GB2611810A

GB2611810A - Plunger

Info

Publication number: GB2611810A
Application number: GB2114818.4A
Authority: GB
Inventors: Ken Cowe Toby; Thomas George Barrett Edward
Original assignee: Owen Mumford Ltd
Current assignee: Owen Mumford Ltd
Priority date: 2021-10-17
Filing date: 2021-10-17
Publication date: 2023-04-19
Anticipated expiration: 2041-10-17
Also published as: GB2611810B; GB202114818D0

Abstract

A push-rod or plunger 100 is disclosed, for use in an injection device 600 comprising a medicament container 602 with a bung or stopper 604 and arranged to drive the bung through the medicament cartridge to expel fluid therefrom. An end 106 of the plunger body 102 contacts the stopper and an electronic delivery status indication system is mounted at least partially within the plunger body. The delivery status indication system comprises at least one detector or switch 146, 148 operable to detect a position of the plunger within the medicament container, and a light-emitting visual indicator 152 signalling delivery of fluid from the medicament container based on data from the detector. The lamp emits light through opposite sides of a transparent or translucent portion of the plunger body. The whole plunger body may be transparent or translucent, and the indicator may comprise two LEDs 152a, 152b mounted within a reflectively coated aperture through a printed circuit board 144.

Description

PLUNGER

Technical field

The invention relates to a plunger for use in an injection device. The injection device being arranged to contain a medicament container for storing medicament and comprising an electronic delivery status indication system.

Background

Injection devices, in particular auto-injectors, are commonly used to self-administer injections of a substance, such as a medicament. Such auto-injectors are configured to receive a medicament container containing the medicament in a body. The medicament container typically has an elastomeric bung in a proximal end and may, for example be provided with a needle at a distal end. Alternatively, the medicament container may be sealed, for example using a septum that is attached to the medicament container using a crimp. The septum may be pierced by a needle during or before use of the injection device.

During use of the injection device the plunger moves distally causing the elastomeric bung to be moved distally pushing the medicament out of a needle in the distal end of the medicament container in order to deliver the medicament to a user. Typically, movement of the plunger occurs without the need for any driving force to be applied by the user, for example the driving force is provided by a compression spring that is released by a user allowing the spring to be released.

During the delivery of a medicament from an auto-injector, the user is required to hold a front end of the auto-injector against the injection site in order to keep the needle associated with the medicament container penetrated in the injection site, while the medicament is delivered. Typically, the user is required to hold the needle in place while the plunger moves the bung completely through the barrel, leading to a so-called 'full-dose delivery' of the medicament.

Various factors can lead to a sub-optimal, or incomplete, delivery of medicament, when the user is holding the auto-injector against the injection site.

An improved mechanism is required to ensure optimal and complete delivery of the medicament before the user removes the device from the injection site, and to alert the user to any problems with the delivery of the substance.

Summary

In accordance with an embodiment of the invention there is provided a plunger for use in an injection device comprising a medicament container including a bung and arrange, in use to drive the bung at least partially through the medicament container to expel a substance therefrom. The plunger comprises a body comprising a distal end configured to contact the bung, wherein at least a portion of the body is transparent or translucent; and an electronic delivery status indication system. The electronic delivery status indication system comprising at least one detector operable to detect a position of the plunger within the medicament container; and a visual indicator configured to provide, dependent upon the detector, a visual indication to a user indicative of delivery of the substance from the medicament container based on data received from the detector wherein the visual indicator is mounted within the plunger body such that light is emitted from the visual indicator through opposed sides of the transparent or translucent portion of the plunger body.

The electronic delivery status indication system may be a printed circuit board, PCB, comprising a distal portion configured to be received within the plunger body, the distal portion comprising an aperture and wherein the visual indicator is mounted within the aperture of the PCB such that light is emitted by the visual indicator from opposed sides of the PCB.

The visual indicator may be a light emitting diode, LED or a pair of LEDs mounted to opposed sidewalls of the aperture.

At least a portion of the aperture may be reflective to maximise the amount of light directed out of the device. Optionally, the plunger may include an optical lens to increase the visibility of the visual indicator by the user of the device.

According to a further embodiment of the invention there may be provided an injection device including a plunger and the medicament container, the plunger configured for receipt within the medicament container during the delivery stroke.

Brief description of drawings

Figure 1 shows a perspective view of an exemplary plunger; Figure 2 shows a perspective view of an exemplary plunger body; Figure 3 shows a perspective view of an exemplary proximal portion; Figure 4 shows a perspective view of an electronic delivery status indication system; Figure 5(a) shows a section view of a portion of an exemplary plunger; Figure 5(b) shows a perspective view of an exemplary proximal portion; and Figure 6 shows a section view of an exemplary injection device.

