HK1149912B - Inhaler - Google Patents

Abstract

An inhaler (10) is disclosed. It comprises a housing (12) to receive a strip (3) having a plurality of blisters (3a), each blister having a breachable lid and containing a dose of medicament for inhalation by a user, an indexing wheel (15) mounted in the housing rotatable to drive a strip to sequentially move blisters into alignment with a blister piercing member (8), a control element (14) pivotally mounted to the housing and a drive mechanism (17) configured to couple the control element to the indexing wheel during part of the rotation of the control element by a user so that the indexing wheel rotates together with the control element.

Description

The present invention relates to an inhalation device for oral or nasal delivery of medicament in powdered form. More specifically, the invention relates to an inhaler having a housing to receive a strip having a plurality of blisters spaced along the length of the strip, each blister having a puncturable lid and containing a dose of medicament for inhalation by a user. The invention also relates to an inhaler containing a strip of blisters each having a puncturable lid and containing a dose of medicament for inhalation by a user of the device according to the invention.

Oral or nasal delivery of a medicament using an inhalation device is a particularly attractive method of drug administration as these devices are relatively easy for a patient to use discreetly and in public. As well as delivering medicament to treat local diseases of the airway and other respiratory problems, they have more recently also been used to deliver drugs to the bloodstream via the lungs, thereby avoiding the need for hypodermic injections.

It is common for dry powder formulations to be pre-packaged in individual doses, usually in the form of capsules or blisters which each contain a single dose of the powder which has been accurately and consistently measured. A blister is generally cold formed from a ductile foil laminate or a plastics material and includes a puncturable lid which is permanently heat-sealed around the periphery of the blister during manufacture and after the dose has been introduced into the blister. A foil blister is preferred over capsules as each dose is protected from the ingress of water and penetration of gases such as oxygen in addition to being shielded from light and UV radiation all of which can have a detrimental effect on the delivery characteristics of the inhaler if a dose becomes exposed to them. Therefore, a blister offers excellent environmental protection to each individual drug dose.

Inhalation devices that receive a blister pack comprising a number of blisters each of which contain a pre-metered and individually packaged dose of the drug to be delivered are known. Actuation of the device causes a mechanism to breach or rupture a blister, such as by puncturing it or peeling the lid off, so that when the patient inhales, air is drawn through the blister entraining the dose therein that is then carried out of the blister through the device and via the patient's airway down into the lungs. Pressurized air or gas or other propellants may also be used to carry the dose out of the blister. Alternatively, the mechanism that punctures or opens the blister may push or eject the dose out of the blister into a receptacle from which the dose may subsequently be inhaled.

It is advantageous for the inhaler to be capable of holding a number of doses to enable it to be used repeatedly over a period of time without the requirement to open and/or insert a blister into the device each time it is used. Therefore, many conventional devices include means for storing a number of blisters each containing an individual dose of medicament. When a dose is to be inhaled, an indexing mechanism moves a previously emptied blister away from the opening mechanism so that a fresh one is moved into a position ready to be opened for inhalation of its contents.

An inhaler of the type described above is known from the Applicant's own copending international application no. PCT/GB2004/004416 filed on 18th October 2004 and claiming priority from GB0324358.1 filed 17th October 2003 . This international application has been published as WO2005/037353 A1 .

According to one embodiment described and claimed in WO 2005/037353 A1 , and illustrated in Figures 1 and 2 of the accompanying drawings, an inhaler 1 has a housing 2 containing a coiled strip 3. The strip 3 has a plurality of individually spaced moisture proof blisters each containing a pre-measured dose of powdered medicament for inhalation. Each blister of the strip comprises a generally hemispherically shaped pocket and a flat puncturable lid permanently heat sealed to the pocket to hermetically seal the dose therein. The strip is preferably manufactured from foil laminate or a combination of foil laminate, such as aluminium, and plastics material.

An indexing mechanism 4 comprising a single actuating lever 5 unwinds the coil 3 one blister at a time so that they pass over a blister locating chassis 6 and successively through a blister piercing station 7, when the actuator 5 is pivoted in a direction indicated by arrow "A" in Figure 2. The blister 3a located at the blister piercing station 7 on each movement of the actuator 5 is pierced on the return stroke of the actuator 5 (in the direction indicated by arrow "B" in Figure 2) by piercing elements 8 on the actuator 5 itself so that, when a user inhales through a mouthpiece 9, an airflow is generated within the blister 3a to entrain the dose contained therein and carry it out of the blister 3a via the mouthpiece 9 and into the user's airway.

