cartridge.

[0008] A problem presented by the handling and disposal of a pen needle assembly is the potential risk of being injured by any of the pointed ends of the needle. This is particular dangerous when following after the penetration of a patient’s skin since the needle then may be contaminated and therefore capable of spreading diseases such as hepatitis and HIV.

[0009] Addressing this problem a great number of pen needle units have been developed where the patient end of the needle is concealed by a spring-loaded and telescopically movable shield during and after the injection, e.g. as disclosed in WO 01 / 91837 WO 03 / 066141 , EP 1 289 587, EP 1 448 256 and US 11 ,497,857.

[0010] WO 03 / 045480 discloses a shielded needle unit comprising an indicator feature in which a marker in the form of a red dot is shown in a shield window when the needle unit has been used and the shield has been locked in an extended position covering the needle distal end, this indicating that it is now safe for the user to remove the needle unit from the drug delivery device on which it is mounted. The marker is provided on an indicator member which is rotated relative to the needle hub when the shield is moved from its retracted to its extended position, this allowing the shield to be mounted non-rotatable relative to the needle hub.

[0011] When a shielded needle unit is provided the shield may also be used to release a spring-driven expelling mechanism. Such a needle unit may be formed integrally with a pen device typically for single-use or it may be provided as a user-mountable needle unit, e.g. as disclosed in WO 2018 / 215605.

[0012] Although it may be desirable to provide a pen needle unit with a shielding arrangement and a shield lock indicator this must be balanced with the requirements for cost-effectiveness, safety and ease of handling and use.

[0013] WO 2022 / 175245 discloses a shield-operated drug delivery device with an integrated multineedle assembly in which a number of needles are axially moveable in a revolving needle carrier. The device housing comprises an indicator opening in which the rotational position of an indicator element can be seen, the indicator element comprising markings allowing the operational state of the integrated needle assembly to be indicated.

[0014] US 2020 / 114090 discloses a shielded needle unit adapted to be mounted on a medication delivery pen. The needle unit comprises a housing in which the shield is arranged axially moveable. The shield is provided with indicators which can be observed through a window in the housing.

[0015] US 10,518,045 discloses a needle unit comprising a needle hub with a manually operated axially moveable shield member. The unit may be provided with means providing a tactile or audible signal when the shield latches into a locked extended position covering the needle.

[0016] US 9,138,546 discloses a shielded needle unit comprising a needle hub, an outer housing and an axially moveable shield member. The outer housing may be provided with an indicator opening allowing an indicator on the shield member or on a member moving therewith to be observed through the opening.

[0017] EP 1 289587 discloses a shielded needle unit comprising a needle hub and a thereon mounted shield member. The shield member rotates on the hub as it is moved between its retracted and extended locked position. A window in the shield member allows an indicator on the needle hub to be visible when the shield has been rotated to its axially locked extended position.

[0018] Having regard to the above, it is an object of the present invention to provide a hypodermic needle unit of the shielded type which can be manufactured cost-effectively, which provides a high degree of safety, and which is both easy and safe to handle during operation and use. Such a needle unit may be provided as a stand-alone product adapted to be used in combination with one or more specific types of drug delivery devices, in combinations with a given drug delivery device, pre-mounted on a given drug delivery device or formed integrally with a drug delivery device.

[0019] DISCLOSURE OF THE INVENTION

[0020] In the disclosure of the present invention, embodiments and aspects will be described which will address one or more of the above objects or which will address objects apparent from the below disclosure as well as from the description of exemplary embodiments. In a first aspect of the invention a needle unit adapted to be mounted on a drug delivery device comprising a needle unit mount is provided. The needle unit comprises a needle hub with a mounting coupling allowing the needle assembly to be mounted on the needle unit mount, a hollow needle mounted in the needle hub and having a pointed distal end protruding from the needle hub, the hollow needle defining a reference axis, and a shield in which the needle hub is arranged, the shield being axially moveable relative to the needle hub between an initial extended position in which the shield axially covers the needle distal end, a retracted proximal position in which the needle distal end protrudes from the shield, and a locked extended position in which the shield axially covers the needle distal end. The shield comprises axial guide means adapted to engage corresponding axial guide means on the drug delivery device allowing the shield to be mounted axially moveable but non-rotatable relative to the drug delivery device. In such a needle unit the shield comprises an indicator window, and the needle hub comprises an indicator marker, wherein the indicator marker is not visible through the indicator window when the shield is in the initial extended position, this corresponding to an indicator first state, and the indicator marker is visible through the window when the shield is in the locked extended position, this corresponding to an indicator second state.

[0021] By this arrangement a shielded needle unit is provided comprising a non-rotating shield member with a shield lock indicator, which by only comprising two components (in addition to the needle perse) can be manufactured in a simple and cost-effective way. As the shield does not rotate there is no friction between the shield and the skin surface of the user to be overcome. A window may in the form of e.g. an opening or a transparent area.

[0022] In an exemplary embodiment the needle hub is rotated relative to the shield when the shield is moved from its retracted to its locked extended position, whereby the indicator marker is rotated from a position in which the indicator marker is not visible in the shield indicator window to a position in which the indicator marker is visible in the shield indicator window. As the needle shield is adapted to be non-rotationally mounted on the drug delivery device it follows that the needle hub mounting hub must be adapted to rotate relative to the needle unit mount.

[0023] The axial guide means on the shield may be in the form of spline structures formed on the proximal outer and / or inner surface of the shield. Alternatively, or in addition, the shield may have a non-circular proximal skirt portion.

[0024] The needle unit may comprise one or more pairs of an indicator window and a corresponding marker, e.g. opposed indicator windows on each side of the shield. In a further aspect of the invention the above-described needle unit is provided in combination with a drug delivery device, the combination forming a drug delivery assembly. The drug delivery device comprises a housing comprising or adapted to receive a drug-filled cartridge, a needle unit mount, and axial guide means adapted to engage the shield axial guide means.

[0025] For such a combination the mounting coupling may be actuatable between (i) a lock state in which a mounted needle unit cannot be removed from the drug delivery device, and (ii) an actuated release state in which the needle unit can be removed from the drug delivery device, wherein the mounting coupling is actuated from the lock state to the release state when the shield is moved from its retracted to its extended position, whereby the indicator second state would also indicate that the needle unit can be removed from the needle unit mount.

[0026] As for the marker movement also, the mounting coupling may be actuated from the lock state to the release state by rotational movement of the needle hub relative to the shield.

[0027] In an exemplary embodiment the drug delivery device of the assembly may further comprise a piston rod adapted to engage and axially displace a piston in a loaded cartridge in a distal direction when rotated to thereby expel a dose of drug from the cartridge, a spring-driven drive mechanism adapted to rotate the piston rod to expel a predetermined amount of drug from the cartridge, a release member axially moveable between a distal position and an actuated proximal position in which the drive mechanism is released to thereby expel the predetermined dose amount, and a return spring providing a distally directed force on the release member, wherein the release member is moved to the distal position by the return spring when the predetermined dose amount has been fully expelled. With the needle unit mounted on the drug delivery device, the shield moves the release member from the distal position to the actuated proximal position to thereby release the drive mechanism when the shield is moved from the initial extended position to the retracted proximal position and is subsequently moved to the locked extended position by the release member when the predetermined dose amount has been fully expelled. In this way the indicator second state additionally indicates that the predetermined dose amount has been fully expelled.

[0028] In a further exemplary embodiment, the drug delivery device housing comprises a housing indicator window with the shield indicator window being located such that in the locked extended position a mounted shield indicator window is arranged in alignment with the housing indicator window, this allowing the indicator marker to be visible through the housing indicator window. of a mounted shield in the locked extended position is arranged in alignment with the housing indicator window, the indicator marker thus being visible through the housing indicator window. By physically arranging the indicator on the drug delivery device per se it may be possible to make the indicator more of a “dose expelled” than a “needle shield locked” indicator if deemed useful.