Detailed description

Generally, disclosed herein is a plunger for use with a medicament container. The plunger may be for use in a body of a medicament container for expelling a substance, such as a drug, therefrom. The plunger comprises a plunger body with a distal end configured to contact a bung of the medicament container and push the bung within the body of the medicament container to expel a dose of the substance from the distal end of the medicament container. The plunger may further comprise an electronic delivery status indication system configured to provide an indication of a substance delivery status to the user of the medicament. For example, the electronic delivery status indication system may provide an indication to the user that a predetermined amount of the substance has been expelled from the medicament container. The predetermined amount may be a part of or all of the contents of the medicament container. Additionally, or alternatively, the electronic delivery status indication system may provide an indication to the user that delivery of the substance contained within the medicament container has commenced.

Exemplary electronic delivery status indication systems may comprise a detector, which may be a dose or full delivery detector, configured to detect that the plunger rod has reached a position on the delivery stroke that is indicative of a delivery of a predetermined amount of or all of the substance from within the medicament container.

Exemplary electronic delivery status indication systems may further comprise an indicator configured to provide an indication to the user that medicament delivery has been achieved based on data received from the detector.

In exemplary plungers at least a portion of the electronic delivery status indication system may be received within the plunger body. For example, at least one detector and the indicator may be received within the plunger body.

In exemplary arrangements, the detector is operable by engagement thereof with the medicament container. In such arrangements, movement of the plunger within the medicament container may bring the detector into engagement with an inner wall of the medicament container when the plunger has reached a position on the delivery stroke corresponding to delivery of a predetermined amount of the substance. The predetermined amount of the substance may be a part or all of the substance contained in the medicament container. This engagement may cause the indicator to provide an indication to the user that a corresponding delivery of the substance has been completed. In exemplary plungers, the detector may comprise a switch, for example a microswitch, which is operated on engagement with the medicament container. For example, the switch may contact an inner wall of the medicament container when the plunger reaches the position on the delivery stroke indicative of delivery of a predetermined amount of the substance from the medicament container, and this contact may operate the switch.

Certain terminology is used in the following description for convenience only and is not limiting. The word "distal" refers to the front, or patient, end of the device. The word "proximal" refers to the rear, or user, end of the device. The term "longitudinal", with or without axis, refers to a direction on an axis through the device in the direction of the longest extension of the device. The term "radial" or "transverse/transversal", with or without axis, refers to a direction generally perpendicular to the longitudinal direction, e.g. "radially outward" would refer to a direction pointing away from the longitudinal axis.

Figure 1 shows an exemplary plunger 100. The exemplary plunger 100 comprises a plunger body 102 and an electronic delivery status indication system 104.

The plunger body 102 comprises a distal end 106 configured to engage a bung contained within the medicament container..

The plunger body 102 may be hollow. The exemplary plunger body 102 shown in Figure 1 comprises a hollow tube which is open at the proximal end 108 of the plunger 102. In exemplary arrangements, the distal end 106 of the plunger body 102 is at least partially open. That is, the distal end 106 may comprise an aperture. However, the skilled person will appreciate that in alternative arrangements, the distal end 106 of the plunger body 102 may be fully open, or alternatively, fully closed. As will be described in more detail below, at least a portion of the electronic delivery status indication system 104 may be received within the plunger body 102.

The plunger body 102 may comprise a slot 110. The slot 110 is visible in Figure 2, which shows the exemplary plunger body 102 in isolation. The slot 110 may provide an opening into the hollow interior of the plunger body 102. As will be explained in more detail below, a portion of the electronic delivery status indication system 104 may extend through the slot 110 when the electronic delivery status indication system 104 is received within the plunger body 102.

The exemplary slot 110 extends axially along the plunger body 102. In the exemplary plunger body 102 shown in Figure 2, the slot 110 extends along substantially the whole of the length of the plunger body 102, with a closed distal end. The skilled person will appreciate that in alternative arrangements, the slot may extend along the plunger body 102 to different extents. The skilled person will appreciate that alternative arrangements are possible. For example, the plunger body 102 may comprise a plurality of discrete slots or apertures, axially spaced along the plunger body 102.

The plunger body 102 may further comprise a connector 112 configured to couple the plunger body 102 to a proximal portion 114 of the plunger 100. The connector 112 may be configured to engage a proximal portion 114 of the plunger 100. The connector 112 may comprise arms 116a, 116b. The arms 116a. 116b may be opposed. The exemplary arms 116a, 116b comprise lugs 118a, 118b at an end thereof. The lugs 118a, 118b may be configured to engage corresponding recesses/apertures in the proximal portion 114 of the plunger 100 to couple the plunger body 102 thereto. In the exemplary arrangement of Figure 1, the plunger body 102 may engage the proximal portion 114 by a snap fit engagement. The skilled person will appreciate that alternative connectors may be utilised, for example interference fit connectors or screw threads.

