Introduction

This invention relates to an inhaler of the kind used to entrain discrete compartments of powder into a patient's airway through sucking on a mouthpiece.

Background of the Invention

Inhalers of this kind usually incorporate either a flat disc that contains a multitude of spaced compartments that are indexed past an opening mechanism to an airway, where, as the patient sucks on the mouthpiece air is drawn through the inhaler to entrain the powder out of the compartment into the lungs of the patient. The inhaler includes an indexing device that moves the disc in increments to move the empty compartment away from the airway and expose the next opened compartment to the airway.

It is also known that instead of using a disc of compartments a blister strip in the form of a coiled roll of spaced receptacles can be used to hold the medication. Cutting, piercing or opening devices are provided within the inhaler to open each compartment as it reaches the airway to effect release of the contents. One of the problems with strips of blister packs is the collection of the strip of used packs after the powder has been expelled. Other issues concern to need to avoid overdosing i.e. the presence of residual powder in the airway to supplement the next dose.

Cutting, piercing or opening devices are provided within the inhaler to open each blister compartment as it reaches the airway to effect release of the contents.

It is known that it is difficult to control the size and configuration of an opening that is pierced or cut in a blister lid because the lid material may not always tear or burst in a consistent way. Flaps of the lid material may be pushed into the blister that can either trap powder in the blister or obscure an opening and hinder air flow through the opened blister. While this may be partially overcome by inserting suction tubes into the opened blister (WO 2005/037353) or providing piercing elements with multiple heads (WO 2006/108877) this increases the size of the blister strip resulting in a large inhaler if it is to contain 60 doses and the used blister strip.

It is known that peeling of the lid material from a blister (US 5,873,360) can open the face of the blister allowing the powder to be removed with relatively low airflow over the dose pocket. However as the inhaler has to receive both the used blister base and the lid that has been peeled away it makes the inhaler complicated to make and assemble and either unnecessarily large or limits the number of doses that can be contained in the inhaler.

While US 2008/0135441 and US2009/0007908 describe how to reduce the overall size of an inhaler by either detaching the used blister from the unused blister pack or crushing the used blister strip within the inhaler, these inhalers can retain some amount of the drug within the device that may be inhaled with another dose.

If an opened dose is not inhaled or not completely inhaled, the powder in the opened blister or receptacle could remain in the inhaler and become available when a subsequent dose is opened and inhaled.

US 2010/0078022 attempts to address this problem of dose containment by providing specific airway channels that align with an inhalation port and capture dry powder from one or more dose containers in a disc array. However by introducing a step to transfer the powder from the opened dose container to the respective air way channel and creating different lengths of the airway channels there can be powder losses or inconsistent dose delivery. There still remains the need for alternate inhalers or dose containment devices that can be used to deliver medicaments.

It is these issues that have brought about the present invention.

Summary of the Invention

According to the present invention there is provided an inhaler comprising a housing with an air inlet and an air outlet, the housing supporting a coiled strip of spaced pockets, each pocket comprising a projecting wall structure arranged to contain dry powder, indexing means to drive each pocket past a cutting head whereby as each pocket is driven past the cutting head spaced cuts are formed in the wall structure, and opening means to open the cuts to define an airway so, as air is drawn through the inhaler via the air inlet, powder in the pocket is picked up and transferred to the user via the airway and air outlet

The opening means to open the cuts may be a displaceable separator.

Alternatively the opening means may include placing the coiled strip under tension so that when the cutting head cuts the pocket the tension is released causing the spaced cuts to open to define the air passageway.

In the embodiment where the opening means is a displaceable separator, the separator is displaceable relative to the blades by the indexing means. More specifically, the separator could be displaceable together with the blades by the indexing means. The displacement of the separator may be transverse to the pocket to open the cuts to define the air

passageway.

In the embodiment where the opening means includes placing the strip under tension, the coiled strip may be placed under tension by a tensioner, or a tension arrangement. For example, this could include an arrangement that both pushes and pulls the strip past the cutting head. Such an arrangement could include a first end of the coiled strip that engages a toothed pushing gear and the other end of the strip that engages a toothed pulling gear spaced from the pushing gear, so that the strip is both pushed and pulled past the cutting head to create tension in the strip. Alternatively or additionally to the above arrangement, the tensioner could be defined by the relative spacing of the teeth of gears of the indexing means, to place the strip under tension.

