Components and sub-assemblies for drug delivery devices

Abstract

A plunger rod for a drug delivery device comprises: a tubular body extending along a longitudinal axis between a closed end and an open end; and a whistle orifice on a tubular wall of the tubular body, wherein the whistle orifice is located between the open end of the tubular body and the closed end of the tubular body.

Description

Technology Field

[0001] The present invention generally relates to components and sub-assemblies for drug delivery devices. Background Technology

[0002] Drug delivery devices, such as pen-type manual syringes or automatic syringes, are generally known to allow patients to self-administer medication without formal medical training. For example, a patient with diabetes may need to repeatedly inject insulin, or a patient may need to regularly inject other types of medication, such as growth hormone. To facilitate the correct self-administration by the patient, one or more indicators representing one or more steps of the drug delivery device's operation are important.

[0003] Furthermore, for certain types of drugs, there is a requirement to release the drug with a substantially constant force. However, existing specific devices for releasing drugs with a substantially constant force are complex and expensive to manufacture. There is a desire to reduce the manufacturing costs of automatic infusion devices while maintaining the reliability of infusion devices that dispense drugs with a substantially constant force.

[0004] It has been understood that a solution may be advantageous for providing one or more indications regarding one or more steps of a drug delivery operation and / or for providing a mechanism for retaining a drug delivered under substantially constant force (Patent Document 1). U.S. Patent Application Publication US2019 / 0307959 A1

[0005] The present invention is defined by the appended claims to be referenced.

[0006] In the present disclosure, when the term "distal direction" is used, it means the direction away from the dose delivery site during the use of the drug delivery device. When the term "distal part / end" is used, it means the part / end of the delivery device or parts / ends of its components located furthest from the dose delivery site during the use of the drug delivery device. Correspondingly, when the term "proximal direction" is used, it means the direction toward the dose delivery site during the use of the drug delivery device. When the term "proximal part / end" is used, it means the part / end of the delivery device or parts / ends of its components located closest to the dose delivery site during the use of the drug delivery device.

[0007] Additionally, the terms "longitudinal," "longitudinal," "axial," or "axial" generally refer to the longest extensional direction of a device and / or component, meaning the direction extending from the proximal end to the distal end along the device or component.

[0008] Similarly, the terms "transverse," "transverse," and "transversely" refer to a direction generally perpendicular to the longitudinal direction.

[0009] Additionally, the terms "circumferential," "circumferential," or "circumferentially" refer to a circumferential or circumferential direction relative to an axis, generally the longest extensional direction of a device and / or component. Similarly, "radial" or "radially" indicates a direction extending radially relative to an axis, and "rotational," "rotational," and "rotatally" refer to rotation relative to an axis.

[0010] A first aspect of the present invention provides a plunger rod for a drug delivery device, wherein the plunger rod comprises: a tubular body extending along a longitudinal axis between a closed end and an open end; and a whistle orifice on a tubular wall of the tubular body, the whistle orifice being located between the open end of the tubular body and the closed end of the tubular body.

[0011] Preferably, according to another embodiment, the tubular body of the plunger rod comprises at least one inclined surface that is angled with respect to the longitudinal axis and extends from the whistle orifice in the direction of the longitudinal axis.

[0012] Preferably, according to another embodiment, the tubular body of the plunger rod comprises a first inclined surface and a second inclined surface; the first inclined surface is angled with respect to the longitudinal axis and extends from the whistle orifice toward the open end of the tubular body; and the second inclined surface is angled with respect to the longitudinal axis and extends from the whistle orifice toward the closed end of the tubular body.

[0013] Alternatively, according to another embodiment, the tubular body of the plunger rod comprises a first inner cylindrical chamber and a second inner cylindrical chamber; the first inner cylindrical chamber is arranged between the open end of the tubular body and a whistle orifice; the second cylindrical chamber is arranged between the closed end of the tubular body and a whistle orifice; and the first inner cylindrical chamber has a diameter smaller than the diameter of the second inner cylindrical chamber.

[0014] Preferably, according to another embodiment, the plunger rod includes two whistle orifices in the tubular wall of the tubular body; the two whistle orifices are arranged symmetrically with respect to the longitudinal axis between the open end of the tubular body and the closed end of the tubular body.

[0015] Preferably, according to another embodiment, the plunger rod comprises a blocking unit arranged within the tubular body of the plunger rod; the blocking unit is configured to releaseably seal the whistle orifice of the plunger rod in response to the flow pressure within the tubular body of the plunger rod.

[0016] Preferably, according to another embodiment, the circuit breaker unit is configured to be hermetically sealed to the inner surface of the tubular body of the plunger rod.

[0017] Preferably, according to another embodiment, the circuit breaker unit can move along the longitudinal axis between a blocking position in which the circuit breaker unit is radially aligned with the whistle orifice with respect to the longitudinal axis so that the whistle orifice is sealed by the circuit breaker unit, and a release position in which the circuit breaker unit is radially misaligned with respect to the longitudinal axis so that the whistle orifice is no longer sealed by the circuit breaker unit.

[0018] Preferably, according to another embodiment, the circuit breaker unit includes a circuit breaker body and a biasing member, and the biasing member is positioned between the closed end of the tubular body and the circuit breaker body.

[0019] Preferably, according to another embodiment, the circuit breaker body is hermetically sealed to the inner surface of the tubular body of the plunger rod.

[0020] Alternatively, according to another embodiment, the circuit breaker unit is a single component and is deformable along the longitudinal axis.

[0021] According to another embodiment, the plunger rod may be used with a drug delivery device comprising a gas canister connected to the open end of the tubular body of the plunger rod.

[0022] According to another embodiment, the plunger rod may be used with a sub-assembly for a drug delivery device, said sub-assembly comprising: a housing extending along a longitudinal axis between a proximal end and a distal end; and a drive assembly configured to be connected to a trigger of the drug delivery device, wherein the drive assembly is connected to the housing and connected to the plunger rod.

