Dry powder inhaler with reproducible flow resistance

Abstract

A dry powder inhalation device is disclosed. In one optional aspect, the device includes a housing, a base plate, a receptacle for a medicament and a mouthpiece. The base plate is engageable with the housing to form a main space with a main air inlet. The mouthpiece includes an inner conduit connected to its outlet and is engageable with the base plate to fluidly connect the inner conduit to the receptacle. The receptacle is fluidly connected to the main space, so that upon inhalation by a user, air can be drawn through the main air inlet into the main space and onward through the receptacle into the inner conduit. The mouthpiece and the base plate form an auxiliary space with an auxiliary air inlet, wherein the auxiliary space is fluidly connected to the main space.

Claims

1. A dry powder inhalation device, comprising: a housing, a base plate, a receptacle for a medicament and a mouthpiece, wherein the base plate is engageable with the housing to form a main space with a main air inlet, the mouthpiece comprises an inner conduit connected to its outlet, the mouthpiece is engageable with the base plate to fluidly connect the inner conduit to the receptacle, and the receptacle is fluidly connected to the main space, so that upon inhalation by a user, air can be drawn through the main air inlet into the main space and onward through the receptacle into the inner conduit, wherein the mouthpiece and the base plate form an auxiliary space with an auxiliary air inlet, wherein the auxiliary space is fluidly connected to the main space, wherein the base plate comprises at least one air exchange opening for connecting the auxiliary space to the main space, wherein flow resistance of each of the main air inlet and the auxiliary air inlet is lower than flow resistance of a path between the main space and the mouthpiece outlet and lower than flow resistance of a path between the auxiliary space and the mouthpiece outlet, the housing having an oval shape comprising two flat side faces and two curved side faces, the two flat side faces being larger than the two curved side faces.

2. The device according to claim 1, wherein the main air inlet, and/or the auxiliary air inlet, comprises a recess in the base plate.

3. The device according to claim 2, wherein the recess comprised in the main air inlet is formed in an area where the base plate is hinged to the housing.

4. The device according to claim 2, wherein the recess comprised in the auxiliary air inlet is formed in an area where the base plate is set in a further recess in the housing.

5. The device according to claim 4, wherein the further recess is placed in at least one of the flat side faces.

6. The device according to claim 1, wherein the inner conduit is connectable to the receptacle via a screen held in a screen holder.

7. The device according to claim 1, further comprising at least one piercing element that is movable into the receptacle by pushing a button against the force of a spring.

8. The device according to claim 1, wherein the housing, the base plate and the mouthpiece are hinged about a common axis of rotation.

9. The device according to claim 1, wherein a first airway is provided between the main space and atmosphere, so that upon inhalation by a user, air can be drawn through the first airway into the main space and onward through the receptacle into the inner conduit, wherein the auxiliary space is fluidly connected to atmosphere by a second airway and to the inner conduit by a bypass air path.

10. The device according to claim 9, wherein flow resistance of the bypass air path is lower than flow resistance of the combination of all leakage paths in the device.

11. The device according to claim 9, wherein the inner conduit is connectable to the receptacle via a screen held in a screen holder.

12. The device according to claim 9, wherein the bypass air path comprises at least one opening and/or recess (8a) in the screen holder.

13. The device according to claim 12, wherein the bypass air path further comprises at least one opening and/or recess in the base plate that cooperates with the opening and/or recess in the screen holder.

14. The device according to claim 12, wherein the screen holder has a circular circumference, and the bypass air path comprises at least four openings and/or recesses in a symmetric arrangement of angular positions along this circumference.

15. The device according to claim 12, wherein the recesses are located in a perimeter of the screen holder.

16. The device according to claim 15, wherein at least one recess in the perimeter of the screen holder cooperates with the base plate to enclose a channel with a cross sectional area above 0.2 mm.sup.2 and below 0.8 mm.sup.2.

17. The device according to claim 12, wherein at least one opening in the screen holder is a hole with a diameter above 0.5 mm and below 1 mm.

18. The device according to claim 11, wherein the screen holder is click-mountable to the mouthpiece.

19. The device according to claim 9, wherein the base plate comprises at least one air exchange opening for connecting the auxiliary space to the main space.

