Variable dosing syringe with needle safety

Abstract

A device may include a plunger rod sub-assembly, comprising: a housing, a plunger rod movably coupled to the housing; and a dial axially constrained by the housing, the dial configured to set a start-of-dose position of the plunger rod by axially translating the plunger rod, and to set an end-of-dose position of the plunger rod. The device may include a needle safety sub-assembly, comprising: a syringe barrel, a needle extending from the syringe barrel; and a shield configured to automatically release at the end-of-dose position to shield the needle.

Description

VARIABLE DOSING SYRINGE WITH NEEDLE SAFETY CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Application 63 / 711,812, filed October 25, 2024, the contents of which are incorporated herein in its entirety.FIELD

[0002] This disclosure relates generally to drug delivery devices, and more specifically, to needle safety devices for use with syringes providing variable dosing.BACKGROUND

[0003] Pre-filled syringes are widely used and include the drug filled into the syringe at the drug manufacturing site. The fill volume is also the dose volume; hence, the intended / indicated dose is administered by emptying the contents of the syringe.Conventional hypodermic syringes have been used to transfer drugs from a vial filled with the drug and have dose markings printed on the syringe barrel enabling the user to set a certain dose prior to injecting it. Since pre-filled syringes are also drug containers, the barrel surface is occupied by a drug label to comply with regulatory requirements for a drug label. Therefore, one cannot simply print dose markings along the entire length of the syringe barrel. Thus, when a drug has different dosages, then different volumes are filled based on various target doses. Alternatively, the drug is reformulated to have different concentrations of the drug that is ultimately filled with a volume corresponding to the target doses. The effect of this is that a single drug has multiple Stock Keeping Units (SKU), which increases operational complexity and can be expensive to maintain and produce for SKUs having a lower number of units.

[0004] Safety-engineered devices have been developed specifically for use with pre-filled syringes. Since product architecture involves emptying the entire contents of the pre-filled syringe for the dose, needle safety mechanisms of the aforementioned safety-engineered devices are actuated close to the end of the injection stroke (e.g., as an axial user input tocomplete dose delivery). The needle safety mechanism shields the needle either by covering it with a shield or by retracting the needle into the syringe.

[0005] One such representative embodiment is illustrated in syringe assembly 20 shown in FIGS. 1A-1C, which is generally representative of safety engineered devices having a sliding shield covering the needle of a pre-filled syringe upon actuation. Shown in FIG. 1A, a prefilled syringe 10 is filled with an injectable drug fluid 22. This syringe includes a pre-attached needle 23, which is enclosed with a cover prior to removal by the user. The syringe 10 includes a plunger stopper 9 configured to seal against the inner, cylindrical surface of the syringe 10 and to axially translate within the syringe 10 when pushed by plunger rod 19 upon receipt of an axial user input. A dose of the injectable drug fluid 22 is completely delivered when the drug fluid 22 is dispensed through needle 23 and the plunger stopper 9 is completely at the bottom of the syringe barrel 10, as shown in FIG. IB. Thus, the syringe 10 accommodates a single dose level. The axial input received from the user is the injection stroke.

[0006] FIGS. 1A-1C also show components of a safety engineered device of the assembly 20 including an outer shield 13, an inner shield 11, and a spring 12. As shown in FIG. 1A, the outer shield 13 includes two symmetric actuation retention beams 13-1 that are initially latched onto axial retention features 11-1 on the proximal side of the inner shield 11, preventing the spring 12 from extending / de-compressing. Upon plunger stopper 9 bottoming out in the syringe 10, the generic plunger rod 19 produces a radial deflection force causing deflection of the outer shield actuation retention beams 13-1, separating them from corresponding retention features 11-1 on inner shield 11 as shown in FIG. IB. This allows the spring 12 to extend, producing relative axial motion between the outer shield 13 and the inner shield 11 until contacting a hard stop, at which point the outer locking features ratchet into position. As shown in FIG. 1C, the outer shield 13 is axially locked in both directions and sufficiently encases the needle 23 to prevent accidental contact and injury.

[0007] The relative motion and rate of actuation between the inner shield 11 and outer shield 13, driven by the spring 12 extension, is controlled by the user through the rate of expanding their hand grip between the generic plunger rod finger pad 19-2 and outer shield finger flanges 13-3. Thus, the actuation of the needle shielding occurs over an axially translated distance. In examples involving microliter volume injections, the amount of axial travel (e.g.,the injection stroke) necessary to deliver the intended / indicated dose volume may be less than the axial travel necessary to inject an accurate dose and actuate the needle safety mechanism.SUMMARY

[0008] According to various aspects, described are syringe assemblies that include a prefilled syringe with a dose metering mechanism enabling selection of variable dose volumes from a fixed total fill volume, while maintaining a common start-of-dose position. The assemblies further include a needle safety mechanism that actuates automatically and independently of the selected or delivered dose. In some aspects, the syringe assembly includes a stroke amplification mechanism that ensures reliable activation of the safety mechanism even for small-volume, microliter-level doses.

[0009] In some aspects, a drug injection device is provided, including: a plunger rod subassembly, including: a housing; a plunger rod movably coupled to the housing; and a dial axially constrained by the housing, the dial configured to set a start-of-dose position of the plunger rod by axially translating the plunger rod, and to set an end-of-dose position of the plunger rod; and a needle safety sub-assembly, including: a syringe barrel; a needle extending from the syringe barrel; and a shield configured to automatically release at the end-of-dose position to shield the needle.

[0010] In some aspects, a method for delivering a drug using a drug injection device is provided, including: setting a start-of-dose position of a plunger rod of the device by engaging a dial of the device, wherein setting the start-of-dose position causes axial translation of the plunger rod; setting an end-of-dose position by engaging the dial; inserting a needle of the device into the subject; and delivering the drug by moving the plunger rod to the end-of-dose position, wherein upon reaching the end-of-dose position, a shield of the device is configured to automatically release to shield the needle.