In another embodiment disclosed in WO2005/037353 A1 , indexing and piercing of a blister positioned at the blister piercing station 7 is carried out in response to rotation of a cap that covers the mouthpiece in a closed position, rather than as a result of direct rotation of the actuator by the user.

Each of the devices disclosed in WO2005/037353 A1 have a drive mechanism that includes an indexing wheel. A blister strip passes over the indexing wheel and the wheel rotates in response to pivotal movement of an acutator or cap so as to drive or index the strip through the device. The drive mechanism is configured such that the indexing wheel rotates in response to rotation of the actuator or cap in one direction but remains stationary when the actuator or cap is rotated in the opposite direction.

The present invention seeks to provide an alternative an inhaler having an improved drive mechanism for coupling the actuator, or cap, to the indexing wheel so that rotation of the indexing wheel occurs during rotation of the cap or actuator in one direction. However, the invention also seeks to provide a modified drive mechanism in which the indexing wheel will rotate during only part of the movement of the actuator or cap in the same direction. In particular, the indexing wheel will rotate to index a strip during a first part of the movement of the actuator or cap in one direction and, when the actuator or cap has reached an intermediate position, the actuator or cap will disengage from the indexing wheel so that, during further movement of the actuator or cap in the same direction beyond the intermediate position, no further rotation of the indexing wheel will occur.

In a cap operated device in which a cap, which normally covers the mouthpiece in a closed position, is pivoted to index a strip and also to move an actuator to cause a piercing element mounted to or associated with the actuator to puncture the lid of a blister, the drive mechanism may be configured such that a fresh blister may be located in alignment with the blister piercing member when the intermediate position of the cap has been reached so that further movement of the cap in the same direction beyond the intermediate position causes the blister piercing member to pierce the pre-aligned and stationary blister.

In WO 2007/012871 , a cap operated inhaler is described, which uses a two-stage opening process. A user can move the cap between a first position and a second position to facilitate cleaning of the mouthpiece. It is only when the cap is moved from the second position to a third position that indexing and opening of the blister strip occurs.

It is known from WO 2005/037353 to provide an inhaler comprising a housing to receive a strip having a plurality of blisters, each blister having a breachable lid and containing a dose of medicament for inhalation by a user, an indexing wheel mounted in the housing rotatable to drive a strip to sequentially move blisters into alignment with a blister piercing member, a control element pivotally mounted to the housing and a drive mechanism including a drive coupling member that rotates together with the control element, the drive coupling member being configured to couple the control element to the indexing wheel during part of the rotation of the control element by a user so that the indexing wheel rotates together with the control element, the indexing wheel being rotatably mounted to the drive coupling member.

An inhaler according to the present invention is characterised in that the drive coupling member comprises an indexing wheel drive dog, the drive mechanism including means to move, as the control element and drive coupling member are rotated, the indexing wheel drive dog into a position in which it cooperates with the indexing wheel so that the indexing wheel rotates together with the control element and the drive coupling member.

In a preferred embodiment, the drive coupling member includes a shaft having an axis coaxial with the axis of the control element, the indexing wheel being mounted on said shaft for rotation about said axis.

The drive coupling member is preferably formed from a resilient material and said means for moving the indexing wheel drive dog into a position in which it cooperates with the indexing wheel moves said indexing wheel drive dog against a bias provided by said resilience.

The drive coupling member may comprise a flange that extends radially from one end of the shaft across one end of the indexing wheel. Preferably, the flange lies in a plane extending substantially at right-angles to the axis of the shaft.

In one preferred embodiment, the flange includes a flexible flange portion that resiliently bends or flexes relative to the remaining portion of the flange about an axis extending substantially at right angles to the axis of the shaft.

The flange may have a cut-out region configured such that the flexible flange portion is joined only to the remaining portion of the flange to a limited extent.

In one embodiment, the flexible flange portion is hinged to the remaining portion of the flange at each end.

Conveniently, the indexing wheel drive dog upstands from a surface of the flexible flange portion in a direction towards the indexing wheel.

Preferably, the means to move the indexing wheel drive dog into a position in which it cooperates with the indexing wheel so that the indexing wheel rotates together with the control element comprises a flange deflecting dog protruding from the flexible flange portion.

