Abstract:
An inhaler comprising a housing to receive a strip having a plurality of blisters is disclosed. Each blister has a puncturable lid and contains a dose of medicament for inhalation by a user. A mouthpiece is pivotally mounted to the housing through which a dose of medicament is inhaled by a user. The inhaler also has an actuating mechanism including a lever operable to sequentially move each blister into alignment with a blister piercing member depending from the mouthpiece. The actuating lever is also operable to cause the mouthpiece to pivot so that the blister piercing member punctures the lid of an aligned blister so that, when a user inhales through the mouthpiece, an airflow through the blister is generated to entrain the dose contained therein and carry it, via the mouthpiece, into the user&#39;s airway.

Description:
FIELD OF THE INVENTION 
     This application claims priority to Great Britain Application No. 1020130.9 filled Nov. 26, 2010 the disclosure of which is hereby incorporated by reference, 
     BACKGOUND 
     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&#39;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&#39;s own co-pending international application that has been published as WO2005/037353 A1. 
     According to one embodiment described and claimed in WO 2005/037353 A1, and illustrated in  FIGS. 1 and 2  of the accompanying drawings, an inhaler  1  has a housing  2  containing a coiled strip of blisters  3 . 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 locator chassis  6  and successively through a blister piercing station  7 , when the actuator  5  is pivoted in a direction indicated by arrow “A” in  FIG. 2 . The blister  3   a  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  FIG. 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  3   a  to entrain the dose contained therein and carry it out of the blister  3   a  via the mouthpiece  9  and into the user&#39;s airway. 
     The device known from WO2005/037353 A1 has already been modified so as provide a fully integrated device, i.e. one in which the used blisters are retained within its housing so that a user never has to come into direct contact with the blister strip. In one modified embodiment, known from the Applicant&#39;s own previous application that has now been published as WO09/007,352 A1, there is provided a flexible and resilient spiral element mounted within the housing of the device into which the used portion of the blister strip is directed so that, as the strip is gradually used up, the spiral expands as more and more of the strip is fed or pushed into it between its coils. The inhaler of the present invention, in its preferred form, is also a fully integrated device that retains the used blisters, although in a preferred embodiment it has a wall to separate the interior of the housing into used and unused blister compartments. The wall is preferably rigid and slideably mounted so that the size of the unused and used blister compartments changes relative to each other as the number of blisters that are used increases and the number of unused blisters decreases. 
     The aforementioned document also describes an embodiment in which used blisters are crushed between the blister strip drive or indexing wheel and the inner surface of the casing of the device, which is also a feature of the inhaler of the present invention. As crushing takes place as the used strip passes around the blister strip drive member, a curl or curved form is imparted to the strip which helps it to coil up within the chamber. 
     The inhaler of the invention may also incorporate a blister strip drive mechanism or indexing mechanism that forms the subject of the Applicant&#39;s own previous international application that has now published as WO2009/092652 A1. 
     The disclosures of WO2005/037353 A1, WO09/007,352 A1 and WO2009/092652 A1 are all incorporated herein by reference. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to provide another inhalation device of the type disclosed in the above-mentioned applications, and which also has a relatively simple construction, is robust, straightforward to manufacture and easy for the patient to use. 
     According to the invention, there is provided an inhaler comprising a housing to receive a strip having a plurality of blisters, each blister having a puncturable lid and containing a dose of medicament for inhalation by a user, a mouthpiece mounted to the housing and through which a dose of medicament is inhaled by a user, a blister piercing member mounted for rotation about a first axis and an actuating mechanism including an actuating lever mounted for rotation about a second axis to sequentially move each blister into alignment with the blister piercing member, wherein the actuating lever cooperates with the blister piercing member so that the blister piercing member pivots about said first axis in response to rotation of the actuating member from an initial position about the second axis to puncture the lid of an aligned blister so an airflow through the blister is generated to entrain the dose contained therein and carry it, via the mouthpiece, into the user&#39;s airway when a user inhales through the mouthpiece. 
     In a preferred embodiment, the blister piercing member is fixed to the mouthpiece and the mouthpiece is pivotally mounted to the housing so that the mouthpiece pivots, together with the blister piercing member, about said first axis in response to rotation of the actuating lever about the second axis. 
     In another embodiment, the blister piercing member is pivotally mounted to the mouthpiece for rotation about said first axis so that the blister piercing member pivots about said first axis relative to the mouthpiece, in response to operation of the actuating lever. 
     Preferably, the actuating lever is pivotable in the same direction about the second axis to sequentially move each blister into alignment with a blister piercing member and to cause rotation of the blister piercing member about the first axis so that the blister piercing member punctures the lid of an aligned blister. 
     The actuating mechanism may be configured such that rotation of the actuating lever about the second axis through a first portion of its stroke moves a blister into alignment with a blister piercing member and, further rotation of the actuating lever about the second axis in the same direction, during a second portion of its stroke, causes rotation of the blister piercing member about the first axis so that the blister piercing member punctures the lid of an aligned blister. 
     The actuating mechanism may include a blister strip drive wheel and the actuating lever may be engaged with said blister strip drive wheel during rotation of the actuating lever to rotate said blister strip drive wheel and drive said strip. 
     In a preferred embodiment, the actuating mechanism is configured such that the actuating lever and blister strip drive wheel disengage at the end of the first portion of the stroke so that the blister strip drive wheel remains substantially stationary during rotation of the actuating lever through said second portion of its stroke. 
     Preferably, the actuating mechanism comprises a drive coupling member rotatable in response to rotation of the actuating lever to rotate the blister strip drive wheel, the blister strip drive wheel being rotatably mounted on said drive coupling member, wherein the actuating mechanism includes means to control rotation of the blister strip drive wheel relative to rotation of the drive coupling member so that the blister strip drive wheel rotates together with the drive coupling member during the first portion of the stroke of the actuating lever but not during the second portion of the stroke of the actuating lever. 