[0011] It will be appreciated that any of the variations, aspects, features, and options described in view of the systems apply equally to the methods and vice versa. It will also be clear that any one or more of the above variations, aspects, features, and options can be combined.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0013] FIG. 1A-1C show an exemplary needle safety syringe and actuation thereof, the needle safety syringe representative of those in the prior art. FIG. 1A shows the needle safety syringe before injection, according to some embodiments. FIG. IB shows the needle safety syringe of FIG. IB after injection, according to some embodiments. FIG. 1C shows the needle safety syringe of FIG. IB with the needle safety device actuated, according to some embodiments.

[0014] FIG.2A shows an exemplary controlled dosage delivery assembly including a needle safety sub-assembly and a plunger rod sub-assembly, components of the plunger rod subassembly shown in an exploded view, according to some embodiments. FIG.2B shows an exploded view of the needle safety sub-assembly shown in FIG.2A, according to some embodiments. FIG.2C shows a perspective view of the exemplary assemblies of FIG.2A, the assemblies detached from one another, according to some embodiments.

[0015] FIG.3A-3F show use of the controlled dosage delivery assembly shown in FIGS. 2A-2C. FIG.3A illustrates priming the assembly, according to some embodiments. FIG.3B illustrates a dose selection of 0.04 mL, FIG.3C illustrates a dose selection of 0.06 mL, and FIG.3D illustrates a dose selection of 0.60 mL, according to some embodiments. FIG.3E illustrates dose delivery, according to some embodiments. FIG.3F illustrates automatic release of the needle safety device, according to some embodiments.

[0016] FIGS.4A-4E shows an exemplary star-of-dose position of the syringe assembly shown in FIGS.2A-2C and various exemplary end-of-dose positions that cause subsequent safety mechanism actuation. FIG.4A shows the exemplary start-of-dose position for the syringe assembly shown in FIGS.2A-2C, according to some embodiments. FIG.4B shows an exemplary end-of-dose position of the syringe assembly shown in FIGS.2A-2C for a 0.15 mL dose, according to some embodiments. FIG.4C shows an exemplary end-of-dose position of the syringe assembly shown in FIGS.2A-2C for a 0.25 mL dose, according to some embodiments. FIG.4D shows an exemplary end-of-dose position of the syringe assembly shown in FIGS.2A-2C for a 0.40 mL dose, according to some embodiments. FIG.4E shows an exemplary end-of-dose position of the syringe assembly shown in FIGS.2A-2C for a 0.60 mL dose, according to some embodiments.

[0017] FIG. 5A shows a perspective view of the cover of the plunger sub-assembly of FIG.2A, according to some embodiments. FIG. 5B shows a perspective view of the housing of the plunger sub-assembly of FIG.2A that attaches to the cover shown in FIG. 5A, according to some embodiments.

[0018] FIG.6A shows a perspective view of the cam of the plunger sub-assembly of FIG.2A that is enclosed by the cover and housing shown in FIGS. 5A-5B, according to some embodiments. FIG.6B shows a bottom view of the cam shown in FIG.6A, according to some embodiments.

[0019] FIG.7A shows a perspective view of the dial of the plunger sub-assembly of FIG. 2A that is axially constrained by the cover and housing shown in FIGS. 5A-5B, according to some embodiments. FIG.7B shows another perspective view of the dial in FIG.7A, the view in FIG.7B showing the opposite side from the view in FIG.7A, according to some embodiments.

[0020] FIG.8A shows a perspective view of the ratchet of the pre-filled syringe of FIG.2 that is fits into the dial shown in FIGS.7A-7B, according to some embodiments. FIG.8B shows a perspective view of the ratchet of FIG.8A contained in the dial shown in FIGS.7A-7B, according to some embodiments.

[0021] FIGS.9A-9J show various stages during the priming and dose selection process shown in FIGS.3A-3E. FIG.9A shows the plunger sub-assembly of FIG.2A in an initial position, according to some embodiments. FIG.9B shows a cross-sectional view of the plunger sub-assembly of FIG.9A, according to some embodiments. FIG.9C shows the plunger sub-assembly of FIG.9A in a penultimate angular priming rotation, according to some embodiments. FIG.9D shows a cross-sectional view of the plunger sub-assembly of FIG. 9C, according to some embodiments. FIG.9E shows the plunger sub-assembly of FIG.9A in a final angular priming rotation, according to some embodiments. FIG.9F shows a cross-sectional view of the plunger sub-assembly of FIG.9E, according to some embodiments. FIG.9G shows the plunger sub-assembly of FIG.9A in a dose setting between an exemplary highest and lowest dose level, according to some embodiments. FIG.9H shows a cross-sectional view of the plunger sub-assembly of FIG.9G, according to someembodiments. FIG.91 shows the plunger sub-assembly of FIG.9A in an exemplary highest dose level, according to some embodiments. FIG.9J shows a cross-sectional view of the plunger sub-assembly of FIG.91, according to some embodiments.

[0022] FIG. 10 shows a perspective view of the plunger rod of the plunger rod sub-assembly shown in FIG.2A, according to some embodiments.

[0023] FIG. 11A shows a partial view of the plunger rod ratchet mechanism at the start of priming, according to some embodiments. FIG. 11B shows a partial view of the plunger rod ratchet mechanism at the end of priming, according to some embodiments.

[0024] FIG. 12 shows a perspective view of the lever of the plunger rod sub-assembly shown in FIG.2A that is axially constrained by the housing and cover shown in FIGS. 5A-5B, according to some embodiments.

