Needle-free syringe dose setting device and method

Abstract

The needle-free injector includes a dose setting device. The needle-free injector includes a hammer housing, a main spring positioned within the hammer housing, and a hammer assembly that engages with the main spring. The hammer assembly can include a hammer sleeve and a hammer that engages with the hammer sleeve, where engagement between the hammer sleeve and the hammer results in changing the forward or rearward position of the hammer relative to the hammer sleeve to select one injection dose from two or more available injection doses. Further embodiments include methods of varying or setting the dose delivered by the needle-free injector.

Description

[Technical Field]

[0001] The present disclosure relates to systems, devices, and methods for setting a dose of an injectable material delivered by a needleless injector. [Background technology]

[0002] The advantages of needle-free injection devices have long been recognized. Some of the advantages of needle-free devices and methods include the absence of needles, which can pose a threat to patients and a risk to healthcare professionals. Furthermore, needle-based injections can increase the risk of cross-contamination between patients. Furthermore, needle-based injection devices carry a substantial risk of needle breakage within the tissue of a human or animal subject. The injection jet generated by needle-free devices is generally more rapid and preferable than the injection provided by hypodermic needle devices.

[0003] Due to these and other advantages, many variations of pneumatically, electronically, or spring-activated needleless injection devices are designed to provide a single injection. Modern needleless injectors are typically designed for use with single-use and / or disposable needleless syringes to minimize the risk of cross-infection. Single-use and / or disposable needleless syringes have a structure that allows the needleless syringe to be attached to a corresponding syringe, easily ejected from the syringe, and then discarded or recycled. Some needleless injectors are integrated with the needleless syringe, and the entire device is single-use and disposable. Typically, each syringe is designed to hold a specific amount of injectable material, and the corresponding syringe is designed to completely expel that specific amount of injectable material during injection. Therefore, with many needleless injector / syringe combinations, it is difficult or impossible to select, change, or vary the amount of injectable material delivered between injections.

[0004] There are times when it is beneficial to vary from the standard dose of a therapeutic injectable material, for example, when the patient is a child, very small, very large, or has a medical condition that affects administration. In many cases, a user must select an entirely different needleless injector / syringe combination if a variation from the standard dose provided by a particular needleless injector / syringe combination is desired.

[0005] The embodiments disclosed herein are directed to overcoming one or more of the above problems. Summary of the Invention

[0006] One general aspect disclosed herein is a needle-free injector including a dose setting device. The needle-free injector includes a hammer housing, a main spring positioned within the hammer housing, and a hammer assembly that engages with the main spring. The hammer assembly can include a hammer sleeve and a hammer that engages with the hammer sleeve, and engagement between the hammer sleeve and the hammer causes the hammer to change a forward or rearward position relative to the hammer sleeve to select one injection dose from two or more available injection doses.

[0007] In some embodiments, the engagement between the hammer sleeve and the hammer is a threaded engagement. The hammer sleeve may include a spring interface shoulder. The hammer may include a hammer stop block. The hammer housing may include a front wall that the hammer stop block contacts upon discharge of the needle-free injector. This embodiment may also include a control assembly for varying the forward or rearward position of the hammer relative to the hammer sleeve. The control assembly may be a dose selector knob, such that rotation of the dose selector knob rotates the hammer relative to the hammer sleeve in the threaded engagement. The control assembly may include indexed structure that becomes engaged to limit rotational movement of the dose selector knob when the dose selector knob rotates through a predetermined rotation angle. The needle-free injector may also include a status indicator and a window through which the status indicator can be viewed. The status indicator may include an indication of the armed status of the needle-free injector, the selected dose to be delivered by the needle-free injector, other information, or a combination of information.

[0008] Other embodiments disclosed herein include a method of setting or selecting a dose to be delivered by a needle-free injector as described above, wherein the dose setting step includes manipulating the engagement between the hammer sleeve and the hammer to vary the forward or rearward position of the hammer relative to the hammer sleeve to select one injection dose from two or more available injection doses. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a front view of an exemplary needle-free injector with a dose setting device disclosed herein.

[0010] [Figure 2] FIG. 2 is a front view of the needle-free injector of FIG. 1 in an armed configuration.

[0011] [Figure 3]2 is a vertical cross-sectional view of the needle-free syringe of FIG. 1, with the cross-section taken along the longitudinal centerline of the syringe.

[0012] [Figure 4] 2 is a vertical cross-sectional view of the front portion of the needle-free injector of FIG. 1 , with the cross-section taken along the longitudinal centerline of the injector, with the needle-free syringe installed and the dose setting device set to deliver the minimum dose.

[0013] [Figure 5] FIG. 2 is a vertical cross-sectional view of the front portion of the needle-free injector of FIG. 1 , with the cross-section taken along the longitudinal centerline of the injector, with the needle-free syringe installed and the dose setting device set to deliver the maximum dose.

[0014] [Figure 6] FIG. 2 is an exploded view of the needle-free syringe of FIG. 1.