20. The device according to claim 9, further comprising at least one piercing element that is movable into the receptacle by pushing a button against the force of a spring.

21. The device according to claim 20, wherein the housing has a recess to accommodate the button.

22. The device according to claim 20, wherein at least one end stop is provided for the piercing element to keep it from completely traversing the receptacle.

23. The device according to claim 20, wherein a first piercing element with a first chamfered tip and a second piercing element with a second chamfered tip are provided, wherein the chamfers of the two tips have opposite orientations towards the longitudinal axis of the receptacle.

24. The device according to claim 9, wherein the housing, the base plate and the mouthpiece are hinged about a common axis of rotation.

25. The device according to claim 24, further comprising a lid for covering the mouthpiece when the device is not in use, wherein the lid is hinged about the same axis of rotation.

26. A dry powder inhalation device, comprising: a housing, a base plate, a screen holder situated on the base plate, a receptacle for a medicament and a mouthpiece, wherein the base plate is engageable with the housing to form a main space with a main air inlet, the mouthpiece comprises an inner conduit connected to its outlet, the mouthpiece is engageable with the base plate to fluidly connect the inner conduit to the receptacle, and the receptacle is fluidly connected to the main space, so that upon inhalation by a user, air can be drawn through the main air inlet into the main space and onward through the receptacle into the inner conduit, wherein the mouthpiece and the base plate form an auxiliary space with an auxiliary air inlet, wherein the auxiliary space is fluidly connected to the main space, wherein the base plate comprises at least one air exchange opening for connecting the auxiliary space to the main space, wherein flow resistance of each of the main air inlet and the auxiliary air inlet is lower than flow resistance of a path between the main space and the mouthpiece outlet and lower than flow resistance of a path between the auxiliary space and the mouthpiece outlet, wherein the auxiliary space is fluidly connected to the inner conduit by a bypass air path, the bypass air path being formed by cooperation between a portion of a hole formed in the base plate and a portion of a hole formed in the screen holder.

27. A dry powder inhalation device, comprising: a housing, a base plate, a receptacle for a medicament and a mouthpiece, wherein the base plate is engageable with the housing to form a main space with a main air inlet, the mouthpiece comprises an inner conduit connected to its outlet, the mouthpiece is engageable with the base plate to fluidly connect the inner conduit to the receptacle, and the receptacle is fluidly connected to the main space, so that upon inhalation by a user, air can be drawn through the main air inlet into the main space and onward through the receptacle into the inner conduit, wherein the mouthpiece and the base plate form an auxiliary space with an auxiliary air inlet, wherein the auxiliary space is fluidly connected to the main space, wherein the base plate comprises at least one air exchange opening for connecting the auxiliary space to the main space, wherein flow resistance of each of the main air inlet and the auxiliary air inlet is lower than flow resistance of a path between the main space and the mouthpiece outlet and lower than flow resistance of a path between the auxiliary space and the mouthpiece outlet, wherein the auxiliary space is fluidly connected to the inner conduit by a bypass air path having a bypass opening, and wherein the at least one air exchange opening is at least one of a different shape and a different size than the bypass opening.

Description

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

(1) In the following, the subject-matter of the invention is illustrated using Figures without any limitation of the claimed scope being intended. The Figures show:

(2) FIG. 1: Exploded view of an optional embodiment of an inhaler.

(3) FIG. 2: Sectional trimetric view of the inhaler of FIG. 1 in its assembled state.

(4) FIG. 3a: Partial top view of the inhaler of FIG. 1 in its assembled state, illustrating aspects of the main air inlet of the inhaler.

(5) FIG. 3b: Partial side view of the inhaler of FIG. 1 in its assembled state, illustrating aspects of the auxiliary air inlet of the inhaler.

(6) FIG. 4: Sectional view detailing main air flow and bypass air flows.

(7) FIG. 5a: Top view of a first optional embodiment of a screen holder.

(8) FIG. 5b: Top view of a second optional embodiment of a screen holder.

(9) FIG. 5c: Partial top view of the inhaler of FIG. 1 in a generally assembled state (with certain parts removed), illustrating the base plate.

(10) FIG. 6a: Simplified sectional view of the inhaler of FIG. 1 in its assembled state, illustrating a first shuttling position.