In a preferred embodiment, the means to move the indexing wheel drive dog into a position in which it cooperates with the indexing wheel also comprises an arcuate guide track in the housing, the arcuate guide track having a first guide surface such that, when the drive coupling member is rotated in response to rotation of the control element in a first direction, the flange deflecting dog cooperates with the first guide surface to deflect the flexible flange portion towards the indexing wheel so that the indexing wheel drive dog cooperates with the indexing wheel to rotate the indexing wheel together with the drive coupling member.

The arcuate guide track is advantageously configured such that the flange deflecting dog drops off the first guide surface prior to rotation of the control element to its maximum extent, the resilience of the flexible flange portion causing it to return to its original undeflected state so that the indexing wheel drive dog no longer cooperates with the indexing wheel, the indexing wheel now remaining stationary during continued rotation of the control element and drive coupling member to its maximum extent.

The arcuate guide track preferably comprises a second guide surface such that, when the flange deflecting dog has dropped off the first guide surface and the drive coupling member is rotated in response to rotation of the control element in a reverse direction, the flange deflecting dog cooperates with said second guide surface so that the flexible flange portion is deflected in the opposite direction, away from the indexing wheel, so that the indexing wheel drive dog does not cooperate with the indexing wheel and the indexing wheel remains stationary.

The flange deflecting dog preferably comprises a first cooperating surface to engage the first guide surface of the arcuate guide track, and, a second cooperating surface to engage the second guide surface of the arcuate guide track.

The first and second guide surfaces of the arcuate guide track may extend parallel to each other but spaced from each other in an axial direction.

Ideally, the first and second guide surfaces have angled end regions such that the flange deflecting dog rides up the angled end regions onto respective guide surfaces.

In a preferred embodiment, the indexing wheel comprises a plurality of vanes and the indexing wheel drive dog contacts one of the vanes when the indexing wheel drive dog is moved into a position in which it cooperates with the indexing wheel so that the indexing wheel rotates together with the drive coupling member and the control element.

In a preferred embodiment, the inhaler comprises a locking element to prevent rotation of the indexing wheel other than during cooperation of the indexing wheel drive dog with the indexing wheel.

In this embodiment, the locking element preferably comprises a cantilevered arm mounted in the housing and having its free end biased against the indexing wheel, said free end of the cantilever arm cooperating with the indexing wheel so as to prevent rotation of the indexing wheel.

The free end of the cantilevered arm may be configured such that when the indexing wheel drive dog is moved towards the indexing wheel, further rotation of the coupling element causes the indexing wheel drive dog to engage the free end of the cantilever arm and deflect it out of locking engagement with the indexing wheel prior to cooperating with the indexing wheel to rotate the indexing wheel.

Preferably, the indexing wheel drive dog disengages the free end of the cantilever arm when the indexing wheel drive dog moves away from the indexing wheel so that the free end of the cantilever arm moves back towards the indexing wheel to lock the indexing wheel in position.

Preferably, the indexing wheel comprises a plurality of vanes and the free end of the cantilever arm comprises an opening or slot, the slot being configured to receive a tip of a vane when the free end of the cantilever arm is biased against the indexing wheel to lock the indexing wheel in position.

Each vane may comprise an enlarged head portion and the slot in the free end of the cantilever arm is configured to receive said enlarged head portion.

Conveniently, the inhaler may comprise a chassis to locate a blister strip as it moves therethrough and the cantilever arm extends from said chassis.

Embodiments of the invention will now be described, by way of example only, with reference to Figures 3 to 8 of the accompanying drawings, in which:

• FIGURE 1 and 2 are side views of a prior art inhalation device to show how a strip is driven to sequentially move blisters into alignment with a blister piercing element by movement of an actuator from the position shown in Figure 1 to the position shown in Figure 2 which drives an indexing wheel. A piercing head on the actuator pierces the lid of an aligned blister when the actuator is returned to its normal position, as shown in Figure 1;
• FIGURE 3 is a partial perspective view of an inhaler according to the present invention incorporating an improved blister strip indexing mechanism, with the actuator in its home, stowed or locked position prior to use of the inhaler;
• FIGURE 4 is a partial perspective view of the inhaler shown in Figure 3 in which the actuator has been rotated into an intermediate position from its home position; FIGURE 5 is the same view as shown in Figure 4, but with the cantilevered chassis arm omitted for clarity;
• FIGURE 6 is a partial perspective view of the inhaler shown in Figures 1 to 5, after the actuator has been rotated to a point at which drive between the drive coupling and the actuator has disengaged;
• FIGURE 7 is a partial perspective view of the opposite side of the inhaler shown in Figures 1 to 6;
• FIGURE 8a is a perspective view of the drive coupling used in the indexing mechanism of the inhalers shown in Figures 1 to 7; and
• FIGURE 8b is a side view of the drive coupling illustrated in Figure 8a in which the flexible flange portion has been deflected in a direction "T" towards the shaft or, towards an indexing wheel mounted on that shaft.