[0025] FIG. 13A shows an axial amplification mechanism of the controlled dosage delivery assembly shown in FIGS.2A-2C in an unactuated state, according to some embodiments.FIG. 13B shows the axial amplification mechanism of the controlled dosage delivery assembly shown in FIGS.2A-2C in an actuated state, according to some embodiments.

[0026] FIG. 14A-14C shows the interface between the lever of the plunger rod subassembly and the outer shield of the needle safety device in FIG.2A to actuate the needle safety mechanism. FIG. 14A shows a cross-sectional view of the controlled dosage delivery assembly in FIG.2A with the lever unactuated and thus the needle safety device unreleased, according to some embodiments. FIG. 14B shows a cross-sectional view of the controlled dosage delivery assembly in FIG.2A with the lever actuated and thus the needle safety device ready to be released, according to some embodiments. FIG. 14C shows a cross-sectional view of the controlled dosage delivery assembly in FIG.2A with the lever actuated and the needle safety device released, shielding the needle, according to some embodiments.

[0027] FIGS. 15A-15C show the motion of the plunger rod and cam of the plunger rod subassembly shown in FIG.2A, relative to the housing of the sub-assembly. FIG. 15A shows a cross-sectional view of the plunger rod axially translating without contacting or translating the cam, according to some embodiments. FIG. 15B shows a cross-sectional view of the plunger rod contacting the cam when the remaining injection stroke is equal to the actuation stroke to complete the injection, according to some embodiments. FIG. 15C shows a cross-sectional view of the plunger rod simultaneously translating the cam until contacting a surface of the housing, according to some embodiments.

[0028] FIGS. 16A-16C shows the cam longitudinal locking mechanism with the housing at an end-of-dose position, according to some embodiments. FIG. 16A shows a perspective view of the radial groove in the housing relative to the cam, according to some embodiments.FIG. 16B shows a partially cross-sectional view of a portion of the cam deflecting off the housing as the plunger rod pushes the cam toward the syringe barrel, according to some embodiments. FIG. 16C shows a partially cross-sectional view of the portion of the cam snapped into a second groove in the housing in an end-of-dose position, according to some embodiments.

[0029] FIGS. 17A-17C show another exemplary controlled dosage delivery assembly including a needle safety sub-assembly and a plunger rod sub-assembly, the assembly further including a removable safety cap, according to some embodiments. FIG. 17A shows a perspective view of the assembly including a removable safety cap, according to some embodiments. FIG. 17B shows an exploded view of the needle safety sub-assembly shown in FIG. 17A, according to some embodiments. FIG. 17C shows a perspective view of the assemblies shown in FIG. 17A, detached from one another, according to some embodiments.

[0030] FIG. 18A-18C show the controlled dosage delivery assembly of FIGS. 17A-17C in various stages of use. FIG. 18A shows the assembly shown in FIG. 17A, at a start-of-dose position, according to some embodiments. FIG. 18B shows the assembly shown in FIG. 18A while releasing the dose, according to some embodiments. FIG. 18C shows the assembly shown in FIGS. 18A-18B upon reaching an end-of-dose position and releasing the needle safety sub-assembly, according to some embodiments.DETAILED DESCRIPTION

[0031] In the following description of the various examples, reference is made to the accompanying drawings in which are shown, by way of illustration, specific examples that can be practiced. The description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the described examples will be readily apparent to those persons skilled in the art, and the generic principles herein may be applied to otherexamples. Thus, the present invention is not intended to be limited to the examples shown but is to be accorded the widest scope consistent with the principles and features described herein.

[0032] In addition, it is also to be understood that the singular forms “a,” “an,” and “the” used in the following description are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is also to be understood that the term “and / or,” as used herein, refers to and encompasses any and all possible combinations of one or more of the associated listed items. It is further to be understood that the terms “includes,” “including,” “comprises,” and / or “comprising,” when used herein, specify the presence of stated features, integers, steps, operations, elements, components, and / or units, but do not preclude the presence of addition of one or more other features, integers, steps, operations, elements, components, units, and / or groups thereof.

[0033] According to an aspect, syringe assemblies include a pre-filled syringe having a dose metering mechanism that maintains a common start-of-dose position and provides various end-of-dose positions based on user-selected dose volume. The dose metering mechanism enables selection of a dosage from among multiple pre-set dose levels, up to the total prefilled volume of injectable fluid contained within the syringe, cartridge, or equivalent rigid container. To achieve multiple user- selectable, single-use dose levels using a pre-filled syringe of fixed volume, the assemblies described herein can accommodate a series of predetermined plunger rod strokes corresponding to different dose levels. A syringe is filled to a maximum target volume that allows for delivery of the largest anticipated dose, while the dose metering mechanism permits delivery of smaller, user-selected doses by maintaining a fixed plunger rod start position and varying the end position according to the selected dose. Thus, the syringe assemblies described herein allow precise, repeatable dosing, including microliter-scale doses (e.g., between 5 and 200 microliters), without requiring printed dose markings on the syringe barrel (as in conventional syringes).

[0034] The syringe assemblies described herein further incorporate a needle safety device that automatically actuates upon or near completion of the injection, independent of the selected or delivered dose volume. This needle shielding mechanism ensures consistent postinjection needle safety regardless of the amount administered.

[0035] In some aspects, the syringe assemblies described herein include a stroke amplification mechanism that compensates for short injection strokes associated with smaller doses. This mechanism amplifies the user-applied plunger stroke to exceed the actuation stroke required for triggering the needle safety device, thereby ensuring complete and reliable activation even during microliter dosing.

[0036] FIG. 2A shows an exemplary controlled dosage delivery assembly 21 that includes a pre-filled syringe arranged within a needle safety device (collectively, needle safety subassembly 15), and a plunger rod sub-assembly 8 including a plunger rod 6, a cam 3, at least one dose setting dial 4, at least one actuation lever 7, and a housing comprising a back cover 1 and a front cover 2. Described in greater detail below, the cam 3 can include one or more circumferentially arranged ‘stop’ features. The plunger rod 6 can include a single ‘stop’ protrusion that when aligned longitudinally will contact the cam 3 at a predetermined axial position.