[0023] Preferably, according to another embodiment, the drive assembly comprises a gas canister, a valve unit, and a sleeve; the valve unit comprises a valve; the valve comprises an air inlet and an air outlet; and the air inlet is connected to the gas canister.

[0024] According to another embodiment, the sleeve extends along the longitudinal axis between the first opening and the second opening; the first opening of the sleeve is connected to the open end of the tubular body of the plunger rod; and the second opening of the sleeve is hermetically connected to the air outlet of the valve.

[0025] Preferably, according to another embodiment, the gas canister can be moved axially with respect to the air inlet of the valve between the gas release position and the gas seal position.

[0026] Preferably, according to another embodiment, the gas canister is rotatable with respect to the air inlet of the valve between the gas release position and the gas seal position.

[0027] Preferably, according to another embodiment, the sub-assembly includes an elastic ring arranged between the tubular body of the plunger rod and the sleeve; the elastic ring is configured to surround at least one of the plunger rod and the sleeve.

[0028] Preferably, according to another embodiment, the sleeve is arranged at least partially within the tubular body of the plunger rod.

[0029] Preferably, according to another embodiment, the plunger rod is arranged at least partially within the sleeve.

[0030] Preferably, according to another embodiment, the sleeve is axially fixed to the housing.

[0031] Preferably, according to another embodiment, the sleeve is axially movable relative to the housing.

[0032] A second aspect of the present invention provides a sub-assembly for a drug delivery device, the sub-assembly comprising: a plunger rod extending along a longitudinal axis between a proximal end and a distal end—the plunger rod comprises a tubular body—; a sleeve extending along a longitudinal axis between a proximal end and a distal end—the sleeve is coaxial with respect to the plunger rod with respect to the longitudinal axis and connected to the plunger rod—; an elastic ring positioned radially with respect to the longitudinal axis between the tubular body of the plunger rod and the sleeve, wherein the plunger rod is axially movable along the longitudinal axis with respect to the sleeve; one of the sleeve and the tubular body of the plunger rod has a diameter that varies monotonically along the longitudinal axis from the proximal end to the distal end; and the elastic ring is attached to the other of the sleeve and the plunger rod.

[0033] Preferably, according to another embodiment, the plunger rod is arranged at least partially within the sleeve.

[0034] Preferably, according to another embodiment, an elastic ring is attached to the outer surface of a plunger rod; and the sleeve is sized to have an inner diameter that gradually increases from the proximal end of the sleeve toward the distal end of the sleeve.

[0035] Alternatively, according to another embodiment, the tubular body of the plunger rod is dimensioned with an outer diameter that gradually increases from the proximal end of the plunger rod toward the distal end of the plunger rod; and an elastic ring is attached to the inner surface of the sleeve and the proximal end of the sleeve.

[0036] Alternatively, according to another embodiment, the plunger rod comprises a tubular body; and the sleeve is arranged within the tubular body of the plunger rod.

[0037] Preferably, according to another embodiment, the sleeve is sized to have an outer diameter that gradually increases from the distal end of the sleeve toward the proximal end of the sleeve; and an elastic ring is attached to the inner surface of the tubular body of the plunger rod.

[0038] Alternatively, according to another embodiment, the tubular body of the plunger rod is dimensioned with an inner diameter that gradually increases from the distal end of the plunger rod toward the proximal end of the plunger rod; and an elastic ring is attached to the outer surface of the sleeve and the proximal end of the sleeve.

[0039] Preferably, according to another embodiment, the sleeve is configured to be connected to a gas canister of a drug delivery device; and the plunger rod is configured to move along the longitudinal axis relative to the sleeve under flow pressure between the sleeve and the plunger rod when gas from the gas canister flows into the sleeve.

[0040] Alternatively, according to another embodiment, the plunger rod is configured to be connected to a spring.

[0041] Preferably, according to another embodiment, the plunger rod is arranged at least partially within the sleeve.

[0042] Preferably, according to another embodiment, an elastic ring is attached to the outer surface of a plunger rod; and the sleeve is sized to have an inner diameter that gradually increases from the distal end of the sleeve toward the proximal end of the sleeve.

[0043] Alternatively, according to another embodiment, the tubular body of the plunger rod is dimensioned with an outer diameter that gradually increases from the distal end of the plunger rod toward the proximal end of the plunger rod; and an elastic ring is attached to the inner surface of the sleeve and the proximal end of the sleeve.

[0044] Alternatively, according to another embodiment, the plunger rod comprises a tubular body; and the sleeve is arranged within the tubular body of the plunger rod.

[0045] Preferably, according to another embodiment, the sleeve is sized to have an outer diameter that gradually increases from the proximal end of the sleeve toward the distal end of the sleeve; and an elastic ring is attached to the inner surface of the tubular body of the plunger rod at the distal end of the tubular body of the plunger rod.

[0046] Alternatively, according to another embodiment, the tubular body of the plunger rod is dimensioned with an inner diameter that gradually increases from the proximal end of the plunger rod toward the distal end of the plunger rod; and an elastic ring is attached to the outer surface of the sleeve and the distal end of the sleeve.

[0047] According to another embodiment, the present invention provides a sub-assembly for a drug delivery device, wherein the sub-assembly comprises a plunger rod extending along a longitudinal axis between a proximal end and a distal end; a sleeve extending along a longitudinal axis between a proximal end and a distal end, wherein the sleeve is coaxial with the plunger rod with respect to the longitudinal axis and is connected to the plunger rod; one of the sleeve and the plunger rod is dimensioned having a diameter that varies monotonically along the longitudinal axis from the proximal end to the distal end; and an elastic ring is attached to the other of the sleeve and the plunger rod and is configured to regulate and maintain a force applied to the plunger rod accordingly.

[0048] Preferably, according to another embodiment, the sleeve is configured to be fluidly connected to a gas canister of a drug delivery device, so that the flow pressure between the sleeve and the plunger rod moves the plunger rod axially relative to the sleeve.

[0049] Preferably, according to another embodiment, an elastic ring is attached to the other of the sleeve and the plunger rod and is configured to regulate and maintain the flow pressure between the plunger rod and the sleeve at a constant pressure level.

