WO2009029029A1

WO2009029029A1 - Inhaler for powdered substances with desiccant compartment

Info

Publication number: WO2009029029A1
Application number: PCT/SE2008/050948
Authority: WO
Inventors: Nicholas John Bowman; David Robert Gale
Original assignee: AstraZeneca AB
Current assignee: AstraZeneca AB
Priority date: 2007-08-24
Filing date: 2008-08-22
Publication date: 2009-03-05
Anticipated expiration: 2010-02-24

Abstract

The invention relates to an inhaler for powdered substance. The inhaler comprises an airflow passage for guiding substance towards an outlet, a substance storing chamber from which substance is provided to the airflow passage, a pressurizable space for establishing an air overpressure in the airflow passage for delivering substance present in the airflow passage to the outlet, a desiccant-containing compartment from which air is enabled to flow to the pressurizable space in order to replenish expelled air, and a filter provided in the desiccant-containing compartment, wherein air flowing from the desiccant- containing compartment to the pressurizable space passes through the filter.

Description

Inhaler for powdered substances with desiccant compartment

Technical field

The present invention relates to an inhaler for powdered substance, from which substance is inhalable by a user.

Background of the Invention

There are different types of inhalers on the market. A pressurized Metered Dose Inhaler (pMDI) releases a fixed dose of substance in aerosol form. Such an inhaler generally comprises a canister with particulate medicament suspended in propellant gas. For environmental reasons, it is desirable to reduce the use of certain propellant gases. Therefore, powder inhalers, which generally release a dose of powdered substance entrained in an air stream, have gained popularity. Powder inhalers commonly comprise a desiccant (drying agent) to reduce the risk of moisture negatively affecting the quality of the powdered substance. While pMDIs have a propellant gas which carries the substance to the user's airways, powder inhalers generally require an inhalation effort by the user to create the air stream in which the powdered substance is entrained. For some users, such an inhalation effort may be challenging. International patent applications PCT/EP2007/052172 and PCT/EP/2007/052178 (AstraZeneca AB) illustrate examples of some recently developed powder inhalers.

Summary of the Invention

The present invention is based on the insight that a powder inhaler can be provided which, similarly to pMDIs, use a propellant gas to provide the substance to the user's airways. The invention is also based on the insight that by using, as said propellant gas, external air which is dried by a desiccant that is kept from following the air stream to the user's airways, a user and environmental friendly alternative can be provided. Thus, air may be used as a propellant gas and the inhaler may then be replenished with air from outside the inhaler. According to at least one aspect of the invention, an inhaler for powdered substance is provided, such as a pharmaceutical substance or a plurality of pharmaceutical substances which are provided separately or in mixture. The inhaler comprises an airflow passage for guiding substance towards an outlet, such as an inhalation interface in the form of a mouthpiece or nasal adaptor. The inhaler further comprises a substance storing chamber from which substance is provided to the airflow passage. The inhaler also comprises a pressurizable space for establishing an air overpressure in the airflow passage for delivering substance present in the airflow passage to the outlet. A desiccant-containing compartment is provided from which air is enabled to flow to the pressurizable space in order to replenish expelled air and a filter is provided in the desiccant-containing compartment, wherein air flowing from the desiccant-containing compartment to the pressurizable space passes through the filter.

Thus, after each use, the inhaler may be replenished with ambient air, which when entering the inhaler, at an early stage (before reaching the pressurizable space) is dried, therefore reducing the risk of incoming ambient air negatively affecting the quality of the powdered substance. The desiccant-containing compartment may be arranged in fluid communication with the ambient air outside the inhaler in various ways. By providing a filter in the desiccant-containing compartment, the risk of desiccant particles entering the pressurizable space is also reduced. Such a filter can be designed in various ways. For instance, it may be designed as an element covering a passageway between the desiccant- containing compartment and the pressurizable space. Another alternative would be to provide a filter in the form of a bag or net which encloses the desiccant particles.

According to at least one example embodiment of the invention, the desiccant- containing compartment is provided with an opening through which air can flow to the pressurizable space, wherein a one-way valve is provided at the opening to prevent air from flowing from the pressurizable space to the desiccant-containing compartment. Thus, by avoiding a bleeding of airflow through the opening to the desiccant-containing compartment, the overpressure established in the pressurizable space can be concentrated to the airflow passage for causing the powdered substance to be delivered to the outlet. The provision of a filter not only reduces the risk of desiccant entering the pressurizable space, and consequently the airflow passage, but may also reduce the risk of desiccant clogging the above-mentioned one-way valve. This is reflected in at least one example embodiment of the invention, wherein the filter is provided adjacent the opening. As previously mentioned, there are various ways of designing a filter. While from a space- saving perspective it may be advantageous to provide the filter adjacent the opening, an alternative would be to provide the filter more remotely from the opening, but in such way that it has a desiccant-obstructing function. Thus, in said example embodiment and said alternative embodiment, various designs and locations of the filter are conceivable as long as the flow path of the incoming ambient air is such that it reaches the filter before it reaches the one-way valve.

According to at least one example embodiment of the invention, the pressurizable space comprises said airflow passage, wherein said opening extends from the desiccant- containing compartment to the airflow passage. Thus, the desiccant-containing compartment is arrangable in fluid communication with the airflow passage.

It is conceivable to provide the desiccant-containing compartment near the substance storing chamber, in order to protect the substance from moisture ingress. In fact, it is conceivable to provide a well-kept desiccant within the substance storing chamber. However, as an alternative to placing the desiccant-containing compartment near the substance storing chamber, an alternative or a complement would be to have a desiccant containing compartment distanced from the substance storing chamber. According to at least one example embodiment of the invention, the substance storing chamber is located on one side of the airflow passage and the desiccant-containing compartment is located on the other side of the airflow passage. The incoming ambient air replenishing the fired inhaler, will suitably enter at the same side of the airflow passage as the desiccant- containing compartment, thus distanced from the substance storing chamber, reducing the risk of moisture from that incoming air ingressing to the substance storing chamber.