[0037] Existing syringes may adjust the start-of-dose position to accommodate specific applications with various fill volumes (e.g., including overfill) and stopper position tolerances during a pre-filled syringe manufacturing process. This in turn limits low volume injections (e.g., less than 200 microliters) due to inability to actuate the safety mechanism, which is an artifact of minimum required axial / longitudinal feature dimensions and syringe cross-sectional area (e.g., constraining the microliters / millimeter travel of the plunger rod).Accordingly, the assembly 21 can include at least one actuation lever 7 configured to amplify the movement of the plunger rod 6 to the cam 3 such that small movements of the plunger rod 6 associated with small volume injections can reliably actuate the safety mechanism. In some aspects, the amplification mechanism provides additional user indication and feedback features, such as end-of-dose completion.

[0038] Various embodiments of the needle safety mechanism can have different form factors and usability features. FIG. 2B shows an exploded view of the needle safety sub-assembly 15 including the needle safety device and syringe 10 shown in FIG. 2A. The needle safety subassembly 15 can include a plunger stopper 9, a syringe 10 including a barrel and a staked needle extending therefrom, inner shield 11, spring 12, outer shield 13, and a cap 14. The plunger rod 6 can push the plunger stopper 9 to deliver fluid through the needle of the syringe 10. The outer shield 13 can extend over the syringe barrel 10. Described in greater detail below, the outer shield 13 can include one or more external finger flanges that extendlaterally from the shield 13, at a proximal end of the shield 13 near the plunger rod 6 when attached to the plunger rod sub-assembly 8. The finger flanges can provide added accommodation to different user hand sizes and may improve ease of depressing the plunger rod 6 to deliver a dose. The needle shield sub-assembly (e.g., at least the outer shield 13 thereof) can be transparent to enable better visualization of the injectable fluid contained in the syringe 10 during pre-filled syringe manufacturing and / or dose setting. The needle safety sub-assembly 15 may be configured to obstruct view of the syringe 10 after the shield is released. This may improve usability as the device is more uniform at the end of actuation state, removing uncertainty in the amount of fluid delivered at various dose setting options due to end-of-dose positional differences.

[0039] FIG. 2C shows the plunger rod sub-assembly 8, assembled, ready for attachment with the needle safety sub-assembly 15. Assembly methods can include a single-action axial push for needle safety sub-assembly 15, including with one-way snap-fits to prevent detachment.

[0040] FIGS. 3A-3F illustrate use of the controlled dosage delivery assembly 21 shown in FIGS. 2A-2C. The assembly 21 can include a plurality (e.g., 10) dose levels at non-uniform volume intervals. FIG. 3A illustrates priming the assembly 21. In order to reach a start-of-dose position, priming is completed by rotating the dial 4 to provide a fixed angular displacement of the dial 4, which causes axial translation of the plunger rod 6 toward the dial 4. The dial 4 can be rotated until an audible click is heard, indicating a lowest dose level (otherwise referred to herein as a start-of-dose position). With brief reference to features of the dial 4 labeled in FIG. 7A and the plunger rod 6 labeled in FIG. 10, a dial threaded priming surface 4-2 of the dial 4 can advance the plunger rod dose control peg 6-2 a predetermined distance axially toward the syringe 10. The distal end 6-3 of the plunger rod can contact the proximal (i.e., non-needle) side of the plunger stopper 9 of the needle safety sub-assembly 15 located in the syringe 10 (see, e.g., FIG. 2B).

[0041] After priming, the dial 4 can be further rotated to select the desired dose level through numerical dose markings 3-6 (e.g., labeled in FIG. 6A) that can be displayed to the user through a dose selection window 2-13 of the cover 2. FIGS. 3B-3D illustrate dose level selection. FIG. 3B illustrates a dose selection of 0.04 mL, FIG. 3C illustrates a dose selection of 0.06 mL, and FIG. 3D illustrates a dose selection of 0.60 mL. Motion of the dial 4 can be bi-directional. In some examples, motion of the dial 4 is constrained from returningto the angular end-of-priming position (otherwise referred to herein as the lowest or start-of-dose position).

[0042] Motion of the dial 4 can be controlled by a ratchet 5, illustrated in FIG. 8A, the ratchet 5 having alignment tabs 5-2. The ratchet 5 can be fixed within the housing 1 and cover 2 (see, e.g., FIG. 2A) and can rotationally slip as a beam head 5-1 of the ratchet 5 deflects while oscillating in and out of a radially notched pattern 4-5 on an inner face of the dial 4, illustrated in FIG. 8B. When the user turns the dial 4, the ratchet 5 can provide discrete positioning of the dial 4 for each dose level.

[0043] With reference to FIG. 3E, once the target dose volume is set (e.g., visible in cover dose selection window 2-13), the user can push the plunger rod finger pad 6-1 to deliver fluid to injection site until reaching a hard stop, at which point the plunger rod 6 contacts the cam 3. At the hard stop, the cam 3 can actuate the lever(s) 7, the assembly 21 can provide an audible click by the radial ratchet beam(s) 7-4 of the lever 7, illustrated in FIG. 12, and release the safety outer shield 13. Thus, the device can provide an audible cue when the end-of-position is reached. FIG. 3F illustrates automatic release of the needle safety device. The rate of release of the outer shield 13 of the needle safety device can be controlled by the user as the user expands their grip between outer shield finger flanges 13-3 and plunger rod finger pad 6-1, releasing force on the finger flanges 13-3. The outer shield 13 can irreversibly shield the needle. The assembly 21 can accordingly be single-use. Outer shield 13 may lock longitudinally in both directions at the full extension position shown in FIG. 3F, preventing exposure of the needle tip as well as reuse of the syringe. Upon safety mechanism actuation, the cam 3 can be rotationally and longitudinally locked via the radial notches 3-3, illustrated in FIG. 6A, which mate with cam locking peg 2-12 of cover 2, illustrated in FIG. 5A. The mechanism between the radial notches 3-3 and cam locking peg 2-12 can ensure outer shield 13 stays released and prevents reuse of the syringe.

