BREATH-ACTUATION

Abstract: An arrangement is disclosed for, in connection to an inhalation operation, opening and closing and air inlet of a dry powder inhaler device (DPI) provided with a dose member (4). The arrangement requires a minimum pressure differential between a surrounding atmosphere and the airways of the inhaling person in order to open the inlet for outside air to enter into the DPI. The arrangement controlling the air inlet presents a biased flap connected to biased catch mechanism. The biased flap (16) closes the air inlet (23) of the DPI to the atmosphere by the force exerted by a compression spring (13), which acts oh the flap through a mechanism of levers. In order to open the flap a force FP bigger than the closing force FC of the spring and lever mechanism must be applied. The necessary force results from a pressure differential resulting when sucking the mouthpiece of the DPI. The catch is through the mechanism of levers released by the flap (16) when the flap opens, and triggers a sequence of events constituting the irreversible process of administering a dose to the user of the inhaler. The mechanism of levers uses rounded shapes (14) where moving parts are in contact with each other to minimize contact areas and rubbing effects to thereby achieve near zero friction losses. The flap is further by a counterweight (15) statically balanced, which almost completely eliminates the risk of external forces, e.g., gravitation or blows of the DPI to accidentally trigger the process of administering a dose.

Description: Breath-actuation TECHNICAL FIELD The present invention relates to a breath- actuated administration of a dose of dry powder from a dry powder inhaler to a user, and more specifically the present invention relates to an arrangement for triggering off the process of delivering the dose to the user also involving opening and closing of an air inlet of a dry powder inhaler when subject to an inhalation operation. BACKGROUND Today supply and distribution of medication powders take place in many different ways. Within health care more and more is focussed on the possibility to dose and distribute powder directly to the lungs of a user by means of an inhaler to obtain an efficient, fast, and user-friendly administration of the specific medication substance. Inhalers have been developed from being very simple to the up-to-date relatively complicated devices. For the up-to-date inhalers some form of mechanical dose forming is almost entirely used for preparing the dose to be inhaled. Most often forming of the dose with the amount to be inhaled takes place industrially in advance in a dose package containing 5-50 doses. The inhaler then is loaded with this dose package as the source of each dose. Other inhalers have a magazine from which the powder is dosed by some device for distribution to the inspiration air. In both cases the powder will generally be strongly agglomerated and therefore must be dispersed. There is a demand for arrangements improving and simplifying administration of medication powder by means of an inhaler providing a possibility to control the start of the inhalation airflow. SUMMARY The present invention discloses an arrangement for triggering off a process of administering a dose of dry powder, for instance a medication drug, by the breath of a person inhaling through a dry powder inhaler (DPI). The arrangement also controls the opening and closing of an air inlet in the inhaler. Particularly the arrangement according to the present invention is to be applied in a new continuous inhaler, i.e. an inhaler that controls the powder concentration and the time interval of the dose delivery to the user, thereby achieving a number of advantages in comparison to inhalers marketed today. The present arrangement requires a certain well-defined minimum pressure differential between a surrounding atmosphere and the airways of the inhaling person to trigger off the process of delivering the dose and to open an inlet for outside air to enter into the interior of the DPI. The arrangement controlling the triggering mechanism and the opening and closing of the inlet of air into the DPI presents a flap connected to a biased catch mechanism. The flap closes the air inlet of the DPI to the atmosphere by the force exerted by a spring, which acts on the flap through a mechanism of levers. In order to open the flap a force bigger than the closing force of the spring and lever mechanism must be applied. The necessary force ensues from the pressure differential across the flap resulting when the user sucks through the mouthpiece of the DPI to a certain degree. The catch is through the mechanism of levers released by the flap when the flap opens, and triggers a sequence of events constituting the irreversible process of administering a dose to the user upon his or hers inhalation through the inhaler. The mechanism of levers connecting the flap, the spring and the catch uses rounded shapes where moving parts are in contact with each other to minimize contact areas and rubbing effects and to achieve near zero friction losses. The biased flap is further provided with a counterweight accomplishing the flap and the catch-mechanism to be statically balanced, which almost completely eliminates the risk that external forces, e.g., force of inertia, gravitation or blows to the DPI accidentally will trigger the process of administering a dose if, for instance, the device should be dropped. An arrangement for triggering off a process of administering a dose of dry powder according to the present invention is set forth by the independent claim 1 and further embodiments of the arrangement are set forth by the dependent claims 2 to 8. DESCRIP ION OF THE DRAWINGS The invention will be described in the form of a preferred and illustrative embodiment and by means of the attached drawings wherein like reference numbers indicate like or corresponding elements and wherein: FIG. 1 illustrates a flow chart of a complete cycle of operating the dry powder inhaler with respect to the arrangement