[0029] To provide the non-rotational engagement between the needle shield and the drug delivery device, the axial guide means on the drug delivery device respectively the shield may be formed by cooperating spline structures on the shield member respectively the housing. Alternatively, or in addition the shield may comprise a non-circular proximal skirt portion, e.g. oval or square, and the drug delivery device housing having a corresponding non-circular distal opening adapted to receive the shield proximal skirt portion to thereby form corresponding axial guide means. The shield may have a general cylindrical configuration having the same non-circular form along its length.

[0030] In a yet further aspect of the invention a drug delivery assembly is provided comprising a drug delivery device in combination with a needle assembly. The assembly comprises a visual indicator operatable between a first and a second indicator state. The drug delivery device comprises a housing comprising or adapted to receive a drug-filled cartridge, a needle unit mount, a piston rod adapted to engage and axially displace a piston in a loaded cartridge in a distal direction when rotated to thereby expel a dose of drug from the cartridge, the piston rod defining a reference axis, a spring-driven drive mechanism adapted to rotate the piston rod to expel a predetermined amount of drug from the cartridge, a release member axially moveable between a distal position and an actuated proximal position in which the drive mechanism is released to thereby expel the predetermined dose amount, and a return spring providing a distally directed force on the release member. The release member is moved to the distal position by the return spring when the predetermined dose amount has been fully expelled. The needle assembly comprises a needle hub with a coupling allowing the needle assembly to be mounted on the needle unit mount, a hollow needle mounted in the needle hub and having a pointed distal end protruding from the needle hub, a shield in which the needle hub is arranged, the shield being axially moveable relative to the needle hub between an initial distal extended position in which the shield axially covers the needle distal end, a retracted proximal position in which the needle distal end protrudes from the shield, and a locked distal position in which the shield axially covers the needle distal end. With the needle assembly mounted on the drug delivery device, the shield moves the release member from the distal position to the actuated proximal position to thereby release the drive mechanism when the shield is moved from the distal extended position to the retracted proximal position, and is moved to the locked distal position by the release member when the predetermined dose amount has been fully expelled, wherein the shield is adapted to operate the visual indicator from the first to the second indicator state when the shield is moved from the retracted to the locked position.

[0031] By this arrangement an end-of-dose indicator is provided which is controlled by the needle unit and not the drug delivery per se, this being possible as the operation of the two components are linked to each other.

[0032] The drug delivery device housing may comprise an indicator window, and the needle assembly may comprise an indicator marker, wherein the indicator marker, with the shield in the initial distal position, is not visible through the window, this corresponding to the indicator first state, and the indicator marker is visible through the window, this corresponding to the indicator first state, when the shield has been moved from the retracted to the locked position. The indicator marker may be a surface portion on the needle hub.

[0033] The needle hub may comprise the indicator marker, wherein the shield is non-rotatable relative to the housing when the needle assembly is mounted on the drug delivery device, and the needle hub is rotated relative to the housing when the shield is moved from its retracted to its extended position, whereby the indicator marker is rotated from a position in which the indicator marker is not visible in the indicator window to a position in which the indicator marker is visible in the indicator window.

[0034] In exemplary embodiments the shield is axially locked relative to the needle hub when the shield is moved from the retracted to the extended position. When the shield is moved from the retracted to the extended position, the shield and the needle hub may rotate relative to each other to a rotational locking position in which the shield cannot be retracted.

[0035] In a yet further aspect of the invention a drug delivery assembly is provided comprising a drug delivery device in combination with a needle assembly adapted to be mounted on the drug delivery device. The drug delivery device comprises a drug-filled cartridge, an expelling mechanism adapted to expel a plurality of predetermined drug amounts, and a visual indicator actuatable by the expelling mechanism when a predetermined drug amount has been fully expelled, wherein the actuated indicator is reset when a needle assembly has been mounted on the drug delivery device.

[0036] By this arrangement an end-of-dose indicator on the drug delivery device is provided which is reset when a new needle unit is mounted, this being possible as the operation of the two components are linked to each other, here: the needle unit can only be used once and thus have to be removed after a single dose-event.

[0037] The needle assembly may comprise a shield moveable between an extended and a retracted position, the shield being axially locked when moved from the retracted position back to the extended position.

[0038] The drug delivery device may comprise an indicator window with the needle assembly comprises an indicator marker, wherein the indicator marker is moved from a position in which the indicator marker is not visible in the indicator window, to a position in which the indicator marker is visible in the indicator window when the shield is moved from the retracted position back to the locked extended position, whereby the indicator is reset when the locked needle assembly is removed from the drug delivery device.

[0039] The expelling mechanism may be spring driven and actuated by the shield being moved from the extended to the retracted position, this preventing actuation of the expelling mechanism before a new needle assembly has been mounted.

[0040] In such a design the expelling mechanism may comprise a release member axially moveable from a distal position to an actuated proximal position in which the expelling mechanism is released to thereby expel the predetermined drug amount, the release member being moved by the shield when the shield is moved from the extended to the retracted position. The release member may be moved to the distal position when the predetermined drug amount has been fully expelled, the release member thereby moving the shield from the retracted to the extended position. The expelling mechanism may comprise a return spring providing a distally directed force on the release member and thus the shield.

[0041] As used herein, the term "drug" is meant to encompass any drug-containing flowable medicine capable of being passed through a delivery means such as a hypodermic needle in a controlled manner, such as a liquid, solution, gel or fine suspension. The drug may have a blood glucose controlling effect, e.g. human insulin and analogues thereof as well as non-insulins such as GLP-1 and analogues thereof.

[0042] BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In the following embodiments of the invention will be described with reference to the drawings, wherein:

[0044] Fig. 1 shows a drug delivery device with a mounted needle unit, fig. 2 shows in a cross-sectional view the drug delivery device 1 with the needle unit being replaced with a cap, fig. 3 shows an exploded view of the components of the drug delivery assembly of figs. 1 and

[0045] 2, figs. 4A and 4B show a perspective respectively a cross-sectional view of the cartridge holder of fig. 3, figs. 5A and 5B show a perspective respectively a cross-sectional view of the drive nut of fig.

[0046] 3, figs. 6A-6C show a perspective respectively cross-sectional views of the housing member of fig. 3, figs. 6D and 6E show in cut-away views details of the structures surrounding the housing tower, figs. 7A and 7B show a perspective respectively a cross-sectional view of the actuator of fig.

[0047] 3, fig. 8 shows a perspective view of the return spring of fig. 3, figs. 9A and 9B show a perspective respectively a cross-sectional view of the control member of fig. 3, figs. 10A and 10B show a perspective respectively a cross-sectional view of the drive member of fig. 3, fig. 11 shows a perspective view of the piston rod of fig. 3, fig. 12 shows a perspective view of the drive spring of fig. 3, figs. 13A and 13B show a perspective respectively a cross-sectional view of the spring base member of fig. 3, fig. 14 shows in cross-section the drug delivery device of fig. 2, the cap, the cartridge, the cartridge holder and the return spring being removed for better visibility, fig. 15 shows a detail proximal cross-sectional view of the drive spring arranged in the spring base, fig. 16 shows a detail distal cross-sectional view of the drive spring arranged in the spring base, fig. 17 shows a detail cross-sectional view of an actuator drop lock flexible finger in engagement with a housing drop lock stop surface, figs. 18A-18F show in a series of perspective views movement of the actuator knob and control member relative to the housing tower portion during expelling of a dose of drug, figs. 19A and 19B show a perspective respectively a cross-sectional view of the shield member of fig. 3, figs. 20A and 20B show a perspective respectively a cross-sectional view of the hub member of fig. 3, figs. 21 A and 21 B show a perspective respectively a cross-sectional view of a container for the needle unit of fig. 1 , fig. 22 shows a cross-sectional view of the needle unit of fig. 1 arranged in the container of fig. 21A, figs. 23A-23J show in a series of cross-sectional views mounting, actuation and removal of the needle unit on the drug delivery device, figs. 23CX and 23GX show cut-away views of the corresponding figs. 23C and 23G, and figs. 24A-24C show in a series of cut-away perspective views movement of the shield and needle hub relative to a housing indicator window during actuation of the needle unit.