[0044] FIGS. 4A-4E illustrate an exemplary start-of-dose position of the syringe assembly 21 and various exemplary end-of-dose positions that cause subsequent safety mechanism actuation. The positions shown in FIGS. 4A-4E can correspond to the injection steps shown in FIGS. 3E-3F; that is, delivering the dose via pushing the plunger rod 6 finger pad 6-1. FIG. 4A shows a start-of-dose position of the syringe assembly 21. FIG. 4B shows an exemplary end-of-dose position of the syringe assembly 21 for a 0.15 mL dose. FIG. 4C shows an exemplary end-of-dose position of the syringe assembly 21 for a 0.25 mL dose.FIG. 4D shows an exemplary end-of-dose position of the syringe assembly 21 for a 0.40 mL dose. FIG.4E shows an exemplary end-of-dose position of the syringe assembly 21 for a 0.60 mL dose. Each of the positions shown in FIGS.4B-4E can start from a common start-of-dose position, shown in FIG.4A.

[0045] FIG. 5A shows the front cover 2 of the housing of the plunger sub-assembly 8 shown in FIG. 2C. FIG. 5B shows the back cover 1 of the housing of the plunger sub-assembly 8 shown in FIG.2C. Features of the front cover 2 and back cover 1 are collectively described herein with reference to the housing, as follows. The housing can include press-fit features 1-1, 2-1 configured to secure front cover 2 to the back cover 1. The housing can include one or more of the following features: cam cavity 1-2, 2-2, plunger rod axial locking beam surface 1-3, plunger rod alignment key 2-3, dial cavity 1-4, 2-4, radial grooves 1-5, 2-5, cam stopping surface 1-6, 2-6, lever pivot post 1-7, 2-7, lever radial latch 1-8, 2-8, inner shield assembly beams 1-9, 2-9, cam beam priming ramp 2-10, max dose selection rotational stop 2-11, cam locking peg 2-12, and dose selection window 2-13.

[0046] FIGS.6A-6B illustrate features of the cam 3, including dose selection stop surfaces 3-1, lever interface surface 3-2, radial notches 3-3, position control beam 3-4, rotational engagement rib 3-5, and numerical dose markings 3-6. An exemplary cam 3 can include any one or more of these features.

[0047] FIGS.7A-7B illustrate features of the dial 4, including plunger rod peg stop 4-1, threaded priming surface 4-2, rotational engagement rib 4-3, radial engagement beam 4-4, and radial ratchet notches. An exemplary dial 4 can include any one or more of these features.

[0048] FIG.8A shows the ratchet beam head 5-1, and FIG.8B shows the ratchet beam head 5-1 assembled in a particular radial notch 4-5 of the dial 4.

[0049] FIGS.9A-9J provide another view of the priming and dosing selection shown in FIGS. 3A-3E. With reference to FIG.9B, which illustrates a cross-sectional view of the plunger sub-assembly 8 in an initial position as shown in FIG.9A, the cam position control beam 3-4 can be initially rotationally positioned between cam beam priming ramp 2-10 and max dose rotational stop 2-11 located on the cover 2. This position can allow the cam 3 to rotationally slip relative to the dial 4 when the dial 4 is rotated (e.g., during priming). The rotational engagement rib 4-3 of the dial 4 can be initially angularly spaced from the cam rotational engagement rib 3-5. FIG.9D shows a cross-sectional view of the plunger sub-assembly in the penultimate angular priming rotation shown in FIG. 9C. As shown in FIG.9D, the dial radial engagement beam 4-4 can be deflected past the cam rotational engagement rib 3-5. In this position, the dial rotational engagement rib 4-3 can contact the cam rotational engagement rib 3-5, rotatably coupling the dial 4 and cam 3 for all subsequent steps. FIG. 9F shows a cross-sectional view of the plunger sub-assembly in the final angular priming rotation (e.g., lowest dose level) shown in FIG. 9E. As shown in FIG. 9F, the cam position control beam 3-4 can be deflected radially inward when the cam 3 is rotated by the dial 4 until the cover beam priming ramp 2-10 is rotationally passed and the cam position control beam 3-4 snaps into the next section of the cover radial groove 2-5.

[0050] The sequence described above can be achieved through beam deflection force ratios — the dial radial engagement beam 4-4 may require less deflection force to bypass the cam rotational engagement rib 3-5 than the cam position control beam 3-4 requires deflecting past the cover beam priming ramp 2-10. The dial 4 and cam 3 may now rotate bi-directionally from the lowest dose level (e.g., as shown in FIGS. 9E-9F) to the highest dose level (e.g., as shown in FIGS. 9L9J). FIG. 9H illustrates a cross-sectional view of the plunger subassembly 8 in a dose setting between an exemplary highest and lowest dose level, 0.08 mL, as shown in FIG. 9G. Each dose level position can be indexed via the ratchet beam head 5-1 and dial radial notches 4-5. FIG. 9J illustrates a cross-sectional view of the plunger subassembly 8 at an exemplary highest dose level, 0.60 mL, as shown in FIG. 91. With reference to FIG. 91, cover beam priming ramp 2-10 and max dose rotational stop 2-11 may bound the cam position control beam 3-4 by providing hard rotational stops at the lowest and highest dose level, thus preventing the now rotatably coupled dial 4 and cam 3 from returning to the lowest dose level (e.g., as shown in FIGS. 9E-9F) directly from the highest dose level (e.g., as shown in FIGS. 9I-9J).

