Dispensing device

Abstract

A device for dispensing individual doses of powder from respective pockets of a disc-shaped carrier by outwardly rupturing a lidding foil by means of pressure on an opposite side surface, the device providing individual respective deaggregation flow paths for each pocket, split airstreams allowing improved entrainment of powder, a cam mechanism for outwardly rupturing the pockets, an indexing mechanism linked to the cam mechanism and a dose counter.

Claims

1. A device for dispensing powdered medicaments, comprising at least one carrier bearing a plurality of respective pockets, each pocket holding a dose of a powdered medicament; a mouthpiece through which to inhale an airstream carrying the dose of the powdered medicament from an opened pocket of the plurality of respective pockets; an indexing mechanism for indexing the at least one carrier between the respective pockets, from a storage position to a discharge position; a first counter ring having a first display surface displaying numbers on the first display surface, the first counter ring being rotatable about a counter axis; and a second counter ring having a second display surface indicating tens counts, the second counter ring being rotatable about the counter axis; the first counter ring being driven with the indexing mechanism, the second counter ring being positioned within the first counter ring, wherein the first display surface and the second display surface are planar and perpendicular to the counter axis.

2. The device according to claim 1, wherein the at least one carrier comprises a first carrier and a second carrier, and the indexing mechanism is configured to index each of the first carrier and the second carrier between respective pockets thereof.

3. The device according to claim 2, wherein the first carrier and the second carrier are indexed such that respective doses of powdered medicament are dispensed from each of the first and second carriers simultaneously.

4. The device according to claim 3, wherein, when the device is indexed, one pocket from the first carrier and one pocket from the second carrier are opened together.

5. The device according to claim 2, wherein the first carrier and the second carrier are indexed such that respective doses of powered medicament are dispensed from each of the first and second carriers sequentially, one at a time in an alternating fashion.

6. The device according to claim 2, wherein the first carrier and the second carrier are arranged side by side; the device comprises a housing and a priming lever extending out of the housing; the priming lever is configured to rotate about a central axis of the device; and the priming lever extends from between the first carrier and the second carrier.

7. The device according to claim 2, wherein the plurality of respective pockets of the first carrier carries a different powered medicament than the plurality of respective pockets of the second carrier.

8. The device according to claim 7, wherein the powdered medicament carried by the first carrier and the powdered medicament carried by the second carrier comprise two different medicaments that are more effective for treating asthma and/or chronic obstructive pulmonary disease together than singularly.

9. The device according to claim 1 wherein, when the device is indexed, only one of the plurality of respective pockets of the at least one carrier is opened each time the device is indexed.

10. The device according to claim 1 wherein, when the device is indexed, two of the plurality of respective pockets of the at least one carrier are opened together.

11. The device according to claim 1, wherein the device comprises a housing and a mouthpiece cover, and the mouthpiece cover is formed as a separate component from the housing, the mouthpiece cover being configured to be rotated relative to the housing to expose the mouthpiece.

12. The device according to claim 1, wherein the device comprises a housing and a priming lever extending out of the housing, and the priming lever is configured to rotate about a central axis of the device.

13. The device according to claim 12, wherein the priming lever has a first position and a second position such that a movement from the first position to the second position is arranged to prime the device, and priming the device comprises exposing at least one dose of powdered medicament carried by the at least one carrier.

14. The device according to claim 13, wherein the priming lever is adjacent to the mouthpiece at the first position.

15. The device according to claim 12, wherein a movement of the priming lever operates the indexing mechanism to index the device such that at least one unused and unopened pocket of powdered medicament is moved into a position for dispensing and is opened.

16. The device according to claim 15, wherein the device comprises a mouthpiece cover, wherein rotation of the mouthpiece cover from an open position to a closed position returns the priming lever to the first position and covers the mouthpiece.

17. The device according to claim 15, wherein when a pocket is opened but the dose of powdered medicament held therein is not inhaled, a further movement of the priming lever indexes the open pocket to a position where the powder released therefrom is held within the device.

18. The device according to claim 15, wherein each of the plurality of respective pockets is sealed by a foil, and a rupturing of the foil during indexing of the device imparts a resistance on the priming lever and thus provides tactile feedback to the user.

19. The device according to claim 18, wherein when the priming lever is rotated, the force required to continue rotating the priming lever is increased due to resistance of the foil until such time as the foil is ruptured, whereupon the force required to rotate the priming lever is reduced.

20. The device according to claim 1, wherein the at least one carrier comprises at least one disc, the at least one disc bearing a plurality of respective pockets.

21. The device according to claim 1, wherein the at least one carrier comprises at least one blister-pack array, the at least one blister-pack array bearing a plurality of respective pockets.

22. The device according to claim 1, wherein each of the plurality of respective pockets is sealed by a lidding sheet.

23. The device according to claim 22, wherein each respective dose of the powdered medicament is exposed by a peeling of the lidding sheet.

24. The device according to claim 22, wherein the lidding sheet is ruptured as a consequence of moving a pocket from a respective storage position to a respective discharge position.

25. The device according to claim 1, wherein the powdered medicament comprises at least one of a long acting beta-agonist, a steroid, or any combination thereof.

26. The device according to claim 1, wherein the powdered medicament comprises at least one of formoterol, salmeterol, fluticasone, budesonide, monetasone, or any combination thereof.

27. The device according to claim 1, further comprising an intermittent-motion mechanism for driving the second counter ring from the first counter ring.

28. The device according to claim 27, wherein the second counter ring rotates between consecutive tens counts when the first counter ring rotates between two predetermined consecutive unit counts.

29. The device according to claim 27, wherein the intermittent-motion mechanism is a Geneva mechanism.

30. The device according to claim 27, further comprising a counter gear engaged with a first gear of the first counter ring, wherein the intermittent-motion mechanism comprises a second gear, and wherein rotation of the counter gear is configured to rotate the first counter ring, with the first counter ring configured to rotate the second counter ring.

31. The device according to claim 30, wherein the first counter ring comprises a peg configured to rotate the second gear, and wherein the peg is positioned on an inner diameter of the first counter ring.

32. The device according to claim 1, wherein the first counter ring includes a pin for engaging a Geneva wheel rotatable about an axis offset from the counter axis and the second counter ring includes features engageable by the Geneva wheel.

33. The device according to claim 1, wherein the first counter ring and the second counter ring rotate about an axis parallel to the axis of the dose carriers.

34. The device according to claim 1, further comprising walls defining at least one first flow path for deaggregating the powdered medicament from an open pocket in the discharge position and at least a second flow path which bypasses the open pocket.

35. The device according to claim 34, wherein the walls defining the first flow path are configured to force the airstream to change direction such that the dose of powder in the airstream is deaggregated.

36. The device according to claim 35, wherein the walls defining the first flow path have rounded comers configured to limit a pressure drop such that the pressure drop does not exceed 4 kPa at 60 I/min.

37. The device according to claim 34, wherein each of the at least one first flow path comprises a section of relatively reduced cross-sectional area oriented so as to be directed towards an open pocket in the discharge position and configured to direct a relatively high velocity airstream into the pocket.

38. The device according to claim 37, wherein the section of relatively reduced cross-sectional area of each of the at least one first flow path is between 50% and 60% of the cross-sectional area of the smallest part of the second flow path.

39. The device according to claim 37, wherein the section of relatively reduced cross-sectional area of each of the at least one first flow path is between 2.0 mm.sup.2 and 10.0 mm.sup.2.