[0048] In the figures like structures are mainly identified by like reference numerals.

[0049] DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0050] When in the following terms such as “upper” and “lower”, “right” and “left”, “horizontal” and “vertical” or similar relative expressions are used, these only refer to the appended figures and not necessarily to an actual situation of use. The term “distal” refers to a portion of an element, assembly or device which during use is oriented towards a skin surface of a user, the term “proximal” referring to the opposed portion. Correspondingly, for a traditional pen drug delivery device the needle is arranged at the distal end and an end-mounted release button is arranged at the proximal end. The shown figures are schematic representations for which reason the configuration of the different structures as well as their relative dimensions are intended to serve illustrative purposes only. When the term member or element is used for a given component, it generally indicates that in the described embodiment the component is a unitary component, however, the same member or element may alternatively comprise a number of sub-components just as two or more of the described components could be provided as unitary components, e.g. manufactured as a single injection moulded part. The term “assembly” does not imply that the described components necessarily can be assembled to provide a unitary or functional assembly during a given assembly procedure but is merely used to describe components grouped together as being functionally more closely related.

[0051] With reference to fig. 1 a drug delivery device 1 with a mounted needle unit 2 is shown. The device has a general tubular configuration defining a general reference axis. Fig. 2 shows in a cross-sectional view the drug delivery device 1 with the needle unit being replaced with a cap. In the shown embodiment the cap fits snugly over the distal part of the drug delivery device and thus does allow a needle unit to be mounted at the same time. The drug delivery device comprises a distal cartridge holder portion 3 in which a drug filled cartridge is arranged, a proximal portion comprising a drive spring system 4 as well as an intermediate portion comprising a control system 5. A piston rod is arranged axially in the device and adapted to be moved distally by the drive spring to expel an amount of fluid drug through a mounted needle unit, the amount of axial travel of the piston rod being controlled by the control system. In fig. 2 the actuator return spring is not shown.

[0052] In the exploded view of fig. 3 the individual components of the drug delivery device and needle unit are shown. The drug delivery device comprises a tubular housing 400 with a proximal engine portion 401 and a distal cartridge portion 402 adapted to house a cartridge holder 300 in which a drug cartridge 390 is arranged, the drug cartridge comprising a distal outlet end with a needle pierceable septum, a proximal circumferential edge 391 and an axially displaceable piston 392 (see fig. 17). A piston washer 395 is arranged in the cartridge engaging the piston proximal surface. An actuator 500 comprises a cylindrical proximal portion 501 from which a pair of legs 502 extend distally interposed between the housing and the cartridge holder. The drive nut 600 is mounted in the housing and adapted to receive piston rod 650 in threaded engagement. The piston rod is non-rotationally received in the distal tubular portion 802 of drive member 800 which is adapted to be rotationally driven by pre-strained drive spring 890 arranged in the proximal portion 801 of the drive member, the drive spring’s proximal end being anchored to the housing via spring base 900. Control member 700 is in splined engagement with the drive member tubular portion 802 and is adapted to be moved axially in and out of engagement with the housing to thereby control rotation of the drive member. A large-diameter return spring 590 is arranged to provide a distally directed biasing force on the actuator. The drug delivery device is adapted to receive a needle unit at its distal end, the needle unit comprising a needle hub 100 with a needle 101 , the needle hub being arranged in a shield member 200. When a needle unit is not mounted on the drug delivery device a cap 490 can be mounted to cover the cartridge portion 402. In the following the individual components will be described in greater detail. The needle unit will be described after the drug delivery device. The cartridge holder 300 has a generally cylindrical configuration with a larger proximal opening 301 allowing a cartridge to be inserted and a smaller distal opening allowing a hollow needle to be inserted through a septum of a mounted cartridge. The distal end comprises a needle unit mount in the form of cartridge mount 310 with a pair of opposed part-circumferential flange portions 311 adapted to receive a pair of flexible needle hub coupling arms (see below). Neighbouring the flange portions are portions 312 with lower and / or less inclined release flanges allowing the hub coupling arms to disengage with ease. The cylindrical main portion comprises a pair of opposed longitudinal openings 315 allowing a user to inspect the content of the cartridge as well as the position of the cartridge piston. Each opening is surrounded by a radially extending window wall 316 adapted to engage with a corresponding window 416 in the housing 400, the wall comprising a number of indicator lines 317 arranged to align with the cartridge piston to thereby indicate to the user the number of remaining doses. Alternatively, indicator bridges could span the window. The cartridge proximal end comprises a pair of opposed circumferentially extending flexible support arms 320 each having a free end portion with a protrusion 321 extending radially into the opening 301 , the flexibility of the arm allowing the protrusion to be moved radially out of the opening to allow insertion of a cartridge. A free space 322 is provided distally of the flexible support arm allowing the support arm to be deformed into the free space when engaging the housing pressure edges 437 during assembling to thereby eliminate axial play of a mounted cartridge (see below). The flexible arms together with the neighbouring parts of the cartridge holder form a cartridge holder proximal edge 323 with gaps corresponding to the flexible arm free ends. In the shown embodiment the edge is arranged generally in a transversal plane.

[0053] The drive nut 600 comprises a generally tubular main portion 610 with an interior thread 611 adapted to engage a corresponding thread on the piston rod 650. The drive nut comprises a first pair of opposed distally oriented flexible mounting fingers 620 adapted to be received in corresponding nut slots in the housing central portion. Each finger is provided with a small flexible finger 621 allowing the drive nut to snap into engagement with the housing - at this stage with a small axial play. The fingers are oriented slightly outwards to secure proper contact with the nut slots during subsequent fixation of the drive nut in the housing, e.g. by application of laser energy through an opening in the housing (see below). The drive nut further comprises a second pair of opposed circumferentially extending flexible fingers 630 each being inclined in the proximal direction to provide a distally directed biasing force during assembling. As shown in figs. 6A, 6B and 6C the generally tubular housing 400 comprises a proximal engine portion 401 , a distal cartridge portion 402 and a generally cylindrical tower portion 430 arranged distally in the engine portion. In the shown embodiment the distal and proximal portions both have a super-elliptic cross-section with n = 2.5 and a b. The tower distal portion is connected to the outer housing via a pair of opposed bridge portions 440 forming a pair of openings therebetween providing axial passageways for the actuator legs 502 (see below) between the cartridge and engine portions. Each bridge portion 440 is provided with a proximally extending lock rib 447 adapted to engage the actuator triangular index positions (see below). A neighbouring proximally facing rib 448 serves as an axial support for the actuator. The cartridge portion 402 comprises a distal indicator opening 405, a pair of opposed windows 410, and a distal pair of opposed shield slots 415 adapted to receive corresponding shield mounting ribs 245 (see below). Proximally on the inner surface a pair of opposed inwardly protruding and distally facing drop lock stop surfaces 407 are provided, as well as a pair of opposed proximally extending point-of-no-return (PONR) flexible arms 408 with a proximally facing PONR stop surface 409 (see fig. 6D). On the outer surface a pair of opposed snap protrusions 403 adapted to engage the cap 490 is provided. The engine portion 401 comprises a distal pair of opposed nut openings 406 allowing access to the drive nut mounting points during assembly, e.g. allowing the drive nut to be fixed to the housing using a laser beam, as well as a proximal pair of opposed flexible snap lock fingers 420 allowing the spring base 900 to be mounted fixedly in the housing and thus form part of the housing, the snap lock fingers each comprising an inwardly protruding snap hook 421 . A number of inner axial ribs 404 provide radial support for the actuator 500 and actuator return spring 590. The tower comprises a pair of opposed axially oriented inner nut slots 432 adapted to receive the drive nut mounting fingers 620. The distal edge of the tower forms a pair of opposed part-circumferential support flanges 431 adapted to be received in the cartridge holder proximal opening 301 . Each support flange is associated with a radially extending pressure edge 437 (see fig. 6E) adapted to engage and deform the cartridge holder flexible arm when the cartridge holder is inserted in the housing (see below). The tower further comprises a proximally oriented helical control surface 433, the ends of the helical surface being connected with an axially oriented stop edge (or stop surface) 434 which extends distally to create a notch 435 in the helical surface. Centrally in the tower an inner circumferential stop flange 438 is provided adapted to engage the drive member 800. Proximally of the stop flange a stop knob 439 is located serving as a second rotational stop for the control member. In the shown embodiment a single indicator opening 405 is provided but alternatively a second opposed opening could be provided. As shown in figs. 7A and 7B the actuator 500 comprises a cylindrical proximal portion 501 from which a pair of legs 502 extend distally. The cylinder portion comprises a distal outer circumferential spring support flange 510 adapted to engage return spring 590, as well as an inner actuator knob 516 and drop lock flange 511 , the latter providing an axial stop for the control member helical flange 710 (see below) and thus serves as a drop lock for the control member 700. The cylinder portion distal edge is provided with a pair of serrated clutch portions 517 each creating two triangular index positions adapted to engage the housing lock ribs 447 in an initial respectively in an actuated rotational position, thereby providing an anti-rotational clutch when engaged. Each actuator leg 501 comprises a proximal outwardly protruding flexible drop lock finger 520 with a proximally facing drop lock surface 521 at the proximal free end adapted to engage a housing drop lock stop surface 407. Each actuator leg 501 further comprises a proximal axially oriented PONR wedge structure 530 with a distally facing stop surface 531 adapted to engage a PONR proximally facing housing stop surface 409. At the distal end each actuator leg comprises a distal-most actuation surface 523 adapted to engage the needle shield 200 as well as a neighbouring inclined release surface 524 adapted to engage the needle hub 100.