[0050] According to another embodiment, the present invention provides a sub-assembly, wherein the sub-assembly comprises a plunger rod extending along a longitudinal axis between a proximal end and a distal end; a sleeve extending along a longitudinal axis between a proximal end and a distal end, wherein the sleeve is coaxial with the plunger rod with respect to the longitudinal axis and is connected to the plunger rod; wherein the sleeve is configured to be fluidly in communication with a gas canister of a drug delivery device, such that the flow pressure between the sleeve and the plunger rod moves the plunger rod axially relative to the sleeve; wherein one of the sleeve and the plunger rod has dimensions having a diameter that varies monotonically along the longitudinal axis from the proximal end toward the distal end; and an elastic ring is attached to the other of the sleeve and the plunger rod and is configured to regulate and maintain the flow pressure between the plunger rod and the sleeve at a constant pressure level.

[0051] Preferably, according to another embodiment, the drug delivery device may be one of an injection device, an inhalation device, or a medical nebulizer.

[0052] Generally, all terms used in the claims shall be interpreted according to their common meaning in the technical field unless otherwise explicitly defined in this specification. Any reference to "a / an / the element, device, component, means, etc." shall be publicly interpreted as referring to at least one instance of the element, device, component, means, etc., unless otherwise explicitly stated. Brief explanation of the drawing

[0053] Now, embodiments of the concept of the present invention will be described merely as embodiments with reference to the accompanying drawings. FIG. 1 schematically illustrates a perspective view of a component of a drug delivery device having a plunger rod according to the present invention. FIGS. 2A and FIGS. 2B show a side view and a cross-sectional view of the plunger rod of FIG. 1. FIG. 3a shows a perspective view of the driving assembly of the drug delivery device of FIG. 1. FIGS. 3b to 3d illustrate cross-sectional views of the drive assembly of FIG. 3a. FIG. 4a shows a perspective view of the drive assembly of FIG. 3a used with the button and the plunger rod of FIG. 1. Figure 4b shows a cross-sectional view of Figure 4a. FIG. 5 shows a perspective view of the housing of the drug delivery device of FIG. 1. FIGS. 6A and FIGS. 6B illustrate cross-sectional views of the plunger rod of FIG. 1 in different embodiments. FIGS. 7A and 7B show side views of the plunger rod of FIG. 1 used with the drive assembly of FIG. 3A. FIG. 8 shows a perspective view of the proximal part of the guide assembly of the drive assembly of FIG. 3a. FIG. 9a shows a perspective view of the drug delivery device of FIG. 1. Figure 9b shows a cross-sectional view of the drug delivery device of Figure 9a. FIG. 9c shows a cross-sectional view of another embodiment of the drug delivery device of FIG. 9a. FIGS. 10 and FIGS. 11 illustrate cross-sectional views of a sub-assembly of a second aspect of the present invention in two different embodiments. FIG. 12 illustrates a cross-sectional view of a drug delivery device using a sub-assembly of a second embodiment of the present invention. FIG. 13 shows a perspective view of a sub-assembly of a second embodiment of the present invention. FIGS. 14 and FIGS. 15 illustrate cross-sectional views of the sub-assembly of FIG. 13 in two different embodiments. Specific details for implementing the invention

[0054] FIGS. 1 to 9c illustrate a first embodiment of the present invention providing a plunger rod (2) for a drug delivery device (1). The plunger rod (2) comprises a tubular body (20) and a whistle orifice (23). The tubular body (20) extends along a longitudinal axis (L) between a closed end (22) and an open end (21). The tubular body (20) comprises a tubular wall forming an internal space of the tubular body (20), as shown in FIG. 2b. The whistle orifice (23) of the plunger rod is located on the tubular wall of the tubular body (20) and is positioned between the open end (21) of the tubular body (20) and the closed end (22) of the tubular body (20).

[0055] The plunger rod (2) is configured to be connected to the power pack of the drug delivery device (1). Typically, the power pack of the drug delivery device includes a drive assembly and a user-accessible trigger, which is a component or assembly connected to the drive assembly that can be manually moved by the user. The drive assembly of the drug delivery device includes an energy source, such as a spring, a gas canister, or a motor, and is connected to the plunger rod (2).

[0056] Movement of the trigger by the user causes the drive assembly to transfer stored energy from the energy source to the plunger rod (2), thereby enabling the plunger rod (2) to actuate the drug contained within the drug delivery device to release the drug to the user. The trigger may be a button, a delivery member guard, or an assembly including a button or a delivery member guard.

[0057] The tubular body (20) of the plunger rod (2) of the present invention is configured to allow airflow within the inner chamber (25) of the tubular body (20) during drug delivery operations. Thus, when the airflow passes through the whistle orifice (23), an auditory indication may be generated for the user.

[0058] In one embodiment, the plunger rod (2) is connected to the drive assembly (3) using a gas canister (31). For example, as shown in FIG. 3a, the drive assembly (3) includes a gas canister that stores pressurized gas, e.g., liquefied gas or pressurized pneumatic gas, a valve unit (32), and a guide assembly (33).

[0059] In one embodiment, as illustrated in FIG. 1, a plunger rod (2) and a drive assembly (3) are used in a sub-assembly for a drug delivery device (1). The sub-assembly includes a housing (10) that extends along a longitudinal axis (L) between a proximal end and a distal end. Both the plunger rod (2) and the drive assembly are accommodated within the housing (10). The plunger rod (2) can move axially relative to the housing (10). The housing (10) can also serve as the housing of the drug delivery device (1).

[0060] The valve unit (32) is configured to release gas from a gas canister. The valve unit (32) includes an air inlet and an air outlet. Preferably, the valve stem (320) extends between the air inlet and the air outlet as shown in FIG. 3C. The air inlet is movable, for example, axially and / or rotationally relative to the gas canister. The relative movement between the air inlets of the valve unit (32) is configured to release gas from the gas canister, allowing gas to flow out from the gas canister from the air inlet of the valve unit (32) to the outlet of the valve unit (32). The valve unit (32) includes a retaining body to accommodate the gas canister (31), so that the gas canister and the valve unit (32) can be attached to a drug delivery device through the retaining body of the valve unit (32).