[0015] [Figure 7] FIG. 1 is a perspective view of a dose setting device disclosed herein.

[0016] [Figure 8] FIG. 8 is a vertical cross-sectional view of the dose setting device of FIG. 7, the cross-section being taken along the longitudinal centerline of the dose setting device.

[0017] [Figure 9A] FIG. 1 is a perspective view of a hammer assembly disclosed herein.

[0018] [Figure 9B] FIG. 9B is a combined cross-sectional and perspective view of the hammer assembly of FIG. 9A.

[0019] [Figure 9C] 9B is a vertical cross-sectional view of the hammer assembly of FIG. 9A, the cross-section being taken along the longitudinal centerline of the hammer assembly. FIG.

[0020] [Figure 10A]FIG. 2 is a vertical cross-sectional view of the needleless injector of FIG. 1 , with the cross-section taken along the longitudinal centerline of the injector, with the needleless syringe installed, the injector disarmed, and the dose setting device set to deliver the minimum dose.

[0021] [Figure 10B] FIG. 2 is a vertical cross-sectional view of the needleless injector of FIG. 1 , with the cross-section taken along the longitudinal centerline of the injector, with the needleless syringe installed, the injector disarmed, and the dose setting device set to deliver the maximum dose.

[0022] [Figure 11A] FIG. 8 is a vertical cross-sectional view of the dose setting device of FIG. 7, with the cross-section taken along the longitudinal centerline of the dose setting device, with the syringe disarmed and the dose setting device set to deliver a minimum dose.

[0023] [Figure 11B] FIG. 8 is a vertical cross-sectional view of the dose setting device of FIG. 7, with the cross-section taken along the longitudinal centerline of the dose setting device, with the syringe disarmed and the dose setting device set to deliver the maximum dose.

[0024] [Figure 12A] FIG. 1 is a vertical cross-sectional view of an alternative syringe embodiment including a dose setting device disclosed herein, with the syringe disarmed and the dose setting device set to deliver a minimum dose, with the cross-section taken along the longitudinal centerline of the syringe.

[0025] [Figure 12B] FIG. 12B is a vertical cross-sectional view of the syringe embodiment of FIG. 12A, with the cross-section taken along the longitudinal centerline of the syringe, with the syringe disarmed and the dose setting device set to deliver the maximum dose.

[0026] [Figure 13A]10B is a vertical cross-sectional view of the needle-free injector of FIG. 10A, the cross-section taken along the longitudinal centerline of the injector after delivery of the minimum dose.

[0027] [Figure 13B] FIG. 10C is a vertical cross-sectional view of the needle-free injector of FIG. 10B, the cross-section taken along the longitudinal centerline of the injector after delivery of the maximum dose.

[0028] [Figure 14A] 12B is a vertical cross-sectional view of the needle-free syringe of FIG. 12A, the cross-section taken along the longitudinal centerline of the syringe after delivery of the minimum dose.

[0029] [Figure 14B] FIG. 12C is a vertical cross-sectional view of the needle-free syringe of FIG. 12B, with the cross-section taken along the longitudinal centerline of the syringe after delivery of the maximum dose.

[0030] [Figure 15] FIG. 1 is a plan view of a dose setting control device disclosed herein.

[0031] [Figure 16A] FIG. 16 is a plan view of the dose setting control device of FIG. 15, showing an alternative indicator through a window.

[0032] [Figure 16B] FIG. 16B is a diagram of the dose setting control device of FIG. 16A highlighting the window and index element.

[0033] [Figure 17] FIG. 10 is a plan view of a label containing indicia indicating the status of the syringe and the selected dose. DETAILED DESCRIPTION OF THE INVENTION

[0034] In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the described embodiments. However, it will be apparent to those skilled in the art that other embodiments may be practiced without some of the specific details. While several embodiments are described herein and various features are attributed to different embodiments, it should be understood that features described with respect to one embodiment may also be incorporated into other embodiments. Similarly, however, no single or multiple features of any described embodiment should be deemed essential to all embodiments of the present invention, as other embodiments of the present invention may omit such features.

[0035] Unless otherwise stated, all numbers used herein to express quantities, dimensions, and the like are to be understood as modified in all instances by the term "about." In this application, the use of the singular includes the plural unless expressly stated otherwise, and the use of the terms "and" and "or" means "and / or" unless otherwise indicated. Furthermore, the use of the term "comprising," as well as other forms such as "comprises" and "includes," should be considered non-exclusive. Also, terms such as "element" or "component" encompass both plural elements and components comprising one unit and plural elements and components comprising two or more units, unless expressly stated otherwise.

[0036] An exemplary needle-free injector 10 including a dose setting device disclosed herein is shown in FIGS. 1-6. Many needle-free injectors include a device configured to drive the plunger of the needle-free syringe toward the syringe nozzle to expel a vaccine, therapeutic, or other liquid injectable substance contained within the needle-free syringe. Furthermore, the injector device must expel the injectable substance with sufficient force to inject the injectable substance into a patient's tissue without the need for an intervening needle. Known needle-free injectors can be configured to inject into intradermal, intramuscular, or subcutaneous tissue layers. Some needle-free injectors can be configured to selectively inject into more than one layer of tissue. The dose setting devices and methods disclosed herein can be implemented with needle-free injectors sized or configured to deliver an injectable substance into any tissue layer.