The inhaler may be designed in various way for enabling the replenishing air to be introduced. According to at least one example embodiment of the invention, the desiccant- containing compartment is via a mouthpiece or nasal adaptor of the inhaler in fluid communication with the atmosphere outside the inhaler, whereby air is enabled to flow from outside the inhaler via the mouthpiece or nasal adaptor and then via the desiccant- containing compartment to the pressurizable space in order to replenish expelled air. Although the above-described example embodiment discusses introduction of air through a mouthpiece or nasal adaptor, an alternative would be to arrange the desiccant-containing compartment in fluid communication with the atmosphere outside the inhaler via an air inlet in the inhaler housing, whereby air is enabled to flow from outside the inhaler via the air inlet and the desiccant-containing compartment to the pressurizable space in order to replenish expelled air. According to at least one example embodiment of the invention, the inhaler comprises a transfer member which is displaceable in the substance storing chamber. The transfer member comprises at least one dosing chamber for taking up substance inside the substance storing chamber, the transfer member being displaceable between a substance- keeping position in which the dosing chamber keeps the substance and a substance- evacuating position in which the dosing chamber presents the substance to the airflow passage, wherein, when the transfer member is in said substance-evacuating position, the dosing chamber is evacuated by the air overpressure in the airflow passage. Thus, the dosing chamber is arranged to travel from inside the actual substance storing chamber to the airflow passage. Suitably, though not necessarily, the displacement of the transfer member from the substance-keeping position to the substance-evacuating position describes a linear motion, that is, moves in a straight direction.

The pressurizable space, including the airflow passage, may be closed in various ways for maintaining the overpressure. As mentioned previously, a one-way valve may be provided for preventing bleeding to the desiccant-containing compartment. The above- mentioned transfer member may also act as or be part of a closure. Thus, according to at least one example embodiment of the invention, said transfer member in its substance- keeping position extends through the airflow passage to close said pressurizable space and to maintain the overpressure until the transfer member is displaced to its substance evacuating position. In the latter position the dosing chamber presents the substance to the airflow passage and the air overpressure. The release of the overpressure causes a stream of air to entrain the substance and deliver it to the outlet (e.g. mouthpiece or nasal adaptor). Suitably, in the substance-evacuating position of the transfer member, the dosing chamber will be located within the airflow passage so as to form part of the flow path. This may be arranged in various ways, one of which being designing the dosing chamber as a cross hole through the transfer member so that the stream of air will be led through the transfer member to entrain the substance.

According to at least one example embodiment of the invention the inhaler comprises an inhaler housing and an actuator. The actuator comprises an action button protruding from the inhaler housing, the action button being displaceable against a return spring, wherein the overpressure is established when the action button is displaced in the inhaler housing, which overpressure, through the displacement of said transfer member, is used in the flow passage for the discharge of substance. The action button may be adapted to be linearly displaced, e.g. by depression thereof. However, the actuator may be provided with various other means for establishing the overpressure. For instance, instead of a linearly depressible action button, the actuator may be provided with a rotating mechanism which, when rotated (e.g. like a tightening screw), reduces the volume of the pressurizable space, thereby establishing the overpressure.

Apart from being used in the function of establishing an overpressure, the actuator may suitably be operatively connected to the transfer member for displacing it from the substance-keeping position to the substance-evacuating position. According to at least one example embodiment of the invention, the actuator, when actuated, causes the overpressure to be established first and then after a brief idling causes the transfer member to be displaced. According to at least one other example embodiment of the invention, the actuator, when actuated, causes the overpressure to be established and subsequently or simultaneously causes the transfer member to become biased towards the substance- evacuating position. In the latter example embodiment the transfer member can, when desired, be released by a release mechanism, e.g. an inhalation triggered-release mechanism. Even though the above-mentioned release mechanism may be operated by hand, it may suitably be triggered by the user's inhalation in order to coordinate the inhalation with the discharge of the substance from the inhaler. This is reflected by at least one example embodiment of the invention, wherein the established overpressure in the pressurizable space is released by an inhalation-triggered release mechanism when a user inhales through a mouthpiece or nasal adaptor of the inhaler.

Although the overpressure in the pressurizable space according to the above-described embodiment could have a release mechanism which is triggered separately from the release mechanism for unlatching the transfer member, the inhaler may suitably use one and the same triggering for releasing the overpressure and unlatching the transfer member. A common triggering may facilitate the timing for entraining the substance into the airflow caused by the released overpressure. In the example embodiment in which the transfer member in its substance-keeping position extends through the airflow passage to close said pressurizable space and to maintain the overpressure until the transfer member is unlatched by the inhalation- triggered release mechanism, the overpressure will automatically be released when the release-mechanism unlatches the transfer member upon inhalation by a user.

The inhalation effort required by the user for triggering the inhalation-triggered release mechanism may be chosen depending on e.g. age of user and type of therapy. The inspiratory air flow threshold to be overcome may be chosen by appropriate design of e.g. inertia and resistive force acting upon the release mechanism.

The inhaler may have several suitable locations for arranging the inhalation- triggered release mechanism. The transfer member could be latched in various ways, e.g. having protrusions or indentations mating with complementary features of the release mechanism. Another example could be that the release mechanism comprises a gripping means which may be closed and open for latching and releasing the transfer member. Yet another example could be that the release mechanism simply stands in the way of the transfer member, preventing it from further displacement until the release mechanism is out of the way. When using the above-described action button in combination with an inhalation- triggered release mechanism, the action button could optionally be latched to maintain the overpressure until the user inhales. After inhalation, the action button may then become automatically or manually unlatched and return to its starting position. Alternatively, a user could keep the action button depressed with a finger until he or she inhales.