[0061] The guide assembly (33) is configured to guide the gas released from the gas canister into the inner chamber (25) of the tubular body (20) of the plunger rod (2). As shown in FIG. 3b, the guide assembly (33) includes a sleeve (330) extending along the longitudinal axis (L) between a first opening (330a) and a second opening (330b). The first opening (330a) of the sleeve (330) is connected to the open end (21) of the tubular body (20) of the plunger rod (2); and the second opening (330b) of the sleeve (330) is hermetically connected to the air outlet of the valve (32) as shown in FIG. 3d. In one embodiment, the sleeve (330) is located at least partially within the inner chamber (25) of the plunger rod (2) as shown in FIG. 4b. The guide assembly (33) optionally includes a base (331) for accommodating at least a portion of the valve unit (32) together with the gas canister (31). The guide assembly (33) may also include an attachment (332) configured to attach the guide assembly to a drug delivery device. The attachment (332) may include a flexible arm (333) that protrudes toward the direction in which the first opening (330a) is located. Additionally, the sleeve (330) may include a recess (330c) on its outer surface and may be located between the first opening (330a) and the second opening (330b). Further details regarding the flexible arm (333) will be described later. In a preferred embodiment, the drive assembly is connected to an elastic ring (4). The elastic ring (4) may be attached to the recess (330c) of the sleeve (330) as shown in FIGS. 7a and 7b. In the first embodiment of the present invention, the elastic ring (4) is configured to hermetically seal the outer surface of the sleeve (330) and the inner surface of the tubular body (20) of the plunger rod (2).Accordingly, gas flowing out from the first opening (330a) of the sleeve (330) into the inner chamber (25) of the tubular body (20) of the plunger rod (2) can only flow toward the closed end (22) of the plunger rod (2).

[0062] A user-accessible trigger for a drug delivery device may be arranged to be connected to a valve, a gas canister, or a guide assembly. For example, the user-accessible trigger is a button (5) attached to a gas canister (31) as shown in FIGS. 4a and 4b. In this embodiment, the guide assembly (33) (also sleeve (330)) and the valve unit (32) are axially fixed to the housing (10), and the user can press the button axially, thereby causing the gas canister to move axially relative to the air inlet of the valve unit (32). The axial movement between the air inlet of the valve unit (32) and the gas canister (31) releases gas from the gas canister (31), causing the gas to flow through the sleeve (330) of the guide assembly (33) into the inner chamber (25) of the plunger rod (2). Once gas flows in the inner chamber (25) of the plunger rod (2) as shown in FIGS. 6a and 6b, some vortex will be created around the whistle orifice (23; 23'); thus, an auditory indication can be produced. Thus, the user can receive an auditory indication as a signal that the drug delivery operation is in progress. The whistle orifice (23; 23') also serves as a pressure release orifice to release the gas within the inner chamber (25) of the plunger rod (2). Thus, the air pressure within the inner chamber (25) of the plunger rod (2) will not continue to increase. Thus, damage to the drug container caused by significant force from the plunger rod can be prevented or minimized.

[0063] Alternatively, the trigger may be connected to the valve unit and the delivery member guard, and it should be noted that in the embodiment, the guide assembly and the gas canister are attached to the housing of the drug delivery device. When a user presses the delivery member guard at the drug delivery site, the valve unit may be moved relative to the gas canister by the delivery member guard. In this embodiment, the guide device (also a sleeve) is fixed axially to the housing. Alternatively, the guide assembly may be connected to the drug delivery member guard so that the guide assembly may move axially relative to the housing together with the drug delivery member guard. In this embodiment, the gas canister is fixed axially to the housing of the drug delivery device. The valve unit may be moved by the guide assembly together with the movement of the delivery member guard by the user.

[0064] Additionally, the drive assembly (3) may include a device for maintaining flow communication between the gas canister (31) and the sleeve (330; 330'). As illustrated in FIG. 9c, the sleeve (330') may include a flange (334), and the drive assembly (3) may include a clip (34). In this embodiment, movement of the trigger will cause relative movement between the clip (34) and the sleeve (330'); thus, the clip (34) will be clipped to the flange (334) of the sleeve (330'). In this embodiment, the clip (34) may be fixedly connected to the gas canister (31). Thus, when the gas canister (31) moves relative to the valve stem (332) in accordance with the movement of the trigger, the clip (34) will be clipped to the flange (334) of the sleeve, thereby maintaining the gas canister (31) in a position where the contents continue to be released from the valve stem. In this embodiment, the user does not need to continuously press the trigger during the entire drug delivery operation.