[0037] Furthermore, various mechanisms are known for providing the force necessary to expel an injectable substance from a needle-free syringe. Known needle-free syringe drive mechanisms include compression springs, compressed gas sources, and electric solenoids. The dose setting devices and methods disclosed herein may be implemented with needle-free syringes that rely on any power source, including, but not limited to, a spring, compressed gas, or an electrical power source.

[0038] The specific needleless injector 10 shown in Figures 1-6 is a spring-driven injector configured to inject into the intradermal layer. As described in detail herein, the exemplary injector includes a device that allows the dose of injectable substance delivered by the injector 10 to be selected or controlled by the user. In certain embodiments, the selectable dose is infinitely variable between two endpoints. For example, an injector 10 configured for intradermal injection may be configured to deliver an infinitely variable dose selected from between a 0.02 mL endpoint and a 0.1 mL endpoint. An alternative device configured for intramuscular or subcutaneous injection may be configured to deliver an infinitely variable dose selected from between a 0.25 mL endpoint and a 0.5 mL endpoint.

[0039] Alternative syringes 10 may include indexing devices that facilitate the selection and delivery of specific incremental doses between endpoints. For example, a syringe configured for intradermal use may be configured to allow a user to select and deliver doses of 0.02 mL, 0.03 mL, 0.04 mL, 0.05 mL, 0.06 mL, 0.07 mL, 0.08 mL, 0.09 mL, and 0.1 mL. Alternative syringes 10 may be configured for injection into intramuscular or subcutaneous tissue and may be configured to allow a user to select doses of 0.25 mL and 0.5 mL. The exemplary dose ranges and increments described above are not intended to limit the scope of the present disclosure. The dose setting mechanisms and methods described herein can be scaled and implemented to provide any desired dose within any selected endpoint.

[0040] Generally, the exemplary syringe 10 of FIGS. 1-6 is prepared for use by installing a mating needleless syringe, disarming the syringe by compressing the mainspring 14, delivering the injection, and then ejecting the syringe. To accomplish these basic tasks, the syringe 10 includes a handle 12 that is manipulated by a user to compress the mainspring 14 and disarm the syringe 10 prior to injection. The handle 12 is attached to a housing or syringe body 16. The syringe portion defines a socket 18 configured to receive a suitable needleless syringe 20, as shown in detailed views in FIGS. 4 and 5. Typically, the syringe 10 also includes various controls used to prepare and deliver the injection. Exemplary controls may include, but are not limited to, an actuation / syringe load button 20 and a syringe eject button 22. Further details regarding intradermal syringe embodiments are contained in commonly owned U.S. Patent No. 9,433,735, entitled "Needle-Free Intradermal Injection Device," the entire disclosure of which is incorporated herein by reference for all that is set forth therein. Further details regarding intramuscular / subcutaneous syringe embodiments are contained in commonly owned U.S. Patent No. 9,408,972, entitled "Needle-Free Injection Device," the entire disclosure of which is incorporated herein by reference for all that is set forth therein.

[0041] The syringe 10 also includes a dose setting device 26, which is described in detail below. The embodiments of the dose setting device 26 disclosed herein are configured to function with replaceable and / or disposable needleless syringes 20. The dose setting device 26 allows the dose delivered by the syringe 10 and needleless syringe 20 combination to be selected from multiple possible doses without requiring any modifications to the mechanical structure of the syringe 20. Thus, the same size and type of syringe can be used with any selected dose. As shown in FIGS. 4 and 5 , a typical needleless syringe 20 typically includes an indexing feature 28 configured to engage with the socket 18 of the syringe 10 prior to injection. Opposite the indexing feature 28 are a nozzle 30 and a skin tensioning ring 32, which are positioned against the patient's skin during use. The syringe body 34 defines an internal cavity 36 extending from the nozzle 30 to an opening 38 opposite the nozzle 30. A plunger 40 is positioned within the internal cavity 36. When the syringe 10 is armed and ready to deliver an injection, a dose space 42 having a specific volume is defined within the internal cavity 36 between the nozzle 30 and the forward surface 44 of the plunger 40. As used throughout this disclosure, the "forward" direction is defined to mean either toward the nozzle end of the needleless syringe 20 or toward the syringe socket end of the syringe 10. The "rearward" direction is defined to be away from the nozzle / socket end of the syringe 10 and syringe 20.