40. The device according to claim 1, wherein the second display surface comprises an indicia indicating that the device is nearing the end of its functional life, and the indicia is displayed when a predetermined number of doses remain within the device.

41. The device according to claim 40, wherein the indicia comprises a symbol, a color, a light, or any combination thereof.

42. The device according to claim 40, wherein the indicia is not a number “0”.

43. The device according to claim 1, wherein the indexing mechanism comprises a wheel and a plurality of gears, and wherein, upon rotation of the wheel and the plurality of gears, the at least one carrier is indexed between the respective pockets.

44. The device according to claim 43, further comprising a counter gear engaged with a first gear of the first counter ring, wherein, upon rotation of a first gear of the plurality of gears of the indexing mechanism, the counter gear rotates to drive the first counter ring.

45. The device according to claim 43, wherein the indexing mechanism comprises a ratchet.

46. A device for dispensing powdered medicaments, comprising a first carrier bearing a plurality of respective pockets and a second carrier bearing a plurality of respective pockets, each pocket of the first and second carriers holding a dose of a powdered medicament; a mouthpiece through which to inhale an airstream carrying the dose of the powdered medicament from an opened pocket of the plurality of respective pockets; an indexing mechanism for indexing the at least one carrier between the respective pockets, from a storage position to a discharge position, the indexing mechanism being configured to index each of the first carrier and the second carrier between respective pockets thereof; a first counter ring having a first display surface displaying numbers on the first display surface, the first counter ring being rotatable about a counter axis; a second counter ring having a second display surface indicating tens counts, the second counter ring being rotatable about the counter axis; the first counter ring being driven with the indexing mechanism, the second counter ring being positioned within the first counter ring, the first display surface and the second display surface being planar and perpendicular to the counter axis; a housing enclosing the at least one carrier; and a priming lever extending out of the housing, the priming lever being configured to rotate about an axis of the device, the priming lever having a first position and a second position such that a movement from the first position to the second position is arranged to prime the device, wherein priming the device comprises exposing at least one dose of powdered medicament carried by the at least one carrier; and a movement of the priming lever operates the indexing mechanism to index the device such that two unused and unopened pockets of powdered medicament, one from the first carrier and one from the second carrier, are moved into a position for dispensing and are opened.

47. The device according to claim 46, wherein the indexing mechanism comprises a wheel and a plurality of gears, and wherein, upon rotation of the wheel and the plurality of gears, the first carrier and the second carrier are indexed between the respective pockets.

48. The device according to claim 47, further comprising a counter gear engaged with a first gear of the first counter ring, wherein, upon rotation of a first gear of the plurality of gears of the indexing mechanism, the counter gear rotates to drive the first counter ring.

49. The device according to claim 47, wherein the indexing mechanism comprises a ratchet.

50. A device for dispensing powdered medicaments, comprising at least one carrier bearing a plurality of respective pockets, each pocket holding a dose of a powdered medicament; a mouthpiece through which to inhale an airstream carrying the dose of the powdered medicament from an opened pocket of the plurality of respective pockets; an indexing mechanism for indexing the at least one carrier between the respective pockets, from a storage position to a discharge position; a first counter ring having a first display surface displaying numbers on the first display surface, the first counter ring being rotatable about a counter axis; and a second counter ring having a second display surface indicating tens counts, the second counter ring being rotatable about the counter axis; the first counter ring being driven with the indexing mechanism, the second counter ring being positioned within the first counter ring, the first display surface and the second display surface being planar and perpendicular to the counter axis; a housing enclosing the at least one carrier; a mouthpiece cover formed as a separate component from the housing, the mouthpiece cover being configured to be rotated relative to the housing to expose the mouthpiece; and a priming lever extending out of the housing, the priming lever being configured to rotate about an axis of the device, the priming lever having a first position and a second position such that a movement from the first position to the second position is arranged to prime the device, wherein priming the device comprises exposing at least one dose of powdered medicament carried by the at least one carrier; and a movement of the priming lever operates the indexing mechanism to index the device such that at least one unused and unopened pocket of powdered medicament is moved into a position for dispensing and is opened.

51. The device according to claim 50, wherein the indexing mechanism comprises a wheel and a plurality of gears, and wherein, upon rotation of the wheel and the plurality of gears, the at least one carrier is indexed between the respective pockets.

52. The device according to claim 51, further comprising a counter gear engaged with a first gear of the first counter ring, wherein, upon rotation of a first gear of the plurality of gears of the indexing mechanism, the counter gear rotates to drive the first counter ring.

53. The device according to claim 51, wherein the indexing mechanism comprises a ratchet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be more clearly understood from the following description, given by way of example only, with reference to the accompanying drawings in which:

(2) FIGS. 1(a) to (c) illustrate operation of an assembled device according to the present invention;

(3) FIGS. 2(a) and 2(b) illustrate a carrier for use with the present invention without and with its lidding sheets;

(4) FIGS. 3(a) and (b) illustrate movement of an insert from the carrier of FIGS. 2(a) to (c);

(5) FIGS. 4(a) and (b) illustrate a preferred arrangement for carriers within the device without and with supports of the device;

(6) FIGS. 5(a) and (b) illustrate airway plates and anvil plates of the device in conjunction with corresponding carriers;

(7) FIG. 6 illustrates an insert of a carrier pushed into its corresponding anvil plate;

(8) FIGS. 7(a) and (b) illustrate movement of an insert of a carrier plate into a corresponding anvil plate;

(9) FIG. 8 illustrates the housing of the preferred embodiment;

(10) FIGS. 9(a) and 9(b) illustrate airflow paths through the preferred embodiment;

(11) FIG. 10 illustrates the chassis and cam member assembly of the preferred embodiment;

(12) FIG. 11 illustrates schematically operation of the dispensing mechanism of the preferred embodiment;

(13) FIG. 12 illustrates schematically the preferred profile for the cam member;

(14) FIG. 13 illustrates sub-assemblies of the preferred embodiment;

(15) FIGS. 14(a) to (f) illustrate the Geneva mechanism of the indexing mechanism of an embodiment of the present invention;

(16) FIGS. 15(a) to (e) illustrate the changeover mechanism of an embodiment of the present invention;

(17) FIGS. 16(a) to (h) illustrate the dispensing mechanism of an embodiment of the present invention;

(18) FIGS. 17(a) and (b) illustrate cross-sections through the components of FIGS. 16(a) to (h);

(19) FIG. 18 illustrates pockets being opened in a device embodying the present invention;

(20) FIGS. 19(a) to (d) illustrate the Geneva mechanism of a counter in an embodiment of the present invention;

(21) FIGS. 20(a) to (e) illustrate operation of the counter of FIGS. 19(a) to (d); and

(22) FIGS. 21(a) and (b) illustrate preferred cross sectional areas at various locations in an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(23) A preferred embodiment of the present invention is an inhalation device from which a user may inhale consecutive doses of medicament in the form of dry powder. The preferred embodiment is illustrated in FIGS. 1(a) to (c).

(24) The device includes a housing 2 on which a mouthpiece cover 4 is rotatably supported.

(25) In order to use the device, the mouthpiece cover 4 is rotated away from the housing 2. As illustrated in FIG. 1(b) this exposes a mouthpiece 6. The mouthpiece 6 may be formed integrally with the housing 2, but, as will be described below, it can also be formed as a separate component for mounting with the housing 2. This allows the material properties, for instance, colour, of the mouthpiece 6 and housing 2 to be varied easily according to the requirements of the device.

