DRY POWDER INHALER

Abstract

A dry powder inhaler with a blister folding device can include a housing to receive a single blister containing a dose of medicament for inhalation by a user, and a mouthpiece through which a dose of medicament is inhaled by a user and a blister opening device. The blister opening device can include a blister support element for supporting a blister containing a dose of medicament for inhalation by a user, and a blister folding element co-operable with the blister support element. The blister folding element and the blister support element can be movable relative to each other between a first position, for insertion of the blister into or onto the blister support element, and a second, burst, position in which the blister folding element has co-operated with the blister support element.

Claims

1. A dry powder inhaler comprising a housing to receive a single blister containing a dose of medicament for inhalation by a user, said blister comprising a blister lid attached to a blister bowl, a mouthpiece through which a dose of medicament is inhaled by a user and a blister opening device, the blister opening device comprising a blister support element for supporting a blister containing a dose of medicament for inhalation by a user, and a blister folding element co-operable with the blister support element, the blister folding element and the blister support element being movable relative to each other between a first position, for insertion of said blister into or onto the blister support element, and a second, burst, position in which the blister folding element has co-operated with the blister support element, movement from the first position to the second position causing two spaced apart portions of said blister to each fold relative to the remainder of the blister along a respective fold line and against the blister support element to produce two spaced apart openings, each opening extending along the circumference of the blister bowl, beginning and terminating at points located on the fold line such that, when a user inhales through the mouthpiece, an airflow through the blister via the two openings is generated to entrain the dose contained therein and carry it out of the blister and via the mouthpiece into the user's airway.

2. The dry powder inhaler as claimed in claim 1, in which the blister folding element and the blister support element are pivotally connected to each other about a pivotal axis.

3. The dry powder inhaler as claimed in claim 1, in which the blister support element comprises a blister seat to support a blister bowl and a blister support surface to support the periphery of a blister surrounding said blister bowl.

4. The dry powder inhaler as claimed in claim 3, in which the blister seat comprises a central portion which has a truncated oval shape, each fold line being one edge of truncation.

5. The dry powder inhaler as claimed in claim 4, in which the blister seat further comprises two depressible end portions adjacent to and either side of the central portion.

6. The dry powder inhaler as claimed in claim 4, in which the blister seat is configured such that the fold lines are of different lengths.

7. The dry powder inhaler as claimed in claim 3, in which a longitudinal extent of the blister seat is arranged in parallel with the pivotal axis.

8. The dry powder inhaler as claimed in claim 3, in which a longitudinal extent of the blister seat is arranged perpendicularly to the pivotal axis.

9. The dry powder inhaler as claimed in claim 3, in which the blister seat incorporates a raised feature to cause an indentation at the base of the blister for internally pressurising the blister.

10. The dry powder inhaler as claimed in claim 1, the blister folding element comprising at least one pair of spaced apart fold members receivable into the blister support element, the one or each pair of fold members extending from a fold support structure.

11. The dry powder inhaler as claimed in claim 10, comprising two pairs of fold members, in which a first pair of said fold members is longer than a second pair of said fold members.

12. The dry powder inhaler as claimed in claim 10, in which a free end of each fold member is bevelled.

13. The dry powder inhaler as claimed in claim 1, in which the blister is curved along its longitudinal extent.

14. The dry powder inhaler as claimed in claim 13, the blister opening device further comprising a stress concentrating means to create a stress concentration in the lid of the blister prior to the blister being folded.

15. The dry powder inhaler as claimed in claim 14, in which the stress concentrating means comprises a piercing head that is curved to match the profile of the curved blister.