[0042] As can be seen by comparing Figure 4 with Figure 5, the dose space 42 can have a greater or lesser volume depending on the positioning of the plunger 40 within the internal cavity 36 prior to injection. Prior to injection, the dose space 42 is filled with an injectable substance. Various embodiments of the dose setting device 26 disclosed herein can be used to set the selected dose space 42 and thus select the dose of the injectable substance to be delivered to the patient. As a non-limiting example, the volume within the dose space 42 shown in Figure 4 is 0.02 mL, and the volume within the dose space 42 shown in Figure 5 is 0.1 mL. These doses are deliverable from the same syringe 10 using mechanically identical needleless syringes 20. Furthermore, the syringe 10 including the dose setting device 26 can adequately deliver the selected dose through intervening tissue layers without the use of a hypodermic needle. Suitable dose delivery characteristics include, but are not limited to, injection of any dose into the desired tissue layer, minimal wastage of injectable material, and relative ease of use that minimizes the risk of operator error during the injection or dose setting steps.

[0043] An exemplary dose setting device 26 is shown in Figures 7 and 8. The dose setting device 26 includes a hammer housing 46 that supports and houses various internal components. The hammer housing 46 may be a unitary structure or may be comprised of any number of multiple sections. The hammer housing 46, as defined herein, is not limited to any specific structure other than being a structure that at least partially houses or houses a hammer assembly 48.

[0044] In the embodiment of the syringe 10 of Figures 1-6, the mainspring 14 surrounds and contacts the hammer assembly 48. Thus, the mainspring 14 is also disposed within the hammer housing 46 in the illustrated embodiment. As noted above, the dose setting device 26 can be utilized within syringes that utilize compressed gas or an electric solenoid to provide the force necessary for needle-free injection. In such embodiments, the hammer assembly 48 includes or comes into contact with a gas or solenoid piston or other structure configured to be urged forward by expanding gas or electromagnetic energy to drive the injection.

[0045] The hammer assembly 48 of FIG. 8 includes various components, which are described in detail below. Generally, however, the hammer assembly 48 is a piston-like device that engages the mainspring 14 or other power source. The hammer assembly 48 also contacts the rear surface 50 of the syringe plunger 40 prior to injection. During injection, the injector 10 operates by releasing energy previously stored in the mainspring 14 to drive the hammer assembly 48 forward, forcing the plunger 40 forward into the syringe 20 and forcing the injection drug through the nozzle 30.

[0046] A representative hammer assembly 26 is shown in FIGS. 9A, 9B, and 9C. The hammer assembly includes a hammer sleeve 52 that engages a hammer 54. As best shown in the exploded view of FIG. 6, the hammer 54 includes at least a forward extension 56 and a rearward extension 58. The forward extension 56 and the rearward extension 58 may be co-formed in a particular hammer 54 embodiment, or, as shown in FIG. 6, the forward extension 56 and the rearward extension 58 may be formed as separate components that are joined together with a threaded joint or by other means during assembly. When the syringe 10 is armed and ready to inject, a forward surface 60 of the forward extension 56 contacts the rearward surface 50 of the syringe plunger 40. Additionally, a portion of the rearward extension 58 contacts a control assembly 62 of the dose setting device 26.

[0047] The hammer 54 extends through a longitudinal inner diameter 64 defined by the hammer sleeve 52. Thus, the hammer 54 can move forward or rearward relative to the hammer sleeve 52. Precise forward or rearward movement of the hammer 54 relative to the hammer sleeve 52 can be achieved by a threaded engagement 66 between the hammer 54 and the hammer sleeve 52. For example, the hammer sleeve 52 can include an internal thread 68 along the internal diameter 64 extending through the hammer sleeve 52. The hammer 54 can include corresponding external threads 70 around its outer surface. In the illustrated embodiment, the external threads 70 are formed around the outer surface of the rearward extension 58. In an alternative embodiment, the external threads 70 can be formed around the outer surface of the forward extension 56. In a threaded embodiment, rotation of the hammer 54 relative to the hammer sleeve 52 provides precise adjustment of the forward or rearward position of the hammer 54 relative to the hammer sleeve 52. Other mechanisms for adjusting the forward or rearward position of the hammer 54 relative to the hammer sleeve 52 are within the scope of this disclosure. For example, the relative position of the hammer 54 and hammer sleeve 52 can be adjusted by a sliding engagement and lock screw or other locking mechanism, or by a ratchet mechanism.

[0048] The hammer sleeve 52 includes a mainspring engagement portion. In the illustrated embodiment, the mainspring engagement portion is a spring interface shoulder 72. The illustrated spring interface shoulder 72 is a flange formed in the outer surface of the hammer sleeve 52. The spring interface shoulder 72 may also be implemented by a separate component, such as a bushing and set screw assembly, a spring engagement pin, or the like. The spring interface shoulder 72 always engages the forward end of the mainspring 14.