Even though gravitational force may be used for making the transfer member drop to its substance-evacuating position when unlatched by the release mechanism, it may be desirable to use some other force which is less dependent of the spatial orientation of the inhaler. Thus, according to at least one example embodiment of the invention, the inhaler comprises a biasing mechanism adapted to bias the transfer member towards the substance- evacuating position, the transfer member being latched in the substance-keeping position by said inhalation-triggered release mechanism which, when a user inhales through the mouthpiece or nasal adaptor, unlatches the transfer member, thereby enabling it to move to the substance-evacuating position. The biasing mechanism could be activated electronically or mechanically. The biasing mechanism could provide the force by a manually maintained pressure, e.g. the user pressing and keeping his/her finger on the biasing mechanism (e.g. comprising said actuator with action button) so as to provide the force urging the transfer member to the substance-evacuating position. Rather than keeping a manual pressure, the biasing mechanism may have some kind of latch for maintaining the bias on the transfer member even after the user has let go of the biasing mechanism. The biasing mechanism may suitably comprise a spring acting on the transfer member. According to at least one example embodiment of the invention, the dosing chamber is located inside the substance storing chamber when the transfer member is latched by the release mechanism in said substance-keeping position and biased towards the substance-evacuating position by the biasing mechanism. Thus, when the inhaler is primed, i.e. in a loaded state ready for inhalation, the substance is kept safely inside the substance storing chamber, or more specifically, the substance is kept inside the dosing chamber which in turn is located inside the substance storing chamber. This arrangement reduces the risk of contamination. Furthermore, the inhaler may be provided with a feature that allows the biasing of the biasing mechanism to be cancelled if a user changes his/her mind and does not want to use the inhaler at present. The substance will then still be kept safe in the substance storing chamber.

Although the above-described example embodiment discusses the dosing chamber being located in the substance storing chamber when the inhaler has been primed, an alternative would be to arrange said substance-keeping position of the transfer member in such way that the dosing chamber is located in an intermediate conduit or the like between the substance storing chamber and the airflow passage, which could still provide a safely shielded location. Thus, the priming could comprise introducing substance into the dosing chamber, displacing the transfer member so that the dosing chamber is moved from the substance storing chamber to said intermediate conduit (the transfer member becomes latched after said displacement) and biasing the transfer member towards the substance- evacuating position. Alternatively, the transfer member may be displaced only a short distance before becoming latched so that the dosing chamber, even though moved, still remains located inside the substance storing chamber. As mentioned previously, the biasing mechanism may be configured in various ways. According to at least one example embodiment of the invention, the biasing mechanism comprises said actuator which is movable towards the transfer member and a spring which is compressible between the actuator and the transfer member, whereby movement of the actuator towards the transfer member, when the transfer member is latched in the substance-keeping position, causes the transfer member to become spring- loaded. Other alternatives to providing a spring between the actuator and the transfer member are conceivable. For instance, there could be provided a hydraulic arrangement, such as comprising a piston movable in a cylinder, for transmitting the biasing force. While a simple linear movement of the actuator towards the transfer member is readily envisaged, there may also be alternatives, such as rotating the actuator (e.g. like a tightening screw)

As mentioned previously the substance storing chamber and the desiccant- containing compartment may be located on respective sides of the airflow passage. Similarly, according to at least one example embodiment of the invention, the substance storing chamber is located on one side of the airflow passage and the inhalation-triggered release mechanism is located on the other side of the airflow passage, wherein the transfer member extends through the airflow passage. Thus, the inhalation-triggered release mechanism and the desiccant-containing compartment may be located on the same side of the airflow passage.

For the case in which the transfer member extends through the airflow passage, the release mechanism may suitably comprise an abutment surface for receiving one end of the transfer member and latching the transfer member in the substance-keeping position. Although the abutment surface may simply be a surface which stands in the way of the travel direction of the transfer member and suitably mating with an end portion of the transfer member, the abutment surface could alternatively engage with other portions and features of the transfer member as mentioned previously.

According to at least one example embodiment of the invention, the release mechanism comprises a movable member being movable from a relaxed position, in which the release mechanism is kept in a latching state, to an energized position in which the release mechanism is caused to be displaced to a releasing state, wherein a first side of the movable member partly defines a first volume which is in fluid communication with the mouthpiece or nasal adaptor, wherein, when a user inhales through said mouthpiece or nasal adaptor, an underpressure is established in said first volume causing the movable member to move from the relaxed position to the energized position. Optionally, the release mechanism may comprise a return spring for urging the release mechanism to the latching state. Such a return spring may be provided in various configurations. One example is a leaf spring, another example is a coil spring. In the case of the release mechanism having a return spring or the like, the energizing force on the movable member will work against the force of the return spring. Thus, the design of the return spring and the movable member should be suitably balanced so that when a user inhales above a certain airflow threshold, the force of the return spring is overcome by the movable member and causes the release mechanism to unlatch the transfer member.

Instead of having a spring for urging the release mechanism to the latching state, other means for returning the release mechanism may be provided. For instance, various types of elastic bodies, hydraulic means or pneumatic means are conceivable alternatives, or some other components that can at least temporarily store energy developed when the release mechanism moves from the latching state to the releasing state. Furthermore, another alternative would be to manually affect the release mechanism to return to its latching state.

According to at least one example embodiment of the invention, the movable member is a diaphragm which is flexed to the energized position upon inhalation by a user. Suitably, the release mechanism comprises a pivotable rocker having an abutment surface for latching the transfer member, wherein the diaphragm is operatively connected to the rocker so that, when the diaphragm is flexed, the rocker is pivoted to said releasing state of the release mechanism. According to at least one example embodiment of the invention, said movable member is a flap which is pivoted to the energized position upon inhalation by a user.

According to at least one example embodiment of the invention, a second side of the movable member, opposite to said first side, partly defines a second volume which is in fluid communication with the atmosphere surrounding the inhaler. When the movable member is moved in response to the underpressure in the first volume, air will be allowed to flow into the second volume on the other side of the movable member, thereby keeping the second volume at atmospheric pressure even if the second volume is increased upon movement of the movable member, thus avoiding counteracting the movement caused by the underpressure in the first volume. The second volume may be small or, alternatively, even infinitesimal if the movable member would form part of the exterior wall portion of the inhaler housing.

Although the above-described example embodiments discuss a defined volume in which underpressure is created to cause movement of the movable member, an alternative or a complement would be to provide an extra flow channel through which the inspiratory flow may propagate and impart its kinetic energy to a movable member which causes the release mechanism to be displaced to its releasing state.