The plunger body 102 may comprise a mounting feature. The mounting feature may be configured to engage the electronic delivery status indication system 104 to facilitate mounting of the electronic delivery status indication system 104 to, and/or within, the plunger body 102. The mounting feature may comprise one or more slots 122a, 122b configured to receive a portion of the electronic delivery status indication system 104 when the electronic delivery status indication system 104 is received within the plunger body 102. In the exemplary plunger body 102, the mounting feature comprises opposed slots 122a, 122b. The skilled person will appreciate that alternative mounting features 120 may be used, such as keyed features, clips, adhesives, etc. in alternative arrangements.

As mentioned above, in exemplary arrangements, the plunger 100 may comprise a proximal portion 114. Figure 3 shows an exemplary proximal portion 114 in isolation. The proximal portion 114 may comprise a proximal portion body 124. The proximal portion 114 may further comprise a retention feature 126.

The proximal portion body 124 may be hollow. The exemplary proximal portion body 124 shown in Figure 3 comprises a hollow tube which is open at both ends. The proximal portion body 124 may have a larger diameter than the diameter of the plunger body 102. As will be described in more detail below, at least a portion of the electronic delivery status indication system 104 may be received within the proximal portion body 124.

The proximal portion 114 may comprise a connector 128 configured to engage the connector 112 of the plunger body 102 to couple the proximal portion 114 thereto. The exemplary connector 128 of the proximal portion 114 comprises recesses 130a, 130b configured to receive the lugs 118a, 118b of the plunger body 102. The skilled person will appreciate that in alternative arrangements, the plunger body 102 may comprise the recesses and the proximal portion 114 may comprise the lugs 118, 118b. Similarly to as described above in respect of the connector 112 of the plunger body 102, in alternative arrangements, alternative connectors may be utilised, for example interference fit connectors or screw threads on the plunger body 102 and proximal portion 114.

The proximal portion 114 may comprise a mounting feature. The mounting feature may be configured to engage the electronic delivery status indication system 104 to facilitate mounting of the electronic delivery status indication system 104 to, and/or within, at least one of the plunger body 102 and the proximal portion 114. The mounting feature may comprise one or more slots 132a, 132b configured to receive a portion of the electronic delivery status indication system 104 when the electronic delivery status indication system 104 is received within the proximal portion 114. In the exemplary plunger body 102, the mounting feature comprises opposed slots 132a, 132b. The opposed slots 132a, 132b may align with the opposed slots 122a, 122b of the plunger body 102 when the proximal portion 114 and the plunger body 102 are coupled. The skilled person will appreciate that alternative mounting features may be used, such as keyed features, clips, adhesives, etc. in alternative arrangements. The skilled person will further appreciate that in alternative arrangements, mounting features may be provided on only one of the plunger body 102 and the proximal portion 114.

The exemplary proximal portion 114 may comprise a flange 134. A plunger driver, for example a compression spring, may abut the flange 128 such that actuation of the plunger rod driver drives the plunger 100 distally within the syringe barrel. The skilled person will appreciate that with alternative plungers, alternative plunger driver arrangements may be used, and the proximal portion 114 need not have a flange. For example, the flange 134 may be present in plungers 100 configured for use with auto-injector devices comprising plunger drivers.

As mentioned above, exemplary proximal portions may comprise a retention feature 126. In the exemplary arrangement shown in Figure 3, the retention feature 126 comprises arms 136a, 136b. The arms 136a, 136b may extend from the proximal portion body 124. In the exemplary arrangement shown in Figures 1(a) and (b), the arms 136a, 136b extend from opposed sides of a rear end of the proximal portion body 124. The arms 136a, 136b may comprise lugs 138a, 138b. The lugs 138a, 138b may be configured to engage recesses within a further component of an injection device when the plunger 100 is received therein, to retain the plunger driver in a primed position prior to actuation of the injection device. Operation of the retention feature 126 will be described in further detail below. However, the skilled person will appreciate that alternative plungers may comprise alternative retention features, or may not comprise a retention feature.

As mentioned above, the exemplary plunger 100 comprises an electronic delivery status indication system 104. The electronic delivery status indication system 104 is shown in isolation in Figure 4.

The electronic delivery status indication system 104 may comprise an electronic circuit, which in this case is printed on a printed circuit board (PCB) 144 or equivalent. The electrical circuit may include one or more processors and other electronic components configured to carry out any part of the methods described herein. In particular, the electrical circuit may comprise one or more of: one or more detectors; one or more indicator(s); a power source; a transmitter; a receiver; and a processor.