In an embodiment, the housing supports a chassis that defines the storage and collection chambers, the chassis including a shoe to guide the strip around an apex in the shoe, the cutting head being positioned just before the apex. The apex of the shoe has a curvature which acts as a guide on the strip and, which in one embodiment, may assist as a tensioner to tension the strip.

In an embodiment, the cutting head comprises a pair of spaced blades to create the spaced cuts, the spaced blades each having a longitudinal cutting edge and the blades are either straight or curved to follow a curved path of the blister strip.

In another embodiment the inhaler comprises containment receptacles that are indexed forward with the blister pockets so that any residual powder is contained by the receptacles and indexed past the air outlet to prevent escape therethrough.

Description of the Drawings

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

Figure 1 is a plan view of one half of a casing that forms part of an inhaler in accordance with a first embodiment of the invention,

Figure 2 is a perspective view taken from the side of part of the casing, Figure 3 is a perspective view taken from the side showing the same part of the casing and illustrating an air flow path,

Figure 4a is an enlarged view of a cutting head that forms part of Figure 1 , Figure 4b is the same view but illustrating forward movement of a separator that forms part of the cutting head,

Figure 5a is a side perspective view of the cutting head,

Figure 5b is a side perspective view of the cutting head with the separator in a forward position,

Figure 6 is a perspective view of a cutting blade and separator assembly separated from the rest of the inhaler,

Figure 7a is a side view of the cutting head,

Figure 7b is a side view of the cutting head with the separator advanced, Figure 8 is a plan view of one half of the casing illustrating an alternative cutting head,

Figure 9a is an enlarged plan view of the cutting head,

Figure 9b is an enlarged plan view of the cutting head in an advanced position, Figure 10 is a perspective view of a cutting blade of Figure 9 separated from the rest of the inhaler,

Figure 1 1 is a perspective view of a coiled strip of blister pockets, Figure 12 is an exploded perspective view illustrating the internal components of an inhaler in accordance with a second embodiment,

Figure 13a is a plan view of a chassis forming part of the inhaler, Figure 13b is a side elevational view of the chassis,

Figure 14 is a perspective view of the casing assembly to show the path of a blister strip,

Figure 15 is a perspective view taken from the side of part of the casing, Figure 16 is a perspective view illustrating interaction of a gear train,

Figure 17 is an underside view of the casing showing interaction of the gear components,

Figure 18a is a side elevational view of a lever,

Figure 18b is a plan view of the lever,

Figure 18c is an underside view of the lever,

Figure 19a and 19b are perspective views of the inhaler illustrating the operation of a cutting head,

Figure 20a is a perspective view showing the air passageway of the inhaler, Figure 20b is an enlarged view of the inhaler within the circle B on Figure 20a, Figure 21 a is a perspective view of a straight blade with a straight cutting edge,

Figure 21 b is a perspective view of a curved top blade with a straight cutting edge,

Figure 21 c is a perspective view of a curved bottom blade with a straight cutting edge,

Figure 21 d is a perspective view of a straight blade with a centrally positioned sickleshaped cutting edge,

Figure 21 e is a perspective view of a straight blade with a sickle-shaped cutting edge at the blade tip, and

Figure 21 f is a perspective view of a circular cutting blade.

Description of the Preferred Embodiments

In a first embodiment shown in Figures 1 to 1 1 an inhaler 10 shown includes a substantially circular outer casing 1 1 that supports a plastic partition 12 to inturn define a storage chamber 21 , a recess 22 for an idler gear 23 that meshes with a drive gear 24. A collection chamber 25 is positioned on the opposite side of the casing 1 1 to the storage chamber 21 . The casing 1 1 is designed to hold a strip 5 of blister pockets 30 each containing a dose of powder to be inhaled. Strip 5 is wound into a coil. The strip 5 as it unwinds passes round the idler gear 23, through the drive gear 24 past a cutting head 50 and airway 13 to the collection chamber 25. An indexing mechanism 28 standard to inhalers of this kind, causes the drive gear 24 to index the strip 5 so that the pockets 30 move, one by one, past the cutting head 50 and airway 13. The strip 5 with empty dose pockets 30 then collects in a loose coil in the collection chamber 25 until all the sealed blister pockets have been emptied at which time the inhaler is replaced.

The plastics partition 12 defines a vertical guide wall 14 that extends around the storage chamber 21 around a portion of the idler gear 23 and drive gear 24 behind the cutting head 50 and airway 13 to the entry into the collection chamber 25. The external vertical wall 14 of the partition 12 also defines the inner wall of the storage chamber 21 .