     In a preferred embodiment, the means for controlling rotation of the blister strip drive wheel is also configured to inhibit rotation of the blister strip drive wheel when the actuating lever is rotated in the opposite direction. 
     The drive coupling member may include a drive gear rotatable together with the drive coupling member and the actuating lever can include a drive gear segment that drivingly engages with the drive gear member so that the drive gear rotates in response to rotation of the actuating lever to rotate the drive coupling to member. 
     Preferably, the means to control rotation of the blister strip drive wheel includes cooperating elements on the drive coupling member and on the housing. 
     In an embodiment where the mouthpiece is pivotally mounted together with the blister piercing element, one of the actuating lever and the mouthpiece can have a drive cam element and the other of the actuating lever and the mouthpiece can have a drive cam surface. The drive cam element cooperates with the drive cam surface so that the mouthpiece pivots about said first axis in response to rotation of the actuating member about the second axis to puncture the lid of an aligned blister. 
     The cam groove may have an arcuately shaped region having an axis that corresponds to the second axis about which the actuating lever rotates such that, during said initial rotation of the actuating lever through its first portion of its stroke, the drive cam element slides along said arcuately shaped region of the cam groove without causing rotation of the mouthpiece about the first axis. 
     In this embodiment, the cam groove can have a second region shaped such that, during further rotation of the actuating lever through its second portion of its stroke, cooperation between the drive cam element and the second region of the cam groove causes the mouthpiece to rotate at the same time as the actuating lever so that the blister piercing element punctures the lid of an aligned blister. 
     Alternatively, in the embodiment where the blister piercing element is pivotally mounted to a fixed housing, one of the actuating lever and the blister piercing member can have a drive cam element and the other of the actuating lever and the blister piercing member can have a drive cam surface. The drive cam element cooperates with the drive cam surface so that the blister piercing element pivots about said first axis in response to rotation of the actuating member about the second axis to puncture the lid of an aligned blister. 
     The cam groove can have an arcuately shaped region having an axis that corresponds to the second axis about which the actuating lever rotates such that, during said initial rotation of the actuating lever through its first portion of its stroke, the drive cam element slides along said arcuately shaped region of the cam groove without causing rotation of the blister piercing member about the first axis. 
     The cam groove may have a second region shaped such that, during further rotation of the actuating lever through its second portion of its stroke, cooperation between the drive cam element and the second region of the cam groove causes the blister piercing element to rotate together with the actuating so that the blister piercing element punctures the lid of an aligned blister. 
     In any of the embodiments, the inhaler may comprise a cap and a coupling pivotally mounting the cap to the housing for rotation about a third axis, the cap covering the mouthpiece in a closed position. 
     The housing preferably comprises a shell and the actuating lever is mounted for rotation about the second axis on the shell and includes a mounting plate that extends within a space between the shell and the cap. 
     In one embodiment, the actuating lever comprises a button extending from said plate and protruding out of said space to enable actuation of the actuating lever by a user. 
     Preferably, the actuating lever comprises an arcuately shaped opening extending about the second axis, the coupling that pivotally mounts the cap to the housing extending through said opening so that the coupling travels along the arcuately shaped opening as the actuating lever pivots about the second axis. 
     The cap and actuating lever may include cooperating means configured such that, when the cap is rotated from its open position back into its closed position in which it covers the mouthpiece, the actuating lever is rotated rotate back into its initial position. 
     Preferably, the cooperating means comprises a wall on the actuating lever and a drive member depending from the cap towards the actuating lever, said wall and drive member being positioned between the second and third axes such that the drive member engages the wall when the cap is rotated in a direction back into its closed position to rotate the actuating member about the second axis back into its initial position. 
     In any embodiment, the inhaler may include a detent mechanism such as a cantilevered arm on the actuating lever and a pawl on the shell, the arm being resiliently deformed by said pawl as the actuating lever reaches the end of the second portion of its stroke, to hold the actuating lever in position until the cap is closed. 
     The cantilevered arm preferably includes a kinked portion that snaps over the pawl when the actuating lever is rotated towards the end portion of its stroke. 
     In a preferred embodiment, a wall is slideably mounted in the housing to divide it into unused and used blister compartments. 
     The wall preferably comprises a baffle extending between opposing housing walls and an elongate foot extending substantially at right-angles to the baffle and being slideably received within a recess in a surface of a wall of the housing. 
     The baffle is preferably attached to a central region of the foot. 
     In a preferred embodiment, the foot is widest at its ends remote from the baffle such that only the ends of said foot contact the walls of said recess in the housing. 
     According to another aspect of the invention, there is provided an inhaler comprising a housing to receive a strip having a plurality of blisters, each blister having a puncturable lid and containing a dose of medicament for inhalation by a user, a mouthpiece pivotally mounted to the housing and through which a dose of medicament is inhaled by a user and an actuating mechanism including a lever operable to sequentially move each blister into alignment with a blister piercing member depending from the mouthpiece said actuating lever also being operable to cause the mouthpiece to pivot so that the blister piercing member punctures the lid of an aligned blister so that, when a user inhales through the mouthpiece, an airflow through the blister is generated to entrain the dose contained therein and carry it, via the mouthpiece, into the user&#39;s airway. 
     A cap is preferably pivotally mounted to the housing that covers the mouthpiece in a closed position. 
     The cap may extend over the actuating lever in a closed position. 
     In one embodiment, the actuating lever is pivotally mounted to the housing and the actuating mechanism is configured such that the actuating lever is pivotable to sequentially move each blister into alignment with a blister piercing member and also pivotable to cause rotation of the mouthpiece so that the blister piercing member punctures the lid of an aligned blister. 