[0065] In another preferred embodiment, the plunger rod (2) includes a circuit breaker unit arranged within the tubular body (20) of the plunger rod (2). The circuit breaker unit is movable along the longitudinal axis (L) between a blocking position in which the circuit breaker unit is radially aligned with the whistle orifice with respect to the longitudinal axis (L) and a release position in which the circuit breaker unit is radially misaligned with the whistle orifice (23) with respect to the longitudinal axis (L). In one embodiment, the circuit breaker unit (6) includes a circuit breaker body (60) and a biasing member (61) as shown in FIG. 8. The biasing member (61) is positioned along the longitudinal axis (L) between the closed end (22) of the plunger rod (2) and the circuit breaker body (60). The biasing member (61) may be a compression spring or a flexible arm. When the biasing member (61) is in its relaxed configuration, the biasing member (61) is configured to support the circuit breaker body (60) and be radially aligned with the whistle orifice (23) of the plunger rod (2); accordingly, the gas flowing within the inner chamber (25) of the plunger rod (2) cannot leak out from the whistle chamber (23). In a preferred embodiment, the circuit breaker body (60) is hermetically sealed to the inner surface of the tubular body (20) of the plunger rod (2). If the gas flowing within the inner chamber (25) of the plunger rod (2) cannot leak out from the whistle chamber (23) and the gas in the gas canister is released by the valve unit (32), the pressure within the inner chamber (25) of the plunger rod (2) will continue to increase. When the pressure inside the inner chamber (25) of the plunger rod (2) reaches a specific level sufficient to compress the biasing member (61) of the circuit breaker unit (6), the circuit breaker body (60) will move to its discharge position under the pressure inside the inner chamber (25) of the plunger rod so that the circuit breaker body (60) is radially misaligned with the whistle orifice (23) with respect to the longitudinal axis (L).When the blocker body (60) is radially misaligned with the whistle orifice (23) with respect to the longitudinal axis (L), the gas flowing within the inner chamber (25) of the plunger rod (2) can be discharged from the whistle orifice (23). There are at least two major advantages that can be provided by the device of the blocker unit (6). First, the blocker unit (6) can keep the plunger rod (2) in a continuously moving state. For example, the force value of the biasing member (61) can be selected according to the viscosity of the drug contained in the drug delivery device having the plunger rod (2) of the present invention. Accordingly, if the released gas power is insufficient to discharge the drug, the blocker body (60) is in the blocked position and the whistle orifice (23) is sealed by the blocker body (60), and as a result, the pressure within the inner chamber (25) of the plunger rod (2) will increase until the accumulated pressure first compresses the biasing member (60) and is sufficient to discharge the drug. When the released gas power is high enough to discharge the drug, the blocker body (60) will be moved to the discharge position under the flow pressure within the inner chamber (25) of the plunger rod (2), and the whistle orifice (23) will be opened due to the misalignment of the blocker body (60) in the radial direction with respect to the longitudinal axis (L). Secondly, the user will obtain a more accurate progress of the drug delivery operation. Since the user can only hear the whistle sound (auditory drug delivery indicator) when the whistle orifice (23) is no longer blocked by the blocker body (60), this means that the flow pressure within the inner chamber (25) of the plunger rod (2) is high enough to compress the biasing member (61) and then move the plunger rod (2). In general, in disposable drug delivery devices, the gas canister is selected to accommodate only a certain amount of gas required to complete a single drug delivery operation.Therefore, when the drug delivery operation is completed, the gas canister cannot supply a sufficient gas flow to compress the biasing member (61) and maintain the flow pressure within the inner chamber (25) of the plunger rod, which is high enough to keep the blocker body (60) in its release position; as a result, when the drug delivery operation is completed, the biasing member (61) moves the blocker body (60) back to the blocking position. Thus, the whistle orifice (23) will be blocked by the blocker body (60) at the end of the drug delivery operation. When the whistle orifice (23) is blocked by the blocker body (60), the whistle sound is no longer produced, so the user can be notified that the drug delivery operation is completed (by the cessation of the whistle sound).

[0066] As provided by the present invention, a plunger rod (2) having a whistle orifice (23; 23') is suitable for connection to any drug delivery device power pack capable of generating an airflow into the tubular body (20) of the plunger rod (2). For example, instead of a gas canister and valve, the drive assembly may include an airflow generating unit, for example, an air pump connected to a sleeve. Thus, the airflow generated by the air pump can enter into the tubular body (20) of the plunger rod (2). The air pump may be connected to a motor and configured so that the motor outputs a force to pressurize the air pump. Alternatively, the air pump may be accessible to a user so that the user can manually pressurize the air pump to generate an airflow and thereby actuate the plunger rod proximally.

[0067] Additionally, in another embodiment, instead of a gas canister or an airflow generating unit, the drive assembly may include a spring or a motor as an energy source. In this embodiment, the open end of the plunger rod may be arranged to aim at the drug container, and the closed end of the plunger rod may be connected to an energy source, for example, a compression spring. In this embodiment, the open end of the plunger rod may be spaced away from the distal seal of the drug container, for example, a stopper, at the initiation. When the energy source moves the plunger rod proximally, the plunger rod will compress the air between the open end of the plunger rod and the distal end of the distal seal of the drug container before the plunger rod reaches the distal seal of the drug container. The compressed air will escape at least partially through the whistle orifice, and thus the user can hear a whistle sound as an indication of the start of the drug delivery operation. In a preferred embodiment, the plunger rod is dimensioned to have a diameter that fits snugly to the diameter of the distal end of the drug container; Alternatively, since the indicator tube can be positioned between the drug container and the plunger rod, the plunger rod must first pass through the indicator tube before entering the drug container or reaching the distal seal of the drug container. Next, the plunger rod is sized to have a diameter that fits snugly to the diameter of the indicator tube.

[0068] The whistle orifice (23; 23') may be formed with different geometric structures, for example, the tubular body (20) of the plunger rod (2) includes at least one inclined surface (23a; 23a') that is angled with respect to the longitudinal axis (L) and extends from the whistle orifice (23) in the direction of the longitudinal axis (L). In another preferred embodiment, as shown in FIG. 6a, the tubular body (20) of the plunger rod (2) includes a first inclined surface (23a) and a second inclined surface (23b). The first inclined surface (23a) is angled with respect to the longitudinal axis (L) and extends from the whistle orifice (23) toward the open end (21) of the tubular body (20). The second inclined surface (23b) is angled with respect to the longitudinal axis (L) and extends from the whistle orifice (23) toward the closed end (22) of the tubular body (20). Alternatively, in another preferred embodiment, as shown in FIG. 6b, the tubular body (20) of the plunger rod (2) comprises a first inner cylindrical chamber (25a') and a second inner cylindrical chamber (25b'). The first inner cylindrical chamber (25a') is positioned between the open end (2T) of the tubular body (20) and the whistle orifice (23'). The second cylindrical chamber (25b') is positioned between the closed end (22) of the tubular body (20) and the whistle orifice (23'). The first inner cylindrical chamber (25a') has a diameter smaller than the diameter of the second inner cylindrical chamber (25b'). In another embodiment, the plunger rod (2) includes two whistle orifices (23) in the tubular wall of the tubular body (20). The two orifices (23) are arranged symmetrically with respect to the longitudinal axis (L) and are arranged between the open end (21) of the tubular body (20) and the closed end (22) of the tubular body (20).