As shown in Figure 1 1 the strip 5 of blister pockets 30 has a base laminate and a heat bonded lid 31. The blister is made from any material(s) known to be used in manufacturing blister strips/blister packets. The base material can, for example, be formed of a plastics/aluminium laminate or a plastics laminate. By further example, the laminate may be a PVC laminate with a PVDC coating to reduce moisture transmission. The base laminate includes spaced pockets 30 that are sealed by lid 31 , which defines a flat surface 32 to the blister strip 5. Each pocket 30 has a well shaped base 33 with upwardly outwardly diverging walls 34. In a preferred embodiment the strip has sixty pockets. The strip 5 is formed into a coil and loaded into the casing 10 so that the pockets 30 face inwardly with the flat surface 32 sliding against the guide wall 14 and as the strip is wound around the idler wheel 23 the pockets 30 protrude outwardly of the strip 5. Each pocket 30 is driven by the drive gear 24 to move the strip 5 forwardly against the cutting head 50. Each pocket 30 is approximately 6.2mm long by 3.2mm wide and has a depth sufficient to contain a dose of powder. For example, the depth could be 1 .5mm. The longitudinal axis of the each pocket 30 is parallel to the longitudinal axis of the cutting head 50.

As shown in Figures 1 to 3 the indexing mechanism 28 comprises an arcuate arm 29 that is displaceable between two positions around the periphery of the casing. The arm moves in one direction that causes the idler and drive gears 23 and 24 to rotate, the arm 29 is then free to return to the initial position without turning the gears. The arm 29 is also geared to an annular containment ring 60 that comprises sixty equally spaced open receptacles 61 that are positioned to move in a path directly underneath the cutting head 50. The indexing mechanism 28 causes the idler gear 23 and drive gear 24 to push a pocket 30 past the cutting head 50 to complete a cutting action at the same time as an open receptacle 61 is positioned underneath the cutting head 50 to collect any residual powder.

The cutting head 50 cuts a small slit at the top and bottom of either side wall 34 of the pocket 30 and opens the slits to define an air passageway so that as the open pocket is adjacent the airway 13 and air is drawn through the inhaler through the mouthpiece (not shown), the air flows into the inhaler through the open pocket 30 to draw out the powder contained therein. The air passageway is shown by the arrow in Figure 3. The air is drawn into the casing through an upper aperture (not shown) in the casing 1 1 to then turn inwardly towards the top of the pocket 30. The air is drawn down through the opened pocket 30 to escape via the base of the pocket through the open receptacle 61 in the containment ring 60 and out through the airway 13. In this manner the air is mixed with the powder in the pocket and the sucking action draws the air and powder out through the air passageway. Most of the powder escapes through the airway but some might drop into the containment ring 60 where it collects in the receptacle 61 to be then moved into the collection zone 25 as the next pocket 30 is indexed past the cutting head 50.

A first example of the cutting head 50 is illustrated in Figures 4a to 7. A cutting blade and separator assembly 70 shown in Figure 6 comprises a top separator in the form of a rectangular plate 71 with a downwardly projecting separating arm 72 and a bottom separator having a rectangular plate 73 and upwardly projecting separator arm 74. The cutting blade is similarly profiled to include a plate 75 and downwardly projecting blade 76 on the top and a plate 77 and upwardly projecting blade 78 on the bottom. The cutting blades 76 and 78 are spaced apart and define cutting edges 79.

As each pocket 30 is pushed past the cutting blades 76 and 78, the longitudinal axis of the pocket 30 is parallel with the longitudinal axis of the cutting blades and the cutting edges 79 of the blades make a slit across the top and bottom of the wall portions of each pocket (see Figure 5a). Figures 4a, 5a and 7a show the blades 76 and 78 cutting the top and bottom of the wall structure 34 of the pocket 30. After the top and bottom of the pocket 30 have been cut by the blades 76 and 78 further indexing of the indexing mechanism 28 causes the separator 70 to move forwards or radially outwardly as shown in the plan view in Figure 4b. Movement is less than 1 mm but is sufficient for the separator arms 72 and 74 to push the base 33 of the pocket 30 outwardly, thereby opening the slits into vertically spaced holes defining the air passageway.

