GB2461153A

GB2461153A - Inhaler with energy absorbing pads

Info

Publication number: GB2461153A
Application number: GB0909757A
Authority: GB
Inventors: Simon Berry; Jorgen Fruensgaaard; Keld Sloth Christensen
Original assignee: AstraZeneca AB
Current assignee: AstraZeneca AB
Priority date: 2008-06-25
Filing date: 2009-06-08
Publication date: 2009-12-30
Also published as: GB0909757D0

Abstract

Breath actuated inhaler (BAT), comprising: a canister 22 containing medicament and having a metering valve 24, a mouthpiece 60 for guiding medicament to the mouth of a user, a nozzle block 62 for communication with the metering valve 24 of the canister 22 and for delivering medicament from the canister 22 into the mouthpiece 60, a loading element 6 capable of being loaded with an actuation force, a breath actuated trigger mechanism 3arranged to counteract the actuation force of the loading element 6, and to fire the inhaler by releasing the actuation force of the loading element to actuate the metering valve 24in response to an inhalation breath, and an energy absorber 80,85 arranged to absorb residual kinetic energy resulting from the actuation force upon firing. There advantage of the device is its ability to avoid discomfort to the user by reducing noise or mechanical shock created in the actuator upon firing.

Description

NEW INHALER 259

Technical Field

The present invention relates to an inhaler for delivery of a medicament by s inhalation and in particular to the actuation mechanism used in the inhaler to actuate a canister to dispense a dose of medicament.

Background of the Invention

Inhalers are commonly used for delivery of a wide range of medicaments. The inhaler holds a canister of medicament, the canister being actuated e.g. by compression to deliver a io dose of medicament through a mouthpiece to a user. The inhaler may be provided with an actuation mechanism to actuate the canister automatically and thus dispense a dose of medicament. Some known actuation mechanisms are breath-actuated, so that they operate in response to inhalation by a user. This ensures that a dose of medicament dispensed on actuation of the canister is supplied whilst the user is inhaling. This is particularly useful is for those users who may find it difficult to co-ordinate the dispensing of a dose of medicament, by for example, the actuation of a button, with inhaling the dose.

A known breath-actuated inhaler has an actuation mechanism operable by compression of a canister of medicament to deliver a dose of medicament in response to inhalation by a user. The actuation mechanism comprises a loading mechanism to bias compression of the canister. A triggering mechanism holds the loading mechanism against compression of the canister. When delivery of a dose of medicament is required, the triggering mechanism releases to allow compression of the canister in response to inhalation by the user. An actuating means is connected to a cover for the mouthpiece and is responsive to the closing movement of the cover for re-setting the actuation mechanism.

Summary of the Invention

The object of the invention is to provide a new breath actuated inhaler which overcomes the drawbacks of the prior art. This is achieved by the breath actuated inhaler as defined in the independent claims.

One advantage of the present invention is its ability to avoid discomfort in the form of noise and/or mechanical shock created in the actuator upon firing.

Another advantage of embodiments of the present invention is that due to the resiliant material enabling a smooth movement and reasonably silent mechanism, wear on moving parts within the BAI is decreased. i0

Other embodiments of the invention are defined in the dependent claims.

Brief Description of the Drawings

is To allow a better understanding, embodiments of the present invention will now be described, by way of non-limitative examples only, with reference to the accompanying drawings, in which: Fig. la to id show schematic side views of a number of states of operation for the breath actuated inhaler (BAI), comprising energy absorbers according to one embodiment.

Detailed Description of the Invention

The following will briefly describe one example of a Breath Actuated Inhaler (BAI) and its mechanism for supplying a dose of medicine in response to an actuating breath applied by a user or pressing the designated firing button. The following will in more detail describe an embodiment arranged to reduce noise, and mechanical shock, arising upon firing as a consequence of the large energy stored in the loading mechanism. A more detailed description of the mechanics and a "part-by-part" description of the constituents in the disclosed BAI mechanism is found in, PCT/SE2008/000005.

Figs. la-id shows one embodiment of the BAI of PCT/SE2008/000005. The s breath actuated inhaler (BAI) actuator mechanism 3 is arranged to counteract the actuation force of the loading element 6 and to fire the actuator 100 by releasing the actuation force of the loading element 6 in response to an inhalation breath. This is one example of a BAI actuator mechanism disclosed in detail below, but there are many other types of BAI actuator mechanisms that can be used in the present BAI embodiment.

io In the disclosed embodiment, the BAI actuator is arranged for actuation of a compression firing canister. However, according to other embodiments, the BAI actuator may be arranged for actuation of canisters with other types of metering valves, such as valves that fire upon withdrawal of a control stem, rotary type valves and the like.

Moreover, according to one embodiment, the metering valve may be of a type that is is biased in the firing direction, and in such case, the biasing force of the metering valve, may be used in lieu of or in combination with the loading element 6.