[0049] As best seen in FIG. 9A , the hammer sleeve 52 also includes a stabilizing slot 74 that receives a hammer stop block 76. The hammer stop block 76 engages with the hammer 54 such that the longitudinal position of the hammer stop block 76 is locked to the hammer, allowing the stop block 76 to move forward or rearward with the hammer 54 while remaining within the stabilizing slot 74 of the hammer sleeve 52. In the threaded hammer assembly 48 embodiment, the hammer 54 must be free to rotate relative to the hammer sleeve 52, so the hammer stop block 76 includes a central channel 78 through which the hammer 54 extends. Because the hammer 54 is not bonded to the central channel 78, the hammer 54 can rotate about its central axis within the central channel 78. The hammer stop block 76 is captured in longitudinal position on the hammer 54 between a flange 80 and a forward shoulder 82 of the rearward extension 58. Thus, as the hammer 54 rotates within the hammer sleeve 52 , the hammer stop block 76 does not rotate but moves forward and rearward within the hammer sleeve 52 while being supported by the stabilizing slot 74 .

[0050] As will be explained in more detail below, hammer stop block 76 contacts front wall 84 of hammer housing 46 upon completion of an injection. Thus, contact between hammer stop block 76 and front wall 84 stops forward movement of the entire hammer assembly 48 at the end of the injection.

[0051] The dose setting device also includes a control assembly 62. The control assembly 62 is used to adjust the forward or rearward position of the hammer 54 within the hammer sleeve 52. The illustrated control assembly 62 includes a dose selector knob 86 that engages with the hammer 54. The illustrated dose selector knob 86 includes a central socket 88 defined by the dose selector knob 86 to mate with a spline 90 or other structure on the hammer 54 to ensure that the dose selector knob 86 rotates and locks to the hammer 54. The hammer 54 and the dose selector knob 86 are not otherwise joined to one another. Thus, the hammer 54 can move freely forward or rearward relative to the dose selector knob 86 while maintaining rotational engagement. As described in more detail below, certain embodiments of the dose selector knob 86 may also move independently forward and rearward while maintaining rotational engagement with the hammer 54.

[0052] The dose selector knob 86 may include or be associated with an indexing structure 92. One example of an indexing structure 92 includes an extension 94 from the dose selector knob 86 that mates with a corresponding gap 96 defined in a corresponding control housing element 97, as shown in FIGS. 6 and 7 . Other possible indexing structure embodiments include, but are not limited to, mating radial splines, other mating shapes that allow for easy engagement and disengagement, pin and socket assemblies, opposing magnets, and the like. Any indexing structure 92 ensures that the dose selector knob 86 cannot easily rotate when the indexing structure 92 is engaged. In contrast, the dose selector knob 86 can easily rotate when disengaged from the indexing structure 92. Furthermore, the dose selector knob 86 can rotate in defined steps having a predetermined angle of rotation determined by the indexing structure 92. Alternatively, any indexing structure 92 may be omitted such that the dose selector knob 86 is infinitely adjustable.

[0053] In embodiments including the indexing structure 92, the dose selector knob 86 may be biased forward by the spring 98 such that when the dose selector knob 86 is rotated to the appropriate angle for engagement, the indexing structure 92, e.g., the extension 94 and the gap 96, come into contact and are biased. In this configuration, before the dose selector knob 86 can be rotated to a different angle, the dose selector knob 86 must be pulled rearward against the bias provided by the spring 98 to disengage the indexing structure 92. The indexing structure 92 and / or the biasing spring 98 provide security against inadvertent rotation of the dose selector knob 86.

[0054] The control assembly 62 may also include a status indicator 100 defined by or attached to the hammer. In the illustrated embodiment, the status indicator is a generally cylindrical status sleeve 102 that is joined to the rearward extension 58 of the hammer 54 so as to rotate and move forward and backward with the hammer 54. The cylindrical status sleeve 102 includes an outward-facing surface 104 that may be marked with indicia 106 relating to device status. As described in detail below, the indicia 106 may be viewed by a user through a window 108 in the housing element 97. In some embodiments, the window 108 includes a magnifying lens 110. Alternatively, the indicia may not be directly visible if there is no covering housing element.

[0055] The above-described device may be used to select, adjust, or otherwise set a dose delivered by a needleless injector. As noted above, it is desirable for a user to be able to set or select an injection dose without having to choose from a variety of dose-specific syringes. The embodiments disclosed herein enable dose selection and dose delivery using interchangeable or disposable syringes that are otherwise structurally identical. It would also be advantageous to set or select a dose without unnecessarily wasting therapeutic injectable material. Finally, it is important that the mainspring 14 is properly compressed according to the design parameters of any selected dose to ensure a complete and proper injection.

[0056] As shown by comparing Figures 4 and 5, the dose delivered from otherwise structurally identical syringes is defined by a dose space 42 between a forward surface 44 of the needleless syringe plunger 40 and the nozzle 30. In the illustrated example, the representative dose space 42 in Figure 4 is approximately the minimum dose (e.g., 0.02 mL) achievable by the illustrated syringe 10. The representative dose space 42 in Figure 5 is approximately the maximum dose (e.g., 0.1 mL) achievable by the syringe 10. Intermediate doses are defined by intermediate plunger positions.