Description

[0047] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:—

[0048] FIG. 1 is a perspective view of an inhaler according to a first embodiment of the invention, with the blister folding element in the first position to reveal the blister support element;

[0049] FIG. 2 is an alternative perspective view of the inhaler of FIG. 1, showing the blister folding element;

[0050] FIG. 3 is a perspective view of a demonstration rig, with a blister placed onto the blister seat and the blister folding element in the first position;

[0051] FIG. 4 is a perspective view of the demonstration rig of FIG. 3 after the blister has been burst, and with the blister folding element back in the first position once more;

[0052] FIG. 5 is a perspective view of a second embodiment of the inhaler, with the cap closed;

[0053] FIG. 6 is a perspective view of the inhaler of FIG. 5, with the cap open and the blister folding element in the first position, ready for placement of a blister onto the blister support element;

[0054] FIG. 7 is a partial cross-sectional view through the side of the inhaler of FIG. 6;

[0055] FIG. 8 is a perspective view of the inhaler of FIG. 5, with the cap open and the blister folding element in the second position, ready for inhalation by a user;

[0056] FIG. 9 is a cross-sectional view through the side of the inhaler of FIG. 8;

[0057] FIG. 10 is a partial perspective cross-sectional view through the side of the inhaler of FIG. 8;

[0058] FIGS. 11 A to E show a cross-sectional side view of a demonstration rig operating in a sequence of steps to achieve blister folding in accordance with the invention, and shows in particular the stress concentrating means;

[0059] FIGS. 12 A to D show a perspective view of the demonstration rig of FIG. 15 in a shortened sequence of steps;

[0060] FIGS. 13 A to C illustrates the step-by-step formation of two openings in a curved blister;

[0061] FIG. 14 shows a side elevation view of a stress concentrating means which has an arcuate lower surface to follow the surface of a curved blister;

[0062] FIGS. 15 A to C are cross-sectional side views of an unmodified blister, a blister with a strengthening rib, and a blister with a pre-tensioned blister lid respectively,

[0063] FIGS. 16A and 16B are cross-sectional side views of the chamber and the pierced blister, used to indicate the travel of a typical large particle/agglomerate through cyclonic airflow, with the ‘A’ figures being cross-sectional side views and the ‘B’ figures being corresponding plan views with hidden details; and

[0064] FIGS. 17A and 17B, 18A and 18B, 19A and 19B, 20A and 20B, 21A and 21B, 22A and 22B, 23A and 23C are all progressions of FIGS. 16A and 16B.

[0065] A first embodiment of the inhaler will now be described with reference to FIGS. 1 to 4. A unit dose dry powder inhaler is indicated generally at 10. The inhaler comprises a cap 12, a housing 14 to which is pivotally mounted a mouthpiece 16 and a blister opening device 18.

[0066] The cap 12 is hinged to the top edge of the housing 14 and is pivotable between a closed position and an open position. The cap 12 completely covers and protects the mouthpiece 16 when closed and prevents contamination thereof or the possible ingress of dirt into the housing 14 which could otherwise be inhaled when the device is used.

[0067] The blister opening device 18 comprises a blister support element 20 for supporting a portion of a blister 22 containing a dose of medicament for inhalation by a user, and a blister folding element 24 which is co-operable with the blister support element 20. The blister folding element 24 and the blister support element 20 are moveable relative to each other between a first position for insertion of a blister 22 into or onto the blister support element 20 as indicated in FIG. 1, and a second position in which the blister folding element 24 has co-operated with the blister support element 20. In the second position, the blister 22 has been burst open.

[0068] The blister support element 20 is incorporated within the housing 14. The blister support element 20 comprises a blister seat 26 for receiving a portion of a blister bowl 28 (FIG. 15A) and a blister support surface 30 to support the periphery 32 of a blister surrounding said blister bowl 28. The blister seat 26 has a truncated oval shape. The blister seat 26 is suspended within a first aperture 34, across a void 36 in communication with the interior of the housing 14. The first aperture 34 is set into an upper surface 38 of the housing 14.

[0069] This configuration of blister seat 26 is intended for use with generally oval shaped blister bowls. In an untruncated state, the blister seat 26 would fully support an oval blister bowl 28. However, in a truncated state, only the middle portion of the blister bowl 28 is supported by the truncated blister seat 26, on central portion 26a, whilst the two end portions of the blister bowl 28 are unsupported. The two edges of truncation 40a, 40b of the blister seat 26 provide pre-determined fold lines, against which a blister 22 can be folded.

[0070] It is envisaged that other configurations of blister seat could be used for use with correspondingly shaped blister bowls, for example rectangular or circular blister bowls, provided that they too are truncated. It is also envisaged that the blister seat could be truncated along one edge only, not two as depicted in the illustrative embodiment. This configuration would produce only one opening in the burst blister.