Figures 7a and 7b show the top and bottom blade assemblies 76 and 78 attached via a lug 81 into aperture 82 of the blade assembly to a block 80 that is fixed within the casing of the housing. The separator plates 71 and 73 are attached to a second block 85 via a lug 86 that locates into aperture 87. The second block 85 is secured to the first block 80 by a screw 88 that extends through the block 80 and block 85 and is secured to the second block via a nut 89 and spring 90. The second block can thus be displaced against the spring 90 longitudinally of the screw 88. The block 85 has a downwardly projecting foot 91 as shown in Figure 7b that interacts with a cam so that the last 20% of movement of the indexing mechanism 28 urges the block 85 forwards to cause the separator arms 72 and 74 to assume the position shown in Figure 7b. The first movement of the indexing mechanism 28 in the next operation causes the separator to move back to the neutral position shown in Figure 7a.

In a second example of the cutting head shown in Figures 8 to 10 the blade and separator are formed as a single component 92, namely a C-shaped member 92 having forwardly projecting spaced flanges 93 and 94 each of which supports a projecting separator arm 95, 96. Each separator arm 95, 96 defines cutting edges 97. As the indexing mechanism 28 forces the pocket 30 past the separator arms 95, 96 the cutting edges 97 form a slit in the top and bottom of the wall portions of the pocket 30. The indexing mechanism 28 then moves the whole blade assembly 92 forwards through a small movement of less than 1 mm that has the effect of causing the separator arms 95, 96 to force open the slits and define the airway. The blade 92 then returns to the neutral position in the same manner as the first example. The blade 92 is drawn forward in the same manner as the first example.

The casing 1 1 is located in a cover member (not shown) that clips to the exterior of the casing 1 1 and pivots relative to the casing to extend over the mouth piece when not in use. To use the inhaler 10, the cover member is rotated to the open position thereby exposing the mouth piece (not shown). The indexing mechanism 28 is then activated so that its first movement is to return the separator to the neutral position as shown in Figure 7a. Further movement of the indexing arm causes the adjacent pocket 30 to be driven against the cutting blades forming the slots in the top and bottom of the pocket 30. The final 20% of the indexing motion moves the separator radially outwardly or forwardly, as shown in the drawings, to open the air passageway in the pocket 30. The user then sucks through the mouth piece causing air to enter the casing 1 1 and through the cut pocket to entrain and draw the powder out of the pocket and into the mouthpiece. Powder that is not picked up drops into the containment receptor 61. The outer cover is then rotated to close off the mouthpiece. This movement has the effect of returning the indexing arm to the neutral position. When the device is again operated the outer cover is opened and the indexing mechanism moves the used receptor in the containment ring past the cutting head and brings another pocket and receptor into line with the cutting head and air passageway.

The used (empty) pockets are collected in a coil on the right hand side of the casing in the collection chamber 25 and any powder that may have dropped into the containment ring 60 is held within the receptacles 61 in the retainer ring cannot be added to any subsequent doses. It is understood that the device would include a number of other conventional components such as an index counter that shows how many doses have been used to provide the user with a ready indication of doses remaining.

The cutting blades and separators are preferably constructed in lightweight steel and the remaining components of the device are manufactured from injection moulded plastics.

Figures 12 to 21 b illustrate a second embodiment of an inhaler 100. Figure 12 is an exploded view of the internal components of the inhaler 100, which has a substantially circular outer casing 1 10 defined by an upper housing 102, a lower housing 103 with a chassis 1 12 positioned therebetween. The casing clips into the interior 101 of a U shaped hollow cover 104. The casing defines an air inlet and an air outlet that is covered by a mouth piece 109 so that when a user sucks on the mouth piece 109 air is drawn through the inhaler 100.

An indexing mechanism comprises a lever 139, a dose counter ring 160, a drum gear driver 137, a drum gear 124, a spool gear 131 , an idler gear 132, and a waste gear assembly 133. A cutting head is defined by a lower blade 151 and an upper blade 152 positioned adjacent the apex of a shoe 145 that forms part of the chassis 112.

The chassis 1 12 defines, as shown in Figure 13a, a storage chamber 121 that is designed to hold a coiled strip 105 of blister pockets 130 (see Figure 14) and a collection chamber 125. The strip is arranged to wind past the cutting head 150 that is positioned adjacent an airway 1 13 (see Figure 15) to then be collected in the collection chamber 125. The indexing mechanism 128, standard to inhalers of this kind, causes a drum gear 124 to index the strip 105 so that the pockets 130 move, one by one past the cutting head and airway 1 13. The strip 105 with empty dose pockets 130 then collects in a coil in the collection chamber 125 until all of the sealed blister pockets 130 have been emptied at which time the inhaler 100 is replaced.