Figs. la to ld show one embodiment of a trigger mechanism comprising: a yoke lever 50 arranged to transform the movement of the yoke 4 to a pivotal movement of a lock end 52 thereof, * a lock member 53 pivotally moveable between an armed position (Fig. la) wherein it is arranged to prevent further pivotal movement of the yoke lever lock end 52 in the actuation direction, and an open position wherein the yoke lever 50 is free to move beyond the armed position in the actuation direction, in the armed position the lock member 53 is biased towards the open position by the yoke lever 52 which in turn is biased in the actuation direction by the loading element 6 via the yoke 4, a trigger element 57 arranged for movement in response to an inhalation breath, and * a release member 55 arranged between the lock member 53 and the trigger element 57 to hold the lock member 53 in the armed position, and to release the lock member 53 in response to movement of the trigger element 57.

The yoke lever 50 is pivotally supported by the chassis 40 by lever hinge pins 130 io or the like, and comprises lever arms 51 that are arranged to engage corresponding yoke grooves 140 formed in the yoke 4. The yoke lever 50 is formed to create a lever effect gearing down the force applied on the components in the triggering mechanism from the loading element 6. The gearing is achieved in that the longitudinal distance between the hinge pivot point 130 and the lever arms 51 is shorter than the distance between the hinge pivot point 130 and the yoke lever lock end 52. In the disclosed embodiment, the yoke lever 50 is arranged so that the lock end 52 performs an upward movement when the yoke 4 moves downwards.

In the disclosed embodiment, the lock member 53 is pivotally supported by the chassis by lock hinge pins 160. The lock member 53 comprises a lock rib 150 arranged to act as a catch member for the lock end 52 of the yoke lever 50 to arm the triggering mechanism. The pivot point 160 of the lock member 53 and the interaction between the lock rib and the lock end 52 of the yoke lever 50 are arranged so that the lock member 53 is biased towards the open position by the yoke lever 50. By designing this interaction properly, a suitable gear down effect is achieved, reducing the force applied on the components of the trigger mechanism even further. A spring element 210 biases the lock member 53 in the closing direction, towards the yoke lever 50, in order to reset the trigger mechanism during loading of the actuation mechanism. The yoke lever 50 comprises a s lock member guide surface 200 at the lock end thereof. As is shown in Figure ic, the lock member guide surface 200 interacts with the lock rib 150 to hold the lock member in the open position when the actuator is unloaded.

The trigger element 57 is arranged at one end of an air flow duct 190 extending from the mouth piece 60 at the other end. The air flow duct 190 may be formed by the io actuator housing 10, the chassis 40, or a combination thereof, and optionally with additional components. According to one embodiment, the trigger element is a pivotal vane with a trigger pivot shaft 58 that is pivotally supported by the chassis 40 at a trigger pivotal point and arranged to pivot about a the pivot axis in response to an air flow in the air flow duct, e.g. an inhalation breath. The release member 55 is, at one end, pivotally is connected to the lock member at a release pivot point 240, and at the other end it is arranged to interact with the trigger pivot shaft 58 to hold the lock member 53 in the armed position, and to release the lock member 53 in response to pivotal movement of the trigger pivot shaft 58. According to one embodiment, the release member 55 is a drop link element.

The trigger pivot shaft 58 comprises an essentially semi cylindrical shaped release surface 220, and stop means 230 that ensure that the release member 55 enters the correct armed position upon arming the triggering mechanism 3. As mentioned above, the release member 55 is biased in the direction of the trigger pivot shaft 58 by the lock member 53, which in turn is biased in the opening direction by the loading element 6 via the yoke lever 50. In the armed position (Fig. la), the release member 55 is arranged to apply the biasing force in a direction that is essentially radial to the trigger pivot axis 58. When the trigger vane 57 is pivoted by an air flow in the air flow duct 190, the interaction end of the release member 55 rotates together with the trigger pivot shaft 58, and the direction of the biasing s force is shifted (lifted) from the trigger pivot axis 58 (Fig. ib), and upon sufficient rotation the shifted biasing force makes the release member 55 detach from its armed state whereby the actuator is fired (Fig. ic).

In order to ensure proper delivery of a dose of medicine, the force stored in the io loading element 6 of a BAI, e.g. a coiled spring, is over dimensioned compared to the force needed to actuate the metering valve. Out of the total energy stored in the loading element 6, only part of it is spent releasing a dose of medicament. A portion of the remaining energy remains as kinetic energy stored in the motion of one or more members of the actuator. This motion generally transforms into noise and mechanical shock when moving is parts within the BAI comes into stopping contact at high speed. This could present an unpleasant experience for the user, who due to the shock might interrupt the inhalation and therefore fully or partly miss the dose of medicament. In addition, the shock can cause increased wear of the actuator mechanism as well as the metering valve.