(26) As illustrated in FIG. 1(b), a priming lever 8 extends out of the housing 2 at a position adjacent the mouthpiece 6. The priming lever 8 is mounted so as to rotate about a central axis within the device (to be discussed further below). In this way, it is moveable by the user around a periphery of the housing 2 to a position as illustrated in FIG. 1(c). Movement of the priming lever 8 from the first position illustrated in FIG. 1(b) to the second position illustrated in FIG. 1(c) is arranged to prime the device, in particular, to expose a dose of powder such that it may be carried with an airstream out of the mouthpiece 6.

(27) It should be noted that locating the first position of the priming lever 8 adjacent the mouthpiece 6 is highly advantageous, since it discourages a user from attempting to inhale from the mouthpiece 6 before moving the priming lever 8 away from the mouthpiece 6 to the second position of FIG. 1(c). In other words, the user is encouraged to prime the device before attempting to inhale through it. Nevertheless, it should be noted that a small space is preferably provided between the mouthpiece 6 and priming lever 8 so as to allow the user to operate the priming lever 8 with his or her finger without touching the mouthpiece 6.

(28) After use of the device, the mouthpiece cover 4 may be rotated back to its stowed position illustrated in FIG. 1(a). In this respect, an inner surface of the mouthpiece cover 4 is provided with a return actuator for engaging with the priming lever 8. In particular, when the mouthpiece cover 4 is moved from its open position of FIGS. 1(b) and (c) to its closed position of FIG. 1(a), the return actuator engages with the priming lever 8 and moves it back from its second position illustrated in FIG. 1(c) to its first position illustrated in FIG. 1(b). As will be described further below, in the preferred embodiment, this movement of the priming lever 8 operates an indexing mechanism for moving a still unused and unopened pocket of powder into line with a dispensing mechanism such that, with subsequent priming of the device, the powder of that pocket is dispensed for inhalation. By operating the indexing mechanism during the return movement of the priming lever 8 immediately after priming and release of a pocket of powder, if the released powder is not inhaled, it is indexed to a position where it can safely be held within the device.

(29) As illustrated in FIGS. 1(a) to (c), the preferred embodiment also includes a window 10 in one side of the housing 2. The window 10 is provided so as to allow a user to view a counter display within the device. A counter mechanism indexes the counter display upon each use of the device so as to provide the user with an indication of how may doses have been dispensed and/or how may doses remain unused.

(30) Many aspects of the present invention are applicable to devices housing a wide variety of different dose carriers. In particular, many of the features of the embodiment described below can be used with carriers having a traditional blister-pack construction, with carriers having various arrays of pockets and, in some arrangements, with some carriers having a single respective pocket. Nevertheless, the present invention is particularly advantageous when used with carriers of the form illustrated in FIGS. 2(a) and (b).

(31) As illustrated in FIG. 2(a), each carrier 12 is formed from a disc-shaped base 14 having a substantially planar first side surface 16 opposite and parallel with a substantially planar second side surface 18. A plurality of through holes 20 are formed between the first and second side surfaces 16, 18 so as to form spaces for housing doses of powder. The base 14 is formed with an appreciable thickness so as to provide the through holes 20 with sufficient space to house the required doses of powder. The through holes 20 are arranged as a circumferential array and, in the preferred embodiment, 30 through holes are provided in the array.

(32) As illustrated in FIG. 2(b), the first and second side surfaces 16, 18 of the base 14 are sealed with respective first and second lidding sheets 22, 24. In this way, the carrier 12 provides a plurality of pockets housing individual respective doses of powder.

(33) As illustrated by the cross-sections of FIGS. 3(a) and (b), the pockets preferably include a respective insert 26 within each through hole 20. The inserts 26 are generally cup-shaped with their open ends facing the first lidding sheet 22. Each contain a respective dose of powder 28.

(34) By pushing on the closed end of the insert 26 from the side of the second lidding sheet 24, it is possible to push the insert 26 outwardly from the base 14 of the carrier 12 through the first lidding sheet 22. This is illustrated in FIG. 3(b), but, for clarity, without either lidding sheet. As illustrated, with the insert 26 extending out of the base 14, it may be more convenient to provide an airflow (such as indicated by arrows) to remove powder from the pocket.

(35) Within the housing 2 of the inhalation device, in a preferred embodiment, two of the carriers 12 are arranged coaxially side by side as illustrated in FIG. 4(a). Each carrier 12 is provided with a support 30 as illustrated in FIG. 4(b). In the illustrated embodiment, each support 30 is positioned adjacent an outwardly facing surface of its respective carrier 12. In particular, the first side surface 16 of each carrier 12 faces a respective support 30 such that a dispensing mechanism may be provided between the two carriers 12 so as to press respective inserts 26 outwardly towards the respective supports 30. The preferred arrangement for this will be described further below.

(36) As illustrated, the priming lever 8 is positioned such that it extends between the carriers 12 and is rotatable about the common axis of the carriers 12 so as to operate a dispensing mechanism and an indexing mechanism.

(37) In the preferred embodiment, each support 30 is made up of two components, namely an anvil plate 32 and an airway plate 34. These are illustrated in FIGS. 5(a) and (b) in conjunction with associated carriers 12.

(38) Each anvil plate 32 has a planar surface 6 which-, in use, abuts against the first side surface 16 of the associated carrier 12 as covered by the first lidding sheet 22. Each anvil plate 32 also includes a plurality of guide through holes 38 corresponding to the through holes 20 of the associated carrier 12.

(39) In this way, as illustrated schematically in FIG. 6, an insert 26 can be pushed out of its through hole 20 and into a corresponding guide through hole 38 of the anvil plate 32. The insert 26 is thus used to outwardly burst through the first lidding sheet 22, but is still held securely in place. Although not of a particular concern here, the anvil plate 32 also supports the first lidding sheet 22 around the through hole 20 and can be used to improve the predictability of the nature of the lidding sheet rupture.

(40) As illustrated by the cross-section of FIG. 7(a), the anvil plate 32 includes a second surface 40 which abuts an inner surface of the associated airway plate 34. The airway plate 34 includes a pair of through holes corresponding to each guide through hole 38 of the corresponding anvil plate 32. In particular, each pair includes an inlet hole 42 and an outlet hole 44.

(41) As illustrated in FIG. 7(a), relative to the surface 40 of the anvil plate 32 abutting the inner surface of the airway plate 34, a recessed channel 46 extends radially inwardly from the outlet 44 so as to communicate with the guide through-hole 38 of the anvil plate 32. Hence, for each guide through hole 38 of the anvil plate 32, the airway plate 34 provides, communicating with it, a corresponding inlet 42 and outlet 44 with its associated recessed channel 46. In particular, each inlet 42 communicates with one side of its associated guide through hole 38 whilst the corresponding outlet 44 communicates with the opposite side of the associated guide through hole 38.

(42) As illustrated in FIG. 7(b), when an insert 26 is pushed outwardly of the through hole 20 of the base 14 into the guide through hole 38 of the anvil plate 32, it is positioned with the open portion of its cup-shape facing the inlet 42 (at one end of the cup-shape) and the recessed channel 46 (at the opposite end of the cup-shape). In this way, as illustrated, an airflow may be drawn through the airway plate 34 such that it passes down into the pocket formed in the insert 26, back up into the recessed channel 46 and then out of the outlet 44. Powder in the insert 26 is thus picked up by the airstream, removed from the insert 26 and carried out of the airway plate 34. A flow path is thus formed into and out of a pocket which may then connect the pocket to the mouthpiece 6 of the device.