[0069] FIGS. 9a through 15 illustrate a second aspect of the present invention providing a sub-assembly for a drug delivery device (1; 1'). The sub-assembly comprises a plunger rod (2; 2') extending along a longitudinal axis (L) between a proximal end and a distal end; and a sleeve (330; 330'; 330"; 330'") extending along a longitudinal axis (L) between a proximal end and a distal end. The sleeve (330; 330'; 330"; 330'") is coaxial with respect to the plunger rod (2; 2') with respect to the longitudinal axis (L) and is connected to the plunger rod (2; 2') with respect to the longitudinal axis (L). The sub-assembly includes an elastic ring (4; 4') positioned between a plunger rod (2; 2') and a sleeve (330; 330'; 330"; 330'"). The elastic ring (4; 4') is configured to surround at least one of the plunger rod (2; 2') and the sleeve (330; 330'; 330"; 330'") as shown in FIG. 7a and FIG. 13. The plunger rod (2; 2') is axially movable along a longitudinal axis (L) relative to the sleeve (330; 330'; 330"; 330'"). The plunger rod (2; 2') includes a tubular body (20; 20'; 20"; 20'"). One of the sleeve (330; 330'; 330"; 330'") and the tubular body (20; 20'; 20"; 20'") of the plunger rod (2; 2') is made of dimensions having a diameter that varies monotonically along the longitudinal axis (L) from the proximal end to the distal end. An elastic ring (4; 4') is attached to the other of the sleeve (330; 330'; 330"; 330'") and the tubular body (20; 20'; 20"; 20'").

[0070] A sub-assembly according to a second aspect of the present invention can maintain the plunger rod moving at a constant proximal direction when receiving force from an energy source. For example, the device defined above can maintain the fluid pressure within the tubular body (20; 20'; 20"; 20'") of the plunger rod (2) and, accordingly, maintain a constant force applied to the plunger rod (2) to move the plunger rod (2) in the proximal direction of the drug delivery device. In this embodiment, the sub-assembly according to the second aspect of the present invention is preferably used with a gas-powered drug delivery device having the gas canister mentioned above, or is connected to an air flow generating unit, e.g., an air pump. The sleeve (330; 330'; 330"; 330'") can be arranged to be connected to the gas canister as an energy source for the drug delivery device (1).

[0071] An exemplary connection between sleeves (330; 330') is arranged as disclosed in the first embodiment of the present invention mentioned above, namely, the sleeves (330; 330') are part of the guide assembly (33) and are located within the tubular body (20; 20") of the plunger rod (2), so that gas released from the gas canister flows into the tubular body (20; 20") of the plunger rod (2) and can actuate the plunger rod (2) to move proximally to the drug delivery device (1). In this embodiment, similar to the first embodiment of the invention mentioned above, the tubular body (20; 20") of the plunger rod (2') comprises a closed end at the proximal end of the plunger rod (2') and an open end at the distal end of the plunger rod (2). In the second embodiment of the invention, the plunger rod (2) may optionally include a whistle orifice as mentioned above; or, as shown in FIG. 4a, an indication of drug delivery operation may be provided by a flexible arm (333) of a guide assembly (33) and a set of teeth (24) on the outer surface of the tubular body (20; 20") of the plunger rod (2).

[0072] Alternatively, the plunger rod (2) may be positioned at least partially within the sleeve (330"; 330'") as illustrated in FIGS. 12 through 15. In this embodiment, the sleeve (330"; 330'") may be connected to a valve for releasing gas from the gas canister. Similar to the trigger device described above, the sleeve (330"; 330'") and the valve may be attached to the housing of the drug delivery device (1'). The gas canister may be connected to a button accessible to the user. Alternatively, the trigger may be connected to a valve unit and a delivery member guard, and in this embodiment, the guide assembly and the gas canister are attached to the housing of the drug delivery device. When the user pressurizes the delivery member guard at the drug delivery site, the valve unit may be moved relative to the gas canister by the delivery member guard. Alternatively, the guide unit may be connected to the drug delivery member guard, and in this embodiment, the gas canister is attached to the housing of the drug delivery device. The valve unit can be moved by the guide unit along with the movement of the delivery member guard by the user. In this embodiment, the tubular body (20'; 20'") of the plunger rod (2) includes a closed end at the proximal end of the plunger rod (2) and an open end at the distal end of the plunger rod (2). When the trigger is moved by the user to trigger a drug delivery operation, the released gas will flow into the tubular body (20'; 20'") of the plunger rod (2) and actuate the plunger rod (2) to move in the proximal direction of the drug delivery device (1').

[0073] Generally, the amount of gas released from a gas canister during a specific period also depends on the flow pressure within the gas canister. For example, when a new gas canister begins to release gas, the amount of gas released from the gas canister during a specific period will be high; consequently, when the plunger rod (2) is connected to the gas canister, the flow pressure within the tubular body (20; 20'; 20"; 20'") will also be high at the start. However, when the gas canister continues to release gas for a while, the amount of gas released from the gas canister during a specific period will decrease due to the falling flow pressure within the gas canister. Thus, when the plunger rod (2) is connected to the gas canister, the flow pressure within the tubular body (20; 20'; 20"; 20'") of the plunger rod (2) will also drop as the plunger rod (2) moves proximal to the drug delivery device for a while.