[0071] It should be noted that the first aperture 34 could alternatively open into a void in the housing 14 and not a recess with a central hole as shown in FIG. 1.

[0072] As best seen in FIG. 2, the blister folding element 24 is mounted to an underside of the mouthpiece 16. The mouthpiece 16 and the blister folding element 24 are pivotable relative to the housing 14 (and therefore the blister support element 20) about a pivotal axis 42.

[0073] The blister folding element 24 comprises a fold support structure 44 and two pairs of spaced apart fold members 46a, 46b, 48a, 48b extending from the fold support structure 44. In this example, the fold support structure 44 is rectangular. The fold support structure 44 has a similar general configuration (i.e. shape and size) to the first aperture 34 of the blister support element 20 such that the blister folding element 24 is at least partially receivable into the blister support element 20. An oval second aperture 50 is provided in the fold support structure 44. This second aperture 50 provides a void 52 into which a lid 54 of the blister 22 curves during the opening process and need not be oval.

[0074] By way of example only, each fold member 46a, 46b, 48a, 48b is a stubby square block, and there is one fold member 46a, 46b, 48a, 48b located in one corner of the rectangular fold support structure 44. The first said pair of spaced apart fold members 46a, 46b is separated from the second said pair of spaced apart fold members 48a, 48b by a distance greater than the length of the central portion 26a of the blister seat 26. The two pairs of fold members 46a, and 46b, 48a and 48b are spaced apart by a distance X that influences the height of the opening 56a, 56b in the burst blister 22. Distance X can be reduced down to a minimum, below which the blister 22 will collapse and no openings 56a, 56b will form during folding.

[0075] Each pair of fold members 46a and 46b, 48a and 48b has two fold members that are spaced apart from each other by a distance Y that restricts the breadth (or it could equally be considered to be the length) of the resultant openings in the burst blister 22. The combination of distances X and Y determine the area of the opening 56a, 56b in the burst blister 22.

[0076] In this particular embodiment, the two fold lines are of the same length since the truncation edges 40a, 40b are of the same length. This produces two openings 56a, 56b of the same area in the resultant burst blister 22 because the distance of each fold line from the mid-point of the blister 22 is the same. Alternatively, the two fold lines (i.e. truncation edges 40a, 40b) may be of different lengths in order to create two differently sized openings 56a, 56b. Two differently sized openings 56a, 56b may also be created when the distance from the mid-point of the blister 22 for each fold line is different. Alternatively, a combination of varying the distance between the mid-point (X/2) and each fold line, and also the breadth (Y) of each fold line could be used to create openings 56a, 56b with different areas.

[0077] The blister folding element 24 does not include any sharp edges or points. Thus contact with the blister by the blister folding element 24 is solely by folding; no cutting, slicing or piercing of the blister is caused by the blister folding element 24.

[0078] In use, as demonstrated by the demonstration rig 57 in FIGS. 3 and 4, when the blister folding element 24 is in the first position, a blister 22 is placed onto the central portion 26a of the blister seat 26. To move the blister folding element 24 from the first position into the second position, the blister folding element 24 is pivoted relative to the blister support element 20. As the blister folding element 24 moves closer and closer to the blister support element 20, the fold members 46a, 46b, 48a, 48b initially make contact with the unsupported portions of the blister, either side of the central portion 26a of the blister seat 26. The fold members 46a, 46b, 48a, 48b pass either side of and adjacent to the central portion 26a, pressing against and subsequently folding the unsupported portions of the blister 22 during this travel. Each of the two unsupported portions of the blister 22 collapses and folds against a truncated edge 40a, 40b of the central portion 26a of the blister seat 26 along a respective fold line. Since the blister bowl 28 of the blister is oval shaped in this example, the blister lid begins to separate from the blister bowl 28 at the pointed ends of the blister 22. Consequently, two openings 56a, 56b are formed, one at each end of the blister bowl 28. In use, one of the openings 56a will act as an airflow inlet into the burst blister 22, whilst the other opening 56b will act as an airflow outlet for powder laden air traveling from the burst blister 22.