The drive mechanism of the present invention will now be described in detail with reference to Figures 3 to 8. It will be appreciated that this drive mechanism may be used in the inhaler described above with reference to Figures 1 and 2 but may also be used in other blister strip inhalation devices. In particular, it can also be used in a blister strip inhalation device in which a cap, which covers the mouthpiece in a closed position, is rotated to index the strip and in which an actuator is operable, either separately or in response to rotation of the cap to cause a blister piercing member to pierce the lid of an aligned blister. It may also be used in devices in which the used blisters are retained within the device.

Therefore, although the following description primarily makes reference to an embodiment in which the actuator is rotated to index the strip, such as the actuator 5 of Figures 1 and 2, any control element is considered to fall within the scope of the invention, such as a "cap" that covers the mouthpiece and which is coupled to a separate actuator.

Referring now to Figure 3, there is shown a partial perspective view of an inhalation device 10 comprising a indexing mechanism 11 according to an embodiment of the present invention. It will be appreciated that parts of the housing 12 and internal components such as the blister location chassis 13 and actuator 14 are only partially shown for the purposes of clarity and ease of understanding.

The indexing mechanism 11 includes an indexing wheel 15 comprising four vanes 15a,15b,15c,15d, each having an enlarged head portion 16a,16b,16c,16d. As is clear from reference to Figures 1 and 2, once a blister strip (not shown in Figures 3 to 8) has passed over the blister location chassis 13, it passes around the indexing wheel 15. A blister locates in the space between two vanes 15a,15b,15c,15d so that, as the indexing wheel 15 rotates in response to rotation of the actuator 14, a vane 15a,15b,15c,15d engages a blister located between the vanes15a,15b,15c,15d so as to drive the strip around the indexing wheel 15 to sequentially move each blister forward by a sufficient distance to move a fresh blister into alignment with a blister piercing element (not shown in Figures 3 to 8).

The indexing mechanism 11 includes a drive coupling member 17 (most clearly shown in Figure 8a and 8b) for selectively or temporarily coupling the actuator 14 to the indexing wheel 15 so that, when coupled, the indexing wheel 15 rotates in response to rotation of the actuator 14 to index the strip. The drive coupling member 17 comprises a shaft 18 defining an axis of rotation "A" (see Figure 8a and 8b) on which the indexing wheel 15 is rotatably received so that it can rotate freely about the shaft 18 about said axis of rotation "A". The actuator 14 is fixedly attached to the drive coupling member 17 (such as by a splined pin - not shown) - that is inserted through the actuator 14, through an aperture 12a (see Figure 7) in the housing 12 and is received within the opening 18a in the shaft 18) so that the drive coupling member 17 rotates together with the actuator 14 at all times. The actuator 14, drive coupling member 17 and indexing wheel 15 are all mounted coaxially for rotation about the same axis "A".

The drive coupling member 17 has a circular flange 19 that extends radially from one end of the shaft 18. A portion 20 of the flange is cut-away (see arcuate opening 21 in Figure 8) over an angle of approximately 180 degrees where the flange 19 joins the shaft 18 so that this portion 20 of the flange 19 is not directly attached to the shaft 18 but only to the remaining portion of the flange 19 at each of its ends 20a, 20b. As a result, this portion 20 of the flange 19 is flexible relative to the rest of the flange 19 and can be deflected out of the plane of the flange 19 that extends at right angles to the axis of the shaft, in an axial direction (indicated by "T" and "S", in Figure 8 and Figure 8b) either towards or away from the shaft 18 or, more importantly, towards or away from the indexing wheel 15 which is mounted on the shaft 18, when force is applied to it. This flexible flange portion 20 hinges about an axis B which intersects the axis A of the shaft 18 and actuator 14 but extends at right angles to it. The drive coupling member 17, or at least the flange 19, is made from a resilient material so that when the deflected flexible flange portion 20 is released, it returns to its neutral, unstressed position, in which it lies coplanar with the remaining fixed portion of the flange 19.