     The actuating lever is preferably pivotable in the same direction to sequentially move each blister into alignment with a blister piercing member and to cause rotation of the mouthpiece so that the blister piercing member punctures the lid of an aligned blister. 
     The actuating mechanism may be configured such that an initial rotation of the actuating lever through a first portion of its stroke moves a blister into alignment with a blister piercing member and, further rotation of the actuating lever causes rotation of the mouthpiece so that the blister piercing member punctures the lid of an aligned blister. 
     In a preferred embodiment, the actuating mechanism is configured such that movement of the strip stops between said initial and further rotation of the actuating lever. 
     The actuating mechanism preferably includes a blister strip drive wheel around which a blister strip received in the housing is fed, said blister strip drive wheel being rotatable in response to rotation of the actuating lever to drive said strip. 
     In one embodiment, wherein the blister strip drive member comprises a plurality of spokes extending from a hub, the spokes being spaced from each other such that a spoke locates between blister cavities as a blister strip passes around the blister strip drive member to engage and drive a strip as the blister strip drive member rotates, the blister strip drive member being positioned relative to a wall such that the distance between the hub and said wall is less than the height of a blister cavity such that onward rotation of the wheel causes a blister cavity to be at least partially squashed or sandwiched between the hub and said wall. 
     The inhaler preferably includes a drive coupling member rotatable in response to rotation of the actuating lever, the blister strip drive wheel being rotatably mounted on said drive coupling member, the drive coupling member and the housing including means to control rotation of the blister strip drive member relative to rotation of the drive coupling member so that the blister strip drive wheel rotates together with the drive coupling member during part of the rotation of the drive coupling member in the same direction. 
     In one embodiment, the means for controlling rotation is configured so that the blister strip drive wheel rotates together with the drive coupling member during part of the rotation of the drive coupling member in the same direction and the blister strip drive wheel does not rotate at all when the drive coupling member rotates in the opposite direction. 
     The drive coupling member may include a drive gear member and the actuating lever includes a drive gear segment that drivingly engages with the drive gear member so that the drive gear member rotates in response to rotation of the actuating lever. The drive coupling member and the drive gear member may be integrally formed as one component. 
     Preferably, the actuating lever includes a mouthpiece drive cam element that cooperates with a cam groove formed in the mouthpiece. 
     The cam groove in the mouthpiece can have an arcuately shaped region such that, during said initial rotation of the actuating lever through its first portion of its stroke, the drive cam element slides along the cam groove with substantially no rotation of the mouthpiece. 
     The cam groove may also have a second region shaped such that, during further rotation of the actuating lever beyond the first portion of its stroke, cooperation between the drive cam element and the cam groove causes the mouthpiece to rotate together with the actuating lever to pull the blister piercing element depending therefrom into the lid of an aligned blister. 
     The cap and the actuating lever may be configured such that, when the cap is rotated from an open position back into its closed position, the cap cooperates with the actuating lever to cause it to rotate back into its initial position. 
     Rotation of the actuating lever back into its initial position in response to rotation of the cap may also cause the drive cam element to slide back along the cam groove and lift the mouthpiece back into its original position in which the blister piercing element is removed from the aligned blister. 
     In a preferred embodiment, the cap includes a drive pin that cooperates with the actuating lever during closure of the cap so that the actuating lever is also rotated back to its initial position. 
     The actuating lever may have a hole therethrough and the drive pin extends from the cap into said hole, the drive pin engaging with the sidewall of said hole when the cap is rotated from its open into its closed position. 
     In one embodiment, the housing comprises a shell that defines a chamber to receive a blister strip, the blister strip drive wheel being received in the shell, the shell having opposing end walls spaced from each other by a side wall, the drive coupling member extending through a hole in one of said opposing end walls such that the drive gear is disposed on the outside of the shell. 
     The actuating member may comprise a plate extending between an actuating button and the gear segment, said plate extending across a surface of an end wall on the outside of the shell. 
     The actuator can be pivotally mounted to a hub upstanding from said surface. 
     The actuating member may also comprise a second plate that extends parallel and spaced from the first plate, the shell being received between said plates and said second plate being pivotally mounted to a hub upstanding from the surface of said opposite end wall of the shell. 
     In one embodiment, the mouthpiece has a peripheral wall that extends across the surface of the outside of the shell. 
     The actuating lever may include an actuating button that extends between said plates and across the side wall of the shell. 
     The cap can have parallel side wall sections spaced from each other by an intermediate section, the side wall sections each extending across a corresponding end wall of the shell, one of said side wall sections of the cover enclosing the first and second plates of the actuating lever and at least a portion of the side wall of the mouthpiece. 
     The intermediate section may extend across the side wall of the shell and covers the mouthpiece in a closed position. 
     In one embodiment, a boss upstands from opposite surfaces of the shell each of which locate in a recess in a corresponding side wall section of the cap to pivotally mount the cap to the shell. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example only, with reference to  FIGS. 3 to 16  of the accompanying drawings, in which: 
         FIGS. 1 and 2  are side views of a conventional 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  FIG. 1  to the position shown in  FIG. 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  FIG. 1 ; 
         FIGS. 3   a  to  3   e  is a sequence of drawings to show the general function and operation of the inhaler according to the invention; 
         FIG. 4  is a side elevation of an inhalation device according to an embodiment of the invention; 
         FIG. 5  is the side elevation of  FIG. 4 , but with the cap removed so that the internal components can be seen; 
         FIG. 6  is the side elevation of  FIG. 5  after removal of one-half of the shell forming the housing of the inhaler; 
         FIG. 7  is an exploded perspective view showing the individual components of the inhaler according to the invention. 