[0057] Figures 10A and 11A correspond to Figure 4 and show a configuration of the syringe 10 or dose setting device 26 configured to deliver a minimum dose. Figures 10B and 11B correspond to Figure 5 and show the same syringe 10 configured to deliver a maximum dose. Each of Figures 10A, 10B, 11A, and 11B shows the syringe 10 in a fully armed configuration immediately prior to injection. The dose setting step described below may be performed before or after compressing the mainspring 14 or otherwise arming the syringe 10. The dose setting step may be performed before or after inserting a filled needleless syringe 20 into the syringe socket 18.

[0058] Dose setting is accomplished by operating the control assembly 62 of the dose setting device 26. For example, rotation of the dose selector knob 86 may rotate the hammer 54 within the hammer sleeve 52 on the threaded engagement 66. Rotation of the hammer in a first direction (clockwise or counterclockwise, depending on the thread) moves the hammer 54 forward relative to the hammer sleeve 52. The configurations shown in FIGS. 4, 10A, and 11A show the hammer fully moved forward, corresponding to the minimum dose. When the hammer is positioned in the forward position relative to the hammer sleeve, the length "L" by which the forward extension 56 of the hammer 54 extends into the opening 38 of the needleless syringe 20 is at its maximum, corresponding to the minimum dose in FIGS. 4, 10A, and 11A.

[0059] 4, 10A, and 11A, the distance "D" between the hammer stop block 76 and the front wall 84 of the hammer housing 46 is minimized because the hammer stop block 76 is positioned fully forward within the stabilizing slot 74 of the hammer sleeve 52. Distance D corresponds to the stroke length of the hammer when an injection is triggered, as the hammer assembly 48 is driven forward by the mainspring 14 until the hammer stop block 76 contacts the front wall 84 of the hammer housing 46. As can be readily seen from FIG. 4, distance D in this configuration directly corresponds to the relatively short length of plunger travel required to fully eject the minimized dose.

[0060] 5, 10B, and 11B show the same syringe 10 after the dose selector knob 86 has been rotated in the opposite direction to move the hammer 54 fully rearward relative to the hammer sleeve 52. This configuration corresponds to the maximum possible dose deliverable by this particular needle-free syringe 10. Note that in FIGS. 5, 10B, and 11B, the length L is minimized and the distance D is maximized, corresponding to the rearward initial plunger position and longer hammer stroke length required to fully expel the maximum dose deliverable by this particular needle-free syringe 10.

[0061] It is important to note that Figures 4, 5, 10A, 10B, 11A, and 11B show specific syringes 10 configured to deliver the minimum or maximum dose achievable by the illustrated device. The control assembly 62 may also be operated to deliver any number of intermediate doses. In some embodiments, the control assembly may provide infinite, unstructured variation between the minimum and maximum achievable doses.

[0062] Alternatively, the syringe 10 may include an indexing structure 92 associated with the control assembly 62. The indexing structure 92 facilitates rotation of the hammer in predetermined steps, with each rotation step corresponding to a selected rotation angle. By controlling the pitch of the threaded engagement 66 between the hammer 54 and the hammer sleeve 52, each rotation step may also correspond to a selectable dose. Any number of intermediate doses may be defined during manufacture of the syringe 10 by controlling the pitch of the threaded engagement 66 and the rotation angle(s) provided between the indexed stops.

[0063] The syringe 10 of FIGS. 4, 5, 10A, 10B, 11A, and 11B is optimized to deliver doses between 0.02 mL and 0.1 mL into the intradermal tissue layer. The dose setting device 26 can be scaled to larger or smaller syringes to provide other dose ranges. For example, FIGS. 12A and 12B show a slightly larger syringe 112 optimized for delivering injections into intramuscular or subcutaneous tissue. The syringe 112 includes a dose setting device 26 substantially as described above, but the hammer assembly 48 and mainspring 14 are relatively large. This component scaling, typically in combination with a slightly larger needleless syringe, results in the syringe 112 being configured to deliver a minimum dose of 0.25 mL, as shown in FIG. 12A, and a maximum dose of 0.5 mL, as shown in FIG. 12B. Intermediate doses are possible, as are alternative syringes with different dose ranges than those shown in the figures.

[0064] The objective of avoiding unnecessary waste of therapeutic injectable substance is substantially met by ensuring that the forward surface 44 of the plunger 40 fully abuts the nozzle 30 of the syringe 20 when the injection is completed. Otherwise, any remaining space between the forward surface 44 and the nozzle 30 after the injection will be filled with wasted injectable material. FIG. 13A shows the minimum dose configuration of the syringe 10 of FIGS. 4, 10A, and 11A after the injection is completed. Note that the hammer stop block 76 is in contact with the forward wall 84 of the hammer housing. Furthermore, the forward surface 44 of the plunger 40 fully abuts the nozzle 30 in the needleless syringe 20.

[0065] Similarly, Figure 13B shows the syringe 10 in the maximum dose configuration of Figures 5, 10B, and 11B after the injection is completed. Note that the hammer stop block 76 contacts the front wall 84 of the hammer housing. Additionally, the front surface 44 of the plunger 40 fully abuts the nozzle 30 within the needleless syringe 20. Similarly, the dose setting device 26 ensures that intermediate dose settings fully expel the injectable material from the dose space 42 because the hammer stroke length corresponding to distance D is equal to the distance the plunger 40 must travel within the needleless syringe 20 to fully expel the selected dose of injectable material at any dose setting.