(43) As illustrated in FIG. 8, the housing 2 may be formed from a pair of casing halves 2a and 2b. As illustrated in FIGS. 9(a) and (b), an inner wall 50 of the casing halves 2a and 2b cooperates with the airway plate 34 so as to form a second flow path to the mouthpiece 6 which bypasses the pocket(s). Alternatively, an additional component may be provided, to define the second flow path.

(44) As illustrated in FIG. 9(b), for each pocket formed by an insert 26, the corresponding inlet 42 of the airway plate 34 is positioned adjacent a periphery of the pocket. The corresponding outlet 44 is provided on an opposite side of the pocket such that the airstream between the inlet 42 and outlet 44 crosses the pocket and, hence, picks up any powder from the pocket.

(45) As illustrated, the inlet 42 is formed as a portion which is directed down into the insert 26 forming the pocket.

(46) In this way, when a user inhales through the device and creates an airstream through it, the airstream drawn through the inlet 42 will be directed down into any powder in the insert 26 so as to dislodge it and move it into the airstream so as to be carried out of the outlet 44. In the illustrated embodiment, the recessed channel 46, which connects the volume of the pocket to the outlet 44, is positioned adjacent the inlet 42. In this way, the airstream from the inlet 42 is deflected from the base of the insert 26 (and any powder there) so as to travel back towards the recessed channel 46. Powder carried in the airstream up into the recessed channel 46 is subjected to a relatively sharp change in direction. As a result of this, powder in the airstream tends to be deaggregated. Furthermore, the powder will tend to hit the surfaces of the recessed channel 46 also contributing to deaggregation.

(47) As is clear from FIG. 9(b), the shape of the airway path is chosen to force large aggregates of powder to impact the walls as the airflow is forced to change direction, thereby deaggregating large clumps of powder. The shape is also designed to ensure that airflow over any surface within the airway is maintained at a high value to avoid excessive powder adhering to the surface. Thus corners are rounded and the cross section at each position along the tube is designed to maintain air velocity without generating excessive pressure drop.

(48) As illustrated in FIG. 9(a), in this embodiment, the airflow through the pocket has its minimum area at the inlet to the pocket defined by the dimension “a” whereas the airflow that bypasses the pocket has its minimum cross section just before the airflow join and so is defined by the dimension A.

(49) The air velocity is highest where the cross sectional area is smallest so this arrangement provides high velocity air to extract the powder from the pocket and uses the high velocity of the bypass air joining the powder contained in the pocket airflow to assist de-aggregation and to protect the walls from powder deposition.

(50) The airflow velocity through the pocket is controlled mainly by the suction pressure created as the user inhales, whereas the volume flow rate is a factor of both velocity and area.

(51) A sufficiently high air velocity should be generated to ensure that the powder is entrained in the airflow. However, if the velocity—and flow volume are too high then there is the possibility that the whole of the mass of powder in the pocket is pushed through the airway as an agglomerated clump. If this happens, the clump may not accelerate to a sufficient velocity for its impact with the walls in the airway to break it up and provide de-aggregation. It is preferred that the powder is removed gradually from the pocket by the airflow. To achieve this, a small gap 46a is provided between the surface of the powder in the pocket and the airway roof formed from the division in the airway plate 34 between the inlet 42 and recessed channel 46. This, combined with a dimension for “a” that limits the flow volume through the pocket, ensures that the powder is eroded from the pocket rather than pushed out.

(52) To enable this, the inlet hole diameter “a” is chosen to be between 0.5 mm and 2.0 mm for pockets—of around 2.0 mm width (in a circumferential direction) and of around 7.3 mm length (in a radial direction). The value chosen depends on the properties of the powder.

(53) In this way, the powder can be removed from the pocket over a time period ranging from between 0.1 s to 1.0 s. This is within the period of the high flow rate of the inhalation cycle and provides good de-aggregation of the powder.

(54) It should be appreciated that, in other embodiments, it is possible for parts of the flow path through the pocket, other than the inlet hole, for instance downstream of the powder, to form the minimum cross-sectional area of that flow path. Similar considerations will still apply for the diameter “a” of the inlet hole.

(55) The arrangement of the inlet hole 42 and channel 46 is particularly advantageous in conjunction with deep narrow pockets of powder. At a particular flow rate, for instance 10 ltr/min, the surface of the powder will be eroded by a certain depth. Increasing the flow rate to, for instance 20 ltr/min, will result in the powder being eroded by a further depth. Since inhalation by users results in flow rates which increase progressively to a maximum, powder is eroded depth by depth and the pocket is emptied gradually over an appropriate period.

(56) Although the volume and strength of inhalation will vary between users, it is important that the device should not provide too much in the way of resistance to inhalation. In this respect, it would be extremely difficult to inhale through an inlet 42 having a desired cross sectional area. Indeed, where possible, it would result in a flow velocity which was far too high and which would entrain of all of the powder from the insert 26 far too quickly. In practice, it is found that approximately only 20% of inhaled air can be used directly for picking up and deaggregating the powder.

(57) As illustrated in FIG. 9(b), a second flow path is formed between an inner wall 50 of the housing 2 and the outside of the airway plate 34. The second flow path bypasses the pocket and increases the overall cross sectional area available through which to inhale. By changing the values of the dimensions a and A, it is possible to change the rates of airflow between the pocket and bypass and to control the overall flow resistance of the device so that it is comfortable for the user to inhale through. A typical flow resistance for the device would be between 2 kPa and 5 Kpa for a flow volume of 601/min. Higher flow resistances are chosen for powders which are harder to deaggregate, whereas lower flow resistances are preferred for devices used by children. The recessed channel 46 and outlet 44 generally have larger cross sectional areas than the inlet 42. It is envisaged that the minimum cross sectional area for the pocket path would be 3.5 mm.sup.2 to 4.0 mm.sup.2 and for the bypass 5.0 mm.sup.2 to 6.0 mm.sup.2.

(58) In this way, it is relatively easy to inhale through the device, since a large proportion of the airflow will be through the second flow path. Nevertheless, some of the flow will occur through the first flow path so as to entrain and deaggregate the powder as described above.

(59) In the preferred embodiment, there is another second flow path for the other side of the device and its corresponding carrier. In use, a patient inhales through both second flow paths whilst drawing powder from the first flow path in use. Each of the second flow paths is expected to carry approximately 40% of the total inhaled air for an average use.

(60) Actual requirements will vary depending upon the nature of the powder and the intended user. For an easily dispensed powder, the portion forming the inlet to the pocket can be small and, for a child or patient with COPD (Chronic Obstructive Pulmonary Disease), the total pressure drop should be low. In this case, an inlet portion could be provided with a cross-sectional area of 2 mm.sup.2 and a bypass second flow path with a minimum cross-sectional area of 8 mm.sup.2, resulting in a ratio of 25%). On the other hand, with sticky powder for a healthy adult, the inlet portion could be provided with a cross-sectional area of 4 mm.sup.2 together with a bypass second flow path having a minimum cross-sectional area of 6 mm.sup.2, resulting in a ratio of 66%. Of course, intermediate values are also possible and a preferred arrangement has an inlet portion of approximately 3 mm.sup.2 with a second flow path minimum cross-sectional area of 6 mm.sup.2, resulting in a ratio of 50%.