(11) FIG. 6b: Simplified sectional view of the inhaler of FIG. 1 in its assembled state, illustrating a second shuttling position.

(12) The following reference signs are used in the Figures:

(13) TABLE-US-00001 Reference Sign Description  1 Dry powder inhalation device (inhaler)  1a common axis of rotation  2 housing  2a recess in housing 2 for button 11  2b windows in housing 2  2c further recess in housing 2 for auxiliary air inlet 7a  3 base plate  3a air exchange opening in plate 3 between spaces 6 and 7  3b recesses in base plate 3 for prongs 9c of screen holder 9  3c central opening in base plate 3  4 receptacle  4a longitudinal axis of receptacle 4  4b bottom of capsule 4d  4c top of capsule 4d  4d capsule for insertion into receptacle 4  5 mouthpiece  5a inner conduit of mouthpiece 5  5b outlet of mouthpiece 5  6 main space  6a main air inlet into main space 6  6b recess in base plate 3 to provide main air inlet 6a  7 auxiliary space  7a auxiliary air inlet into auxiliary space 7  7b recess in base plate 3 to provide auxiliary air inlet 7a  8 bypass air path from space 7 to inner conduit 5a  8a bypass opening and/or recess in screen holder 9  8b bypass opening and/or recess in base plate 3  8c annular bypass groove in base plate 3  9 screen holder for screen 9a  9a screen in screen holder 9  9b circumference of screen holder 9  9c prongs of screen holder 9 for engagement with recesses 3b  9d grooves of screen holder 9 for rotational alignment 10, 10a, 10b piercing elements 11 button for actuation of piercing elements 10, 10a, 10b 12 spring 13a, 13b chamfered tips of piercing elements 10a, 10b 14 lid 15 axle 16 main air stream 21, 22 longer flat side faces of housing 2 23, 24 shorter curved side faces of housing 2 A arrow X lower position of bottom 4b of capsule 4d Y upper position of top 4c of capsule 4d

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

(14) FIG. 1 shows an exploded view of an optional embodiment of a inhaler. The housing 2 has two windows 2b that provide a view of the receptacle 4 in the assembled state of the inhaler 1. The base plate 3 is hinged to the inhaler by means of an axle 15 that will form an axis of rotation 1a. Below the base plate 3, the receptacle 4 having a longitudinal axis 4a is mounted. Two piercing elements 10a and 10b may be pushed into the receptacle 4 by pressing the button 11 against the force of the spring 12. The housing 2 has a recess 2a for accommodating the button 11 in the assembled state of the inhaler 1. The housing 2 optionally has an oval shape with two longer flat side faces 21 and 22 and two shorter curved side faces 23 and 24.

(15) The base plate (deck) 3 has air exchange openings 3a that connect the main space 6 and the auxiliary space 7, which are not shown in the exploded view of FIG. 1 for clarity. The base plate 3 has a central opening 3c through which air can pass from the receptacle 4 on to the mouthpiece 5. The central opening 3c is bordered by an annular groove 8c. On the perimeter of the annular groove 8c, the base plate 3 has four recesses 8b that lead into the annular groove 8c. In the perspective of FIG. 1, only two of the four recesses 8b are visible. The base plate 3 further comprises recesses 3b for engagement with corresponding prongs 9c of the screen holder 9.

(16) The recesses 8a in the screen holder 9, the recesses 8b in the base plate 3 and the annular groove 8c in the base plate 3 together provide a bypass air path into the interior of the screen holder 9, and therefore into the inner conduit 5a of the mouthpiece 5.

(17) The screen holder 9 primarily serves to mount a screen 9a into the airway from the receptacle 4 via the central opening 3c of the base plate 3 on to the mouthpiece 5. In addition, the screen holder 9 comprises four recesses 8a on its perimeter. The four recesses 8a, only three of which are visible in the perspective of FIG. 1, are in a symmetric arrangement of angular positions along a circular circumference 9b of the screen holder 9. The screen holder 9 further comprises grooves 9d on its top for rotational alignment.

(18) After having passed the screen 9a, medicament-laden air is passed into the inner conduit 5a of the mouthpiece that is not visible in the perspective of FIG. 1. Since the screen holder 9 is click-mounted to this inner conduit 5a, it may be regarded as a part of the inner conduit 5a. At the outlet 5b, the air exits the mouthpiece 5 and enters the mouth of the user.