The flexible flange portion 20 has an integrally formed flange deflecting dog 22 projecting radially from its circumferential edge. The flange deflecting dog 22 has first and second angled engaging faces 23,24 on opposite sides. When the drive coupling member 17 is rotated in response to rotation of the actuator 14 in one direction, one of the first or second angled engaging faces 23,24 cooperate with a fixed formation 25 on the housing 12 to cause the flexible flange portion 20 to deflect in a first direction.

When the drive coupling member 17 is rotated in the opposite direction, the other angled engaging face cooperates with the formation 25 on the housing 12 to cause the flexible flange portion 20 to deflect in a second, opposite direction, as will be explained in more detail below.

The flexible flange portion 20 also has an arcuately shaped indexing wheel drive dog 26 that upstands in an axial direction from its surface towards the indexing wheel 15 in the same direction as the shaft 18 and extends partially around the circumference of the flexible flange portion 20. As will now be explained in more detail below, an end face 26a (see Figure 8a) of the indexing wheel drive dog 26 engages a vane 15a,15b,15c,15d of the indexing wheel 15 when the flexible flange portion 20 has been deflected in a first direction, as indicated by arrow "T" in Figure 8b (the flexible flange portion 20 is shown in its deflected position in Figure 8b), so that the indexing wheel 15 is driven together with the drive coupling member 17.

As mentioned above, the flange deflecting dog 22 engages a formation 25 on the housing 12 when the drive coupling member rotates in response to rotation of the actuator 14 so as to flex the deflectable portion of the flange 19. This formation 25 comprises first and second arcuately shaped tracks or paths 27, 28 positioned one above the other or spaced from each other in the axial direction. The surface of the innermost track 27 is visible in Figure 1. The lower or outermost track 28 is located beneath it and is visible in Figure 7. The ends of the tracks 27a, 28a have angled faces for reasons that will become apparent.

When the actuator 14 is rotated in a first direction (the direction indicated by arrow "A" in Figure 3), the drive coupling member 17 rotates together with it and the outwardly facing first angled engaging face 23 on the flange deflecting dog 22 contacts the angled face 27a of the innermost track 27.

Further rotation of the drive coupling member 17 causes the flange deflecting dog 22 to ride up onto the surface of the innermost track 27 thereby deflecting the flexible flange portion 20 inwardly, i.e. in a direction into the housing 12 or towards the shaft 18 and the indexing wheel 15 and the direction indicated by arrow "T" in Figure 8b.

When the flexible flange portion 20 has been deflected inwardly in the direction of arrow T, further rotation of the drive coupling member 17 causes the indexing wheel drive dog 26 to engage a vane, which as shown in Figure 1 is vane 15c, of the indexing wheel 15 so that the indexing wheel 15 rotates together with the drive coupling member 17 and drive to the indexing wheel 15 is engaged.

When the end of the innermost track 27 has been reached, the flange deflecting dog 22 falls off the surface of the track 27 and the resilience of the flexible flange portion 20 causes it to return to its original unstressed or neutral position. When the drive coupling member 17 is rotated further, the indexing wheel drive dog 26 no longer engages with the vane 15c of the indexing wheel 15 and instead passes beneath it so the indexing wheel 15 remains stationary. Therefore, drive to the indexing wheel 15 is disengaged, despite continued rotation of the actuator 14 in the same direction.

When the actuator 14 is rotated back in the opposite direction towards its home position, the inwardly facing second angled engaging face 24 of the flange deflecting dog 22 now contacts the lower or outermost track 28 so that the flange deflecting dog 22 now rides onto the surface of that second track 28, thereby causing the flexible flange portion 20 to deflect outwardly or in the opposite direction to the direction in which it was previously deflected, i.e in the direction indicated by arrow marked "S" in Figure 8b. Engagement of the flange deflecting dog 22 with the outermost track 28 so as to deflect the flange portion 20 in the opposite direction, enables the drive coupling member 17 to rotate in the opposite direction without any drive to the indexing wheel 15. It will be appreciated that, if the flexible flange portion 20 was not deflected in the opposite direction, the flange deflecting dog 22 would simply engage against the end of the formation 25 in the housing 12 when rotated back in the opposite direction, thereby preventing rotation in the opposite direction or, the flange deflecting dog 22 would travel back over the innermost track 27 deflecting the flexible flange portion 20 in the same direction causing the opposite end 26b of the indexing wheel drive dog 26 to engage with a vane 15b of the indexing wheel 15 thereby driving the indexing wheel 15 backwards rather than leaving it stationary with no drive engaged. Therefore, it is necessary to ensure that the flexible flange portion 20 is deflected in the opposite direction, i.e. in the direction of arrow "S" in Figure 8a, so that there is no drive to the indexing wheel 15 during rotation of the coupling member 17 in the opposite direction. When the drive deflecting dog 22 reaches the end of the outermost track 28, the flexible flange portion 20 returns to its original unstressed or neutral position, due to its resilience.