The actuator has hitherto been described as being used for one or two functions, namely for creating an overpressure in the pressurizable space and, optionally, for urging the transfer member towards the substance-evacuating position. In addition, to these functions, the actuation of the actuator may also be used for promoting substance to enter the dosing chamber. Thus, according to at least on example embodiment of the invention, the actuator, when actuated, causes at least a wall portion of the substance storing chamber to move towards the transfer member so that substance is urged into the dosing chamber. Suitably, the transfer member remains unmovable in the substance-keeping position while substance is urged into the dosing chamber. Although the use of the actual substance storing chamber wall for promoting substance to enter into the dosing chamber may be advantageous, alternative example embodiments could include other promoting means. For instance, the actuator could be connected to one or more pushers inside the substance storing chamber, wherein the substance would be pushed into the dosing chamber upon actuation of the actuator. Although the above-described example embodiments encompass the actuator to be involved in three different functions, an alternative would be to provide two or three separate actuators for said functions.

According to at least one example embodiment of the invention, the substance storing chamber wall, consisting of an elastic material, curves in the direction towards the transfer member when the inhaler is actuated. Suitably, the substance storing chamber wall, at least in the dosing chamber region, curves into contact with the transfer member. Press pieces may be provided for curving of the substance storing chamber wall. The press pieces may be provided with cheeks which have impinging surfaces which, in a fully in- turned position of the press pieces, are positioned parallelly to the broadside wall surfaces of the transfer member, if e.g. comprising a flat bar. Suitably, the actuator, or an action button comprised in the actuator, via bevels, pivots the press pieces in the direction towards the transfer member.

According to at least one example embodiment of the invention, the transfer member comprises a rod which is displaceable in its longitudinal (lengthwise) direction. Thus, a dose will be taken up from the substance storing chamber and then, be moved substantially in a straight uncurved direction to the flow passage. The dosing chamber may be incorporated as an integral part of the rod. However, it would also be conceivable to have a separate dosing chamber which is connected to the rod. In either case, the straight movement from the substance storing chamber is achievable. Although the above-described example embodiment discusses a rod which is displaceable in its longitudinal direction, a rotational displacement or pivoting displacement of the rod would also be conceivable depending on the configuration and placement of the substance storing chamber and the airflow passage. Furthermore, instead of or as a complement to a rod, the transfer member may comprise component shapes, such as polygonal or circular. For instance, a rotatable wheel may take up the substance from the substance storing chamber and then, rotate to present the substance to the airflow passage.

As previously mentioned, the dosing chamber may be designed as a cross hole of the transfer member. Additionally, the transfer member may have several dosing chambers consecutively located at the transfer member, which during a dispensing action are successively presented to the airflow passage and are, piece by piece, evacuatable by an overpressure in the airflow passage. In the case of the transfer member comprising a rod, the dosing chambers, suitably in the form of cross holes, would be positioned after each other in the travel direction of the rod, i.e. in its longitudinal extension. The rod may have a circular cross section or polygonal cross section. Suitably, a part of the transfer member, or the actual rod itself, is designed as a flat bar. A flat bar may be advantageous if means are provided for urging substance into the dosing chamber, wherein such means would easily land against the flat bar surface. The inhaler may contain various substances, such as drugs and/or bioactive agents to be inhaled.

The bioactive agent may be selected from any therapeutic or diagnostic agent. For example it may be from the group of antiallergics, bronchodilators, bronchoconsitrictors, pulmonary lung surfactants, analgesics, antibiotics, leukotrine inhibitors or antagonists, anticholinergics, mast cell inhibitors, antihistamines, antiinflammatories, antineoplastics, anaesthetics, anti-tuberculars, imaging agents, cardiovascular agents, enzymes, steroids, genetic material, viral vectors, antisense agents, proteins, peptides and combinations thereof.

Examples of specific drugs which can be incorporated in the inhaler according to the invention include mometasone, ipratropium bromide, tiotropium and salts thereof, salemeterol, fluticasone propionate, beclomethasone dipropionate, reproterol, clenbuterol, rofleponide and salts, nedocromil, sodium cromoglycate, flunisolide, budesonide, formoterol fumarate dihydrate, Symbicort (budesonide and formoterol), terbutaline, terbutaline sulphate, salbutamol base and sulphate, fenoterol, 3-[2-(4-Hydroxy-2-oxo-3H- 1 ,3-benzothiazol-7-yl)ethylamino]-N-[2-[2-(4- methylphenyl)ethoxy]ethyl]propanesulphonamide, hydrochloride. All of the above compounds can be in free base form or as pharmaceutically acceptable salts as known in the art.

Combinations of medicaments may also be employed, for example formoterol/budesonide; formoterol/fluticasone; formoterol/mometasone; salmeterol/fluticasone; formoterol/tiotropium salts; zafirlukast/formoterol, zafirlukast/budesonide; montelukast/formoterol; montelukast/budesonide; loratadine/montelukast and loratadine/zafirlukast.

Further combinations include tiotropium and fluticasone, tiotropium and budesonide, tiotropium and mometasone, mometasone and salmeterol, formoterol and rofleponide, salmeterol and budesonide, salmeterol and rofleponide, and tiotropium and rofleponide.

Brief description of the drawings Figs. Ia- Id illustrate the operation of an example embodiment of the invention.

Fig. 2 illustrates another example embodiment of the invention.

Detailed description of the drawings

In order to clarify the description, terms such as "up", "upwardly", "down", "downwardly", "vertical", "horizontal", etc. are sometimes used: these terms are not limiting and serve merely to facilitate understanding of the drawings.

Figs. Ia- Id illustrate the operation of an example embodiment of the invention. Beginning with Fig. Ia, a vertical section through an inhaler 2 for powdered substance is illustrated. The inhaler 2 comprises a cylindrical housing 4 from which a substantially radially projecting mouthpiece 6 originates. The inhaler 2 comprises an actuator in the form of an action button 8 arranged at the top of the housing 4 and an opposite surface 10 at the bottom of the housing 4, a general geometrical housing axis x extending therebetween. By displacement of the action button 8 along the axis x in the direction towards the opposite surface 10, a substance output becomes obtainable.