The exemplary electronic delivery status indication system 104 comprises a detector 146. The detector 146 may comprise a full delivery detector configured to determine whether a full dose delivery has occurred. The term "full dose delivery" encompasses delivery of substantially all of a substance, such as a drug or medicament, from a barrel of a syringe. In exemplary arrangements, the full delivery detector may be configured to detect that the plunger rod has reached a position on the delivery stroke that corresponds to a full delivery of the substance from within the medicament container.

The detector 146 may comprise a switch, such as a micro-switch. The switch may form part of the circuit printed on the PCB 144. However, other means for detecting may be used. As will be explained in more detail below, the switch may be operated by the medicament container.

The electronic delivery status indication system 104 may comprise a further detector 148. The further detector 148 may be a delivery commencement detector configured to determine that dose delivery has commenced. That is, the further detector 148 may be configured to determine that the plunger 100 has commenced a delivery stroke to expel a substance from a medicament container. In exemplary arrangements, the delivery commencement detector may be configured to detect that the plunger rod has reached a position on that is indicative of commencement of delivery of the substance from within the medicament container. The further detector 146 may comprise a switch, such as a micro-switch. The switch may form part of the circuit printed on the PCB 144. However, other means for detecting may be used. As will be explained in more detail below, the switch may be operated by the medicament container.

The delivery commencement detector and the detector may be axially separated. The distance between the delivery commencement detector and the detector may substantially correspond to the distance that the plunger 100 is configured to travel within the medicament container to achieve dose delivery, for example, it may correspond to the entire length of travel of the plunger along the medicament container required for all of the substance contained in the medicament container to be delivered. In the exemplary arrangement of Figure 4, the detector and the delivery commencement detector are separated along a length of the PCB 144.

The delivery commencement detector may be located distally of the detector. That is, the delivery commencement detector may be located such that it enters the medicament container during the delivery stroke of the plunger 100 before the full delivery detector.

The exemplary electronic delivery status indication system 104 further comprises an indicator. The exemplary electronic delivery status indication system 104 comprises a visual indicator 150. The visual indicator may comprise one or more light emitting diodes, LEDs, 152a, 152b. The skilled person will appreciate that in alternative arrangements, alternative visual indicators may be used. The visual indicator 150 may be mounted to the PCB 144 such that it is visible from both sides of the PCB 144.

In the exemplary arrangement shown in Figure 4, the visual indicator 150 comprises two LEDs mounted within an aperture 154 of the PCB 144. Advantageously, this allows the LEDs to be visible from either side of the PCB 144. The skilled person will appreciate that in alternative arrangements, a different number of LEDs may be mounted within the aperture 154. For example, in an alternative arrangement, a single LED may be mounted within the aperture 154. In further alternative arrangements, reflective material may be mounted to a sidewall of the aperture, or the sidewall may comprise reflective material, such that light emitted from the LED(s) is projected in different directions. For example, an LED may be mounted to a sidewall of the aperture and the opposed sidewall of the aperture may comprise a reflective material. In further alternative arrangements, the visual indicator may further comprise an optical lens. Advantageously, in arrangements where the visual indicator 150 also comprises LEDs, the optical lens may provide increased visibility of the LEDs.

The exemplary electronic delivery status indication system 104 may alternatively, or additionally, comprise an audio indicator 156. The audio indicator 156 may be configured to emit one or more tones, for example, a full delivery tone, a delivery commencement tone and/or a fail tone. The audio indicator 156 may be mounted at a proximal end of the PCB 144. In exemplary arrangements, the audio indicator may comprise a magnetic buzzer.

In exemplary arrangements, all electrical components of the electronic delivery status indication system 104 may be mounted to a single side/face of the PCB 144. For example, the detectors 146, 148 may be mounted to a single side/face of the PCB 144. In exemplary arrangements, the PCB 144 may comprise a side/face on which no electrical components are mounted.

The electronic delivery status indication system 104 may comprise a power source 158. The power source 158 may comprise one or more batteries. The batteries may comprise one or more coin battery cells, for example, one or more silver oxide coin battery cells. The coin battery cells may be mounted such that a longitudinal axis of the coin battery cells is parallel with the longitudinal axis of the PCB 144 (and/or the plunger body 102 when the electronic delivery status indication system 104 is mounted therein).

The power source 158 may be mounted to the PCB 144 within an aperture. The aperture may be dimensioned such that opposed walls of the aperture abut the power source 158. In exemplary arrangements, the aperture may be dimensioned to provide an interference fit with the power source.