In a preferred embodiment, the indexing mechanism 11 also includes means for locking the indexing wheel 15 to prevent its rotation between indexing steps and means for temporarily releasing that lock to allow rotation of the indexing wheel 15 when driven by the indexing wheel drive dog 26. The lock also improves positional accuracy of the strip and, more specifically, the next blister to be pierced. This locking element will now be described in more detail below.

The blister location chassis 13 comprises a resiliently flexible cantilever arm 30 that extends from the body of the chassis towards the indexing wheel 15. The free end of the cantilever arm 30 has an enlarged head portion 31 comprising a letterbox shaped slot, window or opening 32 in which the head 16c of a vane 15c of the indexing wheel 15 is located. The opening 32 is dimensioned such that the head 16c of the vane 15c (as shown in Figure 1) is a snug fit therein so that rotation of the indexing wheel 15 is prevented. In the normal or home position of the actuator 14, the head 16c of a vane 15c is located in said opening 32 in the cantilever arm 30 of the chassis 13 so that rotation of the indexing wheel 15 is prevented.

When the actuator 14 is rotated and the flange drive dog 22 engages the innermost track 27 so as to deflect the flexible portion 20 of the flange 19 inwardly towards the indexing wheel 15, the indexing wheel drive dog 26 initially engages with a protrusion 31a from the enlarged head portion 31 on the cantilever arm 30 of the blister location chassis 13 so that the cantilever arm 30 is deflected outwardly, away from the indexing wheel 15, to free the head 16c of the vane 15c from the opening 32, thereby unlocking the indexing wheel 15. Only once the indexing wheel 15 has been released by the indexing wheel drive dog 26 pushing the cantilever arm 30 away from the indexing wheel 15 does the indexing wheel drive dog 26 subsequently engage a vane 15c of the indexing wheel 15 so that further rotation of the drive coupling member 17 rotates the indexing wheel 15.

Prior to the flange drive dog 22 falling off the end of the innermost track 28 and the flexible flange portion 20 returning to its undeflected state due to its resilience, the indexing wheel drive dog 26 no longer pushes against the cantilever arm 30 and so the cantilever arm 30 is free to move back towards the indexing wheel 15. As the cantilever arm 30 is free to move back just prior to rotation of the indexing wheel 15 being completed, the cantilever arm 30 is prevented from moving all the way back by the head 16b of a following vane 15b which contacts the cantilever arm 30. During further rotation of the indexing wheel, the head 16b slides across the cantilever arm and then drops into the opening 32 thereby allowing the cantilever arm 30 to move all the way back and locking the indexing wheel 15 in position prior to any further rotation of the drive coupling member 17 in response to continued rotation of the actuator 14.

On the return stroke of the actuator 14, it will be appreciated that deflection of the flexible flange portion 20 in the opposite direction, i.e. in a direction away from the indexing wheel 15 and in the direction indicated by arrow "S" in Figure 8b, also ensures that the indexing wheel drive dog 26 clears the cantilever arm 30 and so the indexing wheel 15 is not unlocked, thereby preventing any rotation of the indexing wheel 15 during the return stroke.

It will be appreciated that the extent of rotation of the indexing wheel 15 relative to the extent of rotation of the actuator 14 may be controlled by altering the circumferential length of the inner and outer tracks 27,28. If the tracks are made longer, the flexible flange portion 20 will be deflected for a greater proportion of the angle through which the actuator 14 is rotated and so the indexing wheel drive dog 26 will be engaged with the indexing wheel 15 to rotate the indexing wheel 15 throughout that angle. If required, the tracks 27,28 could be made sufficiently long so that the indexing wheel 15 rotates during rotation of the actuator 14 through its entire angle of movement in one direction. Alternatively, the tracks 27,28 could be made shorter to reduce the angle through which the actuator 14 and indexing wheel 15 rotate together.