[0066] This feature is present in any syringe that uses the dose setting device 26 disclosed herein. See, for example, Figures 14A and 14B, which show the larger syringe configurations of Figures 12A and 12B, respectively, after ejection. While the syringe and plunger elements are not shown in Figures 14A and 14B, note that the hammer stop block 76 contacts the forward wall 84 after ejection when configured to deliver any dose. Furthermore, the forward surface 60 of the forward extension 56 is positioned to fully expel the injectable material from the appropriate syringe at any dose setting.

[0067] A comparison of Figures 10A and 10B, or 12A and 12B, shows that when the syringe is armed at any selected dose, the spring interface shoulder 72 of the hammer sleeve 52 is positioned at the same starting point "A." This configuration ensures that the main spring 14 is fully compressed according to design parameters to successfully deliver the selected dose to the desired tissue layer.

[0068] Some embodiments may include a status indicator 100. One type of status indicator 100 is a stating sleeve 102 having a cylindrical outwardly facing surface 104 on which an indicia 106 may be disposed. The stating sleeve 102 is joined to the rearward extension 58 of the hammer 54. Thus, the stating sleeve 102 rotates with the hammer 54 and moves forward or rearward with the hammer 54. The particular indicia 106 may be viewed through a window 108 in the control housing element 97. The specific indicia 106 that is visible at any time depends on the longitudinal axial position of the hammer 54 and stating sleeve 102 and the rotational position of the hammer 54 and stating sleeve 102.

[0069] 13A and 13B show that after the injection has been delivered and the mainspring has driven the hammer assembly 48 as far forward as possible, the rearmost portion of the cylindrical outward surface 104 is below the window 108. This rearward portion of the cylindrical outward surface 104 may be surrounded by a colored band, for example a red band, to indicate to the user that the syringe 10 has been dispensed. See FIG. 15.

[0070] When the syringe 10 is armed by the hammer assembly 48 while compressing the mainspring 14, causing the hammer assembly to move rearward, the stator sleeve 102 moves rearward. The precise axial position and angular orientation of the cylindrical outward surface 104 of the stator sleeve 102 depends on the selected dose, as the hammer 54 moves forward or rearward relative to the hammer sleeve 52 when the dose is set as described above. For example, the stator sleeve 102 is positioned in a relatively forward position when the syringe 10 is set to deliver the minimum dose, as shown in FIGS. 10A and 11A. This position allows a relatively rearward portion of the cylindrical outward surface 104 to be viewed through the window 108. As shown in FIGS. 10B and 11B, when the dose selector knob 86 is operated to configure the syringe 10 to a higher dose, the stator sleeve 102 moves rearward with the hammer 54. This allows a relatively forward position on the cylindrical outward surface 104 to be viewed through the window 108. By optimizing the position of the indicia 106 on the cylindrical outward facing surface 104, for example, once a dose has been selected and the syringe 10 is armed, a numerical representation of the selected dose can be shown through the window 108. See Figures 16A and 16B.

[0071] FIG. 17 is a representation of a label 114 that can be applied to the cylindrical outward surface 104 to identify individual doses deliverable by the indexed syringe 10, as shown in FIGS. 10A, 10B, 11A, and 11B. In this exemplary embodiment, the pitch of the threads 66 is selected and configured so that a 120° rotation of the dose selector knob 86 in a first direction causes the hammer 54 to move forward within the hammer sleeve 52 a distance corresponding to a 0.01 mL decrease in the selected dose. The syringe 10 includes indexing structures 92 that facilitate rotation of the dose selector knob 86 within 120° increments and limit unintended further rotation. Thus, the label 114 is configured to wrap around the cylindrical outward surface 104 or otherwise applied to the indexing sleeve 102 such that the appropriate indicia 106 are visible below the window 108 once the dose selector knob 86 has been rotated the desired number of 120° increments and the syringe 10 is disarmed.

[0072] The indicator may include any desired type or combination of types of information. For example, the label 114 may include a numerical representation of the selected dose on a green area, with all other background portions 116 of the label being red. Thus, the user sees a green number indicating that the syringe 10 is set to the selected dose and armed. In all other configurations, the window will show a red indicator 106 if, for example, the syringe is discharged, improperly armed, or the dose is incompletely set.

[0073] The indicia 106 on an embodiment of an infinitely variable syringe may include a scale that spirals around the outwardly facing surface 104 from the rear portion of the stating sleeve to the front portion of the stating sleeve so that when the device is disarmed, a number or marking indicating the approximate dose is always visible below the window 108.

[0074] While specific exemplary embodiments have been described, those skilled in the art will recognize that many variations in the structure of the invention, as well as widely different embodiments and applications of the invention, will suggest themselves without departing from the scope of the invention. Thus, for ease of description and to illustrate exemplary aspects of those embodiments, various embodiments are described with or without particular features, but various components and / or features described herein with respect to particular embodiments can be substituted, added, and / or subtracted from other described embodiments, unless the context dictates otherwise. Thus, while several exemplary embodiments have been described above, it will be understood that the invention is intended to cover all modifications and equivalents within the scope of the following claims.