The housing 4 is formed as a hollow cylindrical body, with a circular horizontal projection in the shown embodiment. Also other shapes, different from this shape with a circular horizontal projection, are conceivable, for example elliptical or multi-cornered/- angled shapes. The circular-cylindrical external inhaler housing 12 is closed at the base by an inhaler bottom 14, which forms the opposite surface 10 for the actuation of the inhaler 2. At the side opposite to this bottom 14, the housing 4 is openly designed.

In the base region of the housing 4, the mouthpiece 6 protrudes therefrom in a substantially radial orientation, more specifically in the shown example embodiment, with the inclusion of an acute angle of about 75 to 80° to the inhaler axis x, which mouthpiece 6 is substantially formed as a hollow cylinder body with an orifice pointing axially outwards with regard to the orientation of the mouthpiece 6. A mouthpiece bottom 16, arranged in the transition region from the housing 4 to the mouthpiece 6, has a central opening 18.

When the inhaler 2 is not in use, the mouthpiece 6 may be covered by a cover, in this example illustrated as a screw cap 20. When the inhaler 2 is to be used, the user removes the screw cap 20.

As an alternative to the illustrated example embodiment, it would be conceivable to provide a nasal adaptor instead of the mouthpiece 6. Suitably, instead of sloping downwardly like the illustrated mouthpiece 6, such a nasal adaptor would slope upwardly in relation to the vertical inhaler axis x, thus with the inclusion of an angle to the longitudinal axis x from about 45°.

Returning to the illustrated example embodiment in Fig. Ia, the housing 4 is divided transversely to the axis x by a support 22 attached to the internal wall of the housing 4 on the level of the transition from the housing 4 to the mouthpiece 6. The disc- shaped solid support 22 has a central recess 24, in which a sealing element 26 consisting of a thermoplastic material is inserted. This sealing element 26 is positioned in the recess 24 in a plug-like manner.

The sealing element 26 is provided with an airflow passage 28 which is orientated substantially linearly transversely to the axis x, which airflow passage 28, on both sides, is continued going through the support 22. The airflow passage 28 extends on one side of the sealing element 26 through the support 22 to the central opening 18 of the mouthpiece bottom 16. In the opposite direction, with regard to the sealing element 26, the airflow passage 28 goes, with a widening of its cross-section, to an upper housing section separated by the support 22. The airflow passage orifice 30 is formed on the broad surface of the support 22, which is turned towards the upper housing section.

Consequently, the airflow passage 28 is divided into a passage section on the mouthpiece side and a section on the housing side. In the latter one, the passage orifice 30 is formed. Furthermore, in this section, an after-flow opening 34 is provided, which is opposite the passage orifice 30. The after-flow opening 34 forms a connection between the on-the housing-side section of the airflow passage 28 and a lower space provided by a desiccant-containing compartment 36 formed under the support 22. This after-flow opening 34 is covered by a one-way air inlet valve 38 which is switched such that the after- flow opening 34 is only opened upon an airflow from the desiccant-containing compartment 36 through the airflow passage 28 in the direction of the upper housing section. In the opposite airflow direction, the valve 38 closes this after-flow opening 34. A filter element 33 is provided for reducing the risk of transferring desiccant 37 from the desiccant-containing compartment 36 to the airflow passage 28 when air flows through the after-flow opening 34, and also for reducing the risk of desiccant 37 clogging the valve 38 and preventing it from closing effectively. The airflow passage 28, particularly in the region of the sealing element 26 and the section turned to the mouthpiece 6, is designed essentially smaller than the free cross- section of the mouthpiece 6. Thus, the diameter of the internal space of the mouthpiece 6 corresponds to about ten to thirty times the diameter of the airflow passage, the latter of which is tapered, particularly from the sealing element 26 in the direction of the opening 18 on the mouthpiece side, in the region of a slopingly downward-extending section, for the forming of a nozzle-type duct.

The sealing element 26 merges, in one piece and materially homogeneous, into a funnel-shaped substance storing chamber 40 facing the upper housing section, the substance storing chamber 40 having upwards, i.e. in the direction of the housing opening at the front side, a widening cross-section. The substance storing chamber 40 consists also of a thermoplastic elastomer or another rubber-type material.

The upper end of the substance storing chamber 40, having an expanded diameter, is sealed off by a rolling bellows 42 forming a cover of the substance storing chamber 40. A micronized powdered substance 44 is stored in the substance storing chamber 40, which substance 44 is inhaled in a portioned output by means of the exemplified arrangement.

Dosing chambers 46 are provided for the portioned output of the substance 44, three in the illustrated example embodiment. The size of each dosing chamber 46 defines the output substance quantity.

The dosing chambers 46 are formed as cross holes of a centrally along the axis x extending transfer member 48, herein illustrated as comprising a connector 50 attached to the upper end portion of a rod 52 formed as a flat bar. The cross holes go through the broad side wall surfaces of the flat bar, whereby this in cross-section has a width/length ratio from 1 :5 to 1 :20. In the shown embodiment, a flat bar thickness of about 0.5 mm is chosen, with a crosswise measured length of about 3 to 3.5 mm. The diameter of the cross holes is chosen, such that a formed dosing chamber 46 hosts from 0.05 mg to 0.1 mg.

The rod 52, with the dosing chambers 46, goes through the substance storing chamber 40 centrally in the direction of extension of the axis x. At the bottom of the substance storing chamber 40, the rod 52 further goes through the sealing element 26 with the crossing of the airflow passage 28 formed therein, as a result of this embodiment, by means of the rod 52, a closure of the airflow passage 28 is firstly attained.

In the hereto opposite direction, the transfer member 48 comprising the rod 52 extends upwardly via the substance storing chamber 40, with the passing through the rolling bellows 42, which is attached to the connector 50 of the transfer member 48. The dosing chambers 46, evenly spaced to each other and consecutively located in the longitudinal extension of the rod 52, are, in an initial position of the inhaler 2 according to the view of Fig. Ia, positioned in the lower third of the substance storing chamber 40, surrounded by the stored substance 44. The distance between the dosing chambers 46 corresponds substantially approximately to the diameter of a cross hole forming a dosing chamber.