(19) The mouthpiece 5 is mounted on the same axle 15, and is therefore rotatable about the same axis 1a, as the base plate 3 and the housing 2. When the inhaler 1 is not in use, the mouthpiece 5 is protected by a cover 15 that is mounted on the same axle 15 and rotatable about the same axis 1a.

(20) FIG. 2 shows a sectional trimetric view of the inhaler 1 in its assembled state. In this perspective, the main space 6 enclosed by the housing 2 and the base plate 3, as well as the auxiliary space 7 enclosed by the mouthpiece 5 and the base plate 3, become apparent. The main space 6 and the auxiliary space 7 are interconnected by the kidney-shaped air exchange openings 3a in the base plate 3, only one of which is visible in the perspective of FIG. 2. The arrow A in FIG. 2 illustrates how air passes from the main space 6 into the bottom of the receptacle 4. Because of the air exchange opening 3a, air can be scavenged from the auxiliary space 7 for this purpose as well.

(21) The main air stream traverses the reservoir 4 from bottom to top along its longitudinal axis 4a, passes the screen 9a in the screen holder 9 and traverses the screen holder 9 from bottom to top on to the inner conduit 5a of the mouthpiece 5. Because the screen holder 9 is click-mounted and fluidly connected to the inner conduit 5a, it may be regarded as a part of this inner conduit 5a.

(22) In the embodiment shown in FIG. 2, the screen holder 9 has four holes 8a in a symmetric arrangement around its circumference 9b. Only one hole 8a is visible in the perspective of FIG. 2.

(23) FIG. 2 also details the piercing elements 10a and 10b. The tips 13a and 13b of the piercing elements 10a and 10b are each chamfered, with the chamfers having opposite orientations towards the longitudinal axis 4a of the receptacle 4. The facet of the first tip 13a faces upwards, while the facet of the second tip 13b faces downwards. When both tips 13a and 13b penetrate a capsule in the receptacle 4 simultaneously, the vertical forces exerted by both tips 13a and 13b onto the capsule are neutralized, and the capsule stays in place.

(24) FIGS. 3a and 3b detail the positioning of the main air inlet 6a and the auxiliary air inlet 7a of the inhaler 1.

(25) FIG. 3a is a top view of the inhaler 1; the outlet 5b of the mouthpiece 5 points out of the drawing plane. In the area where the housing 2 is hinged to the lid 14, a recess 6b is provided in the base plate 3. This recess 6b serves as the main air inlet 6a into the main space 6 enclosed by the base plate 3 and the housing 2. The hinge and the lid 14, which are present in the area of the main air inlet 6a, double to keep a finger of a hand holding the inhaler 1 from obstructing the main air inlet 6a.

(26) FIG. 3b is a side view of the inhaler 1. The drawing plane is parallel to the longer flat side face 21 of the housing 2. The base plate 3, which is engaged with the mouthpiece 5, has a recess 7b. By means of this recess 7b, a gap is formed between the base plate 3 and the mouthpiece 5. This gap serves as the auxiliary air inlet 7a into the auxiliary space 7 that is enclosed between the mouthpiece 5 and the base plate 3. The auxiliary space 7 is not visible in the perspective of FIG. 3b; it is shown in the sectional trimetric view of FIG. 2.

(27) FIG. 4 is a partial sectional view of the inhaler 1 that details the providing of bypass air paths 8 in addition to the main air flow 16. From the auxiliary space 7, air passes through the holes 8a in the screen holder 9 that cooperate with recesses 8b in the base plate 3. Because the screen holder 9 abuts the base plate 3 in the area of the holes 8a, in the area of the annular groove 8c in the base plate 3 that surrounds the central opening 3c in the base plate 3, there is a gap between the lower part of the screen holder 9 and the base plate 3. Through this gap, the air can pass on from the recess 8b to the interior of the screen holder 9. In this manner, bypass air flows along bypass path 8, and then mixes with the main air flow 16 inside the inner conduit 5a of the mouthpiece 5.

(28) FIG. 5 further details the cooperation between openings and/or recesses 8a in the screen holder 9 with recesses 8b and an annular groove 8c in the base plate 3.