(61) As illustrated in FIG. 9(a), the walls of the outlet 44 are orientated so as to direct the flow of air and powder into the second flow path at an angle θ relative to the flow in the second flow path. By ensuring that the angle θ is less than 45°, it is possible to substantially reduce the amount of powder which might impact with or stick to the wall 50 opposite the outlet 44. Preferably the angle θ is no greater than 45°, more preferably no greater than 30°. In this way, substantially no powder will adhere to the wall 50 forming the second flow path to the mouthpiece 6. Preferably, with repeated use of the device, no more than 25%, preferably no more than 15% of a dose remains deposited on the wall 50. In this respect, it will be appreciated that the flow from the bypass past wall 50 will act to scour or scavenge powder from the wall 50.

(62) As mentioned above with reference to FIG. 4(b), the anvil plate 32 and airway plate 34 together form a support for a corresponding carrier 12. By means of the priming lever 8 and the indexing mechanism to be described below, a support 30 and its corresponding carrier 12 is moved to consecutive-positions to dispense powder from consecutive pockets. In this regard, it will be appreciated that each pocket has its own first flow path as formed in the airway plate 34. From the description above, it will be appreciated that turbulent flow in removing powder from the pocket and deaggregation of powder occurs within the first flow path. Thus, should any powder adhere to walls within the airway plate 34, this powder is not available for inhalation when subsequent pockets of powder are dispensed.

(63) The device is preferably arranged such that an inlet passage that provides the air for the flow through the pocket and through the bypass is arranged so that it feeds the air only to the pocket positioned for dispensing, such as illustrated in FIGS. 9(a) and (b). The indexing of the carrier 12, anvil plate 32 and airway plate 34 after use repositions the inlet 42 and outlet 44 for a used pocket outside of the airflow for the pocket currently in use.

(64) This arrangement ensures that, even if none of the powder from a pocket is removed after it has been opened, once it has been indexed on, then the powder will be permanently retained within the device such that it will not be inhaled along with a subsequent dose.

(65) The supports 30 and associated carriers 12 may be rotatably mounted within the housing 2 by means of a chassis sub-assembly 58 as illustrated in FIG. 10. The chassis sub-assembly 58 is positioned between the second side surfaces 18 of the carriers 12. It extends axially along the axis of the carriers 12 and is fixed to one or both of the two halves 2a, 2b of the housing 2.

(66) As illustrated in FIG. 10, the priming lever 8 forms part of (or could be attached to) a priming member 60. The priming member 60 has a central pivot opening 62 by which it is rotatably supported on a pivot shaft 64 of a chassis 66.

(67) As illustrated in FIG. 13, the priming member 60 and chassis 66 are together positioned between the two carriers 12 and associated supports 30. Furthermore, the chassis 66 is mounted to the housing 2 so as to be rotatably fixed. In the illustrated embodiment, the pivot shaft 64 may itself be located on a shaft 68 provided on the inside of one or both halves 2a, 2b of the housing 2. Also, a radial extension 70 (shown in FIG. 10) may be provided on the chassis 66 to interact with an inner portion of the housing 2 so as to rotationally fix the chassis 66.

(68) The carriers 12 and associated supports 30 may be rotationally mounted on the chassis 66.

(69) The priming member 60 includes an elongate cam member 72 which extends in a circumferential direction and has a cam surface 74 on each of two opposites sides.

(70) Each cam surface 74 interacts with a respective member 76 which will be described as a prodger.

(71) Operation of the priming member 60, cam member 72, cam surfaces 74 and prodgers 76 will be described with reference to the schematic illustration of FIG. 11.

(72) When the priming lever 8 is moved from its first position to its second position, the priming member 60 is rotated relative to the chassis 66, the carriers 12 and their supports 30 such that, in the schematic illustration FIG. 11, the cam member 72 moves upwardly.

(73) As can be seen in FIG. 10, the priming member 60 includes elongate openings either side of the cam member 72 through which arms 80 of the prodgers 76 can extend. The chassis 66 holds the prodger 76 rotationally but allows them to move in an axial direction of the device, in other words towards and away from the carriers 12 on either side. Indeed, as illustrated, an aperture 82 exists in the chassis 66 allowing one of the prodgers 76 to extend through the chassis 66 towards a corresponding carrier 12.

(74) As illustrated in FIG. 11, the cam surface 74 on either side of the cam member 72 is such that, as the priming member 60 rotates and the cam member 72 moves upwardly as illustrated in FIG. 11, the prodgers 76 are moved outwardly towards their respective carriers 12.

(75) In FIG. 11, the right hand prodger 76 is illustrated in alignment with a pocket in its corresponding carrier 12. Thus, when the priming member 60 rotates and the cam member 72 moves upwardly in FIG. 11, the right hand prodger 76 will be moved outwardly towards its corresponding carrier 12, will penetrate the through hole 20 and push the insert 26a out of the first side surface 16. In this respect, FIG. 11 illustrates one insert 26b which has already been pushed out by the prodger 76.

(76) An indexing mechanism, to be described below, rotates the right hand carrier 12 and its corresponding support 30 to the next position in which the prodger 76 is aligned with a new, unopened pocket. The operation of opening a pocket can then be repeated.

(77) It will be appreciated from FIG. 11 that carriers 12 on either side of the priming member 60 could have respective pockets aligned with the prodgers 76 such that operation of the cam member 72 simultaneously opens pockets of the respective carriers 12. However, in the illustrated embodiment, the indexing mechanism arranges for one of the prodgers 76 to be aligned with a pocket whilst the other of the prodgers 76 is at a position between pockets. In this way, the dispensing mechanism formed from the cam member 72 and prodgers 76 only opens one pocket at a time.

(78) Referring to FIG. 2(a), it will be seen that the preferred carrier 12 has an array of through holes 20 which includes a space 82 in which a through hole 20 is not formed.

(79) Using carriers of this type, it is possible to position one carrier 12 with the blank portion 82 opposite a prodger 76 whilst consecutively indexing the other carrier 12 around each of its through holes 20 and the pockets they form until all have been emptied. The indexing mechanism can then rotate the empty carrier to a position in which its blank portion 82 is opposite the prodger 76 and rotate the other carrier 12 around all of the positions in which the corresponding prodger 76 aligns with the through holes 20. In this way, the same dispensing mechanism is used for dispensing powder from both carriers and using the same operation.

(80) Although it is the intention that substantially all of the powder dispensed from the individual pockets will be removed from the device by way of inhalation, it is possible that some powder will remain within the device. Indeed, where different types of carrier are used or the device has a different application, it might be that more powder does remain within the device.

(81) As illustrated in FIG. 10, the cam surfaces 74 are provided with one or more grooves or channels 84. Any excess powder can thus fall into the grooves 84 such that contact and movement between the cam surface 74 and the prodger 76 is not impeded.