of the present invention; FIG. 2 illustrates a principal sketch of the biased flap and catch mechanism; FIG. 3 illustrates an embodiment of the internals of the inhaler, with a dosing . cassette, a flap, a spring and a catch mechanism after an inhalation operation has ended; FIG. 4 illustrates the embodiment of the internals of the inhaler, with the dosing cassette, the flap, the spring and the catch mechanism prior to an inhalation operation; FIG. 5 illustrates the embodiment of the internals of the inhaler, with the dosing cassette, the flap, the spring and the catch mechanism, the moment after the inhalation by the user has begun; FIG. 6 illustrates a principal sketch of the internals of the inhaler, with the dosing cassette, the flap, the spring and the catch mechanism, a few moments after the inhalation has started and the cassette is in motion; and FIG. 7 illustrates a principal sketch of how the rounded surfaces interact. DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT Figure 1 describes a complete cycle of operating an illustrative dry powder inhaler, DPI, by illustrating in a flow chart the actions performed by a user and the events these actions give rise to. Taking reference in the flow chart the operation of the present invention is illustrated. The starting point in Figure 1 is step 100, i.e. the DPI is in the open state where the DPI has delivered a dose to the user, who has stopped inhaling, which is also schematically illustrated in Figure 3. A movable dose member 4, carrying one or more pre-metered doses, is in the released state and a biased flap 16 is in the closed position, stopping air from entering the DPI through the air inlet, illustrated as vent holes 23. In a preferred embodiment the dose member 4 is a replaceable cassette containing a number of enclosed pre-metered doses of powder for inhalation purposes. In the next step 110 the DPI is put into the closed state, schematically illustrated in Figure 4. The cassette 4 is pushed back, sliding like a sleeve on a pillar, by the closing action performed by the user and brought in a position for delivering a next dose. When the DPI is closed a drive spring (not illustrated) is tensed, acting on the cassette 4, which is secured in this position by a plunger element (not illustrated). The catch 12 of the flap mechanism is forced into a mating notch in the cassette by the compression spring 13, thereby also locking the cassette 4 in a ready position. When the user according to step 120 then again opens the DPI to get access to the mouthpiece (not illustrated), the plunger element mentioned before is removed leaving only the catch 12 to hold the cassette 4 in position, ready to deliver a dose. As the user, in step 130, starts to inhale the flap 16 remains shut preventing air to flow into the inhaler and consequently the cassette 4 remains in its initial position until the pressure differential induced by the user's sucking creates an opening force F p on the flap 16 that is big enough to counteract the closing force F c . Fc is the resulting force on the flap of force F s from the compression spring 13, acting through the levers 28 to keep the flap 16 closed. The forces acting on the flap 16 directly and indirectly are summarized and compared in step 140. As soon as the user's suction is strong enough, which from the user's point of view is felt to be immediately after the inhalation begins, in step 150, the biased flap 16 is forced open, the catch 12 releases the cassette 4 so that it can be pushed forward by its drive spring (not illustrated) acting on the cassette with force F . This condition is schematically illustrated in Figure 5. In step 160 the cassette 4, now free to move, is propelled forward as schematically illustrated in Figure 6, at constant or variable speed as the case may be, with the object of delivering the dose continuously to the user. The air now inhaled picks up the powder of the pre-metered dose from the cassette 4 and brings the powder into the user's airways, lungs or deep lungs or a combination thereof depending on what is the overall objective for the inhalation. An illustrative embodiment of the invention is disclosed in Figure 2. The inlet of air into the body wall 8 of the DPI is illustrated as a number of vent holes 23, but the inlet can be realized in different ways in additional embodiments of the invention. If necessary to stop the ingress of dirt etc into the DPI an optional fine mesh filter (not illustrated) may be affixed to the air inlet. The flap 16 is pivoted in the body of the DPI preferably using low friction materials and arranged to minimize friction so that the flap can move freely. The flap 16 is fixed to a lever 26 as is further illustrated by Figure 7. The flap 16 in Figure 2 is pushed tightly against the inside of the DPI body wall 8 by the force given by the compression spring 13, which is acting on the flap 16 through the lever 28 over the rounded means 14 and through lever 26. The flap and the inner surface of the DPI body are preferably made such that the flap in the closed position effectively closes the inlet of air 23 into the DPI with as little leakage as possible. The lever 28 is pivoted in the body of the DPI preferably using low friction materials and arranged to minimize friction so that the lever can move freely. When the user begins to inhale through the mouthpiece (not illustrated) of the DPI the suction results in a building up of a pressure differential between the surrounding atmosphere and the airways of the user, such that the local pressure in the airways of the subject is lower than the atmospheric pressure. Since the flap 16 is closed at this stage air cannot flow through the vent holes 23 into the DPI, through the mouthpiece and into the mouth of the user. Depending on the efficiency of the flap 16 there is almost no flow of air past the flap, so that almost the full pressure differential is present across the front and back of the flap, which results in a force acting on the flap counteracting the closing force of the spring 13. When the