The power source 158 may be electrically connected to the PCB via electrical contacts 160a, 160b. In exemplary arrangements at least one of the electrical contacts 160a, 160b may be a sprung electrical contact (shown as feature 160a in Figure 4). The sprung electrical contact 160a may be configured to bias the power source 158 towards the other electrical contact 160b. In the exemplary arrangement shown in Figure 4, in which the power source 158 comprises coin batteries, the sprung electrical contact 160a is configured to contact a first face of at least one of the coin batteries and bias an opposed face of another of the coin batteries into contact with the other electrical contact 160b. The skilled person will appreciate that in arrangements comprising a single coin battery, the sprung electrical contact 160a may contact a first face of the coin battery and bias an opposed face of the coin battery into contact with the other electrical contact 160b. The sprung electrical contact 160a may be configured to axially secure the power source 158 in at least one plane. In the exemplary arrangement shown in Figure 4, the sprung electrical contact is configured to axially secure the power source 158 in the plane of the PCB 144.

The inventors have appreciated that plungers, such as the plunger 100, may be exposed to high forces when actuated, particularly when used with auto-injector devices. The forces associated with actuating, or firing, the device which in some cases may cause the plunger rod to impact a bung located within the medicament container, may cause the power source to become dislodged from the electrical contact (such as electrical contacts 160a, 160b).

Generally disclosed herein is a power source retainer configured to resist axial movement of the power source and retain the power source in contact with the electrical contacts.

The power source retainer may be configured to axially secure the power source in at least one plane, which is different to the plane of the electrical contacts. In exemplary arrangements, the power source retainer may be configured to axially secure the power source in a plane transverse to the plane of the electrical contacts (or the plane of the PCB 144).

In the exemplary arrangement shown in Figures 5a and 5b, the power source retainer comprises opposed ribs 164a, 164b. Figure 5a shows a section view of a portion of the plunger 100, and Figure 5b shows a perspective view of the proximal portion 114. The opposed ribs 164a, 164b may be configured to abut opposed surfaces of the power source 158 to prevent axial movement of the power source (for example, in the plane of the opposed ribs 164a, 164b). The skilled person will appreciate however that alternative mechanical retainers may be used prevent axial movement of the power source 158 and secure the power source 158 in contact with the electrical contacts 160a, 160b. For example, the power source retainer may comprise a keyed aperture configured to receive the power source. Alternatively, the power source retainer may comprise a latch arrangement, a lug and recess arrangement or an interference/friction fit arrangements. The skilled person will be able to envisage further arrangements.

In the exemplary plunger 100, the proximal portion 114 comprises the opposed ribs 164a, 164b. As will be explained in more detail below, when the plunger rod is assembled, at least a portion of the power source 158 may be received within the proximal portion 114. Receipt of the power source 158 within the proximal portion causes the power source 158 to be brought into contact with the ribs 164a, 164b. The skilled person will appreciate that in alternative arrangements, the power source retainer may be located on another component of the plunger 100, or alternatively on a component of the injection device into which the plunger 100 is configured to be inserted.

The skilled person will appreciate that in the exemplary plunger 100, the power source 158 is secured in three perpendicular planes. That is, the power source 158 is secured in a first plane defined by the electrical contacts 160a, 160b by the sprung electrical contact 160a; a second plane defined by the aperture within the PCB 144 and within which the power source 158 is received via an interference fit; and a third plane by the opposed ribs 164a, 164b. The skilled person will appreciate that in alternative arrangements, the power source 158 may not be secured in the three planes mentioned, and may be secured in one or more of the planes using one or more of the methods/arrangements.

Figure 1 shows the plunger 100 assembled.

During assembly of the plunger 100, a portion of the electronic delivery status system 104 is inserted into the plunger body 102. In the exemplary arrangement shown in Figures 1-4, a portion of the PCB 144 is inserted into the plunger body 102. The PCB 144 may comprise a distal portion configured to be inserted into the plunger body 102.

The distal portion may comprise the full delivery detector and the delivery commencement detector. The distal portion may comprise the visual indicators 152a, 152b.

The distal portion of the PCB 144 is inserted into the plunger body 102 such that the detectors 146, 148 are received within the slot 110 of the plunger body 102. In the exemplary arrangement shown in Figure 1, the detectors 146, 148 extend through the slot 110 when the PCB 104 is inserted into the plunger body 102. In the specific arrangement shown in Figure 1, the detectors 146, 148 comprise a switch, such as a microswitch, and a portion of the switch extends laterally through the slot 110 of the plunger body 102.

Insertion of the distal portion of the PCB 144 into the plunger body during assembly results in the visual indicators 152a, 152b being received within the plunger body 102. In exemplary arrangements, at least a portion of the plunger body may be transparent or translucent to allow a user to see the visual indicator when light is emitted therefrom.