[0074] FIG. 10 illustrates one embodiment of a sub-assembly of a second aspect of the present invention. In this embodiment, a sleeve (330') is arranged within the tubular body (20) of a plunger rod (2). The sleeve (330') is sized to have an outer diameter that gradually increases from the distal end of the sleeve toward the proximal end of the sleeve (330'). In this embodiment, an elastic ring (not shown in FIG. 10) is attached to the inner surface of the tubular body (20) of the plunger rod (2) and fixed to the plunger rod (2) in the direction of the longitudinal axis (L); for example, the inner surface of the plunger rod may include an annular groove for receiving the elastic ring. An elastic ring can be attached to the distal end of the plunger rod (2), so that when the plunger rod (2) is actuated by the gas released from the gas canister as an energy source for the drug delivery device (1), the plunger rod (2) and the elastic ring will move together axially with respect to the sleeve (330') toward the proximal direction of the housing of the drug delivery device. Since the outer diameter of the sleeve (330') gradually increases from the distal end of the sleeve toward the proximal end of the sleeve (330'), the gap between the elastic ring and the outer surface of the sleeve (330') becomes larger when the plunger rod (2) begins to move toward the proximal direction of the housing of the drug delivery device. The gap between the elastic ring and the outer surface of the sleeve (330') will become narrower as the plunger rod (2) moves closer and closer to the proximal end of the sleeve (330') together with the elastic ring. As mentioned above, the discharged gas will flow from the sleeve (330') into the tubular body (20) of the plunger rod (2); when the gas canister is initially triggered to discharge the contained gas, some of the discharged gas leaks out due to the gap between the elastic ring and the sleeve (330'); accordingly, the flow pressure within the tubular body (20) of the plunger rod can only be increased to a certain level.When the gas canister is triggered for a while, as the amount of released gas drops due to the reduced pressure within the gas canister, the plunger rod (2) together with the elastic ring now moves closer to the proximal end of the sleeve (330); the gap between the elastic ring and the sleeve (330') also becomes narrower, or the elastic ring can hermetically seal between the plunger rod (2) and the sleeve (330'); accordingly, gas leakage in the gap between the elastic ring and the sleeve (330') is reduced or even stopped. Thus, the flow pressure within the tubular body (20) of the plunger rod (330') can be maintained at a specific level without dropping along with the decreasing amount of released gas.

[0075] Instead of arranging the sleeve (330') such that the outer diameter gradually increases from the distal end of the sleeve (330') toward the proximal end of the sleeve (330'), the tubular body (20") of the plunger rod (2) is dimensioned with an inner diameter that gradually increases from the distal end of the tubular body (20") of the plunger rod (2) toward the proximal end of the tubular body (20") of the plunger rod (2) as shown in FIG. 11. In this embodiment, the elastic ring is secured to the proximal end of the sleeve (330), just as the elastic ring can be secured to the recess (330c) of the sleeve (330) as mentioned above in the first embodiment of the invention. Similar to the embodiment shown in FIG. 10, as the plunger rod (2) moves relative to the sleeve in the proximal direction of the drug delivery device, the radial gap between the plunger rod (2) and the elastic ring will become narrower; thus, leakage of gas flow from the gap may be reduced or even eliminated. Therefore, the flow pressure within the tubular body (20) of the plunger rod (2) can be maintained at a specific level.

[0076] In another embodiment, the plunger rod (2) is at least partially located within the sleeve (330"; 330'") as shown in FIGS. 12 to 15. Similar to the description above, at least one of the tubular body (20'; 20'") of the plunger rod (2') and the sleeve (330"; 330'") must have dimensions having a diameter that gradually increases from the proximal end of at least one of the tubular body (20'; 20'") of the plunger rod (2') and the sleeve (330"; 330'") to the distal end of at least one of the tubular body (20'; 20'") of the plunger rod (2') and the sleeve (330"; 330'"), contrary to the above embodiment.

[0077] For example, FIG. 14 illustrates a plunger rod (2') being received within a sleeve (330"), and an elastic ring (4') being attached to an outer surface, preferably the distal end of the plunger rod (2'), as shown in FIG. 13. In this embodiment, the sleeve (330") is sized to have an outer diameter that gradually increases from the proximal end of the sleeve (330") toward the distal end of the sleeve (330"). Alternatively, the body (20") of the tubular plunger rod (2') is dimensioned with an outer diameter that gradually increases from the proximal end of the plunger rod (2') toward the distal end of the plunger rod (2'), as shown in FIG. 15. In the latter embodiment, an elastic ring is attached to the inner surface of the sleeve (330") and the proximal end of the sleeve (330"). Thus, when the plunger rod (2') is moved relative to the sleeve (330") in the proximal direction of the drug delivery device, the radial gap between the plunger rod (2') and the elastic ring will become narrower; accordingly, leakage of gas flow from the gap may be reduced or even eliminated. Thus, the flow pressure within the tubular body (20'; 20'") of the plunger rod (2') can be maintained at a specific level.

[0078] It should be noted that whether the elastic ring ultimately needs to herniately seal the space between the plunger rod (2; 2') and the sleeve (330; 330'; 330"; 330'"), and / or where the elastic ring begins to herniately seal the space between the plunger rod (2; 2') and the sleeve (330; 330'; 330"; 330'"), and what exact flow pressure level needs to be maintained within the tubular body (20; 20'; 20"; 20'") of the plunger rod (2; 2'), depends on the design of the drug delivery device, for example, on the volume of the drug or the viscosity of the drug. In addition, in the second embodiment of the present invention, since the flow pressure within the tubular body (20; 20'; 20"; 20'") of the plunger rod (2; 2') is controlled by the amount of gas leakage from the radial gap between the elastic ring and the plunger rod, the sub-assembly preferably does not include a blocking unit (6) as described in the first embodiment of the present invention.

[0079] It should be noted that the above description refers to a gas or airflow energy source as an example; however, the sub-assembly of the second aspect of the invention may also be used with other suitable energy sources, such as a spring, for example. As mentioned above, one of the tubular body of the plunger rod and the sleeve is dimensioned to have a diameter that varies monotonically along the longitudinal axis (L) from the proximal end to the distal end. An elastic ring is attached to the other of the sleeve and the plunger rod. However, if the energy source is, for example, a compression spring, the sub-assembly can be deformed so that the elastic ring tightly seals the gap between the sleeve and the plunger rod at the beginning of the drug delivery operation, and later the seal loosens or moves away from either the plunger rod or the sleeve due to the monotonically changing diameter. Thus, the elastic ring can initially generate significant friction between the sleeve and the plunger rod, acting as a brake for the plunger rod, and later gradually reduce the resistance.