The connector 50 extending upwardly from the substance storing chamber 40 has a mushroom-shaped head 54. This is captured by towing arms 56 formed on the underside of the action button 8. Between the towing arms 56, a biasing coil spring 58 extends from the action button 8 to the head 54 of the connector 50.

The action button 8 extending substantially transversely to the inhaler axis x merges into a cylindrical section formed concentrically with the axis x and with a pot-shaped wall 60 which, with its opening, is downwardly dipping into the housing 4. The external diameter of the wall 60 is adapted to the internal diameter of the cylindrical housing section 12. The action button 8 is with its wall 60 insertable into the housing 4 when guided through the cylindrical section 12, with stop limitation in every end position.

The movement area of the action button 8 is sealed off by a rolling bellows 62 which rolls into a gap between the action button 8 and the housing 4.

In the region of free end of the action button wall 60, which free end extends into the housing 4, a circumferential nut is provided in the external mantle wall, for housing a piston ring 64 consisting of an elastomeric material, which for sealing goes towards the inner wall of the cylindrical housing section 12.

The initial position of the action button 8 according to the view of Fig. Ia, is supported by a return coil spring 66 acting on the underside of the action button 8, which spring 66 surrounds the connector 50 of the transfer member 48 and the towing arms 56 of the action button 8, and is supported at its other side by a holder 68 which holds the upper portion of the substance storing chamber 40 and its associated covering rolling bellows 42. In this initial position, the two concentric coil springs 58, 66 are in their relaxed uncompressed state. In the path of displacement of the action button wall 60 come wedge-shaped connecting protrusions 70 with upwardly pointing bevels 72 of two diametrically opposite supporting arms 74 which support radially inwardly projecting press pieces 76 in the lower free end region. The arms 74 and the radially inwardly pointing impinging surfaces 78 of the press pieces 76 forming cheeks 80 extend in a horizontal projection respectively in a cross- section through the inhaler 2 parallelly spaced to a broadside surface of the rod 52. Correspondingly, the impinging surfaces 78 are positioned turned to the broadside surface of the rod 52, whereby the impinging surfaces 78 are evenly formed. Particularly the arms 74, further particularly the hinge region 82 on the circular annular support are, with regard to the choice in material and/or with regard to the material thickness, chosen such that a radial pivoting about the hinge region 82 in the direction of the axis x is allowed. The resilient properties of the chosen plastic material are used for the self-acting return of the arms 74 to the original position. The length of the arms 74, measured in the axial direction, is chosen such that the press pieces 76, provided on the end side, extend approximately at the level of the lower third of the storing chamber 40.

When a user pushes the action button 8, it is slidingly lowered into the housing 4 along the axis x, as illustrated in Fig. Ib. The housing 4 and, conditioned by the sealing via the piston ring 64, the pot shaped action button 8 form a compressed-air cylinder C, in which, in connection with the lowering of the action button 8, an air overpressure is produced. The internal underside of the action button 8 forms hereby a piston surface.

Thereto, in connection with the downward movement, the connecting protrusions 70 are impinged via the front edge of the wall 60 provided with a chamfer, which with a further lowering of the action button 8 results in a pivoting of the arms 74 about the hinge region 82. As a result of this, the press pieces 76 pivot, in a radial and inward direction, around a radius to the hinge region 82 with the curving of the substance storing chamber wall 84 to the filling position according to the view of Fig. Ib, in which the impinging surfaces 78 reach to parallel orientation to each other and to the broadside surfaces of the rod 52, in which position, at the intermediate position of the storing chamber wall sections, substance portions are pushed into the dosing chambers 46. The substance, present on both sides of the dosing chamber openings in the initial position of the inhaler 2, is pushed into the cross holes by means of the substance storing chamber wall 84 and the press pieces 76 acting on this, whereupon, particularly with a micronized powdered substance, a self- retaining in the dosing chambers 46 is provided.

The curving of the substance storing chamber wall 84 for the pushing of substance 44 into the dosing chambers 46 is supported by the air overpressure produced in the compressed-air cylinder C in connection with this procedure.

Even though not shown in the drawings, the action button 8 could be held in the depressed position by a latching means. Alternatively, the user could keep his finger on the depressed action button 8.

As the action button 8 is pushed downwardly the biasing coil spring 58 will become compressed and exert a downwardly-directed force on the transfer member 48. However, at this stage, due to a latching inhalation-triggered release mechanism arrangement 86, the transfer member 48 will remain in this substance-keeping position and the dosing chambers 46 will be kept safely inside the substance storing chamber 40.

In the illustrated example embodiment, the inhalation-triggered release mechanism 86 comprises a movable member, herein shown as a flap 88, which is mounted to a circular bearing 90 around which it can pivot. The inhalation-triggered release mechanism 86 further comprises a blade spring 92 urging the flap 88 towards the latching state shown in Figs. Ia-Ib. The bearing 90 is provided with a bore which, in the latching state, is in register with a recess in the mounted end portion of the flap 88. The rod 52 extends through the bore and to the bottom of the recess which forms an abutment surface 94. The abutment surface 94 thus prevents the rod 52 from being displaced under the force of the biasing spring 58.

In this latching state, the flap 88 extends from the circular bearing 90 substantially along the axis x and its free end portion is pressed by the blade spring 92 against a projection 96 from the inhaler bottom 14. In this latching state the flap 88, the projection 86 and the inhaler housing define a first volume Vl on the mouthpiece-side of the flap 88 and a second volume V2 on the opposite side of the flap 88. The first volume Vl is in fluid communication with the mouthpiece 6 via a first opening 98 and the second volume V2 is in fluid communication with the atmosphere surrounding the inhaler 2 via a second grille- formed opening 100.