Claims

1. A needleless syringe, Hammer housing, a main spring positioned within the hammer housing; a hammer assembly engaging the main spring, Hammer sleeves, and a hammer engaging the hammer sleeve, the engagement between the hammer sleeve and the hammer causing a forward or rearward position of the hammer relative to the hammer sleeve to change to select one injection dose from two or more available injection doses; the hammer assembly including: The needle-free syringe.

2. The needle-free injector of claim 1 , wherein the engagement between the hammer sleeve and the hammer is a threaded engagement.

3. The needle-free injector of claim 1 , wherein the hammer sleeve includes a spring interface shoulder.

4. The needle-free injector of claim 3 , wherein the hammer includes a hammer stop block.

5. 5. The needle-free injector of claim 4, wherein the hammer housing includes a front wall that contacts the hammer stop block upon dispensing of the needle-free injector.

6. The needle-free injector of claim 4 , wherein the hammer includes a forward extension that extends forward of the hammer stop block, the forward extension having a fixed length.

7. 10. The needle-free injector of claim 1, further comprising a control assembly engaging the hammer, wherein articulation of the control assembly changes the forward or rearward position of the hammer relative to the hammer sleeve.

8. 8. The needle-free injector of claim 7, further comprising a threaded engagement between the hammer sleeve and the hammer, the control assembly being a dose selector knob, and rotational movement of the dose selector knob rotates the hammer in the threaded engagement relative to the hammer sleeve.

9. 9. The needle-free injector of claim 8, further comprising an indexed structure that becomes engaged to limit rotational movement of the dose selector knob when the dose selector knob is rotated through a predetermined angle of rotation.

10. 10. The needle-free injector of claim 9, further comprising a bias spring that biases the indexed structure into engagement until the dose selector knob is displaced against the bias of the bias spring, causing the indexed structure to disengage.

11. a status indicator defined by or attached to said hammer; a viewing window through which the status indicator can be viewed; 9. The needle-free injector of claim 8, further comprising:

12. 12. The needle-free injector of claim 11, wherein the status indicator includes an indication of at least one of an armed state of the needle-free injector and the selected dose to be delivered by the needle-free injector.

13. 1. A method for selecting a dose to be delivered by a needleless injector, comprising: The needle-free syringe includes: Hammer housing, a main spring positioned within the hammer housing; a hammer assembly engaging the main spring, Hammer sleeve, a hammer engaging the hammer sleeve; the hammer assembly, providing, manipulating the engagement between the hammer sleeve and the hammer to vary a forward or rearward position of the hammer relative to the hammer sleeve to select one of two or more available injection doses; The method comprising:

14. 14. The method of claim 13, wherein the engagement between the hammer sleeve and the hammer is a threaded engagement, and wherein the step of manipulating the engagement between the hammer sleeve and the hammer to change the forward or rearward position of the hammer relative to the hammer sleeve includes rotating one of the hammer sleeve or the hammer relative to the other in the threaded engagement.

15. providing a dose selector knob engaging said hammer; providing a status indicator defined by or attached to said hammer; Providing a viewing window; rotating the dose selector knob to rotate the hammer relative to the hammer sleeve in the threaded engagement; viewing the status indicator through the viewing window; 15. The method of claim 14, further comprising:

16. providing an indexing structure operably associated with said dose selector knob; rotating the dose selector knob through a predetermined angle of rotation such that the indexing structure becomes engaged; 15. The method of claim 14, further comprising:

17. 1. A method for selecting a dose to be delivered by a needleless injector, comprising: The needle-free syringe includes: a hammer housing defining a front wall; a main spring positioned within the hammer housing; a hammer assembly engaging the main spring, Hammer sleeve, a hammer including a hammer stop block engaging said hammer sleeve; the hammer assembly, providing, manipulating the engagement between the hammer sleeve and the hammer to vary a distance between the hammer stop block and the front wall when the needle-free injector is armed, the selected distance between the hammer stop block and the front wall corresponding to an injection dose selected from two or more available injection doses; The method comprising:

18. 18. The method of claim 17, wherein the engagement between the hammer sleeve and the hammer is a threaded engagement, and wherein the step of changing the distance between the hammer stop block and the front wall includes rotating one of the hammer sleeve or the hammer relative to the other in the threaded engagement.

19. providing a dose selector knob engaging said hammer; providing a status indicator defined by or attached to said hammer; Providing a viewing window; rotating the dose selector knob to rotate the hammer relative to the hammer sleeve in the threaded engagement; viewing the status indicator through the viewing window; 20. The method of claim 18, further comprising:

20. providing an indexing structure operably associated with said dose selector knob; rotating the dose selector knob through a predetermined angle of rotation such that the indexing structure becomes engaged; 20. The method of claim 19, further comprising:

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