         FIG. 8  is a partial perspective view of the blister strip indexing mechanism for use in the inhaler of the invention; 
         FIG. 9  is a partial perspective view of the blister strip indexing mechanism shown in  FIG. 8  following partial rotation of the actuating lever into an intermediate position from its home position; 
         FIG. 10  is the same view as shown in  FIG. 9 , but without the optional cantilevered chassis arm; 
         FIG. 11  is a partial perspective view of the blister strip indexing mechanism shown in  FIGS. 8 to 10 , after the actuating lever has been rotated to a point at which drive between the drive coupling and the actuator has disengaged; 
         FIG. 12  is a partial perspective view of the opposite side of the indexing mechanism shown in  FIGS. 9 to 11 ; 
         FIG. 13   a  is a perspective view of the drive coupling used in the indexing mechanism of the inhaler shown in  FIGS. 9 to 12 ; 
         FIG. 13   b  is a side view of the drive coupling illustrated in  FIG. 13   a  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. 
         FIG. 14  is a partial view of the inhaler according to the invention showing the form and position of the indexing wheel that may be used in order to crush used blisters as they pass around the indexing wheel; 
         FIG. 15  is an exploded perspective view showing the individual components of the inhaler according to another embodiment of the invention; and 
         FIG. 16  is a cross-sectional side view of the inhaler shown in  FIG. 15 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS. 3   a  to  3   e  of the accompanying drawings, there is shown an inhaler  10  having a housing  11  formed from two shell portions  11   a ,  11   b  (see  FIGS. 6 and 7 ), a cap  12  pivotally mounted to the housing  11  for rotation about an axis marked “C” (see  FIGS. 5 to 7 ) from a closed position as shown in  FIG. 4  in which the cap  12  covers and protects a mouthpiece  13  to a fully open position, as shown in  FIGS. 3(   b ) to  3 ( d ) and in a direction indicated by arrow “R” in  FIG. 3(   a ), in which the mouthpiece  13  is exposed to enable a user to inhale a dose of medicament through the mouthpiece  13 . 
     It should be noted that the cap is ‘passive’ in the sense that it can be opened and closed freely without performing the function of indexing of the blister strip or causing a blister piercing member  15  depending from the mouthpiece  13  to pierce the lid of an aligned blister. 
     The cap  12  is rotated into its fully open position in the direction of arrow “R”. An actuating lever  14  is revealed as soon as the cap  12  is rotated out of its closed position. The user then applies pressure to the actuating lever  14 , so that it rotates in the direction indicated by arrow “S” in  FIG. 3(   b ). 
     During initial rotation of the actuating lever  14  through a first portion of its stroke into the position as it is shown in  FIG. 3(   b ), the strip is indexed so as to move an unused blister into alignment with the blister piercing member  15 . 
     When the actuating member is rotated through a second portion of its stroke beyond the position shown in  FIG. 3(   b ) and after having completed the first portion of its stroke, in the direction of arrow “T” in  FIG. 3(   c ), the strip remains stationary but the mouthpiece  13  is now pivoted so that the blister piercing member  15  pierces the lid of the previously aligned blister. 
     Although reference is made to a blister piercing member  15 , it will be appreciated that multiple openings are formed in the lid of the blister so that air can be drawn into the blister through one or some of those openings and flow out of the blister together with an entrained dose of medicament, through one or more other openings and via the mouthpiece into a patient&#39;s airway. 
     Once the actuating lever is in the position shown in  FIG. 3(   c ), the user now inhales through the mouthpiece  13 , as shown by arrows indicated by “U” in  FIG. 3(   d ). 
     After inhalation, the user rotates the cap in the opposite direction, i.e. in the direction indicated by “V” in  FIG. 3(   e ). During this movement, the cap  12  engages with the actuating lever  14  so that the actuating lever  14  also returns to its initial position as shown in  FIG. 3(   a ), the strip remaining stationary during this return movement of the actuating lever  14 . 
     As mentioned above, the cap  12  is passive, although it does perform the function of re-setting the actuating member back to its original position in the event that the actuating lever is depressed prior to closing the cap. 
     As previously mentioned, the inhaler of the invention has an indexing mechanism that has previously been described with reference to WO2009/092652 A1. This aspect of the inhaler of the invention will now be described in detail with reference to  FIGS. 8 to 13   a . Although the drawings show a slightly different arrangement, in which an actuator  54  takes the place of a drive gear  16  attached to the drive coupling member  57  in the present invention, the principle remains the same as the actuator  54  and the drive gear are both rotated to index the strip. Therefore, rotation of the drive gear  16  performs the same function as rotation of the actuator  54  referred to in the description of  FIGS. 8 to 13   a  below. 
     Referring now to  FIG. 8 , there is shown a partial perspective view of an inhalation device  50  comprising an indexing mechanism  51 . 
     The indexing mechanism  51  includes an indexing wheel  55  comprising four vanes  55   a , 55   b , 55   c , 55   d , each having an enlarged head portion  56   a , 56   b , 56   c , 56   d . As is clear from reference to  FIGS. 1 and 2 , once a blister strip (not shown in  FIGS. 8 to 14 ) has passed over the blister locating chassis  53 , it passes around the indexing wheel  55 . A blister locates in the space between two vanes  55   a , 55   b , 55   c , 55   d  so that, as the indexing wheel  55  rotates in response to rotation of the actuator  54 , a vane  55   a , 55   b , 55   c , 55   d  engages a blister located between the vanes  55   a , 55   b , 55   c , 55   d  so as to drive the strip around the indexing wheel  55  to sequentially move each blister forward by a sufficient distance to move a fresh blister into alignment with a blister piercing element. 