When the user inhales through the mouthpiece 6, an underpressure is established in the first volume Vl and causes the flap 88 to pivot around the circular bearing 90 towards the mouthpiece 6 against the force of the blade spring 92. This is illustrated in Fig. Ic. The flap 88 could in its relaxed state completely separate the first volume Vl from the second volume V2, and as the flap 88 starts opening due to the underpressure, the air will also be enabled to flow from the second volume V2 to the first volume Vl across the flap 88 for further assisting the pivoting of the flap 88. Alternatively, the flap 88 may only partially separate the two volumes Vl, V2, wherein, when a user inhales the underpressure and the flow from the second volume V2 will together cause the flap 88 to open. The pivoting of the flap 88 results in that the recess with its abutment surface 94 is displaced from being in register with the bore, thereby presenting the release mechanism 86 in a releasing state. In this releasing state, the rod 52 can under the force of the biasing spring 58 (and gravity) move downwardly along the axis x. Suitably, a filter (not shown) is provided to reduce the risk of desiccant moving past the flap 88 and into the mouthpiece 6.

As illustrated in Fig. Id, in connection with the downward displacement of the rod 52 after the dosing chamber filling, the filled dosing chambers 46 successively go in overlap to the airflow passage 28. Until then, the airflow passage 28 has been slidingly closed by the closing solid portion of the rod 52, enabling the producing of the overpressure in the pressurizable space which comprises the compressed-air cylinder C and the on-the housing-side section of the airflow passage 28. When a dosing chamber 46 reaches the airflow passage 28 (the substance-evacuating position of the transfer member 48), the so formed valve is temporarily opened. The cross hole forming the dosing chamber 46 becomes part of the airflow passage 28. The produced air overpressure causes a blow- type exhaustion of the portioned substance from the dosing chamber 46 to jet this portion into the mouthpiece 6. Since the transfer member 48 in the illustrated example embodiment is provided with three dosing chambers 46, it will consequently have three substance- evacuating positions. According to the arrangement of three consecutively provided dosing chambers 46 in the shown example embodiment, the result is, in dependency of the force of the biasing spring 58, a fast momentary compressed-air supported ejection of the substance portion.

By terminating a pushing contact of the action button 8 or releasing it if latched, the action button 8, together with the guided transfer member 48, will return to the initial position under the force produced by the return coil spring 66. The arms 74 having the press pieces 76 are also released and, due to the resilient properties of the chosen material, pivot back to the original position illustrated in Fig. Ia.

In connection with the return-displacement of the action button 8 and the therewith following enlargement of the volume of the compressed-air cylinder C, ambient air is fed in. This via said second opening 100 (possibly also via said first opening 98), the desiccant-containing compartment 36 and the after-flow opening 34. In the flow path of the ambient air entering the pressurizable chamber, the filter 33 is placed before the valve 38, thereby reducing the risk of desiccant 37 entrained in the air stream reaching the valve 38 and the airflow passage 28. The ambient air thus introduced to the pressurizable space will be used in creating an air overpressure in a subsequent dispensing action.

Conditioned by the funnel-shaped design of the substance storing chamber 40, the substance material 44 slides self-actingly after the outer force on the storing chamber wall 84 by means of the press pieces 76 has terminated, whereby through the influence of the storing chamber wall 84 through the curving, such a moving-up of substance is supported by flex leveling.

With the exception of the elements having sealing properties and the substance storing chamber 40, and if applicable also with the exception of the construction part having resilient properties with arms 74 and press pieces 76, the inhaler 2, particularly the housing 4 and the action button 8 with the wall 60 and the holder 68 with the support 22, may consist of a plastic material, further particularly of a hard-plastic material. Also the transfer member 48 can comprise such a hard-plastic material. Suitably, with regard to this, the rod 52 may be made of a metallic material. Fig. 2 illustrates another example embodiment of the invention. Features in Fig. 2 which correspond to the features illustrated in Figs. Ia- Id are represented by the same reference signs.

The example embodiment illustrated in Fig. 2 resembles to the example embodiment illustrated in Fig. 1, however, there are some differences. The example embodiment illustrated in Fig. 2 does not comprise an inhalation-triggered release mechanism. The transfer member 48 can travel downwardly inside a tubular guide 120 provided in the desiccant-containing compartment 36. The tubular guide 120 is surrounded by desiccant 37 and extends between the sealing element 26 and the inhaler bottom 14. The desiccant-containing compartment 36 is in fluid communication with the outside of the inhaler through an opening 122 in the mouthpiece 6.

Air inflow openings 124 are formed in the mouthpiece wall evenly distributed along a periphery line, thereby enabling an airflow through the mouthpiece 6 as the user inhales. Unlike the example embodiment illustrated in Figs. Ia- Id, the example embodiment illustrated in Fig. 2 does not have a biasing coil spring 58. Furthermore, the towing arms 56, capturing the head 54, are shorter, however, the towing arms 56 have a length which exceeds (e.g. approximately twice or treble) the length of the head 54 in the extending direction of the axis x. Thus, an idling is provided between the top of the head 54 facing the action button 8 and the underside of the action button 8. Due to this idling, the substance 44 will be pushed into the dosing chambers 46 (as explained for the embodiment illustrated in Figs. Ia- Id), while the transfer member 48 remains in its initial position. After the dosing chamber filling, the underside of the action button 8 contacts the head 54 of the transfer member 48, for the movement of the transfer member 48 upon further downward displacement of the action button 8. The dosing chambers 46 will then be evacuated as previously explained.

In connection with the return-displacement of the action button 8 and the therewith following enlargement of the volume of the compressed-air cylinder C, air is fed in via the opening 122 and the after- flow opening 34, with a through flow of desiccant 37. The after- flow opening 34 is provided with the previously explained filter 33 and valve 38. The drawings have been provided for non- limiting illustrative purposes. Consequently, alternative embodiments are conceivable. For instance, the filter may be provided elsewhere, e.g. as a net around the desiccant, in order to perform said function of reducing the risk of desiccant clogging the valve or entering the air flow passage. Also, the illustrated transfer member could instead of a rod comprise another geometrically-shaped component as previously discussed. Furthermore, other types of release mechanisms may be provided than those illustrated in Figs. Ia- Id. For instance instead of a release mechanism comprising a flap, it would be conceivable to use other movable members such as a diaphragm or a sliding piston. Likewise, other types of biasing mechanisms may be provided instead of the illustrated one which comprises an action button and spring. Furthermore, the size and number of dosing chambers may be varied, and a mechanism may be provided for adjusting how many of the dosing chambers will be presented to the airflow passage during firing of the inhaler.