The chassis 1 12 defines a structure that defines the collection chamber 125 and the storage chamber 121 . As shown in a plan view in Figure 13a, the right hand side of the chassis 1 12 has an outer wall 141 defining one side of the storage chamber 121 with two curved pointed surfaces 142, 143 defining a separation between the storage chamber 121 and the collection chamber 125 and which in use, assists in the coiling and uncoiling of the blister strip. An aperture 144 in the centre of the collection chamber 125 facilitates location of the waste gear assembly 133 and the collection chamber is also defined by the outer left hand arcuate wall 126 of the chassis 1 12. The lower side of the chassis 1 12 as shown in Figure 13a has an upstanding arcuate shoe 145 that guides the blister strip as it is indexed forward. The shoe 145 positioned alongside a central aperture 146 through which the drum gear 124 extends. The same end of the chassis includes a profiled wall structure 147 (see also Figure 13b) to support the blades 151 , 152 of the cutting head.

Figure 14 shows the path of the blister strip 105 forming a loose coil in the storage chamber 121 , extending around the drum gear 124 and then turning sharply back around the apex of the shoe 145 to extend into the collection chamber 125 to be collected on the waste gear assembly 133 that is located substantially centrally of the collection chamber 125.

The arcuate shoe 145 has a diameter that is comparable to the distance between pockets 130 when measured from their midpoint. This ensures that each pocket is reliably presented at the same location before the cutting head to produce consistently accurate cuts while reducing the risk of strip buckling.

As shown in Figures 18a to 18c, the indexing mechanism comprises a lever 139 in the form of an arcuate arm that is displaceable between two positions around the periphery of the casing. The lever drives the drum gear driver 137 that in turn meshes with the drum gear 124, through the spool gear 131 to the dose counter ring 160 and idler gear 132 and the waste gear assembly 133. The gears are located within apertures in the lower housing 103 and they operate to drive the strip 105 of pockets 130 past a pair of blades 151 , 152 that define the cutting head 150. The arm moves in one direction to engage the drum gear driver 137. Disengagement of the drum gear driver 137 allows the lever 139 to return to its initial position without turning the other gears.

The indexing motion causes the drum gear 124 to push a pocket 130 past the cutting head 150 to complete the cutting action and at the same time open the pocket to effect release of power contained therein.

The meshing of gears is shown in Figures 16 and 17. The drum gear 124 drives the waste gear assembly 133 via an idler gear 132. The waste gear assembly 133 includes an engagement member in the form of spirally extending radial arms 135 that engage the blister strip 105 and cause it to be wound up in the collection chamber 125. The drum gear 124 has a central aperture 136 into which is located the drum gear driver 137 which is in turn driven by a gear 138 (see Figures 18a to 18c) on the end of the lever 139. As shown in Figure 12 the outer ring 160 has an internal ring of teeth 161 and is positioned on the underside of the gear assembly to turn via the drum gear 124 and spool gear 231 with each indexing of the lever 139 to provide a dose counter.

As shown in Figures 14, 19a and 19b the strip 105 of blister pockets 130 is constituted by a base laminate that defines the spaced pockets 130 that are sealed by heat bonded lid that defines a flat inner surface 162 to the blister strip 105. Each pocket 130 has a well shaped base 163 with upwardly outwardly diverging walls 164 and curved ends 165, 166. In a preferred embodiment the strip has sixty four pockets 130. As shown in Figure 14, the strip 105 is formed into a coil and loaded into the casing 1 10 so that the pockets 130 face inwardly so that as the strip is wound around the drum gear 124 the pockets 130 protrude outwardly of the strip 105. The drum gear 124 is designed to have a series of radial spines 121 that define gaps 122 therebetween. These vertical gaps 122 are specifically shaped to accommodate the well shaped base 163 of a projecting pocket 130. Four pockets 130 are located in the gaps 122 between spines 121 of the drum gear 124 to ensure positive drive of the blister strip 105. Each pocket 130 is driven by the drum gear 124 to move the strip 105 forwardly against the cutting head 150.

In this embodiment each pocket 130 is approximately 6.2mm long by 3.2mm wide. The depth of the pockets is sufficient to contain the desired dose of powder. For example, in this embodiment the depth could be 1.5mm. The longitudinal axis of each pocket 130 is parallel to the longitudinal axis of the cutting head 150.