(82) It will be appreciated that, with the arrangement where one or other of the prodgers 76 abuts a portion 82 of a carrier 12 where there is no pocket, in order for the priming member 60 to rotate and the cam member 72 to move a prodger 76 towards the other carrier 12, it will be necessary for the cam member 72 to move away from the portion 82. In some embodiments, it might be possible to allow the entire priming member 60 to move axially or for the carriers 12 to move axially. However, in the preferred embodiment, the cam member 72 has itself a limited amount of flexibility. As illustrated, the cam member 72 is provided as an elongate member which is attached to the rest of the priming member 60 at each end with an elongate opening either side of it. This will allow sufficient flexibility for the cam member 72 to move towards and away from the carriers 12.

(83) Considering the overall embodiment as described with reference to FIG. 1(a) to (c), it will be appreciated that it is highly desirable to ensure that the user moves the priming lever 8 through its entire length of travel so as to fully dispense a dose of powder. In particular, considering FIG. 11, it would be undesirable for a user to partly operate the priming lever 8 and priming member 60 such that a prodger 76 pushes an insert 26 far enough to partly rupture a lidding sheet on the first side surface 16, but without fully extending the insert 26 to the position illustrated in FIGS. 6 and 7(b).

(84) As the motion of the inserts 26 is restricted by the foils 22, 24 sealing both surfaces of the carrier plate 12, a high force is required to cause the inserts 26 to start to move. This force increases to the point at which the foils 22, 24 rupture after which the force decreases substantially. Thus, the user feels a resistance to the motion of the priming lever 8 for the early part of its travel. At some point along its travel, the resistance suddenly reduces, as the foil 22, 24 rupture. The user cannot reduce the applied force instantaneously so that the priming lever 8 is rapidly pushed to the end of its available stroke. This tactile feedback encourages the user to fully open the pockets.

(85) If the cam member 72 driving the prodgers 76 was solid as shown in FIG. 11, then the inserts 26 would be forced to the positions shown. However, in the preferred embodiment where the parts are moulded in plastic, it is impossible to control the dimensions of all parts with absolute accuracy. Thus, where the distance moved by the insert 26 is smaller than the space allowed for it, there would be a gap above the pocket but where the distance moved is greater than the distance allowed for it, the anvil plates 32 would be pushed apart from the carriers 12 by the force. This force would be transmitted to the casework causing it to deform if sufficiently high force was applied to the priming lever 8.

(86) To avoid this potential problem, the cam member 72 is made to a form that varies its force versus distance profile along its length.

(87) An example of a suitable form is shown in FIG. 12. The preferred embodiment includes two such members arranged back to back. The solid wedge shape profile at the right hand side as illustrated in FIG. 12 has the same profile as shown in FIG. 11. This form rigidly transmits the force applied by the priming lever 8 to the insert 26. The length of this profile is chosen so that, for all devices, the prodgers 76 will be moved sufficiently far to break the foils 22, 24 by this profile. Once the foils 22, 24 are broken, much less force is required, but the distance that the insert 26 must move may vary from device to device. Thus, for the last part of its travel, the cam member 72 cross-section is designed to provide compliance in its movement. This ensures that the cam member 72 provides sufficient force for the insert 26 to be pushed to the end of its available travel in the anvil plate 32. However, after the insert 26 is stopped at the end of its travel, the force that the cam member 72 applies to the prodger 76 is limited to that generated as it deforms. This can be much less than the force that would be applied if the prodger 76 were rigidly connected to the priming member 60.

(88) In this way, reliable opening of the pocket is achieved using components that can be manufactured using conventional materials and moulding processes.

(89) The action of cam member 72 and prodger 76 is further illustrated in FIGS. 16(a) to 16(h). These Figures show the cam member 72 and prodger 76 at sequential positions as the priming lever 8 and priming member 60 are moved to open a pocket. The Figures are grouped in pairs, each group giving two views of the same position.

(90) FIGS. 16(a) and 16(b) show the prodger 76a in its fully retracted position at one end of the cam member 72. The prodgers 76a and 76b are identical components that clip together with the cam member 72 between them. Each prodger 76 has features 86 at the ends of their arms 80 that locate with additional cam surfaces 88 formed on the priming member 60 either side of the elongate openings though which the arms 80 extend.

(91) Where a prodger member 76 has penetrated past the first surface of a carrier disc in order to push the pocket through the second surface, then it is necessary to retract the prodger member 76 before the carrier disc can be indexed to its next position.

(92) A spring could be used to achieve this if it were positioned to press the prodger member 76 against its base surface. However, it is preferable to have an active method for retracting the prodger member 76 that acts as the cam member 72 is returned to the original position. However, where the action of returning the cam member 72 to its original position is also used to index the carrier disc, it is important to ensure that the retraction of the prodger members 76 is completed before the carrier disc is indexed.

(93) A preferred method of achieving this is by the use of the further cam surfaces 88 located in the non-moving housing in which the cam member and carrier discs are located.

(94) FIG. 17(a) shows a schematic cross section through the prodgers 76a and 76b also in their retracted position.

(95) The location of prodger 76a is constrained by the surface 90 of the cam 88 and the cam surface 74 of the cam member 72. The cams 88 and cam member 72 are designed so that their thickness CI and C2 change along the direction of the primary member 60 motion. FIG. 17(b) shows the prodgers 76a and 76b in their open position where it can be seen that C2 has increased and CI decreased compared to their values at the closed position.

(96) The cam member 72 has a rectangular cross section C2 at one end that gradually increases in area. At the point that it starts to become a compliant wedge, rather than a rigid one, the wedge splits into a central part that pushes up 74 and two side parts that push down 74a.

(97) This arrangement provides a positive force to both open and close the prodgers 76a and 76b.

(98) FIGS. 16(c) to 16(h) show how the concept illustrated in FIGS. 17(a) and (b) might be implemented.

(99) FIGS. 16(c) and (d) show the prodgers 76a and 76b where the cam member 72 has completed approximately one third of its full travel. The cam member 72 over this section is of uniform thickness such that the prodgers are fully retracted. This allows the movement of the rotary priming member 60 on the return stroke over this section to drive the indexing mechanism (as will be described below).

(100) FIGS. 16(e) and (f) show the prodgers 76a and 76b where the cam member 72 has completed two thirds of its travel. The cam member 72 along this section includes the circumferential grooves 84 mentioned above. The raised parts of the cam member 72 are sufficient to rigidly couple the force applied to the priming lever 8 to the prodgers 76a and 76b and the grooves 84 are provided solely to increase the tolerance of the mechanism to stray powder that may have collected on the cam surface 74.

(101) FIGS. 16(g) and (h) show the prodger where the cam member 72 has completed its travel. In this section, the cam member 72 is not solid but split into a central section and two side sections arranged so that the central section presses up against one prodger whilst the two outer sections press down against the other prodger.

(102) If the prodgers 76a and 76b reach the end of their travel before the cam member 72 reaches the end of its travel, then the thinned section of the cam member 72 at this point will be deflected, thereby limiting the force applied to the prodgers 76a and 76b over the remaining travel of the cam member 72.

(103) In the preferred embodiment, the indexing of the two carrier assemblies (FIGS. 5(a) and (b)) is accomplished by an indexing mechanism that causes a carrier 12 to be incremented by one pocket each time the priming lever 8 is actuated and a changeover mechanism that causes the indexing mechanism initially to drive the first carrier 12 but, when the last pocket of that carrier 12 has been used, for that carrier 12 to remain stationery whilst the second carrier 12 is incremented when the indexing mechanism is actuated.