     The indexing mechanism  51  includes a drive coupling member  57  (most clearly shown in  FIGS. 13   a  and  13   b ) for selectively or temporarily coupling the actuator  54  to the indexing wheel  55  so that, when coupled, the indexing wheel  55  rotates in response to rotation of the actuator  54  to index the strip. The drive coupling member  57  comprises a shaft  58  defining an axis of rotation “A” (see  FIGS. 13   a  and  13   b ) on which the indexing wheel  55  is rotatably received so that it can rotate freely about the shaft  58  about said axis of rotation “A”. The actuator  54  is fixedly attached to the drive coupling member  57  (the gear drive would also be fixedly attached to the drive coupling member  57 ) so that the drive coupling member  57  rotates together with the actuator  54  at all times. In the embodiment illustrated and described with reference to  FIGS. 8 to 12 , the actuator  54 , drive coupling member  57  and indexing wheel  55  are all mounted coaxially for rotation about the same axis “A”. However, it will be appreciated that in the embodiment of  FIG. 7 , the mouthpiece  13  and actuating lever  14  are not coaxially mounted with Axis ‘A’. 
     The drive coupling member  57  has a circular flange  59  that extends radially from one end of the shaft  58 . A portion  60  of the flange is cut-away (see arcuate opening  61  in  FIG. 8 ) over an angle of approximately 180 degrees where the flange  59  joins the shaft  58  so that this portion  60  of the flange  59  is not directly attached to the shaft  58  but only to the remaining portion of the flange  59  at each of its ends  60   a , 60   b . As a result, this portion  60  of the flange  59  is flexible relative to the rest of the flange  59  and can be deflected out of the plane of the flange  59  that extends at right angles to the axis of the shaft, in an axial direction (indicated by “T” and “S”, in  FIG. 13   b ) either towards or away from the shaft  58  or, more importantly, towards or away from the indexing wheel  55  which is mounted on the shaft  58 , when force is applied to it. This flexible flange portion  60  hinges about an axis B which intersects the axis A of the shaft  58  and actuator  54  but extends at right angles to it. The drive coupling member  57 , or at least the flange  59 , is made from a resilient material so that when the deflected flexible flange portion  60  is released, it returns to its neutral, unstressed position, in which it lies coplanar with the remaining fixed portion of the flange  59 . 
     The flexible flange portion  60  has an integrally formed flange deflecting dog  62  projecting radially from its circumferential edge. The flange deflecting dog  62  has first and second angled engaging faces  63 , 64  on opposite sides. When the drive coupling member  57  is rotated in response to rotation of the actuator  54  in one direction, one of the first or second angled engaging faces  53 , 54  cooperate with a fixed formation  65  on the housing  52  to cause the flexible flange portion  60  to deflect in a first direction. When the drive coupling member  57  is rotated in the opposite direction, the other angled engaging face cooperates with the formation  65  on the housing  52  to cause the flexible flange portion  60  to deflect in a second, opposite direction, as will be explained in more detail below. 
     The flexible flange portion  60  also has an arcuately shaped indexing wheel drive dog  66  that upstands in an axial direction from its surface towards the indexing wheel  55  in the same direction as the shaft  58  and extends partially around the circumference of the flexible flange portion  60 . As will now be explained in more detail below, an end face  66   a  (see  FIG. 13   a ) of the indexing wheel drive dog  66  engages a vane  55   a , 55   b , 55   c , 55   d  of the indexing wheel  55  when the flexible flange portion  60  has been deflected in a first direction, as indicated by arrow “T” in  FIG. 13   b  (the flange portion  60  is shown in its deflected position in  FIG. 13   b ), so that the indexing wheel  55  is driven together with the drive coupling member  57 . 
     As mentioned above, the flange deflecting dog  62  engages a formation  65  on the housing  52  when the drive coupling member rotates in response to rotation of the actuator  54  so as to flex the deflectable portion  60  of the flange  59 . This formation  65  comprises first and second arcuately shaped tracks or paths  67 ,  68  positioned one above the other or spaced from each other in the axial direction. The surface of the innermost track  67  is visible in  FIG. 8 . The lower or outermost track  68  is located beneath it and is visible in  FIG. 12 . The ends of the tracks  67   a ,  68   a  have angled faces for reasons that will become apparent. 
     When the actuator  54  (or the drive gear) is rotated in a first direction, the drive coupling member  57  rotates together with it and the first outwardly facing angled surface  63  on the flange deflecting dog  62  contacts the angled face  67   a  of the innermost track  67 . Further rotation of the drive coupling member  57  causes the flange deflecting dog  62  to ride up onto the surface of the innermost track  67  thereby deflecting the flexible flange portion  60  inwardly, i.e. in a direction into the housing  62  or towards the shaft  58  and the indexing wheel  55 . 
     When the flexible flange portion  60  has been deflected inwardly in the direction of arrow T, further rotation of the drive coupling member  57  causes the indexing wheel drive dog  66  to engage a vane, which as shown in  FIG. 8  is vane  55   c , of the indexing wheel  55  so that the indexing wheel  55  rotates together with the drive coupling member  57  and drive to the indexing wheel  55  is engaged. 
     When the end of the innermost track  67  has been reached, the flange deflecting dog  62  falls off the surface of the track  67  and the resilience of the flexible flange portion  60  causes it to return to its original unstressed or neutral position. When the drive coupling member  57  is rotated further, the indexing wheel drive dog  66  no longer engages with the vane  55   c  of the indexing wheel  55  and instead passes beneath it so the indexing wheel  55  remains stationary. Therefore, drive to the indexing wheel  55  is disengaged, despite continued rotation of the actuator  54  in the same direction. 