[0079] Each opening 56a, 56b begins as a very small hole and rapidly increases in size as the tear between the blister lid 54 and the blister bowl 28 travels, following the line of the circumference of the blister bowl 28. The tear is confined between two points, each point being positioned on the fold line. The opening 56a, 56b is thus defined as extending along the circumference of the blister bowl 28, beginning and terminating at points located on the fold line.

[0080] The opening 56a, 56b is enlarged to its final configuration when the lidding material curves upwards during the final stages of opening 56a, 56b formation. This curvature is caused by the upper forming surfaces folding across the rounded bowl 28 edges. The curved blister bowl 28 is relatively strong compared to the flat foil surface of the blister lid 54; therefore the blister bowl 28 retains its shape and causes the perimeter foil to be curved around it. The flat perimeter and lid foil is ‘shorter’ than the curved edge it is being folded around, therefore the sides of the blister 22 must move closer together resulting in the lid foil being curved upwards. As the blister lid 54 pops upwardly, the blister bowl 28 below is left intact and largely unaltered in shape.

[0081] In the second position, the mouthpiece 16 and the blister folding element 24 lie generally against the upper surface 38 of the housing 14. The fold support structure 44 of the blister folding element 24 lies in a plane parallel to that of the first aperture 26 and is spaced apart from the blister support surface 34. This spacing 58 or gap provides a channel for a secondary airflow in which fresh air is able to bypass the burst blister 22. This secondary airflow supplements the primary airflow, which is through the burst blister and acts to entrain and evacuate powder contained therewithin. This will be explained in more detail with reference to the second embodiment.

[0082] A second embodiment of the invention will now be described with reference to FIGS. 5 to 18 and is indicated generally at 60. Similar features have been given the same reference numerals as in the previous figures and a detailed description has been omitted.

[0083] As with the first embodiment, a protective cap 12 covers the mouthpiece 16 when in a closed condition, as shown in FIG. 5, and reveals the mouthpiece 16 in an open condition, as shown in FIG. 8. For inhalation, the cap 12 is placed into its open condition. To prepare for inhalation, the mouthpiece 16 is moved such that the blister folding element 24 is placed into its first position, as explained previously.

[0084] As best seen in FIGS. 6 and 7, the blister support element 20 is formed in and on an upper surface 38 of the housing 14. A tab stop 62 is located on the upper surface 38 of the housing 14 and is provided to prevent slippage of the blister 22 relative to the housing 14 during use. The blister seat 26 is recessed into the upper surface 38 of the housing 14 and is shaped for receiving an elongate blister bowl 28 of a blister 22. The blister seat 26 in this embodiment has a central portion 26a and two depressible end portions 26b, 26c, one either side of the central portion 26a. The blister support surface 30 is provided as part of the upper surface 38 of the housing 14, this being the housing surface extending between the blister seat 26 and the tab stop 62.

[0085] The blister folding element 24 comprises a pair of spaced apart fold members 64, 66 depending from a fold support structure 44. Each fold member 64, 66 is arch-like, having two fold feet 64a, 64b, 66a, 66b connected by an arcuate fold body 64c, 66c, the fold body 64c, 66c being intermediate the fold feet 64a, 64b, 66a, 66b. Each fold foot 64a, 64b, 66a, 66b has a bevelled free end. The first fold member 64 is shorter than the second fold member 66, when measured from the fold support structure 44. The fold member 64 situated nearest the pivotal axis 42 is shorter than the other fold member 66. The fold members 64, 66 are configured so as to be receivable within the voids created when the depressible portions 26b, 26c of the blister seat 26 are depressed.

[0086] As can be seen in FIG. 10, the depressible portions 26b, 26c of the blister seat 26 are provided by a moveable first support arm 68, which is configured to co-operate or mate with the central portion 26a of the blister seat 26. The rigid first support arm 68 is pivotally connected at one end to the housing 14. The first support arm 68 pivots within the housing 14 about the same pivotal axis 42 as the cap 12 and the blister folding element 24.