According to one embodiment there is provided a BAI comprising an energy absorber arranged to absorb residual kinetic energy resulting from the actuating force upon firing. The energy absorber is arranged to reduce the noise and mechanical shock, by at least partly absorbing the residual kinetic energy. The energy absorber is so arranged that it has the ability to absorb energy with very little noise and provide a "soft stop" as compared to a collision like "hard stop" between members of the BAI actuator. Examples of energy absorbers includes resilient elements that are arranged to intervene the residual motion, friction elements, pneumatic, hydraulic or electrical dampeners, combinations thereof, and the like In one embodiment the actuation of the metering valve involves an actuation s motion of the canister 20 with respect to the nozzle block 62 and wherein the energy absorber is arranged to absorb the residual kinetic energy of the actuation motion. The actuation motion may be a linear motion, but it may also be a curved and/or pivotal motion or a combination thereof According to one embodiment the energy absorber is arranged to absorb residual kinetic energy of a trigger member of the trigger mechanism. Due to different designs of trigger mechanisms, the trigger member may be arranged to perform different types of motions, whereby the energy absorber has to be adapted to each specific design. In the BAI disclosed in figs. la to id, the trigger member is represented by the yoke lever 50 that is arranged to perform a pivotal lever movement in response to a longitudinal actuation is movement of the canister with respect to the nozzle block. The energy absorber may be a stop pad of a resilient material arranged to retard ftirther movement of the trigger member at a predetermined position by having the ability to compress during the process of absorbing residual kinetic energy, due to the elasticity of the material. Not only the choice of material, but also the design might have impact on the performance of the stop pad. For instance, a triangular shaped stop pad will continuously increase its energy absorption and resistance from the moment of impact until the members of the actuation mechanism are drained of residual kinetic energy. The nature of the resilient material allows it to retain its original geometry after compression and decompression, thus retaining its ability to ftinction as an energy absorber.

In the BAI schematically shown in figs. la to id a lever stop pad 80 is arranged to absorb residual kinetic energy of the yoke lever 50, and canister stop pads 85 are arranged to absorb residual kinetic energy of the canister 20. Figs. la to id schematically show the BAI actuator in different states of operation, wherein: * Fig 1 a illustrates the armed state, when the actuator is ready to be fired by an inhalation breath or by use of the firing button 48. The protective cover 2 which functions as loading means and actuation locking means is in its open or armed position whereby the actuation mechanism is able to be fired.

As is discussed in detail above, the loading element 6 is loaded with an io actuation force that exceeds the reset bias force in the metering valve of the canister 20, and the triggering mechanism 3 counteracts the actuation force via the yoke 4.

* Fig. lb illustrates an initial phase of a firing of the actuator by an inhalation breath, wherein the trigger vane 57 is pivoted an amount, but the release member 55 is still in locking contact with the trigger pivot shaft 58 and thus prevents firing of the actuator.

* Fig. lc illustrates an initial firing state, wherein the trigger vane 57 is further pivoted and the release member 55 has been detached from the pivot shaft 58 and the lock member 53 is pivoted to release the yoke lever 50 whereby the actuation force is released and the canister 20 is depressed to fire a dose of medicament into the inhalation air flow through the mouth piece 60. At this initial state, the lock end 52 of the yoke lever 50 engages and deforms the lever stop pad 80, and the valve end of the canister 22 engages and deforms the canister stop pads 85 whereby residual kinetic energy of the mechanism is gradually absorbed.

Fig. 1 d illustrates a rest state after firing, wherein all residual kinetic energy resulting from the actuation force is absorbed by the lever stop pad 80 and the canister stop pads 85, 86 In Figs. la to id, the lever stop pad 80 is arranged onlat the chassis 40 where the lock end 52 of the yoke lever 50 would otherwise impact. The lever stop pad 80 in Fig. la to id has a triangular shape, although that is not intended to be limiting, thus the absorbing io element 80 can be designed to have virtually any shape. The canister stop pads 85 in the embodiment in Fig. 1 a to 1 d are located in between the nozzle block 62 and the valve end of the canister 20, and arranged to retard the motion and absorb the residual kinetic energy charged in the canister 20 and the yoke 4, resulting in a soft stop as compared to a hard stop. The stop pad may e.g. be comprised of an annular pad that fully or partly encloses the is valve stem, or by two or more pads arranged about the stem.

Arranging the stop pads can, which is obvious for a person skilled in the art, be done in several ways. Below, some possible embodiments will be suggested, but this is not intended to be limiting; * The stop pads can be arranged between the valve end of the canister 20 and the nozzle block 62 * Stop pads can be arranged so as to be integrated in the nozzle block 62 or at the valve end of the canister 20, or any other combination between the two * Another way of arranging the stop pads can be between the lock end of the yoke lever 50 and the chassis 40, or to integrate the stop pads within the elements of the trigger mechanism.

The energy absorber may be provided in other forms and at other locations, such as being integrated in the nozzle block, in the form of a hydraulic damper or the like. It can also be arranged to receive the valve end of the canister 20, arranged along the side of the canister 20 and/or work directly on the yoke 4, or it may be arranged on any other part moving in connection with the movement of the canister 20.