[0054] The helical return spring 590 shown in fig. 8 is generally open wound but to prevent tangling during manufacturing the spring is provided with distal, central and proximal tightly wound sections.

[0055] As shown in figs. 9A and 9B the generally tubular control member 700 comprises an outer helical flange 710 serving to control axial movement of the control member relative to the housing. The helical flange comprises a helical distal surface 713 adapted to engage the helical surface 433 on the tower, a helical proximal surface 719 adapted to engage the distal end of the actuation knob 516, and a longitudinally extending control edge 714 (serving as a control surface) connecting the ends of the helical flange 710 and being adapted to engage the stop edge 434 on the housing tower. Rotationally aligned with the control member control edge 714 an axially oriented release flange 716 is arranged on the outer surface of the control member. In the distal direction the control edge 714 extends to form a pointed catch 715 adapted to be seated the tower notch 435. The majority of the helical flange 710 has a first larger diameter whereas cut-out portions 711 on each side of the control edge 714 have a smaller diameter corresponding to the height of the control edge, this allowing the actuator knob 516 to axially pass. The control member further comprises a distally oriented helical edge 720, the ends of the helical edge being connected with an axially oriented second control edge 729 adapted to engage tower stop knob 439. The control member inner surface comprises an opposed pair of spline ridges 730 adapted to engage corresponding spline slots in the drive tube. At the distal end and aligned with the spline ridges an opposed pair of stop flanges 735 are arranged adapted to engage the piston rod stop surface 655.

[0056] As shown in figs. 10A and 10B the drive member 800 comprises a proximal cylindrical spring housing portion 801 and a distal drive tube portion 802. The drive tube portion comprises at the distal end an inner pair of opposed axially oriented drive flanges 810 adapted to engage the piston rod drive grooves. Along the length of the drive tube portion a pair of opposed spline slots 830 is provided adapted to engage the corresponding control member spline ridges 730. As described below, the spline slots may comprise friction structures providing that the control member cannot slide freely on the drive member tube portion 802. The spring housing 801 comprises at the distal end an inner circumferential flange creating a circumferential groove 820 adapted to receive the distal end of the drive spring, the groove comprising an oblong catch opening 821 adapted to receive the drive spring distal hook. The spring housing comprises an opposed pair of flexible arms 822 protruding slightly into the interior of the spring housing, the arms being adapted to engage and axially hold the spring in place during assembling. At the proximal end an outer part-circumferential support flange 823 is provided to ensure concentricity between the drive member 800 and the spring base 900, as well as a single circumferentially oriented and outwardly protruding flexible clicker finger 825 having a free end adapted to rotationally engage a circumferential ratchet surface 915 on the spring base 900.

[0057] Fig. 11 shows the piston rod 650 comprising along its length a thread 651 as well as a pair of opposed drive grooves 652. The proximal end comprises a distally facing stop flange 655 adapted to engage the control member stop flanges 735. The distal end 654 is adapted to engage the piston washer 395 which in the shown embodiment is a flat disk. Alternatively, the piston washer may be provided with proximally facing centring means adapted to engage the piston rod distal end, e.g. the piston washer and the piston rod distal end may be provided with corresponding snap coupling structures.

[0058] The drive spring 890 as shown in fig. 12 is a tight wound helical spring without any spacing between adjacent coils and comprises a distal hook portion 891 arranged in an axial plane and a proximal hook portion 892 arranged in a transversal plane.

[0059] As shown in figs. 13A and 13B the spring base 900 comprises a proximal planar end surface 901 from which extend in the distal direction an outer circumferential skirt 902, an inner circumferential skirt 910 with a distal support edge 912 for the return spring 590 proximal end, as well as a central tower portion 920 providing an inner support for the drive spring. Distally the inner surface of the inner skirt comprises a circumferential ratchet surface 915 adapted to engage clicker finger 825. The inner skirt further comprises an opposed pair of catch openings 911 adapted to engage the housing snap lock finger hooks 421. Between the inner skirt and the central tower portion an opposed pair of distally extending fingers 930 are provided, each finger comprising a longitudinally extending free spring edge 932 adapted to engage the drive spring proximal hook 892 in axial sliding engagement. The sliding engagement allows the spring base to be inserted into the housing after the spring has been strained just like the spring hook can slide on the spring edge as the spring shortens during de-straining.

[0060] Having described the individual components of the drug delivery device 1 , fig. 14 shows a cross-sectional view of the assembled device. For clarity the cartridge holder, the cartridge and the return spring has been removed, however, the former components can be seen in fig. 2. More specifically, the strained drive spring 890 is arranged in the spring housing 801 providing a rotational force to the piston rod 650 via the drive tube portion 802 and thereby distal axial movement through the treaded engagement with the drive nut 600. The drive tube portion 802 is in splined engagement with the control member 700 and thus prevented from rotating as long as the control member is in its rotationally “parked” position with the control member control edge 714 engaging the tower stop edge 434 (see below). The control member is released from the parked position when moved proximally by the actuator member when the latter is moved proximally by the needle unit shield (see below).

[0061] Fig. 15 shows in a detail view how the drive spring proximal hook 892 engages a longitudinally extending free spring edge 932 in axial sliding engagement. Fig. 16 shows in a detail view how the drive spring distal hook 891 has been rotated into engagement with the catch opening 821. Fig. 17 shows in a detail view how a drop lock finger 521 engages the housing drop lock surface 407 to prevent accidental axial movement of the actuator. The figure also shows the piston rod 650 engaging the cartridge piston 392 via the piston washer 395.