(104) The preferred indexing mechanism illustrated in FIGS. 14(a) to (f) uses a 3 peg Geneva 100 that rotates exactly 120° each time the indexing mechanism is actuated. The Geneva peg wheel 100 has two gears co-axial with the peg-wheel arranged so that the gears can engage with teeth 35 on the airway plates 34.

(105) To avoid having both airway plates 34 driven simultaneously, it is arranged that, at one location around the airway plate 34, the gear teeth 35 are missing. As a result, at this location, rotation of the Geneva peg wheel 100 does not rotate the airway plate 34. Thus, the indexing mechanism drives the first carrier 12 via the Geneva 100 and its gears until it reaches the end of the gear teeth 35 for that carrier 12. The next indexing moves the first carrier 12 to its non-driven position, i.e. where the gear teeth 35 are missing, and engages a changeover mechanism which rotates the second carrier 12 until its gears 35 are engaged with the gears on the Geneva peg wheel 100.

(106) A preferred embodiment of the indexing mechanism is illustrated in FIGS. 14(a) to 14(f). In these, it can be seen that the peg wheel 100 is located with its axis parallel t0 the axis of the dose carriers 12 and rotary priming member 60.

(107) The rotary priming member 60 incorporates many of the functional elements described previously within a single moulded component. It includes the priming lever 8, the cam member 72 and the prodger closing cams 83, as well as being the driving member for the indexing Geneva 100.

(108) The Figures start with the priming member 60 at the end of its travel where a pocket has been opened and shows what happens as the priming lever 8 is returned to its start position by the closing of the mouthpiece cover 4.

(109) The peg wheel 100 has six pegs 102a-102c, 103a-103c arranged at 60° intervals around its edge. Three of these pegs 102a, 102b, 102c are longer than the other three 103 a, 103b, 103 c and are shown with black ends for clarity. As the rotary priming member 60 moves from its position in FIG. 14(a) to that in FIG. 14(b), the leading part 101 of a driving member 104 formed by the priming member 60 passes over the short peg 103 a with its periphery touching the edges of the longer pegs 102a and 102c preventing the peg wheel 100 from rotating. At the position shown in FIG. 14(b), a ratchet 105, which slopes downward and forward from the driving member 104, engages with the peg 103 a. As the priming member 60 and the driving member 104 continue to move from the position of FIG. 14(b) to that of FIG. 14(c), the peg wheel 100 is driven around. To permit the peg wheel 100 to rotate, a slot 106 is cut into the driving member 104 of the priming member 60 into which the long peg 102c can enter. At the position of FIG. 14(c), the ratchet 105 is starting to disengage with the peg 103 a but the trailing edge 107 of the slot 106 now engages with the long peg 102c and continues to drive the peg wheel 100 around through to the position shown in FIG. 14(d). At the position of FIG. 14(d), the edge 108 of the driving member 104 passes over the short peg 103 c. The peg wheel 100 then continues to rotate to the position of FIG. 14(e) to complete the forward motion of the peg wheel 100. The slot 109 is provided to accommodate the long peg 102b. At this position, the dose carrier 12 has been driven so that the next pocket to be opened is beyond its desired location and the mouthpiece cover 4 that has been driving the rotary priming member 60 is fully closed.

(110) When the priming lever 8 is pushed in the reverse direction by the user to open a pocket, the initial part of the travel, over which the prodgers 76a and 76b are not moved, takes the rotary priming member 60 plate back from the position shown in FIG. 14(e) to that shown in FIG. 14(b). The angled face 110 in the slot 109 on the rotary priming member 60 pushes on the long peg 102b causing the peg wheel 100 to rotate backwards until the two long pegs 102b and 102c are both dis-engaged from the driving edges and pressing against the outer periphery 108 of the rotary priming member 60.

(111) This accurately defines the rotary position of the peg wheel 100, ensuring that the prodgers 76a and 76b accurately line up with the pockets. The short peg 103c, that is within the outer periphery of the rotary priming member 60, is short enough to allow the ratchet 105 to return over the top of it. Thus, after the initial movement, the peg wheel 100 is held stationary throughout the remainder of the stroke opening a pocket. Thus, each indexing operation causes the peg wheel 100 to rotate 120°. The gears above and below the plane of the peg wheel 100 are shown in FIG. 14(f) which for clarity is viewed from the opposite side from FIG. 14(a) to 14(e). FIG. 14(f) shows the gears 35 on one of the airway plates 34 engaged with the gear on the peg wheel 100. The number of gear teeth on the airway plates 34 and peg wheel 100 are arranged so that the 120° motion of the peg wheel increments the dose carrier plate exactly one pocket pitch.

(112) The arrangement described here is advantageous in achieving precise intermittent motion control of two disks within very tight space allocation and with a minimal number of components.

(113) As described previously, for the device to operate with two disk carrier plates, a changeover mechanism is preferably provided to cause the indexing mechanism initially to drive a first disk and, when this has had all of its pockets opened, to then drive a second disk. Such a changeover mechanism will be described with reference to FIG. 15(a) to FIG. 15(e). These Figures show the device viewed edge on with the two airway plates 34 arranged horizontally.

(114) FIG. 15(a) shows the device in its position before a first pocket is opened.

(115) In FIG. 1(b), airway plate 34a has been indexed by one position to the right. The two features 123 on the periphery of the airway plate 34a can be seen to have shifted.

(116) FIG. 15(c) shows the position after the last pocket of the lower carrier 12 of airway plate 34a has been opened. The rotation has brought the features 123 right around the device to the position shown. The next indexing operation causes the lower airway plate 34a to move as before.

(117) However, the leading feature 123 pushes on a changeover component 124 which pushes on the feature 122 on the upper airway plate 34b causing both plates 34a and 34b and carriers 12 to move together. When the upper airway plate 34b was in its original position, the prodger 76b was aligned to the missing pocket part 82 providing a hard surface against which that prodger 76b could push whilst the other prodger 76a pushed against a pocket of the lower airway plate 34a. In addition, at this location, the missing teeth on the gear 35 of the upper airway plate 34b aligned with the gear on the Geneva peg wheel 100 and, hence, rotation j of the peg wheel 100 did not index the upper airway plate 34b. However, the indexing operation performed by the changeover component 124 on the upper airway plate 34b moves the gear of the upper airway plate 34b to engage with the gear of the peg wheel 100 and aligns the first pocket of the upper carrier 12 with the prodgers 76. Simultaneously, indexing by the priming member 60 causes the lower airway plate 34a to continue to move to a position which the gear teeth 35 on the lower airway plate 34a disengage from the gear on the peg wheel 100. The priming member 60 and peg wheel 100 move the lower airway plate 34a to a position in which the missing teeth on the gear 35 of the lower airway plate 34a are aligned with the gear on the Geneva peg wheel 100 and the missing pocket segment 82 of the lower dose carrier 12 is aligned with the prodgers 76.

(118) The clip 125 provides an interlock that prevents any frictional coupling from causing the upper airway plate 34b to move before the lower airway plate 34a has arrived at the correct location.

(119) Thus, changeover from the indexing of one disc to the other is achieved automatically and with minimal number of components and in a very small space.

(120) The indexing of the device, in addition to moving the next pocket into alignment with the prodgers 76, preferably actuates a dose counter that provides a visual indication to the user of the number of doses remaining. The operation of the dose indicator will be described with reference to FIGS. 19 and 20.

(121) It is preferable that the device, when dispensing medicament, indicates to the user the number of doses remaining in the device.