In exemplary arrangements substantially all of the plunger body 102 may be transparent or translucent. In alternative arrangements, the portion of the plunger body 102 adjacent to the visual indicator may be transparent or translucent. In exemplary arrangements in which the visual indicator is mounted within the aperture 154 of the PCB 144, light is emitted by the visual indicator from opposed sides of the PCB 144, and therefore light is emitted from opposed sides of the plunger body 102.

In the exemplary plunger 100, the PCB 144 is received within the slots 122a, 122b of the plunger body 102. Receipt of the PCB 144 within the slots 122a, 122b may cause rotational movement of the PCB 144 within the plunger body 102 to be resisted.

Further, receipt of the PCB 144 within the slots 122a, 122b may orientate the PCB 144 correctly within the plunger body 102, ensuring that the detectors 146, 18 extend through the slot 110 of the plunger body 102. The skilled person will appreciate that alternative mounting arrangements may be utilised, as described above.

The PCB 144 may comprise a ledge configured to abut a shoulder of the plunger body 102. The PCB 14 may be inserted into the plunger body 102 until the ledge of the PCB 144 abuts the plunger body 102.

The proximal portion 114 may be coupled to the plunger body 102. During assembly of the plunger 100, the proximal portion 114 is coupled to the plunger body 102 once the distal portion of the PCB 144 has been inserted into the plunger body 102. For example, once the ledge of the PCB 144 abuts the shoulder of the plunger body 102.

At least a portion of the electronic delivery status indication system 104 may be received within the proximal portion 114. In the exemplary arrangement shown in Figures 1-4, the proximal portion 114 is placed over the portion of the electronic delivery status indication system 104 that is not received within the plunger body 102.

In the exemplary arrangement shown in the Figures, at least the power source 158 and the audio indicator 156 are not received within the plunger body 102.

During assembly, the PCB 144 may be received within the opposed slots 132a, 132b of the proximal portion 114. This allows the proximal portion 114 to be moved axially along the PCB 144 and towards the plunger body 102, but prevents relative rotational movement of the proximal portion 114 and the PCB 144.

The proximal portion 114 may be slid along the PCB 144 towards the plunger body 102 such that the power source 158 is brought into contact with the opposed ribs 164a, 164b.

The proximal portion 114 may be moved further axially distal towards the plunger body 102 to engage the connector 128 of the proximal portion 114 with the connector 112 of the plunger body. Engagement of the connectors 112, 114 couples the plunger body 102 and the proximal portion 114. In the exemplary arrangement shown in Figures 1-4, engagement of the connectors 112, 114 comprises the lugs 118a, 118b of the plunger body 102 being received within corresponding recesses 130a, 130b of the proximal portion 114.

In the exemplary arrangement shown in Figure 1, the audio indicator 156 extends from the proximal portion 114. In alternative arrangements, the audio indicator 156 may be received within the plunger body 102 or the proximal portion 114 when the plunger 100 is assembled.

In the assembled plunger 100, the PCB 144 may be rotationally and axially fixed with respect to the plunger body 102 and the proximal portion 114.

Figure 6 shows the plunger 100 mounted within an exemplary injection device 600.

The injection device 600 may be an auto-injector. The injection device 600 is provided as an example, and the skilled person will appreciate that the plunger 100 is configured for use with a variety of injection devices, and not limited to the specific arrangement shown in Figure 6. For example, the plunger 100 may be used with auto injector devices of different configurations, or alternatively may be used with non-auto injector/manual devices.

The injection device 600 comprises a medicament container 602 configured to receive a substance therein, such as a medicament. A bung 604 may be received within the medicament container 602. The plunger 100 may be configured to contact the bung 604 and drive the bung distally, i.e. towards a needle end of the medicament container 602 to expel the substance from the medicament container.

The injection device 600 may further comprise a driver 606. The driver 606 may be configured to drive the plunger 100 distally within the medicament container 602 on actuation thereof. In the exemplary arrangement shown, the driver 606 comprises a compression spring held in a primed state and released from the primed state of actuation of the driver 606. The power source 158 may be received within the hole of the compression spring (i.e. the compression spring may be mounted around the power source 158). Specifically, in the exemplary arrangement shown in Figure 6, the proximal portion 114, within which the power source 158 is received, is received in the hole of the compression spring. The skilled person will be able to envisage alternative drivers, including but not limited to a torsion spring or a motor.

The driver 606 may be coupled to the plunger 100. In the exemplary arrangement shown in Figure 6, a distal end of the driver 606 abuts the flange 132 of the plunger 100.