[0051] FIG. 10 illustrates features of the plunger rod 6, including finger pad 6-1, dose control peg 6-2, plunger stopper interface 6-3, and end of priming axial locking beam 6-4. An exemplary plunger rod 6 can include any one or more of these features.

[0052] FIGS. 11A-11B illustrate the plunger rod end-of-priming axial locking beam 6-4 at the start and end of priming. As shown in FIG. 11 A, initially, the beam 6-4 may be positioned below a housing locking surface 1-3 in an undeflected state. During priming, the plunger rod 6 can advance to the start-of-dose axial position. As shown in FIG. 11B, when the plunger rod 6 advances to the start-of-dose axial position, the beam 6-4 can deflect andsnap over the housing locking surface 1-3 to ensure that the plunger rod 6 cannot be withdrawn back from the start-of-dose position.

[0053] FIG. 12 illustrates features of the lever 7, including pivot through hole 7-1, actuation driving peg 7-2, actuation engagement arm 7-3, and radial ratchet beam 7-4. An exemplary lever 7 can include any one or more of these features.

[0054] FIGS. 13A-13B illustrate axial amplification via an actuation interface between the plunger rod 6, cam 3, and lever 7 that can enable reliable actuation of the needle safety mechanism even at low injection volumes. Typically, the plunger rod dose control pegs 6-2 (e.g., as shown in FIG. 10) contact the cam dose selection stop features 3-1 (e.g., as shown in FIG. 6B) with a fixed, uniform displacement of the plunger rod that is maintained for all dose options. This fixed longitudinal travel can constrain the lowest dose level as it corresponds to at least the minimum volume of fluid intended to be expelled from the syringe. For larger dose levels above the lowest level, the plunger rod dose control peg 6-2 can travel longitudinally without contacting the cam dose stop surfaces 3-1 until the minimum volume of fluid remains in the injection stroke. Thus, according to aspects described herein, the minimum displacement (e.g., the lowest dose volume) and / or the amplification ratio can be adjusted.

[0055] As shown in FIG. 13A, the cam lever interface surface 3-2 can interface with the lever actuation driving peg 7-2 before the lever 7 is actuated. The lever 7 can be actuated by rotating the cam 3 a predetermined angular amount. For example, amplification of the lever 7 can be derived from the ratio of the distance from the lever pivot axis 7-5 (shown in the perspective view of the lever 7 in FIG. 12) to the lever actuation driving peg 7-2 and the distance from the lever pivot axis 7-5 to the distal end of the lever actuation engagement arm 7-3. As shown in FIG. 13B, amplification in a rotatable body can be achieved when an outer point is located at a further distance from the rotational axis compared with another point located between the further point and the rotational axis. In FIGS. 13A-13B, the axial amplification ratio between axial travel of the plunger rod 6 and axial movement of the lever 7 is 2.6, amplifying the minimum axial travel of the plunger rod 6 of 1.15 mm to axial movement of the lever 7 of 3 mm.

[0056] In some aspects, the same or a similar amplification effect can be achieved by a compound gear with a rack and pinion arrangement. In some aspects, the amplification ratiomay be varied based on other requirements of the injectable drug but may utilize the underlying concept described herein at least with respect to FIGS. 13A-13B.

[0057] FIGS. 14A-14C illustrate the interface between the lever 7 and outer shield 13 to actuate the needle safety mechanism. As shown in FIG. 14A, the outer shield actuation retention beams 13-1 can be initially latched onto the proximal side of the inner shield 11, preventing the spring 12 from extending. The distal end of the lever actuation engagement arm 7-3 can be in direct contact with the outer shield actuation retention beams 13-1 in this position. As shown in FIG. 14B, upon rotating the cam 3 (not illustrated in FIGS. 14A-14C for clarity) to cause actuation of the lever 7, the lever 7 can deflect the outer shield actuation retention beams 13-1 a predetermined distance to reliably disengage the latch mechanism. As shown in FIG. 14C, the spring 12 can extend until the maximum outer shield 13 position is reached. The lever 7 can be rotationally locked at the end of actuation with the lever radial rachet beam 7-4 deflecting around and latching onto the housing lever rotational locking notch 1-8. This ratcheting mechanism can ensure that the lever 7 is fixed at the apex outer shield actuation retention beam 13-1 deflection location regardless of whether the user applies pressure on the plunger rod finger pad 6-1. Put another way, the position of lever 7 can be a function of axial position of plunger rod 6 rather than the amount of force applied to plunger rod finger pad 6-1. The deflecting and latching of lever radial rachet beam 7-4 may produce an audible sound, which may be a helpful usability cue to the user signaling end-of-dose delivery. This audible cue may be critical because, as described herein, the outer shield actuation retention beams 13-1 may be released from the mechanism and free to extend, but the user may still be axially restricting the outer shield finger flanges 13-3 and the plunger rod finger pad 6-1 such that the user is preventing the spring 12 from extending.

[0058] FIGS. 15A-15C illustrate the axial motion and contact surfaces between the plunger rod 6, cam 3, and housing (back cover 1, front cover 2) and radial alignment of the plunger rod 6 and cam 3 based on the selected dose level. For the lowest dose level, plunger rod dose control peg 6-2 and cam dose stop surfaces 3-1 may be in contact and translate longitudinally for the entirety of the dose stroke. As shown in FIG. 15A, for all other dose levels, the plunger rod 6 may first translate axially without contacting or translating the cam 3. As shown in FIG. 15B, when the remaining injection stroke is equal to the actuation stroke, the plunger rod dose control peg 6-2 can contact the cam dose stop surface 3-1 and complete the injection stroke. As shown in FIG. 15C, the plunger rod dose control peg 6-2 cansimultaneously translate the cam 3 until contacting the distal housing cam stopping surface 1- 6.