[0062] The shown embodiment may be assembled in the following steps: (i) The drive nut 600 is inserted in the housing snapping in place with an axial play, (ii) the control member 700 is inserted in the housing tower with the stop and control edges aligned, (iii) the actuator 500 is inserted with the legs arranged in the housing cartridge portion and with the cylindrical proximal portion 501 surrounding the control member and housing tower, shoulders on the housing inner wall serving to deflect the legs inwardly allowing them to be moved into the cartridge portion, (iv) the drive member drive tube portion 802 is inserted in the housing tower, (v) the return spring 590 is inserted distally engaging the actuator spring support flange 510 and proximally temporarily being held in place by the housing snap lock finger hooks 421 , (vi) the piston rod 650 is inserted in the drive tube which is turned 180 degrees back and forth to allow the piston rod thread to engage the drive nut thread, (vii) the drive spring 890 is inserted in the spring housing 801 with the drive spring distal hook being rotated to be received in the catch opening 821 , (viii) the spring base 900 is inserted partly into the housing and rotated to strain the drive spring, whereby during initial rotation one of the spring edges 932 engages the drive spring proximal hook 892, (ix) the spring base is subsequently moved fully into the housing whereby it snaps into engagement with the housing snap lock finger hooks 421 thereby displacing the return spring which then becomes seated against the spring base distal support edge 912, at the same time the clicker finger 825 engages the ratchet surface 915, (x) the cartridge 390 is inserted into the cartridge holder and the piston washer is placed onto the cartridge piston, (xi) the housing cartridge portion is slightly ovalized allowing the cartridge holder to be inserted with the window walls 316 snapping into engagement with housing windows 416 while at the same time the flexible cartridge support arms 320 engage the pressure edges 437 and are deformed into the free space 322 distally of the arms to thereby eliminate axial play of the mounted cartridge. In addition to the cartridge being forced into engagement with the cartridge holder distal portion, also the cartridge holder is forced distally into engagement with the housing, e.g. the window wall 316 distal end is forced into engagement with the housing window 416 distal end, to thereby eliminate axial play between the cartridge and the housing. At the same time the piston washer 395 engages the piston rod distal end whereby the piston rod and the drive nut are moved slightly proximally with no gap being formed between the piston rod and the piston washer, and (xii) the drive nut is fused to the housing by application of e.g. a laser beam through housing nut openings 406. As a final step a label (not shown) is applied to the housing proximal portion to cover the snap locks and the nut openings. In an alternative embodiment a modified piston washer is snapped onto a modified piston rod before the cartridge holder is inserted into the housing, this preventing the piston washer from being dislocated before it is engaged by the piston rod.

[0063] Before turning to a description of the needle unit, operation of the drug delivery device (when actuated by a needle unit) will be described below with reference to figs. 18A-18F. As the drug delivery device can only be released to expel a dose of drug via a mounted needle unit the two units in combination can be said to form a combined drug delivery system.

[0064] When a needle unit is mounted on the cartridge mount 310 the actuator legs 502 are engaged by the needle unit hub 100 and shield 200 whereby the actuator is rotated (here: 20 degrees) from the initial lock position to an actuated un-locked position in which (i) the drop lock fingers 521 are no longer aligned with the housing drop lock surfaces 407, this allowing the actuator to subsequently be moved proximally, (ii) the PONR wedges 530 are aligned with the housing PONR flexible arms 408, and (iii) the anti-rotational clutch 517 is moved from its initial to its actuated position, the latter being described in greater detail below in connection with mounting of the needle unit.

[0065] More specifically, fig. 18A shows (in part) the device in its pre-dosing state after a needle unit has been mounted. The control member 700 is positioned in its distal-most position with the control edge 714 engaging the tower stop edge 434, this preventing the drive spring from rotating the drive tube 802 as the control member and the drive tube are in splined engagement. In addition (not shown) the second control edge 729 engages tower stop knob 439. The actuation knob 516 has been rotated into alignment with the release flange 716.

[0066] When the user inserts the needle of the needle unit subcutaneously (see below), the actuator is moved proximally by the needle shield against the force of the return spring, the actuator actuation knob 516 thereby moving over the control edge 714 and into engagement with the control member release flange 716 distal end. As the drop lock flange 511 moves with the actuator knob 516 the control member can be moved proximally. When the needle shield and thus the control member have been moved to their proximal-most position the control member control edge 714 has been moved out of axial engagement with the tower stop edge 434 (see fig. 18B), this allowing the control member and thereto splined drive tube 802 to rotate, this resulting in rotation and distal movement of the piston rod and thereby expelling of drug. During rotational movement of the drive member a clicking sound is produced as the clicker finger 825 is rotated relative to the ratchet surface 915.

[0067] Before the expelling mechanism is released the actuator PONR wedges 530 have been moved over the housing PONR stop surfaces (allowed by the flexibility of PONR flexible arms 408), this preventing the actuator, and thus the needle shield, from being returned to their initial position. Correspondingly, should the user pull out the inserted needle at this point, the nonreturned needle shield will indicate to the user that actuation of the device is “in progress” and that an injection should be performed. Additionally, the PONR arrangement prevents the return spring exerting a force to the control member via the activation knob 516. If this was allowed, it would create friction and slow down dose delivery. When the control member 700 starts to rotate, the helical flange 710 is moved into the gap between the tower helical end surface 433 and the distal end of the actuation knob 516, the three structures forming a threaded connection which assures that the control member is moved distally as it rotates (see fig. 18C).

[0068] Fig. 18D shows the state just prior to end-of-dose. The control member control edge 714 approaches engagement with the tower stop edge 434 and the control member release flange 716 approaches the actuation knob 516. Ultimately the control and stop edges engage each other, and rotation and out-dosing come to an end-state. At the same time the release flange 716 has rotated the actuation knob 516 and thus the connector back to its initial rotational lock position (see fig. 18E).

[0069] It should be noted that at this final state the actuation knob 516 is aligned with the flange cutout 711 which would allow the control member to move proximally, e.g. by gravity if the device was used in an upside-down orientation, this moving the control edge 714 axially out of engagement with the tower stop edge 434 thereby allowing the control member 700 to continue rotating and thus a further dose to be expelled. To prevent such a gravity-induced situation from arising, the splined engagement 730, 830 between the control member and the drive tube may be provided with friction structures, the friction being easily overcome by the energy provided by the drive spring but not by gravity. Alternatively, the control member may comprise an integrated return spring or an additional helical spring may be position between the two components.

[0070] When the user withdraws the needle from the skin, the actuation knob 516 is aligned with the flange cut-out 711 allowing the return spring to move the actuator (see fig. 18F) and thereby also the needle shield distally to their initial distal-most positions. During this axial movement the actuator drop lock fingers 521 are rotationally aligned with the housing drop lock surfaces 407, however, due to their flexibility they will pass over the drop lock surfaces. Oppositely, during the final rotation of the actuator, the PONR wedges 530 are moved out of rotational alignment with the housing PONR stop surfaces 409. As the actuator is moved distally the drop lock flange 511 (hidden in fig. 18F, see fig. 18A) re-engages the control member flange 710 thereby moving the control member back to its initial distal position (see fig. 18F) with the pointed catch 715 seated in the tower notch 435, and the serrated clutch portions 517 reengage the housing to re-activate the anti-rotational clutch in its initial rotational position. At this state the control member 300, the actuator 500, and the drive member 800 have returned to their initial positions, whereas the piston rod has been moved distally corresponding to the pre-set dose size and the drive spring has been de-strained corresponding to a single dose. When the number of doses for which the device is designed, e.g. 4 doses, have been expelled the piston rod has been moved to its distal-most position in which the piston rod stop surface 655 is positioned in close proximity to control member stop flanges 735, this preventing the control member to be further actuated. Alternatively, a stop surface between piston rod and nut can could prevent the piston rod from rotating further and thereby prevent activation of the device.

[0071] In the above-described exemplary embodiment a single axially oriented stop edge and a single axially oriented control edge is provided, this allowing the control member to rotate 360 degrees between the control edge disengaging and re-engaging the stop edge. In an alternative embodiment (not shown) two stop edges spaced 180 degrees apart are provided, this allowing a correspondingly modified control member to rotate 180 degrees between the control edge disengaging and re-engaging a stop edge. In a further alternative (not shown), three stop edges spaced 120 degrees apart are provided, this allowing a correspondingly modified control member to rotate 120 degrees between the control edge disengaging and re-engaging a stop edge. Such modified the above-described drug delivery device could be adapted to expel 8 or 12 fixed volume doses instead of four as disclosed.