Claims

1. An inhaler for powdered substance, comprising an airflow passage for guiding substance towards an outlet, a substance storing chamber from which substance is provided to the airflow passage, a pressurizable space for establishing an air overpressure in the airflow passage for delivering substance present in the airflow passage to the outlet, a desiccant-containing compartment from which air is enabled to flow to the pressurizable space in order to replenish expelled air, and a filter provided in the desiccant-containing compartment, wherein air flowing from the desiccant-containing compartment to the pressurizable space passes through the filter.

2. The inhaler as claimed in claim 1, wherein the desiccant-containing compartment is provided with an opening through which air can flow to the pressurizable space, wherein a one-way valve is provided at the opening to prevent air from flowing from the pressurizable space to the desiccant-containing compartment.

3. The inhaler as claimed in claim 2, wherein the filter is provided adjacent the opening.

4. The inhaler as claimed in any one of claims 2-3, wherein the pressurizable space comprises said airflow passage, wherein said opening extends from the desiccant- containing compartment to the airflow passage.

5. The inhaler as claimed in any one of claims 1-4, wherein the substance storing chamber is located on one side of the airflow passage and the desiccant-containing compartment is located on the other side of the airflow passage.

6. The inhaler as claimed in any one of claims 1-5, wherein the desiccant-containing compartment is via a mouthpiece or nasal adaptor of the inhaler in fluid communication with the atmosphere outside the inhaler, whereby air is enabled to flow from outside the inhaler via the mouthpiece or nasal adaptor and then via the desiccant-containing compartment to the pressurizable space in order to replenish expelled air.

7. The inhaler as claimed in any one of claims 1-6, comprising a transfer member which is displaceable in the substance storing chamber and which comprises at least one dosing chamber for taking up substance inside the substance storing chamber, the transfer member being displaceable between a substance-keeping position in which the dosing chamber keeps the substance and a substance-evacuating position in which the dosing chamber presents the substance to the airflow passage, wherein, when the transfer member is in said substance-evacuating position, the dosing chamber is evacuated by the air overpressure in the airflow passage.

8. The inhaler as claimed in claim 7, comprising an inhaler housing, and an actuator, wherein the actuator comprises an action button protruding from the inhaler housing, the action button being displaceable against a return spring, wherein the overpressure is established when the action button is displaced in the inhaler housing, which overpressure, through the displacement of the transfer member, is used in the flow passage for the discharge of substance.

9. The inhaler as claimed in any one of claims 7- 8, wherein the established overpressure in the pressurizable space is released by an inhalation-triggered release mechanism when a user inhales through a mouthpiece or nasal adaptor of the inhaler.

10. The inhaler as claimed in claim 9, comprising a biasing mechanism adapted to bias the transfer member towards the substance-evacuating position, the transfer member being latched in the substance-keeping position by said inhalation-triggered release mechanism which, when a user inhales through the mouthpiece or nasal adaptor, unlatches the transfer member, thereby enabling it to move to the substance-evacuating position.

11. The inhaler as claimed in claim 10, wherein said pressurizable space comprises said airflow passage and wherein said transfer member in its substance-keeping position extends through the airflow passage to close said pressurizable space and to maintain the overpressure until the transfer member is unlatched by the inhalation-triggered release mechanism.

12. The inhaler as claimed in any one of claims 9-11, wherein the substance storing chamber is located on one side of the airflow passage and the release mechanism is located on the other side of the airflow passage, wherein the transfer member extends through the airflow passage.

13. The inhaler as claimed in claim 12, wherein the release mechanism comprises an abutment surface for receiving one end of the transfer member and latching the transfer member in the substance-keeping position.

14. The inhaler as claimed in any one of claims 9-13, wherein the release mechanism comprises a movable member being movable from a relaxed position, in which the release mechanism is kept in a latching state, to an energized position in which the release mechanism is caused to be displaced to a releasing state, wherein a first side of the movable member partly defines a first volume which is in fluid communication with the mouthpiece or nasal adaptor, wherein, when a user inhales through said mouthpiece or nasal adaptor, an underpressure is established in said first volume causing the movable member to move from the relaxed position to the energized position.

15. The inhaler as claimed in claim 14, wherein a second side of the movable member, opposite to said first side, partly defines a second volume which is in fluid communication with the atmosphere surrounding the inhaler.

16. The inhaler as claimed in claim 8 or any one of claims 9-15 when dependent from claim 8, wherein the actuator, when actuated, causes at least a wall portion of the substance storing chamber to move towards the transfer member so that substance is urged into the dosing chamber.

17. The inhaler as claimed in claim 16, wherein the substance storing chamber wall, consisting of an elastic material, curves in the direction towards the transfer member when the inhaler is actuated.

18. The inhaler as claimed in claim 17, wherein the substance storing chamber wall, at least in the dosing hole region, curves into contact with the transfer member.

19. The inhaler as claimed in any one of claims 17-18, wherein press pieces are provided for curving of the substance storing chamber wall.

20. The inhaler as claimed in claim 19, wherein the press pieces are provided with cheeks which have impinging surfaces which, in a fully in-turned position of the press pieces, are positioned parallelly to the broadside wall surfaces of the transfer member.

21. The inhaler as claimed in any one of claims 19-20, wherein the actuator via bevels, pivots the press pieces in the direction towards the transfer member.

22. The inhaler as claimed in any one of claims 7-21, wherein the displacement of the transfer member from the substance-keeping position to the substance-evacuating position describes a linear motion.

23. The inhaler as claimed in any one of claims 7-22, wherein the transfer member comprises a rod which is displaceable in its longitudinal direction, wherein the dosing chamber is provided in the rod.

24. The inhaler as claimed in any one of claims 7-23, wherein said at least one dosing chamber is designed as a cross hole of the transfer member.

25. The inhaler as claimed in any one of claims 7-24, wherein a part of the transfer member is designed as a flat bar.

26. The inhaler as claimed in any one of claims 7-25, wherein the transfer member has several dosing chambers consecutively located at the transfer member, which during a dispensing action successively are presented to the airflow passage and are, piece by piece, evacuatable by the air overpressure in the airflow passage.