(29) FIG. 5a shows a top view of a first embodiment of a screen holder 9. In a symmetric arrangement along the circular circumference 9b of the screen holder 9, four holes 8a are provided. FIG. 5b shows a top view of a second embodiment of a screen holder 9. In an analogous symmetric arrangement along the circular circumference 9b, four recesses 8a are provided in the perimeter of the screen holder 9.

(30) FIG. 5c shows a top view of the inhaler 1 in a state where the lid 14 and the mouthpiece 5 have been disengaged from the housing 2 and base plate 3. The lid 14 and the mouthpiece 5 have been flipped over, and the screen housing 9 has been removed.

(31) When the prongs 9c of the screen holder 9 are inserted into the corresponding recesses 3b in the base plate 3, the holes and/or recesses 8a of the screen holder 9 will be laterally aligned with the recesses 8b in the base plate 3. In this manner, bypass air will be passed on from the auxiliary space 7 through holes and/or recesses 8a in the screen holder 9, recesses 8b in the base plate 3, and the annular groove 3b in the base plate 3 into the area of the central opening 3c in the base plate 3. The bypass air will then be drawn into the inner conduit 5a and outlet 5b of the mouthpiece 5, together with the medicament-laden main air stream from the receptacle 4.

(32) FIGS. 6a and 6b show simplified sectional views of the inhaler 1, to illustrate the influence of the reciprocating movement (shuttling) of the capsule 4d along the longitudinal axis 4a of the receptacle 4 on the flow resistance of the inhaler 1. The flow resistance can be calculated by dividing the square root of the pressure drop in the mouthpiece by the flow rate (volume per unit time) through the inhaler 1. The resistance along the main air flow path from the main space 6 through the receptacle 4 and the screen 9a on to the mouthpiece 5 has the largest single influence on the total flow resistance of the inhaler 1.

(33) FIG. 6a illustrates the lower point of the shuttling motion, where the bottom end 4b of the capsule 4d is in the position marked X. In this position, the air inlet from the main space 6 to the receptacle 4 via the bottom of the reservoir 4 is partially or completely blocked by the capsule 4d, so the instantaneous flow resistance is extremely high.

(34) In this position, the capsule 4d experiences an upward pressure force, in the direction from X to Y. This pressure differential is caused because the suction from the mouthpiece 5 creates a relatively low pressure at the top 4c of the capsule 4d, whereas the atmospheric pressure of the main space 6 creates a relatively high pressure on the bottom 4b of the capsule 4d.

(35) This pressure force causes the capsule 4d to accelerate to the position shown in FIG. 6b, where the top 4c of the capsule 4d abuts against the screen 9a. In this position, the flow resistance of the inhaler 1 is not significantly influenced by the presence of the capsule 4d; i.e., the instantaneous resistance is the same as that measured without the capsule 4d present.

(36) In this position, the capsule 4d experiences a downward pressure force, i.e., from Y to X. This pressure force is caused by the flow field that is set up around the hemispherical bottom 4b of the capsule 4d. The air jet entering the receptacle 4 at its bottom impinges on the bottom 4b of the capsule 4d and accelerates around this bottom 4b, creating an annular region of very low pressure.

(37) This pressure force causes the capsule to accelerate back to the position shown in FIG. 6a, and the movement starts anew.

(38) Therefore, the measured flow resistance of the inhaler 1 is a time-averaged resistance over a number of shuttling cycles. This time-averaged resistance will always be greater than the resistance measured without a capsule 4d present. The time-averaged resistance will be influenced by the rate of shuttling. A high shuttling rate will result in a relatively high resistance; a low shuttling rate will result in a relatively lower resistance. In the extreme where there is no shuttling (i.e., the capsule 4d remains fixed in the position shown in FIG. 6b), the measured resistance will be equal to the resistance measured without a capsule 4d.

(39) The key design variable for influencing the rate of shuttling, and hence its contribution to flow resistance, is the length of the receptacle 4, and hence of the longitudinal path along which the capsule 4d may travel. Increasing the length of the receptacle 4 reduces the downward pressure force experienced by the capsule 4d in the position shown in FIG. 6b, which will reduce the rate of shuttling and hence the resistance. In addition, the increased length also increases the shuttling distance, which further reduces the rate of shuttling and hence the resistance.