[0087] When the first support arm 68 is in a rest position, the depressible portions 26b, 26c of the blister seat 26 are located adjacent to the central portion 26a of the blister seat 26. When the first support arm 68 is in an active position, the depressible portions 26b, 26c of the blister seat 26 are depressed relative to their initial rest position. In such a condition, the depressible portions 26b, 26c of the blister seat 26 are positioned away from the central portion 26a of the blister seat 26 and situated on an arcuate travel path about the pivotal axis 42.

[0088] A spring 70 is connected to an underside of the first support arm 68 at one end 72 and to an interior wall of the housing 14 at the other end 74. The spring 70 ensures that the first support arm 68 is biased towards its rest position.

[0089] In contrast to the blister support element 20 of the first embodiment, the blister support element 20 of the second embodiment is oriented differently with respect to the pivotal axis 42. In this embodiment, a longitudinal extent of the (untruncated) blister seat 26 is arranged perpendicularly relative to the pivotal axis 42 of the inhaler 60. In the first embodiment, the longitudinal extent of the (untruncated) blister seat 26 is arranged in parallel with the pivotal axis 42 of the inhaler 10 (see FIG. 1).

[0090] An airflow conduit 76 fluidly connects the blister opening device 18 with a cyclone chamber 78.

[0091] The cyclone chamber 78 is arranged within the mouthpiece 16. The chamber 78 is cylindrical and has a longitudinal axis 80 that extends between an airflow inlet 82 and an airflow outlet 84. The airflow inlet 82 is positioned at one end of the chamber 78 for the flow of drug laden air into the chamber 78 from a burst blister 22 and the airflow outlet 84 is positioned at an opposing end for the flow of drug laden air out of the mouthpiece 16 and into a patient's airway via orifice 85.

[0092] The longitudinal axis 80 of the chamber 78 is arranged at an acute angle relative to the plane 86 of the blister seat 26. Advantageously, this means that when a user places the inhaler to their mouth, the burst blister 22 is inclined to empty into the cyclone chamber 78 under gravity, even without inhalation. This contributes towards a higher emitted dose.

[0093] The chamber 78 has a spiraled floor 88, near or at the airflow inlet 82, to encourage a swirling airflow between the inlet 82 and the outlet 84 of the chamber 78.

[0094] The chamber 78 comprises a bypass air inlet 90 for the flow of clean air into the chamber 78 to interact with the drug laden air flowing between the inlet 82 and the outlet 84. However, two or more bypass inlets could be provided. As shown in FIG. 9, the bypass air inlet 90 is arranged near the outlet 84. Also, the bypass air inlet 90 is arranged tangentially to the chamber 78 so that, in use, a cyclonic airflow is generated from clean air around the drug laden airflow. Further detail on the deagglomeration process that takes place within the cyclone is provided later.

[0095] This embodiment of the blister opening device 18 operates in a very similar manner to the first embodiment in so far as a blister folding element 24 is pivotable relative to a blister support element 20 between a first position, for insertion of a blister 22 into or onto the blister support element 20 and a second position in which the blister folding element 24 has co-operated with the blister support element 20. As the blister folding element 24 moves from the first position into the second position, the fold members 64, 66 urge against the depressible portions 26b, 26c of the blister seat 26, and the first support arm 68 is forced into the active position. Such movement causes the two portions of the blister 22 which overlie the depressible portions 26b, 26c to fold relative to the rest of the blister 22 and two openings 56a, 56b to form, in a similar manner to the first embodiment.

[0096] After use, the cap 12 is returned to its closed condition. The cap 12 is retained in its closed condition by virtue of a snap-fit engagement (not shown) of the cap 12 over the housing 14. An annular step is provided at a peripheral extent of the upper surface of the housing 14. A bead is arranged on an upper wall of the step, and protrudes radially outwardly. A protrusion extends around an inner wall of the cap 12, near the mouth of the cap 12 and protruding radially inwardly. The bead and the protrusion are co-operable together to produce the aforementioned snap-fit engagement of the cap 12 on to the housing 14.