[0059] FIGS. 16A-16C shows the cam longitudinal locking mechanism with the housing at an end-of-dose position, according to some embodiments. FIG. 16A illustrates the housing radial groove 1-5. As shown in FIG. 16B, the cam position control beam 3-4 can be deflected by the housing radial groove 1-5 as the plunger rod 6 pushes the cam 3 towards the syringe barrel. As shown in FIG. 16C, upon cam 3 contacting the back cover 1 of the housing at the end-of-dose position, the cam position control beam 3-4 can snap into a second groove of the housing radial groove 1-5, thereby preventing the cam 3 from leaving the end-of-dose axial position.

[0060] FIGS. 17A-17C illustrate another exemplary controlled dosage delivery assembly 22 incorporating an alternate needle safety sub-assembly 18. Unless explicitly stated otherwise herein, the components and mode of operation of assembly 22 can be identical or equivalent to assembly 21 described above. As shown in FIGS. 17A and 17B, the needle safety subassembly 18 can include an additional removable needle safety cap 17 that is connected to the cap 14 of the staked needle syringe 10 and removable by pulling or twisting. The additional cap 17 can improve the user’s ability to safely remove the original cap 14. The needle safety sub-assembly 18 can include a flange adapter 16 that can obstruct the user’s view of the syringe at the end of actuation, upon releasing the shield 13. As shown in FIG. 17C, assemblies can be attached to one another using a two-action push-and-twist.

[0061] Additional features of assembly 22 are shown and described with respect to FIGS. 18A-18C. The needle safety sub-assembly 18 can provide a reduced grip span between the outer shield finger flanges (e.g., as compared to flanges 13-3 described with respect to assembly 15) and the plunger rod finger pad 6-1.

[0062] FIGS. 18A-18C also illustrate the dose injection stroke and safety actuation steps for the alternate needle safety sub-assembly 18. FIG. 18A shows the plunger rod finger pad 6-1 being pushed toward the needle safety sub-assembly. As shown in FIG. 18B, as the plunger rod is pushed toward the syringe, the plunger stopper 9 comes into view in an opening in the shield 13. As shown in FIG. 18C, when the end-of-dose position is reached, the flange adapter syringe cover 16-2 can obstruct the view of the fluid within the syringe.EMBODIMENTS

[0063] The following embodiments are merely exemplary and are not intended to limit the scope of the disclosure provided herein.

[0064] Embodiment 1. A drug injection device, comprising: a plunger rod sub-assembly, comprising: a housing; a plunger rod movably coupled to the housing; and a dial axially constrained by the housing, the dial configured to set a start-of-dose position of the plunger rod by axially translating the plunger rod, and to set an end-of-dose position of the plunger rod; and a needle safety sub-assembly, comprising: a syringe barrel; a needle extending from the syringe barrel; and a shield configured to automatically release at the end-of-dose position to shield the needle.

[0065] Embodiment 2. The drug injection device of embodiment 1, wherein the shield is configured to irreversibly shield the needle.

[0066] Embodiment 3. The drug injection device of embodiment 1 or 2, wherein the device is single-use.

[0067] Embodiment 4. The drug injection device of any one of embodiments 1-3, wherein the needle shield sub-assembly is configured to obstruct a view of the syringe barrel and the needle after the shield is released.

[0068] Embodiment 5. The drug injection device of any one of embodiments 1-4, wherein the shield comprises at least one finger flange extending laterally from the shield.

[0069] Embodiment 6. The drug injection device of embodiment 5, wherein a release rate of the shield is controllable by a user releasing force on the at least one finger flange.

[0070] Embodiment 7. The drug injection device of any one of embodiments 1-6, wherein at least the shield of the needle safety sub-assembly is transparent.

[0071] Embodiment 8. The drug injection device of any one of embodiments 1-7, wherein the shield comprises at least one window for viewing the syringe barrel and the needle.

[0072] Embodiment 9. The drug injection device of any one of embodiments 1-8, wherein the plunger rod sub-assembly comprises a cam coupled to the dial and configured to couple to the plunger rod at the end-of-dose position.

[0073] Embodiment 10. The drug injection device of embodiment 9, wherein the housing comprises at least one window for viewing a selected dose on the cam.

[0074] Embodiment 11. The drug injection device of any one of embodiments 1-10, wherein the dial is configured to be constrained from returning to the start-of-dose position after moving toward the end-of-dose position.

[0075] Embodiment 12. The drug injection device of any one of embodiments 1-11, wherein setting the end-of-dose position using the dial does not further axially translate the plunger rod.

[0076] Embodiment 13. The drug injection device of any one of embodiments 9-12, comprising a lever configured to amplify movement of the plunger rod compared to movement of the cam.

[0077] Embodiment 14. The drug injection device of any one of embodiments 1-13, wherein the device is configured to provide an audible click upon reaching at least one of the start-of-dose position and the end-of-dose position.

[0078] Embodiment 15. A method for delivering a drug using a drug injection device, comprising: setting a start-of-dose position of a plunger rod of the device by engaging a dial of the device, wherein setting the start-of-dose position causes axial translation of the plunger rod; setting an end-of-dose position by engaging the dial; inserting a needle of the device into the subject; and delivering the drug by moving the plunger rod to the end-of-dose position, wherein upon reaching the end-of-dose position, a shield of the device is configured to automatically release to shield the needle.

[0079] Embodiment 16. The method of embodiment 15, wherein the shield irreversibly shields the needle.

[0080] Embodiment 17. The method of embodiment 15 or 16, comprising disposing the device after a single use.

[0081] Embodiment 18. The method of any one of embodiments 15-17, wherein a needle shield sub-assembly of the device that includes the shield obstructs a view of a syringe barrel of the device and the needle after the shield is released.