Ideally, the track length can be selected so that the indexing wheel 15 is rotated through a sufficient angle to move the next, unused blister, into alignment with the blister piercing element, any further rotation of the actuator 14 can either be lost motion, i.e. it performs no function or some other function. For example, if it is the cap that is rotated, this last period of rotation of the cap can operate a separate actuator to cause it to pierce the lid of said blister that has just been moved into alignment with the blister piercing element.

It will be appreciated that the indexing mechanism 11 is designed to enable a stroke to be aborted when the actuator 14 or cap has been rotated through an angle which is sufficient to cause initial indexing of the strip but which is not such that the drive to the indexing wheel 15 has disengaged, i.e. a position in which the flange deflecting dog 22 has not reached the end of the innermost track 27. If the stroke is aborted and the actuator 14 returned to its rest position before drive to the indexing wheel 15 has disengaged, the strip will be driven backwards into its original position as a rear surface 26b of the indexing wheel drive dog 26 will engage a preceding vane 15b to drive the indexing wheel 15 in the opposite direction. It will be appreciated that this has the advantage that the user may partially open the actuator 14 to enable them to inspect and/or clean a mouthpiece and then close it again without having indexed the strip or pierced a blister.

The flange 19 is provided with a downwardly depending lug 19a (see Figure 8b) that engages with a feature (not shown) on the casework when the actuator or cap has reached its fully open extent, thereby preventing any further rotation of the actuator or cap.

Many modifications and variations of the invention falling within the terms of the following claims will be apparent to those skilled in the art and the foregoing description should be regarded as a description of the preferred embodiments of the invention only.

It will be appreciated that the inhalation device of the present invention may be used in conjunction with a spiral wound element and/or a fixed or flexible wall separating a chamber containing unused blisters from a chamber that receives the used blisters.

Such modifications are known from the Applicant's own earlier European patent applications nos. 07111998.6 ( EP2011538 ) and 07111996.0 ( EP2011537 ).

Claims (21)