The retention features 126 of the plunger 100 may engage corresponding retention features 608 of the injection device 600 to hold the driver 606 in a primed state. On actuation of the injection device, the retention features may disengage allowing the driver 606 to drive the plunger 100 distally within the barrel.

Operation of the plunger 100 is described below.

Prior to use of the plunger 100, at least a portion of the plunger 100 is positioned outside of the medicament container 602. Figure 6 shows a position of the plunger 100 within an injection device prior to use. As can be seen in Figure 6, substantially all of the plunger 100 is positioned outside of the medicament container, with only the distal end 106 of the plunger body 102 being received within the medicament container. In exemplary arrangements, different extents of the plunger 100 may be received within the medicament container 602. Prior to use, the detectors 146 and 148 are positioned proximally to the medicament container 602.

During use, the plunger 100 may be moved distally within the medicament container, for example, on a delivery stroke to dispense a substance from the medicament container. In the specific arrangement shown in Figure 6, the injection device 600 may be actuated, causing the retention features 126 of the plunger 100 to disengage from the retention features 608 on the injection device 600, which releases the driver 606 to drive the plunger 100 distally within the medicament container 602. In alternative arrangements, distal movement of the plunger may be actuated in a different way, or alternatively, a user may manually move the plunger within the device.

Movement of the plunger 100 distally within the medicament container causes the delivery commencement detector 148 to engage the medicament container.

Specifically, the delivery commencement detector is brought into engagement with an inner wall of the medicament container 602. Engagement of the delivery commencement detector 148 and the inner wall of the medicament container 602 operates the delivery commencement detector 148. Engagement may comprise contact of the delivery commencement detector 148 with the inner wall of the medicament container 602. The commencement detector 148 may be positioned along the length of the plunger 100 such that engagement with the medicament container 602 occurs on or shortly after commencement of movement of the plunger 100 within the medicament container 602.

As described above, the delivery commencement detector 148 may be configured to provide power to the electronic delivery status indication system 104 on operation thereof. The skilled person will appreciate that in alternative arrangements, the electronic delivery status indication system may be continuously powered.

Operation of the delivery commencement detector 148 may alternatively (or further) cause a signal to be transmitted to the processor of the electronic delivery status indication system 104 indicating that the plunger 100 has commenced a delivery stroke to expel a substance from the medicament container 602 and/or that delivery is in progress. The processor may then enter a delivery sequence and control the visual indicator 152a, 152b and/or audio indicator 156 to indicate to a user that delivery is in progress/delivery has commenced. For example, where the visual indicators comprise LED(s), the processor may control the LED(s) to flash, and may control the audio output to emit a delivery commencement tone. In exemplary arrangements, the processor may control the visual indicator 152a, 152b and/or audio indicator 156 to indicate commencement of the delivery stroke to the user according to a delivery stroke commencement programme. The delivery stroke commencement programme may comprise a predetermined indication sequence, for example, the LED may flash a predetermined colour according to a flash cycle and/or the audio indicator may emit a delivery commencement tone at a predetermined frequency and/or according to a predetermined tone cycle. The skilled person will appreciate that the delivery stroke commencement programme may comprise alternative sequences such as a continuous tone, or a continuous lighting of the LED, and the above sequence is provided only as an example. In one example, the LED may flash at 1 second intervals and the audio indicator may emit regular tones.

The plunger 100 continues to move distally on the delivery stroke after engagement of the delivery commencement detector 148 with the medicament container 602. At, or just before, the point of full dose delivery, i.e. the point at which the plunger 100 reaches the end of the medicament container 602, the full delivery detector 146 engages the medicament container 602. Specifically, the full delivery detector 146 is brought into engagement with an inner wall of the medicament container 602. Engagement may comprise contact of the full delivery detector 146 with the inner wall of the medicament container 602. Engagement of the full delivery detector 146 and the inner wall of the medicament container 602 operates the full delivery detector 148.

This results in a signal being transmitted to the processor to indicate that full dose delivery has occurred.

The processor may then enter a full delivery sequence and control the visual indicator 152a, 152b and/or audio indicator 156 to indicate a successful dose delivery to a user.

For example, where the visual indicators comprise LED(s), the processor may control the LED(s) to flash, and may control the audio output to emit a successful delivery tone. In exemplary arrangements, the processor may control the visual indicator 152a, 152b and/or audio indicator 156 to indicate a successful dose delivery to a user according to a successful dose delivery programme. The successful dose delivery programme may be different to the delivery stroke commencement programme. For example, the LED may flash a different colour or flash according to a different flash cycle to that of the delivery stroke commencement programme, and/or the audio indicator may emit a different frequency of tone and/or a different tone cycle. In one example, a blue LED may be illuminated and the audio indicator may emit a continuous tone.