[0080] The concept of the present invention has been described primarily with reference to a few embodiments. However, as will be readily understood by those skilled in the art, other embodiments other than those disclosed above are equally possible within the scope of the concept of the present invention as defined by the appended claims.

Claims

Claim 1 A plunger rod (2) for a drug delivery device comprising: a tubular body (20) extending along a longitudinal axis (L) between a closed end (22) and an open end (21); and a whistle orifice (23; 23') on a tubular wall of the tubular body (20), wherein the whistle orifice (23; 23') is located between the open end (21) of the tubular body (20) and the closed end (22) of the tubular body (20). Claim 2 In claim 1, the tubular body (20) of the plunger rod (2) comprises at least one inclined surface (23a; 23a') that is angled with respect to the longitudinal axis (L) and extends from the whistle orifice (23; 23') in the direction of the longitudinal axis (L). Claim 3 In claim 2, the tubular body (20) of the plunger rod (2) comprises a first inclined surface (23a) and a second inclined surface (23b); the first inclined surface (23a) is angled with respect to the longitudinal axis (L) and extends from the whistle orifice (23) toward the open end (21) of the tubular body (20); and the second inclined surface (23b) is angled with respect to the longitudinal axis (L) and extends from the whistle orifice (23) toward the closed end (22) of the tubular body (20). Claim 4 In claim 1, the plunger rod (2) comprises a blocker unit (6) arranged within a tubular body (20); the blocker unit (6) is movable along the longitudinal axis (L) between a blocking position in which the blocker unit (6) is radially aligned with the whistle orifice (23) with respect to the longitudinal axis (L) and a release position in which the blocker unit (6) is radially misaligned with the whistle orifice (23) with respect to the longitudinal axis (L). Claim 5 In claim 4, the circuit breaker unit (6) comprises a circuit breaker body (60) and a biasing member (61), and the biasing member (61) is a plunger rod positioned between the closed end (22) of the tubular body (20) and the circuit breaker body (60). Claim 6 A sub-assembly for a drug delivery device comprising a plunger rod described in any one of claims 1 to 5, comprising: a housing (10) extending along a longitudinal axis (L) between a proximal end and a distal end; and a driving assembly (3) configured to be connected to a trigger of the drug delivery device, wherein the driving assembly (3) is connected to the housing and connected to the plunger rod (2). Claim 7 In claim 6, the drive assembly (3) comprises a gas canister (31), a valve unit (32), and a sleeve (330); the valve unit (32) comprises a valve; the valve comprises an air inlet and an air outlet; the air inlet is connected to the gas canister (31); the sleeve (330) extends along a longitudinal axis (L) between a first opening (330a) and a second opening (330b); the first opening (330a) of the sleeve (330) is connected to an open end (21) of the tubular body (20) of the plunger rod (2); and the second opening (330b) of the sleeve (330) is hermetically connected to the air outlet of the valve; The above gas canister (31) is a sub-assembly that is axially movable with respect to the air inlet of the valve between the gas release position and the gas seal position. Claim 8 In claim 7, the sub-assembly comprises an elastic ring (4) arranged between the tubular body (20) of the plunger rod (2) and the sleeve (330); the elastic ring is configured to surround at least one of the plunger rod (2) and the sleeve (330). Claim 9 A sub-assembly for a drug delivery device comprising: a plunger rod (2; 2') extending along a longitudinal axis (L) between a proximal end and a distal end — said plunger rod (2; 2') comprises a tubular body (20; 20'; 20"; 20'") —; a sleeve (330; 330'; 330"; 330'") extending along a longitudinal axis (L) between a proximal end and a distal end — said sleeve (330; 330'; 330"; 330'") is coaxial with the plunger rod (2; 2') with respect to the longitudinal axis (L) and connected to the plunger rod (2; 2') —; and the tubular body (20; 20'; 20"; 20'") of said plunger rod (2; 2') in a radial direction with respect to the longitudinal axis (L) and said It includes an elastic ring (4; 4') positioned between sleeves (330; 330'; 330"; 330'"), wherein the plunger rod (2; 2') is axially movable along a longitudinal axis (L) relative to the sleeves (330; 330'; 330"; 330'"); one of the tubular bodies (20; 20'; 20"; 20'") of the sleeves (330; 330'; 330"); and the plunger rod (2; 2') has a diameter that varies monotonically along the longitudinal axis from a proximal end to a distal end; the elastic ring (4; 4') is attached to the other of the sleeves (330; 330'; 330"; 330'") and the plunger rod (2; 2'), and the sleeves (330; A sub-assembly in which, depending on the axial movement of the plunger rod (2; 2') with respect to the sleeve (330; 330'; 330"; 330'") and the tubular body (20; 20'; 20"; 20'") of the plunger rod (2; 2') and the elastic ring (4; 4') gradually decreases. Claim 10 In claim 9, the plunger rod is a sub-assembly arranged at least partially within the sleeve. Claim 11 In claim 10, the elastic ring is attached to the outer surface of the plunger rod; and the sleeve is a sub-assembly having dimensions with an inner diameter that gradually increases from the proximal end of the sleeve toward the distal end of the sleeve. Claim 12 In claim 10, the tubular body of the plunger rod is sized to have an outer diameter that gradually increases from the proximal end of the plunger rod toward the distal end of the plunger rod; and the elastic ring is a sub-assembly attached to the inner surface of the sleeve and the proximal end of the sleeve. Claim 13 In claim 9, the plunger rod comprises a tubular body; and the sleeve is a sub-assembly arranged within the tubular body of the plunger rod. Claim 14 In claim 13, the sleeve is sized to have an outer diameter that gradually increases from the distal end of the sleeve toward the proximal end of the sleeve; and the elastic ring is a sub-assembly attached to the inner surface of the tubular body of the plunger rod. Claim 15 In claim 13, the tubular body of the plunger rod is sized to have an inner diameter that gradually increases from the distal end of the plunger rod toward the proximal end of the plunger rod; and the elastic ring is a sub-assembly attached to the outer surface of the sleeve and the proximal end of the sleeve.

Images