[0097] As best seen in the demonstration rig 101 of FIGS. 11 A to E, the blister opening device 18 optionally comprises a stress concentrating means 102 for creating a stress concentration in the lid of the blister 22 immediately prior to the blister 22 being folded. The stress concentrating means 102 comprises a preferably circular piercing head 104 and two piercing teeth 106 depending therefrom. The piercing head 104 is connected to a resilient second support arm 110. The second support arm 110 is pivotally connected about a pivot point 112. In such an arrangement, the second support arm 110 passes through the fold support structure 44 such that the piercing head 104 extends between the two fold members 64, 66.

[0098] The stress concentrating means 102 is releasably engageable with the two fold members 64, 66. The stress concentrating means 102 is moveable between first, second and third positions.

[0099] In the first position, the piercing head 104 is engaged with each fold member 64, 66 at its distal end (see FIGS. 11 A and B). In the second position, the piercing head 104 is engaged mid-way up the fold members 64, 66 (see FIGS. 11 C and D). In the third position, the piercing head 104 is engaged with each fold member 64, 66 at its proximal end (see FIG. 11E).

[0100] The sequence of steps relating to the blister opening with pre-folding piercing is explained now with reference to FIGS. 11 A to E, FIGS. 12 A to D and FIGS. 13 A to C. [0101] The blister opening device 18 is opened by pivoting the blister folding element 24 relative to the blister support element 20 (FIG. 12A); [0102] A blister 22 (FIG. 13A) is inserted into the blister support element 20 (FIG. 11A, FIG. 12B); [0103] The blister folding element 24 begins to move from the first position. The stress concentrating means 102 moves and makes contact with the blister 22 and pierces two small holes in the blister lid 54 (FIG. 11B); [0104] Further movement of the fold members 64, 66 downwards overcomes the latch retaining the piercing head 104. The piercing head 104 moves up due to the energy in the resilient second support arm 110 (FIG. 11C); [0105] After finally making contact with the blister 22, the initial movement of the fold members 64, 66 causes the blister to morph into the intermediate form of the blister 22, now with a curved upper surface (FIG. 11D, FIG. 13B); [0106] Final movement of the fold members 64, 66 bursts open the blister 22 whilst forming the two large openings 56a, 56b at the end of the blister 22. An air path through the blister 22 via the two openings 56a, 56b, as indicated by the two short arrows 114 is now possible. It is at this point that the inhaler 60 is ready for inhalation (FIG. 11E, FIG. 12C, FIG. 13C); and [0107] The blister opening device 18 is opened once more by pivoting the blister folding element 24 relative to the blister support element 20, to reveal the used blister form (FIG. 12D).

[0108] The fold support structure 44 is adapted to provide a bypass air conduit 58 for the flow of clean air over the burst blister 22 when the blister folding element 24 is in the second position. This can be seen in FIG. 11E. A bypass airflow path through the bypass air conduit 58 is indicated by a dashed arrow 116.

[0109] Typically, the total airflow through the inhaler 60 to the user comprises 30% coming via the bypass air inlet(s) 90 on the cyclone chamber 78, 35% via the bypass air conduit 116 over the burst blister, and 25% through the actual burst blister 22 via the two openings 56a, 56b. Thus 70% of the airflow is from fresh air and 25% is powder laden air. The three airflow paths meet in the cyclone chamber 78 to promote deagglomeration of the cohesive agglomerates intended for use with this inhaler 60.

[0110] A blister 22 having a curved upper surface may be used in either of the two embodiments already described. The blister may include a conventional blister tab 118. The blister 22 may be curved along the longitudinal extent 120 of the blister bowl 28, as shown in FIG. 13A. Such a pre-curved blister 22 is advantageous as it means that the blister lid 54 will consistently pop upwards during blister opening. In the intermediate blister form, (FIG. 13B) the resultant formed blister is curved along the lateral extent of the blister bowl 28 (i.e. across the longitudinal extent of the blister bowl 28). In the final blister form (FIG. 13C), the curve 122 across the blister bowl 28 is increased and openings 56a, 56b are formed.

[0111] Alternatively, the blister may be curved about the lateral extent of the blister bowl 28.