[0072] As will be described below for the needle unit, in this state the needle shield has been locked in its distal position and thus prevents the dose engine to be released, this providing protection against double-dosing. To allow a further dose to be expelled a new needle unit has to be mounted.

[0073] As seen e.g. in fig. 6A, the housing distal end comprises an indicator opening 405. When the needle unit hub member 100 is rotated during actuation an indicator portion on the hub member moves into alignment with the indicator opening, this indicating that a dose of drug has been expelled.

[0074] Having described in detail the components and operation of the drug delivery device perse, in the following the needle unit and its operation will be described in detail.

[0075] As shown in figs. 1 and 3 the drug delivery device 1 is adapted to receive a shielded needle unit 2, comprising a needle hub 100 adapted to be mounted on a corresponding mount on the drug delivery device, a subcutaneous hollow needle 101 mounted in the hub and comprising a pointed free distal end portion adapted to be inserted subcutaneously through the skin of a user and a pointed free proximal end portion adapted to be penetrate a pierceable drug cartridge septum, as well as a shield member 200 in which the needle hub is arranged. The subcutaneous hollow needle 200 comprises bevelled proximal and distal ends and is arranged in a hub bore and secured in place by e.g. adhesive. The needle unit is supplied as a needle assembly further comprising a container 280 (see fig. 22) adapted to receive the needle unit in an assembled state, the container having an open end adapted to be sealed with a flexible foil member thereby providing a sealed, sterile interior for the needle unit when supplied to the user.

[0076] Needle unit

[0077] Fig. 1 shows a needle unit 2 mounted on an injection device 1 adapted to releasably receive the needle unit. In the shown embodiment the shield has an outer super-elliptic cross-section configuration allowing it to be received in the correspondingly formed distal opening of the injection device 3. Alternatively other non-circular designs could be implemented, e.g. square or triangular, or the needle unit could have a circular design with rotational orientation being provided by cooperating guide structures.

[0078] As will be apparent from the below detailed description of an exemplary embodiment of a needle unit the functionality of the unit relies on rotational movement between the hub and the shield, this irrespective of the outer configuration of the shield.

[0079] As will be explained in greater detail below, the needle hub 100 (in the following also just “hub” or “hub member”) and the shield member 200 (in the following also just “shield”) comprise a number of interacting structures allowing the shield and hub to move axially and rotatably relative to each other in a controlled manner during use and operation of the needle unit. In the below-described embodiment the shield is rotationally locked relative to the cartridge mount and the hub is axially locked relative to the cartridge mount when the needle unit is mounted on the cartridge mount. Rotational movement of the hub is controlled by axial movement of the shield relative to the cartridge mount and thus the hub.

[0080] As will also be explained in greater detail below, the container and the shield member comprise interacting structures allowing the container to be used as a mounting and removal tool for the needle assembly during use in an efficient and user-friendly manner. The shield, hub and container generally comprise functional structures in opposed pairs, however, any suitable numbers of such structures could be used, e.g. one, two or three.

[0081] As shown in figs. 19A and 19B the shield 200 has a generally tubular configuration with a circumferential outer wall 210, a proximal opening with a circumferential edge 211 , and a distal end surface 201 with a smaller distal opening 212 from which a tower structure protrudes axially inwardly. The tower structure comprises a circumferential skirt portion 215 from which first and second pairs of opposed arms extend proximally with a rotational offset of 90 degrees in the shown embodiment. Between the arms the skirt portion comprises free grip edge portions 216. The first pair of longer arms are in the form of flexible assembly arms 220 each having a hook portion 225 at the proximal free end with a distally facing axial stop surface 221 adapted to engage corresponding proximally facing stop surfaces 121 on the hub tower portion (see below) as well as a proximally facing ramp surface 222 used during assembling of the needle unit. The second pair of shorter arms is in the form of flexible control arms 230 each having a hook portion 235 at the proximal free end with a proximally facing ramp surface 231 and a distally facing control surface 232, the surfaces being adapted to engage corresponding distally facing ramp surfaces respectively proximally facing control surfaces on the hub tower portion (see below). At the proximal end the shield comprises opposed pairs of inner actuation ribs 213 adapted to engage corresponding flexible hub arms (see below). The actuation ribs 213 also serve to lock the coupling arms (see below) and to centre the generally circular hub in the super-elliptic shield and thus assure stability during axial and rotational movement between the hub and shield during operation. The shield further comprises a pair of opposed locking ribs 217 on the shield inner wall surface, each rib having a proximally facing locking surface 218 adapted to engage a corresponding locking surface on the hub. The locking ribs proximally extend into lower torque ribs 219 adapted to engage torque flanges on the hub (see below). The shield wall 210 is further provided with an outer pair of opposed mounting ribs 245 adapted to engage corresponding shield slots 415 in the housing, a pair of opposed windows 240 adapted to allow outwards movement of the hub coupling arms (see below), as well as a first indicator opening 241 and a second indicator opening 246. In the shown embodiment the first indicator opening 241 is “open” as for design reasons the shield edge 211 comprises cutouts for structures in the drug delivery device.

[0082] As shown in figs. 20A and 20B the hub 100 comprises a distal tower portion 110 comprising a central bore 111 adapted to receive a subcutaneous needle as well as a proximal skirt portion 120. At the distal end the tower portion comprises three pairs of opposed function surfaces adapted to cooperate with corresponding surfaces on the shield: (i) a pair of proximally facing stop surfaces 121 adapted to engage the distally facing stop surfaces 221 on the shield assembly arms, (ii) a pair of distally facing ramp surfaces 131 adapted to engage the proximally facing ramp surfaces 231 on the shield, and (iii) a pair of inclined proximally facing control surfaces 132 adapted to engage the distally facing control surfaces 232 on the shield during operation. At the proximal end the tower portion comprises a pair of opposed snap indentations 135 adapted to engage the control arm hook portions 235. The skirt portion 120 comprises an opposed pair of proximally extending flexible coupling arms 126, each arm having an outer surface 123 adapted to engage the shield inner actuation ribs 213 during operation, and an inwardly facing snap coupling ridge 127 arranged at the free proximal end of the coupling arm and adapted to engage a corresponding coupling structure on the cartridge mount 310. The skirt portion further comprises a pair of distally facing lock surfaces 118 adapted to engage the proximally facing shield locking surfaces 218 during operation. The skirt portion further comprises a pair of radially protruding opposed drop lock release flanges 114 adapted to engage the actuator leg release surfaces 524, a pair of radially protruding opposed torque flanges 119 adapted to engage the shield torque ribs 219, as well as a pair of opposed indicator cut-outs 115. The torque interface could also be located on other portions of the shield and the hub, e.g. between the assembly arms and the hub tower portion.

[0083] As shown in figs. 21 A and 21 B the container 280 has a generally tubular configuration with a super-elliptic circumferential outer wall 281 , a proximal opening with a circumferential flange 282 and a closed distal end 283 from which a tower structure 285 and a pair of opposed snap lock fingers 290 extend axially inwardly. The snap lock fingers each comprises an outwardly oriented snap protrusion 296 adapted to releasably engage the shield tower grip edge portions 216 to provide a snap coupling. Distally the container further comprises a plurality of inner support ribs 286 adapted to engage the shield outer surface and support the shield when arranged in the container. With the shield mounted in the container the proximal portion provides a circumferential space 299 (see fig. 22) between the container and the shield allowing the correspondingly shaped drug delivery housing portion to be received therein during mounting of the needle unit on the drug delivery device.