differential pressure is big enough the resulting force F p acting to open the flap overcomes the closing force F 0 resulting from the spring force F s acting through the lever system 28 and 26 so that the flap opens and lets air into the DPI. By using a different spring 13 with a different rate or changing the positions of the pivot points for the levers 28 and 26 or by using a different lever geometry, or a combination of these methods, it is possible to adjust the closing force acting on the flap. In this way the required minimum force F p = Fm-nimum to open the flap can easily be chosen to suit the particular DPI and serve the objectives of the DPI to the best advantage. When the inhalation opens the flap the opening force acts through the lever 26 over the rounded surfaces 14 onto lever 28 and compresses the spring 13. The induced movement of lever 28 withdraws the catch 12, which is fixed to the lever, from its locking position. Then the cassette 4 held by the catch is made free to move, which is also indicated by Figure 5, where this state is schematically illustrated. By subsequently controlling the motion of the released cassette 4 the administration of the pre-metered dose will be controlled in an appropriate manner. In Figure 7 the rounded contact area 14 is disclosed in more detail. The rounded shapes of the contact area contribute strongly to the efficiency of the arrangement according to the present invention by transmitting power from lever 26 to lever 28 or vice versa almost without friction loss. The inevitable relative movement between the levers is not a rubbing action but a rolling action such that the point of contact moves like two cogs meshed in a gear wheel, resulting in very low friction loss. Preferably the materials and surface qualities of the rounded surfaces 14 are selected to further reduce friction and power loss in the materials. The illustrative embodiment of the invention in Figure 2 shows a counterweight 15 fixed to the same member as the flap 16 and the lever 26. Its construction and position relative the flap and the lever are such that it balances the masses of the flap and the lever statically, so that the center of gravity is in the center of the pivot. This will minimize the risk of forces of inertia, acting on the triggering mechanism, unintentionally activating the dose delivery process, e.g. if the DPI is dropped. Another counterweight 29, which is fixed to the same member as the lever 28, is fitted if necessary to balance the lever 28 in the same manner as described for the counterweight 15. It will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departure from the scope thereof, which is defined by the appended claims.

Claims: CLAIMS 1. An arrangement, in connection with an inhalation operation, triggering off the process of delivering a dose of powder and opening and closing an air inlet of a dry powder inhaler device (DPI) provided with a pre- metered dose member (4), characterized in a releasing means (12) for the dose member (4) actuated by a biased flap (16) via a joint (14) presenting very low friction loss, whereby when the biased flap is influenced by an air suction exceeding a threshold value counteracting an exerted force (F c ) acting on the releasing means, the biased flap opens the air inlet and the releasing means (12) sets the pre-metered dosing member (4) free for a powder administration operation for a controlled release of a metered powder dose to a user of the dry powder inhaler, whereby the biased flap (16) controls the air inlet of the dry powder inhaler, and acts as a valve opening or closing the air inlet. 2. The arrangement according to claim 1, characterized in that the joint (14) is positioned at a first end of a first lever (26) having a second end attached to the biased flap (16) at its pivoting center and at a first end of a second lever (28) carrying the releasing means and pivoted at a second end (27), the exerted force (F c ) forcing the lever (28) to move the releasing means to lock the pre-metered dosing member (4), the second lever then further via the joint (14) acting on the first lever (26) to force the biased flap (16) to the closed position. 3. The arrangement according to claim 2, characterized in that the joint (14) is formed by two rounded members making a point contact and in motion moving like two cogs meshed in a gear wheel to thereby present a low friction contact. 4. The arrangement according to claim 3, characterized in that the first lever (26) and/ or second lever (28) further at an end opposite to the joint (14) is provided with a counterweight (15; 29) for statically balancing the masses of the biased flap and levers of the arrangement. 5. The arrangement according to claim 1, characterized in that the biased flap (16) in its closed position makes an inlet opening or several inlet openings (23) in the inhaler body wall (8) airtight from a user's point of view. 6. The arrangement according to claim 1, characterized in that the pre-metered dosing member (4) is biased for a longitudinal or rotating motion or a combination thereof upon its release by a driving force, which is tensed by a closing of the inhaler device case. 7. The arrangement according to claim 1, characterized in that the pre-metered dosing member (4) is a replaceable cassette containing a number of enclosed pre-metered doses of powder for inhalation purposes. 8. The arrangement according to claim 1, characterized in that the closing force (F c ) acting on the second lever (28) and via the joint (14) acting on the first lever (26) to force the biased flap (16) to the closed position can be widely adjusted by arranging a different biasing for obtaining the closing force (F c ) or by changing the pivot points or the geometry of the interacting levers (28) and (26) or a combination thereof.

Inventors: GRAESSL HERBERT, MYRMAN MATTIAS, GRAESSL, HERBERT, MYRMAN, MATTIAS
Applicants: GRAESSL HERBERT, MICRODRUG AG, MYRMAN MATTIAS, GRAESSL, HERBERT, MYRMAN, MATTIAS
Application year: 2001
Main classification: A61M15
IPC codes: A61M15