1. An inhaler comprising a housing (12) to receive a strip having a plurality of blisters, each blister having a breachable lid and containing a dose of medicament for inhalation by a user, an indexing wheel (15) mounted in the housing (12) rotatable to drive a strip to sequentially move blisters into alignment with a blister piercing member, a control element (14) pivotally mounted to the housing (12) and a drive mechanism including a drive coupling member (17) for selectively coupling the control element (14) to the indexing wheel (15) so that, when coupled, the indexing wheel (15) rotates in response to rotation of the control element (14) to index the strip, the drive coupling member (17) being configured to couple the control element (14) to the indexing wheel (15) during part of the rotation of the control element (14) by a user so that the indexing wheel (15) rotates together with the control element (14), the indexing wheel (15) being rotatably mounted to the drive coupling member (17), characterised in that the drive coupling member (17) comprises an indexing wheel drive dog (26), the drive mechanism including means to move, as the control element (14) and drive coupling member (17) are rotated, the indexing wheel drive dog (26) into a position in which it cooperates with the indexing wheel (15) so that the indexing wheel (15) rotates together with the control element (14) and the drive coupling member (17).
2. An inhaler according to claim 1, wherein the control element (14) rotates relative to the housing (12) about an axis and the drive mechanism comprises a drive coupling member (17) in the housing 12) for rotation about the same axis.
3. An inhaler according to claim 2, wherein the drive coupling member (17) includes a shaft (18) having an axis coaxial with the axis of the control element (14), the indexing wheel (15) being mounted on said shaft (18) for rotation about said axis.
4. An inhaler according to any preceding claim, wherein the drive coupling member (17) is formed from a resilient material and said means for moving the indexing wheel drive dog (26) into a position in which it cooperates with the indexing wheel (15) moves said indexing wheel drive dog (26) against a bias provided by said resilience.
5. An inhaler according to claim 4, wherein the drive coupling member (17) comprises a flange (19) that extends radially from one end of the shaft (18) across one end of the indexing wheel (15).
6. An inhaler according to claim 5, wherein the flange (19) includes a flexible flange portion (20) that resiliently bends or flexes relative to the remaining portion of the flange (19) about an axis extending substantially at right angles to the axis of the shaft (18).
7. An inhaler according to claim 6, wherein the flange (19) has an arcuate cut-out region (21) configured such that the flexible flange portion (20) is joined only to the remaining portion of the flange (19) at each end.
8. An inhaler according to claim 7, wherein the flexible flange portion (20) is hinged to the remaining portion of the flange (19) at each end.
9. An inhaler according to any of claims 6 to 8, wherein the indexing wheel drive dog (26) upstands from a surface of the flexible flange portion (20) in a direction towards the indexing wheel (15).
10. An inhaler according to claim 9, wherein the means to move the indexing wheel drive dog (26) into a position in which it cooperates with the indexing wheel (15) so that the indexing wheel (15) rotates together with the control element (14) comprises a flange deflecting dog (22) protruding from the flexible flange portion (20).
11. An inhaler according to claim 10, wherein the means to move the indexing wheel drive dog (26) into a position in which it cooperates with the indexing wheel (15) also comprises an arcuate guide track (27,28) in the housing (12), the arcuate guide track (27,28) having a first guide surface such that, when the drive coupling member (17) is rotated in response to rotation of the control element (14) in a first direction, the flange deflecting dog (22) cooperates with the first guide surface to deflect the flexible flange portion (20) towards the indexing wheel (15) so that the indexing wheel drive dog (26) cooperates with the indexing wheel (15) to rotate the indexing wheel (15) together with the drive coupling member (17).
12. An inhaler according to claim 11, wherein the arcuate guide track (27, 28) is configured such that the flange deflecting dog (22) drops off the first guide surface prior to rotation of the control element (14) to its maximum extent, the resilience of the flexible flange portion (20) causing it to return to its original undeflected state so that the indexing wheel drive dog (26) no longer cooperates with the indexing wheel (15), the indexing wheel (15) now remaining stationary during continued rotation of the control element (14) and drive coupling member (17) to its maximum extent.
13. An inhaler according to claim 11 or claim 12, wherein the arcuate guide track (27,28) comprises a second guide surface such that, when the flange deflecting dog (22) has dropped off the first guide surface and the drive coupling member (17) is rotated in response to rotation of the control element (14) in a reverse direction, the flange deflecting dog (22) cooperates with said second guide surface so that the flexible flange portion (20) is deflected in the opposite direction, away from the indexing wheel (15).
14. An inhaler according to claim 13, wherein the flange deflecting dog (22) comprises a first cooperating surface (23) to engage the first guide surface of the arcuate guide track (27, 28), and, a second cooperating surface (24) to engage the second guide surface of the arcuate guide track (27, 28).
15. An inhaler according to claim 14, wherein the first and second guide surfaces of the arcuate guide track (27, 28) extend parallel to each other but spaced from each other in an axial direction.
16. An inhaler according to claim 15, wherein the first and second guide surfaces have angled end regions (27a, 28a) such that the flange deflecting dog (22) rides up the angled end regions (27a, 28a) onto respective guide surfaces of the guide track (27,28).
17. An inhaler according to any preceding claim, wherein the indexing wheel (15) comprises a plurality of vanes (15a,15b,15c,15d) and the indexing wheel drive dog (26) contacts one of the vanes (15a,15b,15c,15d) when the indexing wheel drive dog (26) is moved into a position in which it cooperates with the indexing wheel (15) so that the indexing wheel (15) rotates together with the drive coupling member (17) and the control element (14).
18. An inhaler according to any preceding claim, comprising a locking element (30,31,32) to prevent rotation of the indexing wheel (15) other than during cooperation of the indexing wheel drive dog (26) with the indexing wheel (15).
19. An inhaler according to claim 18, wherein the locking element (30,31,32) comprises a cantilevered arm (30) mounted in the housing (12) and having its free end biased against the indexing wheel (15), said free end of the cantilever arm (30) cooperating with the indexing wheel (15) so as to prevent rotation of the indexing wheel (15).
20. An inhaler according to claim 19, wherein the free end of the cantilevered arm (30) is configured such that when the indexing wheel drive dog (26) is moved towards the indexing wheel (15), further rotation of the drive coupling element (17) causes the indexing wheel drive dog (26) to engage the free end of the cantilever arm (30) and deflect it out of locking engagement with the indexing wheel (15) prior to cooperating with the indexing wheel (15) to rotate the indexing wheel (15).
21. An inhaler according to claim 20, wherein the indexing wheel drive dog (26) disengages then free end of the cantilever arm (30) when the indexing wheel drive dog (26) moves away from the indexing wheel (15) so that the free end of the cantilever arm (30) moves back towards the indexing wheel (15) to lock the indexing wheel (15) in position.