One of the challenges with inhalers of this kind is maintaining the consistent tension in the blister strip as it is indexed to ensure that all doses can be accessed. In the inhaler of the subject application the blister strip is both pushed by the drum gear 124 and pulled by the waste gear assembly 133. By using a combination of pushing and pulling as well as getting the distance correct between the two gears 124, 133 and by turning the blister strip back on itself around the shoe 145 of the chassis 1 12 it has been discovered that the blister strip 105 is under sufficient tension to ensure that it is possible to consistently index all sixty doses. The blister strip has been lengthened to have sixty four dose pockets where the last four pockets are empty. There is an equal gap between all pockets and the end of the blister strip is wound onto the shaft of the waste gear assembly 133 to apply the correct tension on the blister strip during the assembly process. For the drum gear 124 to effectively push the pockets there needs to be a minimum of four pockets in the drum gear, hence, pockets one to sixty contain the doses and pockets sixty one to sixty four are empty pockets to make sure that the 60 ^th dose is available.

As shown in Figures 14 and 19a the cutting head assembly 150 comprises two vertically spaced blades 151 , 152. Each blade has an essentially flat rectangular elongate profile with a U-shaped notched end 153. The cutting edges 156 of the blade are on each longitudinal edge. The blades are positioned as shown in Figures 14 and 20a in vertical alignment defining a gap therebetween and the cutting of the pocket is shown with particular reference to Figure 19b that shows the blades 151 , 152 engaging opposite ends 165, 166 of the pocket 130. Although the blade is shown essentially straight it is understood that it could have a slight curvature or other shape and it is also understood that the blades may be positioned slightly inclined to the approaching pocket.

Figures 21 a to 21f illustrate variations on possible blade structures.

Figure 21 a illustrates a straight blade 151 (or 152) having a straight cutting edge 156. When mounted on the arcuate shoe 145, this blade is inclined relative to the path of the approaching pocket. Figures 21 b and 21 c illustrate a top blade 152 and a bottom blade 151 respectively, where the blades are curved about a longitudinal direction so that when mounted on the arcuate shoe 145, these blades are presented parallel to the path of the approaching pocket 130.

Figures 21 d and 21 e illustrate a sickle shape notch in the cutting edge 156 located at two optional positions on the edge 156 and Figure 21f illustrates another possibility of a circular blade with a continuous cutting edge and a central mounting hole. The sickle shape is designed to provide a concentrated point of initial contact to create a first cut in the pocket which can then be easily followed through with the straight part of the sharp edge 156. The blister strip 130 is arranged to move past the blades 151 , 152 with the planar surface of the strip parallel to the blade edges 156. As shown in Figure 19b each pocket approaches the blades 151 , 152 so that each blade contacts the curved ends 165, 166 of the pocket 130 to provide a horizontal slit 157 across each curved end which is at the top and bottom of the pocket as shown in Figure 19b. The blade cuts through the top and bottom of the pocket 130 and the pocket is then moved past the blade to return to the collection chamber 125. The blades 151 , 152 are specifically positioned forward of the apex of the shoe 145 of the chassis 1 12 so that as each pocket 130 is both pushed and pulled around the apex of the shoe 145 comes into contact with the blades 151 , 152 as the pocket moved around the apex.

As shown in Figures 20a and 20b, when the upper and lower blades 151 , 152 cut the pocket there is a loss of tension on the cut section of the pocket and a gap 159 is formed on the pocket between the outer surface of the blade and the inside of the pocket. This gap provides an air passage so that when a user sucks on the mouthpiece 109 the air flowing through the inhaler flows through a passage 108 in the chassis into the gap 159 to pick up and entrain the powder within the pocket 130 into the air to then be transferred to the lungs of the user via the outlet 1 13 and mouthpiece 109. Powder that is not picked up by the air and remains in the pocket 130 is then transferred to the waste collection chamber 125.

The airflow is shown by the arrow in Figures 20a and 20b.

Research indicates that the best position to cut and evacuate the blister pocket is when the pocket is sitting, or almost sitting, on the apex of the shoe of the chassis. Additionally, cutting and evacuation is effective when the blister strip is held under tension in a position of curvature with the pockets facing outward of the curvature. This creates a tension in the base laminate that aids cutting and the creation of a passage, or gap, in the pockets of the blister. Because there is greater and consistent tension in the blister strip, when the top and bottom sections are cut the centre section of the base lamiante is under more tension than the cut ends and a small gap forms between the outer cut ends of the blister and the surface of the blades. This small gap allows sufficient air to enter the pocket to evacuate the dose.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.