[0084] During assembly the hollow subcutaneous needle 101 with bevelled proximal and distal ends is arranged in the hub bore and secured in place, e.g. by means of adhesive, this providing a free distal end portion 102 and a free proximal end portion 103. The hub 100 is subsequently inserted in the shield 200 with the stop surfaces 121 and the ramp surfaces 131 rotationally aligned with the shield stop surfaces 221 respectively the shield ramp surfaces 231 , this allowing the shield stop surfaces to snap into engagement with the hub stop surfaces 121 . Also the hub coupling arms 126 are rotationally aligned with the shield actuation ribs 213. In the shown embodiment the hub proximal end is arranged slightly proximally of the shield proximal edge 211 . The assembled needle unit is then inserted into the container with the container snap lock fingers 290 snapping into engagement with the shield tower grip edge portions 216. As seen in fig. 22 an axial gap is provided between the container tower proximal end and the hub tower distal end. As a final assemble step a flexible foil member (not shown) is attached to the container proximal flange 282 thereby sealing the interior for subsequent sterilization. Fig. 22 shows in cross-section the needle assembly with the needle unit positioned in the container before the seal foil is attached.

[0085] In the following the different features and aspects of the above-described needle unit and container combination will be described with reference to figs. 23A-23J showing a needle unit being mounted on a corresponding drug delivery device, operated to allow an amount of fluid drug to be injected subcutaneously and subsequently removed from the drug delivery device. The indicator functionality is additionally shown in figs. 24A-24C.

[0086] After the flexible seal foil has been removed from the container 280 by the user, the container is intended to be used as a tool to mount the needle unit on the drug delivery device 1 with a corresponding cartridge mount 310, see fig. 23A. In the shown embodiment the cartridge mount is arranged proximally of the distal end of the drug delivery device housing cartridge portion 402 with a circumferential space between the cartridge holder 300 and the housing adapted to receive the shield 200 proximal portion in non-rotational engagement by the cooperating mounting ribs 245 and shield slots 415. In the shown embodiment the non-circular design makes it easy for the user to orient the needle assembly rotationally correct relative to the drug delivery device in either of its two possible rotational positions.

[0087] Initially the locked hub coupling arms 126 engage the cartridge mount coupling flange portions 311 , this allowing the shield to be pushed forward by the container to an axial position in which the shield actuation ribs 213 are not engaging the flexible hub arm outer surfaces 123, see fig. 23B. The control arms 230 are free to bend outwardly to allow proximal shield movement, but they will not snap overthe ramp surfaces 131. It is to be noted that in fig. 23B the two structures for drawing reasons are shown as overlapping. Alternatively, a clearance could be provided between the two structures.

[0088] The container assures that the shield and hub can be pushed firmly into engagement with the cartridge mount by the user, this allowing the free proximal needle end portion 103 to penetrate the cartridge septum 394 and the flexible hub coupling arms 126 to be initially moved radially outwards in the receiving shield windows 240 and subsequently snap radially inwards into engagement with the corresponding snap coupling flanges 311 on the cartridge mount, see fig. 23C.

[0089] During the axial coupling movement of the needle unit the hub drop lock release flanges 114 engage the inclined leg release surfaces 524 on the spring-biased actuator legs 502. Initially the actuator is moved axially until the anti-rotational clutch portions 517 are moved out of engagement with the housing, this allowing the actuator to be rotated by the axial movement of the hub. To counter the torque exerted on the hub during rotation of the actuator, the hub is supported by the shield (which is non-rotationally coupled to the housing 400) via the torque flanges 119 engaging the torque ribs 219. Subsequently the shield actuator ribs 213 engage the leg actuation surfaces 523 of the actuator legs 502 and moves axially together with the drop lock release flanges 114. Depending on the actual design of the different components, the actuator may be fully rotated (here: 20 degrees) during mounting of the needle unit. Alternatively, final rotation of the actuator may take place when the actuator subsequently is allowed to be moved distally by the return spring 590.

[0090] Axial mounting movement of the needle unit stops when the hub engages the cartridge mount, this indicating to the user that the needle unit has been mounted on the cartridge hub. When the user stops pushing on the container (or starts to pull the container away) the spring-biased actuator legs 502 will push the shield 200 slightly distally until the distally facing axial stop surfaces 221 on the shield assembly arms engage the corresponding proximally facing stop surfaces 121 on the hub tower portion. The control arms 230 are moved back to their initial position. At the same time the clutch portions 517 reengage with the housing lock ribs 447 in the actuated rotational position. As the shield is moved distally the shield actuation ribs 213 will move into engagement with the flexible hub arm outer surfaces 123 and thereby prevent radial outwards movement thereof, this securely locking the hub 100 to the cartridge mount 310 corresponding to an actuated hub coupling lock state in which a mounted needle unit cannot be removed from the drug delivery device, see fig. 23D.

[0091] As the user pulls the container 280 further distally to fully remove it, the container snap coupling 296 will disengage the shield 200. When the container is fully removed the drug delivery device with the mounted needle unit is ready for use as shown in fig. 23E. In this state the housing indicator opening 405 is aligned with a shield first indicator opening 241 and a hub indicator cut-out 115. The hub skirt 120 is thus not visible to the user (see fig. 24A). When the user pushes the needle unit towards a skin surface the shield 200 is pushed proximally allowing the needle distal end 103 to be inserted subcutaneously. During initial proximal movement of the shield the ramp surfaces 231 on the flexible control arms 230 are pushed over the hub tower ramp surfaces 131. As the shield is moved further proximally to its fully retracted position the shield actuator ribs 213 pushes the pair of actuator legs 502 proximally to thereby release the drug delivery device expelling mechanism thereby starting subcutaneous injection as described above, see fig. 23F. As appears, the actuator legs 502 serve both as a locking actuator for the hub coupling and as release members for the expelling mechanism. During out-dosing the shield is held in its fully retracted position by the snap lock 135, 235. In this state the housing indicator opening 405 is aligned with the shield second indicator opening 246 and the hub indicator cut-out 115. The hub skirt 120 is thus not visible to the user (see fig. 24B).

[0092] After the clicking sound stops and the dose thus has been fully expelled, the user withdraws the needle unit from the skin surface thereby allowing the spring-biased actuator legs 502 to push on the shield actuation ribs 213 to thereby move the shield 200 distally to its fully extended position again covering the needle distal portion 103. During this movement the control surfaces 232 on the control arms 230 will engage the inclined proximally facing control surfaces 132 on the hub tower (see fig. 20A), which will force the needle hub 100 to rotate as the shield is rotationally locked to the drug delivery device, see fig. 23G. In the shown embodiment the hub is rotated 45 degrees relative to the shield, compare figs. 23CX and 23GX.

[0093] During rotation of the hub relative to the shield a number of structures are moved into and out of engagement with each other:

[0094] (i) As the hub rotates, a portion of the hub skirt 120 neighbouring the hub cut-out 115 aligned with the housing indicator opening 405 will rotate into alignment with the opening and thus be visible to the user (e.g. by having a contrasting colour), this indicating that the needle unit has been used and correspondingly that a dose of drug has been expelled. During drug expelling with the shield in its retracted position the shield second indicator opening 246 is aligned with the housing indicator opening 405 (see fig. 24C).

[0095] (ii) As the hub rotates, the flexible hub coupling arms 126 rotate out of engagement with the shield actuation ribs 213 thereby allowing the coupling arms to move radially outwards, see fig. 23H, and thus the hub 100 to be removed from the cartridge mount 310. To reduce the force necessary to disengage the hub coupling arms from the cartridge mount, the hub coupling arms are rotated to a position on the cartridge mount having lower and less inclined release flange portions 312.

[0096] (iii) As the needle is fixed in the hub it follows that the needle will rotate with the rotating hub, however, it may not be desirable that the needle rotates when fully inserted subcutaneously. Correspondingly, the hub and shield can be designed with an axial “play” before the shield control surfaces 232 engages the inclined hub control surfaces 132, this allowing the needle to be at least partly withdrawn from the skin before rotation starts. Indeed, the later rotation starts the steeper the inclination of the hub control surfaces has to be.