In exemplary arrangements, the processor may be configured to enter a failed delivery sequence if a threshold time is exceeded without the full delivery detector 146 being operated. For example, the processor may be configured to enter a failed delivery sequence if the full dose delivery detector 146 is not operated within a threshold time of the delivery commencement detector 148 being operated. The threshold time may be one or more of: substantially 5 seconds; substantially 7 seconds; substantially 10 seconds; substantially 12 seconds, and substantially 15 seconds.

If the full delivery detector 146 is not operated within the threshold time, the processor is configured to control the visual indicator 152a, 152b and/or audio indicator 156 to indicate a failed delivery to a user. For example, where the visual indicators comprise LED(s), the processor may control the LED(s) to flash, and may control the audio output to emit a failed delivery tone. In exemplary arrangements, the processor may control the visual indicator 152a, 152b and/or audio indicator 156 to indicate a failed delivery to a user according to a failed delivery programme. The failed delivery programme may be different to the delivery stroke commencement and the successful dose delivery programme. For example, the LED may flash a different colour or in a different sequence to that of the delivery stroke commencement and successful delivery programmes, and/or the audio indicator may emit a different frequency of tone and/or a different tone sequence. In one example, a red LED may be illuminated and flash for 5 seconds, and the audio indicator may emit a constant tone for 5 seconds.

Although the plunger has been described as having two portions, the skilled person will understand that the plunger may comprise a single part or more than two portions. Additionally, although the plunger body has been described as a tube the skilled person will understand that the different parts of the plunger may be any suitable shape.

The skilled person would also understand that any suitable detector may be used to determine the position of the plunger relative to the medicament container. For example, although the detector of the present invention has been described as being a micro-switch, the skilled person would understand that other detectors such as a light switch or a hall-effect sensor may be used. In the instance that a light switch or hall-effect sensor are used as a detector the medicament container should be provided with a corresponding feature on, for example, the wall of the medicament container that can be detected by the sensor in the plunger to allow the position of the plunger relative to the medicament container to be determined. In the event that a detector such as a light sensor or hall-effect sensor is used then the skilled person will understand that there is no requirement for a corresponding slot to be provided within the plunger.

Optionally a plurality of different detectors may be provided. For example, the most distal detector may be a microswitch and the proximal detectors may be a light switch or hall-effect sensor. In this case the plunger may be provided with a slot which only allows the microswitch to extend out of the plunger body or alternatively, the slot may extend the length of the plunger as described above. This positioning of the detector types provides the advantage that the microswitch completes the circuit to allow power to the indicator and more proximally placed detector. This prolongs the life of the batteries in the plunger.

For example, the microswitch may be the delivery commencement detector. In such an instance when the plunger moves forward the microswitch contacts the medicament container completes the circuit on the PCB causing power to flow in the electronic plunger and an indicator to indicate that delivery has commenced. More proximal detectors, for example a full delivery detector, then have power provided to allow them to detect the position of the plunger relative to the medicament container.

The skilled person will be able to envisage further embodiments of the invention without departing from the scope of the appended claims.

Claims

CLAIMS: 1. A plunger for use in an injection device comprising a medicament container including a bung and arrange, in use to drive the bung at least partially through the medicament container to expel a substance therefrom, the plunger comprising: a body comprising a distal end configured to contact the bung, wherein at least a portion of the body is transparent or translucent; and an electronic delivery status indication system comprising: at least one detector operable to detect a position of the plunger within the medicament container; and a visual indicator configured to provide, dependent upon the detector, a visual indication to a user indicative of delivery of the substance from the medicament container based on data received from the detector, wherein the visual indicator is mounted within the plunger body such that light is emitted from the visual indicator through opposed sides of the transparent or translucent portion of the plunger body.
2. A plunger according to claim 1, wherein the electronic delivery status indication system comprises a printed circuit board, PCB, comprising a distal portion configured to be received within the plunger body, the distal portion comprising an aperture, and wherein the visual indicator is mounted within the aperture of the PCB such that light is emitted by the visual indicator from opposed sides of the PCB.
3. A plunger according to claim 1 or 2, wherein the visual indicator comprises a light emitting diode, LED.
4. A plunger according to claim 3, when dependent on claim 2, wherein the visual indicator comprises a pair of LEDs mounted to opposed sidewalls of the aperture.
5. A plunger according to claim 3 or 4, when dependent directly or indirectly on claim 53, wherein at least a portion of the aperture is reflective.
6. A plunger according to any preceding claim, further comprising an optical lens.
7. An injection device comprising: a plunger according to any of claims 1 to 6; and the medicament container, the plunger configured for receipt within the medicament container during the delivery stroke.