     When the actuator  54  is rotated back in the opposite direction towards its home position, the second inwardly facing angled surface  64  of the flange deflecting dog  62  now contacts the lower or outermost track  68  so that the flange deflecting dog  62  now rides onto the surface of that second track  68 , thereby causing the flexible flange portion  60  to deflect outwardly or in the opposite direction to the direction in which it was previously deflected. Engagement of the flange deflecting dog  62  with the outermost track  68  so as to deflect the flange portion  60  in the opposite direction, enables the drive coupling member  57  to rotate in the opposite direction without any drive to the indexing wheel  55 . It will be appreciated that, if the flange portion  60  was not deflected in the opposite direction, the flange deflecting dog  62  would simply engage against the end of the formation  65  in the housing  62  when rotated back in the opposite direction, thereby preventing rotation in the opposite direction or, the flange deflecting dog  62  would travel back over the innermost track  67  deflecting the flexible flange portion  60  in the same direction causing the opposite end  66   b  of the indexing wheel drive dog  66  to engage with a vane  65   b  of the indexing wheel  65  thereby driving the indexing wheel  65  backwards rather than leaving it stationary with no drive engaged. Therefore, it is necessary to ensure that the flexible flange portion  60  is deflected in the opposite direction so that there is no drive to the indexing wheel during rotation of the coupling member  67  in the opposite direction. 
     When the drive deflecting dog  62  reaches the end of the outermost track  68 , the flexible flange portion  60  returns to its original unstressed or neutral position, due to its resilience. 
     It will be appreciated that the extent of rotation of the indexing wheel  55  relative to the extent of rotation of the actuator  54  may be controlled by altering the circumferential length of the inner and outer tracks  67 , 68 . If the tracks are made longer, the flexible flange portion  60  will be deflected for a greater proportion of the angle through which the actuator  54  is rotated and so the indexing wheel drive dog  66  will be engaged with the indexing wheel  55  to rotate the indexing wheel  55  throughout that angle. If required, the tracks  67 , 68  could be made sufficiently long so that the indexing wheel  55  rotates during rotation of the actuator  54  through its entire angle of movement in one direction. Alternatively, the tracks  67 , 68  could be made shorter to reduce the angle through which the actuator  54  and indexing wheel  55  rotate together. Ideally, the track length can be selected so that the indexing wheel  55  is rotated through a sufficient angle to move the next, unused blister, into alignment with the blister piercing element. 
     The further rotation of the actuator  54  (the gear drive) causes the mouthpiece to rotate so that the blister piercing member pierces the lid of a blister that has just been moved into alignment with the blister piercing element. 
     It will be appreciated that the indexing mechanism  51  is designed to enable a stroke to be aborted when the actuator  54  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  55  has disengaged, i.e. a position in which the flange drive dog  62  has not reached the end of the innermost track  67 . If the stroke is aborted and the actuator  54  returned to its original position before drive to the indexing wheel  55  has disengaged (or the drive gear rotated back to its initial position), the strip will be driven backwards into its original position as a rear surface  66   b  of the indexing wheel drive dog  66  will engage a preceding vane  55   b  to drive the indexing wheel  55  in the opposite direction. 
     The indexing mechanism  51  also includes optional means for locking the indexing wheel  55  to prevent its rotation between indexing steps and means for temporarily releasing that lock to allow rotation of the indexing wheel  55  when driven by the indexing wheel drive dog  66 . The lock also improves positional accuracy of the strip and, more specifically, the next blister to be pierced. This locking arrangement will now be described in more detail below, although it should be noted that the locking mechanism can be omitted altogether. 
     The blister location chassis  53  may optionally comprise a resiliently flexible cantilever arm  70  that extends from the body  53  of the chassis towards the indexing wheel  55 . The free end of the cantilever arm  70  has an enlarged head portion  71  comprising a letterbox shaped slot, window or opening  72  in which the head  56   c  of a vane  55   c  of the indexing wheel  55  is located. The opening  72  is dimensioned such that the head  56   c  of the vane  55   c  (as shown in  FIG. 8 ) is a snug fit therein so that rotation of the indexing wheel  55  is prevented. In the normal or home position of the actuator  54 , the head  56   c  of a vane  55   c  is located in said opening  72  in the cantilever arm  70  of the chassis  53  so that rotation of the indexing wheel  55  is prevented. 
     When the actuator  54  is rotated and the flange drive dog  62  engages the innermost track  67  so as to deflect the flexible portion of the flange  60  inwardly towards the indexing wheel  55 , the indexing wheel drive dog  66  initially engages with a protrusion  71   a  extending from an inner side of the enlarged head  71  on the cantilever arm  70  of the chassis  53  so that the cantilever arm  70  is deflected outwardly, away from the indexing wheel  55 , to free the head  56   c  of the vane  55   c  from the slot  72 , thereby unlocking the indexing wheel  55 . Only once the indexing wheel  55  has been released by the indexing wheel drive dog  66  pushing the cantilever arm  70  away from the indexing wheel  55  does the indexing wheel drive dog  66  subsequently engage a vane  55   c  of the indexing wheel  55  so that further rotation of the drive coupling member  57  rotates the indexing wheel  55 . 
     Prior to the flange drive dog  62  falling off the end of the innermost track  67  and the flexible flange portion  60  returning to its undeflected state due to its resilience, the indexing wheel drive dog  66  no longer pushes against the cantilever arm  70  and so the cantilever arm  70  is free to move back towards the indexing wheel  55 . As the cantilever arm  70  is free to move back just prior to rotation of the indexing wheel  55  being completed, the cantilever arm is prevented from moving all the way back by the head  56   b  of a following vane  55   b  which contacts the cantilever arm  70 . During further rotation of the indexing wheel, the head  56   b  slides across the cantilever arm and then drops into the opening  72  thereby allowing the cantilever arm  70  to move all the way back and locking the indexing wheel  55  in position prior to any further rotation of the drive coupling member  57  in response to continued rotation of the actuator  54 . 
     On the return stroke of the actuator  54 , it will be appreciated that deflection of the flexible flange portion  60  in the opposite direction, i.e. in a direction away from the indexing wheel, also ensures that the indexing wheel drive dog  66  clears the chassis arm  70  and so the indexing wheel  55  is not unlocked, thereby preventing any rotation of the indexing wheel  55  during the return stroke. 