(122) It is preferable that such indication is easily readable and, as such, very small numbers indicating the remaining doses would be a disadvantage. Within the size constraints of a pocket portable device that contains 60 doses providing such a display is challenging.

(123) The simplest arrangement of marking the carrier discs with numbers visible through windows in the casework requires, where two carrier discs are used, the user to view different windows and, in addition, the space available around the carrier disc means that the size of the numbers would be small.

(124) A preferred method is to employ a display with separate units and tens indication, driven such that the tens display index one number as the unit display index from 9 to 0. This allows larger numbers to be used within the same casework. The two discs may be provided concentrically one within the other and preferably co axially with the axis of the device, for instance on the shaft 68 illustrated in FIG. 13. The displayed units and tens are visible through the window 10 illustrated in FIG. 1(a).

(125) In a preferred embodiment, the display counts down to zero, but the tens disc is not provided with a “0”. Instead, it is provided with an indicator, for instance a symbol, colour light etc to indicate to the user that the device is nearing the end of its functional life.

(126) The preferred embodiment uses another Geneva and gear arrangement that is driven from the movement of the carrier discs. It is preferable that a single counter is increment initially by the motion of the first carrier disc and subsequently by the motion of the second carrier disc such that the fact that the device contains two carrier discs is not apparent to the user.

(127) FIG. 20(a) shows a view of the dose counter display. The counter consists of two concentric rings 130, 131 with numbers formed in the rings facing toward the outer casing 2 of the device. The outer ring is the units counter 130 and the inner ring is the tens counter 131. The window 10 is provided in the outer casework 2 is arranged to permit the user to see only one digit of the units counter 130 and the adjacent digit of the tens counter 131. In FIG. 20(a), the counter indicates that there are 21 doses left. The operation of the counter requires the units counter 130 to index by 36° every time the indexing mechanism is actuated and for the tens counter to index by 36° only as the units counter moves from displaying 9 to 0. It can be seen that the units digits are evenly distributed around the ring whereas, for the example shown in FIG. 20(a) which has 60 doses, there are only the digits 1 to 6 on the tens counter 131.

(128) The counter is driven by a gear 133 which itself is driven by one of the gears on the indexing Geneva peg wheel 100. In the preferred embodiment described above, the indexing Geneva 100 turns through 120° for each indexing operation and the gear on it has six teeth. The gear 133 has fifteen teeth and engages with the twenty teeth 134 of the units counter illustrated in FIG. 19(a). Thus, the 120° rotation of the indexing Geneva 100 drives the units counter 130 through 36°. FIG. 19(a) shows the units counter ring 130 viewed from behind the face on which the numbers are formed.

(129) A counter Geneva wheel 135 is shown located inside the units counter ring 130 for mounting on a fixed post which is part of chassis 66.

(130) An actuated peg 136 for the counter Geneva mechanism is located on the inner diameter of the units counter wheel 130. This peg 136 engages with one of the three indentations 137 in the Geneva wheel 135 causing the Geneva wheel 135 to rotate by 120° as the peg 136 passes by the wheel 135 during its 36° rotation between displaying the digits 9 and 0.

(131) It should be noted that in this Geneva mechanism, the peg 136 is on the outer larger diameter component 130 and this drives the slotted smaller wheel 135 whereas, for the indexing Geneva 100, the slots are on the larger wheel and they drive the pegs on the smaller wheel. However, both are examples of a Geneva type mechanism providing intermittent rotation with accurate location between the rotations.

(132) The Geneva wheel includes cam faces 138 which contact against the inner wall 139 of the units counter 130 preventing the Geneva 135 rotating between indexing. To permit the Geneva 135 to rotate as it is pushed by the peg 136, there is a gap 139a in the inner wall 139 adjacent to the peg 136.

(133) The Geneva has a 3 tooth gear on its underside engaging with pegs on the tens counter ring to drive it.

(134) FIG. 19(a) through to FIG. 19(e) show the positions of the Geneva wheel 135, the drive gear 133 and the units counter 130 at four stages during the 36° rotation of the units counter.

(135) FIG. 20(a) to FIG. 20(c) show the motion of the two counter wheels as they index from 21 doses to 20 doses remaining, when only the outer units counter 130 moves. FIG. 20(c) to FIG. 20(e) show the corresponding situation from 20 to 19 doses remaining where both counters index.

(136) After the last dose has been used, the remaining doses display will read 0 indicating that the device is empty to the user.

(137) However, if the user does not look at the display, they may actuate the device again when desiring further doses.

(138) It is preferable that the device provides some positive feedback to the user, as it is being actuated, that it is empty.

(139) This feedback can be in the form that the priming lever 8 cannot be moved to its operating position with the level of force normally used. This tactile feedback provides a lockout feature.

(140) A preferred method of achieving this with the two disc device is to arrange that after the last dose has been used, the second disc indexes such that it has no pocket under the prodger. At this point, the two prodger members 76 both face surfaces of the discs without pockets. Thus as the priming lever 8 is moved, neither prodger member 76 can move onto a disc and the resulting force on the prodger members 76 is transmitted back through the drive mechanism to the priming lever 8 and hence to the user.

(141) Whilst the user may be able to apply sufficient force to move the priming lever 8 through to its home position, this will only be possible by forcing the discs to separate against the constraint of the casework. The force required to do this can be made sufficiently greater that the normal actuation force as to be obvious to the user.

(142) From the description, it can be seen that this mechanism provides a clear visual indication of the number of doses remaining with a minimal number of components.

(143) The preferred embodiment described above is arranged consecutively to dispense the powder from each pocket of one carrier and then subsequently the powder from each pocket of the other carrier. However, it should be appreciated that it is also possible for a device to dispense powder from pockets alternately from one carrier and then the other carrier. Alternatively, pockets of both disks may be dispensed simultaneously.

(144) By dispensing powder from both carriers, either one after the other or simultaneously, it is possible for the user to inhale the powder from both carriers simultaneously. This arrangement is particularly advantageous when used with disks containing different medicament. In particular, it is preferred to provide disks containing a combination of medicaments that are more effective together than singularly. By way of example, a steroid compound could be dispensed from one disk and a long acting beta agonist (LABA) from the other disk for the treatment of, for example, asthma or chronic obstructive pulmonary disease. Examples of long acting beta agonists include formoterol and salmeterol and examples of steroids include fluticasone propionate. budesonide and monetasone furoate.

(145) It is also possible to adapt the mechanism so to as to arrange for selective dispensing from one or both carriers. Where both disks are provided with the same medicament, this may be used to vary the dispensed dosage.

(146) Although a device has been described with reference to a particular type of carrier, in particular having through holes and sealed with lidding sheets on either side, it is also possible to use other carriers, such as more conventional blister packs. These could include inserts similar to those described above. However, alternatively, powder in the pockets themselves could outwardly burst the lidding sheet. Also certain aspects of the device are applicable with other opening arrangements such as peeling or cutting of the lidding sheet.

(147) Finally, it should be appreciated that the device can be provided with carriers pre-installed or, alternatively, ready for use with appropriate carriers.

(148) As illustrated in FIG. 13, the preferred arrangement described above can be provided conveniently as three assemblies for use with carriers 12. In particular, a first cover sub-assembly A receives one carrier 12 and a second cover sub-assembly B receives another carrier 12. The two cover sub-assemblies A and B are then secured to one another with a chassis sub-assembly C therebetween.