[0082] Embodiment 19. The method of any one of embodiments 15-18, wherein the shield comprises at least one finger flange extending laterally from the shield.

[0083] Embodiment 20. The method of embodiment 19, comprising controlling a release rate of the shield by releasing force on the at least one finger flange after delivering the drug.

[0084] Embodiment 21. The method of any one of embodiments 15-20, wherein the shield is transparent.

[0085] Embodiment 22. The method of any one of embodiments 15-21, wherein the shield comprises at least one window for viewing a syringe barrel of the device and the needle.

[0086] Embodiment 23. The method of any one of embodiments 15-22, wherein the device comprises a cam coupled to the dial and configured to couple to the plunger rod at the end-of-dose position.

[0087] Embodiment 24. The method of embodiment 23, wherein a housing of the device comprises at least one window for viewing a selected dose on the cam.

[0088] Embodiment 25. The method of any one of embodiments 15-24, wherein the dial is constrained from returning to the start-of-dose position after moving toward the end-of-dose position.

[0089] Embodiment 26. The method of any one of embodiments 15-25, wherein setting the end-of-dose position using the dial does not further axially translate the plunger rod.

[0090] Embodiment 27. The method of any one of embodiments 23-26, wherein the device comprises a lever that amplifies movement of the plunger rod compared to movement of the cam.

[0091] Embodiment 28. The method of any one of embodiments 15-27, wherein the device provides an audible click upon reaching at least one of the start-of-dose position and the end-of-dose position.

[0092] The foregoing description, for the purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodimentswere chosen and described in order to best explain the principles of the techniques and their practical applications. Others skilled in the art are thereby enabled to best utilize the techniques and various embodiments with various modifications as are suited to the particular use contemplated. Although the disclosure and examples have been fully described with reference to the accompanying figures, it is to be noted that various changes and modification will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the disclosure and examples as defined by the claims. Finally, the entire disclosure of the patents and publications referred to this application are hereby incorporated herein by reference.

Claims

CLAIMSWhat is claimed is:

1. A drug injection device, comprising:a plunger rod sub-assembly, comprising:a housing;a plunger rod movably coupled to the housing; anda dial axially constrained by the housing, the dial configured to set a start-of- dose position of the plunger rod by axially translating the plunger rod, and to set an end-of-dose position of the plunger rod; anda needle safety sub-assembly, comprising:a syringe barrel;a needle extending from the syringe barrel; anda shield configured to automatically release at the end-of-dose position to shield the needle.

2. The drug injection device of claim 1, wherein the shield is configured to irreversibly shield the needle.

3. The drug injection device of claim 1, wherein the device is single-use.

4. The drug injection device of claim 1, wherein the needle shield sub-assembly is configured to obstruct a view of the syringe barrel and the needle after the shield is released.

5. The drug injection device of claim 1, wherein the shield comprises at least one finger flange extending laterally from the shield.

6. The drug injection device of claim 5, wherein a release rate of the shield is controllable by a user releasing force on the at least one finger flange.

7. The drug injection device of claim 1, wherein at least the shield of the needle safety sub-assembly is transparent.

8. The drug injection device of claim 1, wherein the shield comprises at least one window for viewing the syringe barrel and the needle.

9. The drug injection device of claim 1, wherein the plunger rod sub-assembly comprises a cam coupled to the dial and configured to couple to the plunger rod at the end-of-dose position.

10. The drug injection device of claim 9, wherein the housing comprises at least one window for viewing a selected dose on the cam.

11. The drug injection device of claim 1, wherein the dial is configured to be constrained from returning to the start-of-dose position after moving toward the end-of-dose position.

12. The drug injection device of claim 1, wherein setting the end-of-dose position using the dial does not further axially translate the plunger rod.

13. The drug injection device of claim 9, comprising a lever configured to amplify movement of the plunger rod compared to movement of the cam.

14. The drug injection device of claim 1, wherein the device is configured to provide an audible click upon reaching at least one of the start-of-dose position and the end-of-dose position.

15. A method for delivering a drug using a drug injection device, comprising:setting a start-of-dose position of a plunger rod of the device by engaging a dial of the device, wherein setting the start-of-dose position causes axial translation of the plunger rod;setting an end-of-dose position by engaging the dial;inserting a needle of the device into the subject; anddelivering the drug by moving the plunger rod to the end-of-dose position, wherein upon reaching the end-of-dose position, a shield of the device is configured to automatically release to shield the needle.

16. The method of claim 15, wherein the shield irreversibly shields the needle.

17. The method of claim 15, comprising disposing the device after a single use.

18. The method of claim 15, wherein a needle shield sub-assembly of the device that includes the shield obstructs a view of a syringe barrel of the device and the needle after the shield is released.

19. The method of a claim 15, wherein the shield comprises at least one finger flange extending laterally from the shield.

20. The method of claim 19, comprising controlling a release rate of the shield by releasing force on the at least one finger flange after delivering the drug.

21. The method of claim 15, wherein the shield is transparent.

22. The method of claim 15, wherein the shield comprises at least one window for viewing a syringe barrel of the device and the needle.

23. The method of a claim 15, wherein the device comprises a cam coupled to the dial and configured to couple to the plunger rod at the end-of-dose position.

24. The method of claim 23, wherein a housing of the device comprises at least one window for viewing a selected dose on the cam.

25. The method of claim 15, wherein the dial is constrained from returning to the start-of-dose position after moving toward the end-of-dose position.

26. The method of claim 15, wherein setting the end-of-dose position using the dial does not further axially translate the plunger rod.

27. The method of claim 23, wherein the device comprises a lever that amplifies movement of the plunger rod compared to movement of the cam.

28. The method of claim 15, wherein the device provides an audible click upon reaching at least one of the start-of-dose position and the end-of-dose position.

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