     The blister strip drive member or indexing wheel  15  of the invention may take a slightly different form to that described with reference to  FIGS. 8 to 13   b , although the principle still remains the same. In particular, the indexing wheel  15  may be used to squeeze the used blister cavities as they pass around it, thereby at least partially crushing them. This is achieved by enlarging the axle or hub  18  of the indexing wheel so that the distance (X in  FIG. 14 ) between the hub and the casing or wall of the device  11 , or a component fixed to the casing  11 , is less than the maximum height of a blister cavity. As the blister cavities are entrained between the spokes  17   a  of the indexing wheel  17 , onward rotation of the wheel  17  causes the cavities to be at least partially squashed or sandwiched between the enlarged hub  18  of the indexing wheel  17  and the casing  11  of the device. The advantage of at least partially crushing the empty blister cavities is that they then take up less space when coiled within the used blister chamber of the device as the coiled strip has a smaller diameter. Furthermore, a natural curvature is imparted to the strip, both as a result of being fed around the blister drive wheel and also as a result of the crushing of the blister cavities. This encourages the used portion of the strip to coil more readily. It is also apparent that, when the blister cavities have been crushed, the cavity is more resilient to denting at the point at which the spoke of the blister drive wheel contacts the strip, i.e. at the root where the blister cavity meets the remainder of the strip. Therefore, a more positive and precise drive of the strip is achieved when the blisters have been crushed. 
     As mentioned above, the drive coupling member  57  of the inhaler of the present invention is modified in that the drive gear  16  is attached thereto in place of the actuator  54  so that the drive coupling member  57  rotates in response to rotation of the drive gear  16 . It is also envisaged that the drive gear  16  may be moulded integrally with the drive coupling member  57 . 
     It will be apparent from  FIG. 7 , that the drive coupling member  57  extends into an opening  19  in a side wall of the shell  11   b  of the housing  11  and the drive gear  16  is coupled thereto so that it is disposed on the outside surface of said side wall, only the drive coupling member  57 , the blister strip drive wheel  17  and the blister strip itself, being received within the housing between the shell portions  11   a ,  11   b.    
     The actuating lever  14  has a first plate-like portion  20  that extends across the outside surface of the shell lib and has a hole  21  therein to receive a boss  22  upstanding from said surface, to pivotally mount the actuating lever  14  to the shell  11  for rotation about a second axis (A-A in  FIGS. 7 and 15 ). The actuating lever  14  may also have a second plate-like portion  23  that is parallel to and spaced from the first portion  20  by an actuating button  24 . The second plate-like portion extends across the opposite surface of the shell  11   a  and also has a hole  25  to engage with a corresponding boss upstanding from said opposite surface so as to pivotally couple the actuating member  14  to the shell  11  with the actuating button extending between the plates  20 , 23  and opposite surfaces of the shell portions  11   a ,  11   b.    
     The first plate  20  has a further aperture  26  therein and the cap  12  is pivotally mounted to the outer shell portion  11   b  by a coupling such as a boss  80  upstanding from a surface of the shell portion  11   b  that locates in a corresponding recess (not shown in  FIG. 7 , but see hole  92  in  FIG. 15 ) in the cap  12 , for rotation of the cap  12  about a third axis. The boss  80  extends through the aperture  26  in the actuating member  14 . The aperture  26  is arcuately-shaped and has the second axis as its centre so that, when the actuating lever  14  is rotated about the second axis, the boss  80  travels within the aperture  26  without engaging the actuating member  14 , and so the cap  12  remains stationary. The actuately-shaped aperture  26  acts as a clearance hole for the pivotal attachment of the cap  12  to the shell  11   b  and so as to allow rotation of the actuating lever  14  about the second axis. 
     A drive member (not shown) extends from an inner surface of the cap  12 . The drive member is located between, and spaced from, each of the second and third axes and extends towards the actuating lever  14  and the actuating lever  14  includes a wall  27  for engagement by said drive member when the cap  12  is rotated it about its third axis back towards its closed position and after the actuating member  14  has been rotated about its second axis. The drive member and wall  27  meet at a location between the second and third axes so that, upon further rotation of the cap  12  back towards its closed position, the drive member pushes against the wall  27 . Pressure of the drive member against the wall  27  causes the actuating member  14  to rotate back into its original position, together with the cap  12  into its closed position. 
     The cap  12  and actuating lever  14  are configured so that, when the cap  12  is in its closed position and the actuating lever  14  has returned to its initial position, the cap  12  overlies the actuating button  24  which is pressed by a user to operate the device. This prevents a user from attempting to operate the device by rotating the actuating member  14  prior to opening the cap  12 . 
     The actuating member  14  has a gear segment  28  that drivingly meshes with the gear drive  16  so that rotation of the actuating member  14  also causes rotation of the gear drive  16  and selective rotation of the blister strip drive member relative to the gear drive  16  whilst the actuating member  14  is rotated through the initial portion of its stroke, due to the indexing mechanism described above, so that the blister strip is initially driven to move the next blister into alignment with the blister piercing member  15 . During further rotation of the actuating member  14  through the second portion of its stroke, the blister strip is prevented from moving as the drive coupling member  57  is de-coupled from the blister strip drive wheel  17 . During rotation through the second portion of its stroke, the blister piercing member  15  carried by the mouthpiece  13  is rotated so that it pierces the aligned, and now stationary, blister. 
     A cam drive member (not shown) extends from the first plate  20  towards the second plate  23 . The cam drive member is received in a cam groove or slot  29  formed in a peripheral wall  30  depending from the mouthpiece  13 . As is apparent from  FIG. 7 , the cam groove or slot  29  has an arcuate portion  29   a  followed by a leg portion  29   b  at one end. It will be appreciated that the slot  29  may alternatively be provided in the actuating lever  14  and the cam drive member may extend from the mouthpiece  13  to achieve the same function. 