[0097] (iv) Before operation of the needle unit, the pair of locking ribs 217 on the shield inner surface were free to move in the axial direction thus allowing the shield to be moved from its extended to its retracted position. As the hub is rotated the pair of distally facing locking surfaces 118 are rotated into alignment with the proximal ends 218 of the locking ribs 217 thereby preventing repeated retraction of the shield and thus use of the needle unit, thereby providing a safety lock, see figs. 19B and 20A. Correspondingly, the locking surfaces should be designed to withstand relatively large forces to prevent re-activation of the needle unit, e.g. if the pen device is dropped on a hard surface or in a mis-use scenario. Further, in case the drug delivery device as in the present embodiment is shield released the shield lock will also serve as a double dose prevention means.

[0098] (v) In the shown embodiment the container is intended to be used as a tool also for removing the needle unit, see fig. 23I. When the user re-attaches the container, the container snap coupling 296 will engage the shield 200. The container snap coupling is designed to have a release force larger than the release force necessary to pull the ridges 127 of the flexible hub coupling arms axially out of engagement with the cartridge mount release flanges 312, this allowing the needle unit to be removed from the cartridge mount securely held in the container after which it can be safely discarded, see fig. 23J. As the needle unit is locked to the container via the container snap coupling and the proximal end is positioned a certain distance inside the container and only being surrounded by a small free space, removal of the needle unit from the container would be difficult.

[0099] (vi) As the hub rotates, the drop lock release flanges 114 are rotated out of alignment with the actuator leg release surfaces 524, this preventing that a used and locked needle unit can be used to release the actuator drop lock. Alternative embodiments:

[0100] In the above-described embodiment, when the hub rotates relative to the cartridge mount the flexible coupling arms 126 are rotated to align with the inclined release flanges 312 allowing the hub coupling arms to disengage with ease which may encourage the user to remove the needle unit without using the container. T o encourage the user to use the container, the release flanges may be modified to require a larger release force which would make it more difficult to merely grab and pull the shield out of engagement with the hub mount. To allow this the snap coupling between the container and the shield has to be able to transfer the required force, however, as the same snap coupling should be designed to allow for easy removal of the container after initial mounting of the needle unit this may not be desirable.

[0101] Correspondingly, a needle assembly may be provided comprising a snap coupling between the container and the shield, the snap coupling being actuatable between a first state in which the needle unit can be removed from the container using a first amount of force, and a second state in which the needle unit can be removed from the container using a second higher amount of force. The assembly may be operated between the two states by the rotational movement of the hub inside the shield. A detailed description of such an arrangement is described in co-pending application EP 23174814.6 which is hereby incorporated by reference.

[0102] In the above-described embodiment an indicator is incorporated in the drug delivery housing and being operated by the rotational movement of the hub. Although indicator actuation is controlled by the needle unit, the placement of the indicator window 405 on the housing is designed to associate the indicator with operation of the device per se and thus indicate that a dose of drug has been expelled which will be the case when the shield has been returned to its extended and now locked position.

[0103] However, it may be desirable to provide the indicator on the shield to instead directly indicate that the needle unit has been used and is now locked. Correspondingly, instead of the device housing the shield may be provided with an indicator window and the hub may be provided with an indicator surface which initially is not aligned with the window but moved into alignment therewith when the hub is rotated after use.

[0104] In the above description of exemplary embodiments, the different structures and means providing the described functionality for the different components have been described to a degree to which the concept of the present invention will be apparent to the skilled reader. The detailed construction and specification for the different components are considered the object of a normal design procedure performed by the skilled person along the lines set out in the present specification.

Claims

CLAIMS1. A needle unit (2) adapted to be mounted on a drug delivery device (1) comprising a needle unit mount (310), the needle unit comprising: a needle hub (100) with a mounting coupling (126) allowing the needle assembly to be mounted on the needle unit mount (310), a hollow needle (101) mounted in the needle hub and having a pointed distal end (102) protruding from the needle hub, the hollow needle defining a reference axis, and a shield (200) in which the needle hub (100) is arranged, the shield being axially moveable relative to the needle hub between an initial extended position in which the shield axially covers the needle distal end (102), a retracted proximal position in which the needle distal end protrudes from the shield, and a locked extended position in which the shield axially covers the needle distal end, wherein the shield comprises axial guide means (245) adapted to engage corresponding axial guide means (415) on the drug delivery device allowing the shield to be mounted axially moveable but non-rotatable relative to the drug delivery device, wherein: the shield (200) comprises an indicator window (241), the needle hub comprises an indicator marker (120), the indicator marker is not visible through the indicator window when the shield is in the initial extended position, this corresponding to an indicator first state, and the indicator marker (120) is visible through the indicator window (241) when the shield is in the locked extended position, this corresponding to an indicator second state.

2. A needle unit as in claim 1 , wherein: the needle hub (100) is rotated relative to the shield (200) when the shield is moved from its retracted to its locked extended position, whereby the indicator marker is rotated from a position in which the indicator marker is not visible in the shield indicator window to a position in which the indicator marker is visible in the shield indicator window.

3. A needle unit as in claim 1 or 2, wherein the needle hub is fully enclosed in the interior of the shield when the shield is in its retracted proximal position.

4. A needle unit as in any of claims 1-3, wherein the axial guide means on the shield is in the form of: spline structures (415, 245) formed on the proximal outer and / or inner surface of the shield, and / or the shield having a non-circular proximal skirt portion5. A needle unit (2) as in any of claims 1-3 in combination with a drug delivery device (1), the combination forming a drug delivery assembly, the drug delivery device comprising: a housing (400) comprising or adapted to receive a drug-filled cartridge, a needle unit mount (310), and axial guide means (415) adapted to engage the shield axial guide means.

6. A drug delivery assembly as in claim 5, wherein: the mounting coupling (126) is actuatable between (i) a lock state in which a mounted needle unit (2) cannot be removed from the drug delivery device (1), and (ii) an actuated release state in which the needle unit can be removed from the drug delivery device, and the mounting coupling (126) is actuated from the lock state to the release state when the shield (200) is moved from its retracted to its extended position, whereby the indicator second state indicates that the needle unit can be removed from the needle unit mount.

7. A drug delivery assembly as in claim 6, wherein: the mounting coupling (126) is actuated from the lock state to the release state by rotational movement of the needle hub (100) relative to the shield (300).

8. A drug delivery assembly as in any of claims 5-7, the drug delivery device further comprising:a piston rod (650) adapted to engage and axially displace a piston in a loaded cartridge (390) in a distal direction when rotated to thereby expel a dose of drug from the cartridge, a spring-driven drive mechanism (700, 800, 890) adapted to rotate the piston rod to expel a predetermined amount of drug from the cartridge, a release member (500) axially moveable between a distal position and an actuated proximal position in which the drive mechanism is released to thereby expel the predetermined dose amount, a return spring (590) providing a distally directed force on the release member (500), wherein the release member is moved to the distal position by the return spring when the predetermined dose amount has been fully expelled, wherein the shield (200), with the needle unit mounted on the drug delivery device: moves the release member (500) from the distal position to the actuated proximal position to thereby release the drive mechanism when the shield is moved from the initial extended position to the retracted proximal position, and is moved to the locked extended position by the release member (500) when the predetermined dose amount has been fully expelled, whereby the indicator second state indicates that the predetermined dose amount has been fully expelled.

9. A drug delivery assembly as in any of claims 5-8, wherein: the drug delivery device housing (400) comprises a housing indicator window (405), and the shield indicator window (241) of a mounted shield in the locked extended position is arranged in alignment with the housing indicator window (405), the indicator marker (120) thus being visible through the housing indicator window.

10. A drug delivery assembly as in any of claims 5-9, wherein: the axial guide means on the drug delivery device respectively the shield is formed by cooperating spline structures (415, 245).

11. A drug delivery assembly as in any of claims 5-10, wherein: the shield has a non-circular proximal skirt portion, and the drug delivery device housing has a corresponding non-circular distal opening adapted to receive the shield proximal skirt portion to thereby form corresponding axial guide means.

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