[0112] When the stress concentrating means 102 is intended for use with curved blisters, the piercing head 104 may be arcuate, as shown in FIG. 14. An arcuate or curving form, matching the curved profile of the blister, helps to retain the shape of the blister 22 during pre-folding piercing. Otherwise, when a piercing head with a flat lower surface is lowered onto a blister with a curved upper surface, the piercing head will push down onto the uppermost points of the blister lid, causing the lower central portion of the blister lid to pop upwards prematurely. The subsequent movement of the blister folding element relative to the blister support member does not then controllably open the blister as desired. Consequently, opening is less predictable.

[0113] The stress concentrating means 102 may be implemented into either of the two embodiments described herein.

[0114] With either of the embodiments described above, a traditional blister 22 may be used with a planar blister lid 54 and a blister bowl 28 (FIG. 15A). Optionally, a blister 22 may incorporate at least one indentation 124. This causes slight pre-tensioning of the blister lid 54, as indicated by the arrows in FIG. 15B. Alternatively or additionally, the blister lid 54 may be significantly pre-tensioned by compressing the blister 22 inwardly, as indicated by the arrows in FIG. 15C.

[0115] Although demonstration rigs 57, 101 have been used for the purpose of introducing certain features, it is fully intended that these features be implemented in either one or both of the two embodiments described herein.

[0116] In brief, the blister opening device provides a predictable and reliable way of accessing powdered medicament stored within a blister. It also contributes to improved emitted doses for relatively cohesive powders.

[0117] Turning now to FIGS. 16 to 23, deagglomeration of a cohesive powder within the chamber will now be described in more detail. As mentioned earlier, agglomerates are broken up by impact or collision with the internal surfaces of the cyclone chamber. Generating particle fines is unlikely to be achieved in a single impaction. These figures show a progression of how a single (isolated) large particle/agglomerate typically behaves in a cyclonic airflow and demonstrate how that with this particular configuration of chamber, the particle undergoes several collisions.

[0118] First arrow 126 shows the path that the particle will take to get to the position in the subsequent pair of figures. Second arrow 128 shows the path that the particle has taken to get to the position it is currently in. Third arrow 130 represents the particle and its velocity.

[0119] After the blister has been opened and upon initial inhalation by the user, the particle begins to travel out from the blister, as indicated in FIGS. 16A and 16B. The particle 130 passes into the airflow conduit 76, as indicated in FIGS. 17A and 17B. The particle 130 then moves though the chamber airflow inlet 82. Guided by the spiraled floor 88 of the chamber 78, the particle 130 immediately impacts the interior chamber wall, best seen in FIG. 17B. The particle 130 continues to travel in the inspiratory airflow towards the airflow outlet 84, and due to the earlier impact, is caused to traverse the chamber to then strike the chamber wall once again, as shown in FIGS. 18A and 18B. At this point, the particle 130 comes under the influence of the incoming airflow from the bypass air inlet(s) 90 and is forced downwards, back towards to the airflow inlet 82, as shown in FIGS. 19A and 19B and FIGS. 20A and 20B. This is why the location of the bypass air inlet(s) is so important as being at the top of the chamber, at or near the airflow outlet 84. When the particle 130 consequently strikes the spiraled floor 88, as seen in FIGS. 21A and 21B, the particle 130 begins to move back towards the airflow outlet 84 once more. Bypass airflow originating from the bypass air conduit 116 at the bottom of the chamber 78 contributes towards forcing the swirling airflow upwards and the particle 130 back towards the airflow outlet 84, as shown in FIGS. 22A and 22B and FIGS. 23A and 23B.

[0120] A trajectory such as the one described above is optimised when the bypass air cyclone(s) 90 is(are) used in conjunction with the spiraled floor 88 and the bypass airflow from the bypass airflow conduit 116. However, any combination of these three features offers benefits over known cylindrical chambers with a flat base.

[0121] This particle 130 is just one of many particles making up the powder coming from the opened blister. When the powder is seen acting in bulk, the finer particles tend to enter the chamber 78, and exit soon after with a minimal number of impactions, whereas the larger particles become drawn into repeating loops, incurring impaction after impaction until their inertia is such that they can escape from the chamber 78. Consequently, the residence time within the chamber 78 is much greater for the larger particles than for the finer particles. This significantly improves the fine particle fraction of the dose for cohesive formulations.

[0122] 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 only.