     During initial rotation of the actuating member  14  through the first portion of its stroke, the cam drive member slides along the arcuate portion  29  of the cam slot  29  without causing any movement of the mouthpiece  13 , as the arcuate portion  29   a  of the cam slot  29  has the second axis as its radius. However, during subsequent rotation of the actuating member  14 , the cam member reaches the leg portion  29   b  of the cam slot  29  and engages the side walls of the cam groove  29  so as to cause the mouthpiece  13  to rotate about a first axis B-B together with the actuating member  14  thereby pulling the blister piercing member  15 , depending from the mouthpiece  13 , into the aligned blister. 
     Although reference is made to a pivoting mouthpiece  13 , it will also be appreciated that, in an alternative embodiment, the blister piercing member  15  may be pivotally attached to a mouthpiece  13  or mounted in a support or module that is pivotally attached to the mouthpiece  13 . In these embodiments, the mouthpiece  13  itself remains stationary so that, in response to operation of the actuating member  14 , the blister piercing member  15  pivots relative to the stationary mouthpiece  13  to puncture the lid of an aligned blister. 
     During rotation of the cap  12  from its open to its closed position, rotation of the actuating member  14  due to rotation of the cap  12  also causes rotation of the mouthpiece back to its original position as the cam member travels back along the cam slot  29   b.    
     As shown in  FIG. 7 , a spiral element  31  is also optionally mounted within the housing  11  into which the used portion of the strip is fed. 
     Although a region is provided within the housing  11  to receive the used portion of the strip, it will be appreciated that the invention is also applicable to other inhalation devices (not shown) in which used blisters are not retained within the housing  11  but pass out through an opening (not shown) in the wall of the housing  11  for periodic detachment by a user. 
     Although piercing of an aligned blister only occurs after movement of the strip has stopped, it is envisaged that the mechanism could be configured so that de-coupling of the blister strip drive wheel  17  and the drive coupling member  57  only occurs after the blister piercing element  15  has pierced, or begun to pierce, the lid of a blister so that the piercing element is drawn across and through the lid of the blister as it enters it. This creates a larger hole relative to the size of hole created when the strip is stationary prior to being puncturing by the blister piercing element. A larger hole can advantageously ensure that all the drug dose is entrained and removed from the blister. 
     A modified embodiment is shown in  FIGS. 15 and 16 . This embodiment is similar to the previous embodiment and functions in the same way but additionally includes a detent mechanism for holding the actuating lever  81  at the end of its stroke so that a small force must be applied to it to overcome the hold placed on it by the detent mechanism and allow the actuating lever  81  to return to its initial position. The detent mechanism includes a cantilever  82  that extends from the actuating lever  81  and has a kinked region  82   a  which engages with a pawl  83  on the shell portion  84   b  as the actuating lever  81  approaches the end of the second portion of its stroke, so that the cantilever  82  is resiliently deformed and as it rides over the kinked region  82   a  and springs back to its original shape once the pawl  83  has cleared the kinked region  82   a . When the actuating lever  81  is rotated back towards its initial position, sufficient force must initially be applied to the actuating lever  81  so that the cantilever  82  is deformed by the pawl  83  and rides back over it. In addition to providing a slight resistance to initial movement of the actuating lever  81 , it also generates an audible ‘click’ as the end of the second portion of the stroke of the actuating lever  81  is reached and so provides an audible signal to the user that the end of the travel of the actuating lever  81  has been reached. 
     This embodiment also includes a rigid dividing wall  85  that separates the interior of the housing into an unused and used blister chamber  86 , 87  (see  FIG. 16 ). The wall  85  is slideably mounted within the shell portion  84   a  of the housing so that, as more of the blisters are used, the force of the used coil of blisters in the used blister chamber  86  presses against the wall  85  and pushes it in the direction indicated by arrow ‘P’ in  FIG. 16 , to enlarge the space for the used blisters and reduce the space previously occupied by the unused blisters. 
     The sliding wall  85  comprises an elongate foot  88  which is attached to and integrally formed with a baffle  89  that divides the compartment. An approximate central region  88   a  of the foot  88  is attached to the baffle  89  so that it extends in opposite directions on either side of the baffle  89 . The foot  88  is slideably received in a recess  90  formed in a wall of the housing and is wider at its ends  88   b  than in its centre  88   a  where it joins the baffle  89  so that contact with the walls of the recess  90  is primarily made with the wider ends  88   b  of the foot  88 . 
     A deeper, narrower recess  91  may extend deeper into the wall within the first recess  90  to receive a strengthening rib (not shown) depending from the underside of the foot  88 . 
     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. For example, although reference is made to a “mouthpiece”, the invention is also applicable to devices in which the dose is inhaled through the nasal passages. Therefore, for the purposes of this specification, the term “mouthpiece” should also be construed so as to include within its scope a tube which is inserted into the nasal passages of a patient for inhalation therethrough. 
     Furthermore, although the blister piercing member  15  is described as being attached to the mouthpiece so that the mouthpiece  13  and the blister piercing member rotate together, it is also envisaged that the mouthpiece itself could remain stationary and the blister piercing element  15  could be pivotally mounted to the mouthpiece  13  so that the blister piercing member  15  rotates relative to the mouthpiece  15  to pierce the lid of an aligned blister. 
     In another embodiment, the cap and the actuating member could be combined into a single component so that rotation of the cap also causes indexing of the strip and piercing of an aligned blister. 
     It will be appreciated that the inhaler of the invention may be either a passive or active device. In a passive device, the dose is entrained in a flow of air caused when the user inhales through the mouthpiece. However, in an active device, the inhaler would include means for generating a pressurised flow of gas or air through the blister to entrain the dose and carry it out of the blister through the mouthpiece and into the user&#39;s airway. In one embodiment, the inhaler may be provided with a source of pressurised gas or air within the housing.