Inhalation device

Abstract: An inhalation device is provided by means of which material in powder form can be inhaled. The device comprises a body (55) defining a reservoir (56) for medicaments in powder form, an outlet (57) through which a user can inhale and a dosing member (53) with at least one metering recess (65) formed therein. The dosing member (53) is moveable between a position in which the at least one metering recess (65) communicates with the reservoir (56) to receive a dose of powder therefrom and a position in which the at least one metering recess (65) communicates with the outlet (57) to permit the user to inhale the dose. The at least one metering recess (65) is formed in a face of the dosing member (53), the said face being mounted in contact against a similar mating face (60) of the body (55) at the lower end of the reservoir (56). At least one moveable weight may be incorporated within the device, adapted to strike an anvil surface when the device is shaken.

Description: This invention relates to an inhalation device by means of which metered doses of medicament in the form of a powder can be dispersed to a user. In particular it relates to a device of the type in which the medicament powder is held in bulk in a reservoir with which the device is provided, and is metered to the user from the reservoir. In devices of the type just described, it is difficult to obtain doses which are equal to a nominal value to within the appropriate tolerance. It will be understood that the tolerance permitted is often very small, as it is important that the user should be given a dose which is very close to the nominal value. In order to maintain the medicament powder in a manageable state it needs to be kept dry. Any ingress of moisture into the reservoir from outside can cause the medicament powder to agglomerate and this may be detrimental to its free flowing properties rendering it difficult to meter consistent doses from the reservoir. In the absence of adequate reservoir sealing it may be necessary to incorporate a desiccant cartridge into the reservoir to absorb any moisture that does enter. This is often insufficient to prevent deterioration of the medicament powder. WO 92/00771 discloses a dry powder inhaler, according to the preamble of claim 1, with means for ensuring that the cup from which the substance is dispensed is substantially free from the substance before being presented to the storage chamber. FR A 967 494 discloses a dry powder inhalation device having a ball to jolt the powder to ensure it is fine enough to be dislodged into the airflow, ready for inhalation. FR 2233842 discloses a new type of dispenser which can be instantly unblocked. It is an object of the present invention to provide a device of the type just described, in which doses can be repeatedly accurately dispersed, without requiring a dispensing mechanism of undue complexity. It is a further object of the present invention to provide a device of the type just described, but which additionally incorporates a simple and efficient sealing means to prevent ingress of moisture into the reservoir. According to the present invention there is provided an inhalation device comprising a body defining a reservoir for medicament in the form of a powder, an outlet through which a user can inhale, and a dosing member with at least one metering recess formed therein, the dosing member being moveable between a first position in which the at least one metering recess communicates with the reservoir to receive a dose of powder therefrom and a second position in which the at least one metering recess communicates with the outlet to permit the user to inhale the dose, the at least one metering recess being formed in a face of the dosing member, the said face being mounted in contact against a similar mating face of the body. The face of the dosing member and the mating face of the body are sealing faces with highly polished smooth surfaces which form a kinetic seal which excludes substantially all air from the interface therebetween. The sealing faces have a surface texture sufficiently smooth to have a roughness average value (Ra) of 0.5 microns or less, preferably 0.2 microns or less. Suitably the sealing faces are flat. More suitably they have a flatness of 0.005mm or less, preferably 0.003mm or less. Alternatively the sealing faces may be frusto-conical. The sealing faces may alternatively be cylindrical. In a further alternative the sealing faces may be spherical. The sealing surfaces are suitably made of a hard rigid material such as acetal resins, ceramics or metals. Suitably, the inhalation device includes a reservoir for medicament in the form of a powder, an outlet through which a user can inhale, a metering means adapted to communicate with the reservoir to receive a dose of powder therefrom and with the outlet to permit the user to inhale the dose, and at least one weight moveable in the device and adapted, when the device is shaken, to strike an anvil surface defined in the device. Suitably, the inhalation device includes a body forming a reservoir for medicaments in the form of a powder, an outlet through which a user can inhale, and a dosing member with at least one metering recess formed therein, the dosing member being moveable between a position in which the at least one metering recess communicates with the reservoir to receive a dose of powder therefrom and a position in which the at least one metering recess communicates with the outlet to permit the user to inhale the dose, the at least one metering recess being formed in a face of the dosing member, the said face being mounted in contact against a similar mating face of the body. The said face of the dosing member and the said mating face of the body have highly polished smooth surfaces which form a contacting face to face kinetic seal which excludes substantially all air from the interface. The term 'kinetic seal' in this context means a seal that can withstand relative movement of the two faces. Suitably, the sealing faces form a sliding seal which excludes substantially all air from the interface therebetween. The invention is further described below with reference to the accompanying drawings in which: Figure 1 is a section through a second embodiment of a device according to the invention; Figure 2 is a section on line X-X in Figure 1; and Figures 3 to 5 are perspective views showing three steps in the operation of the devices according to Figures 1, 2 and 6 to 9. Figure 6 is a section through a third embodiment of a device according to the invention. Figure 7 is a section on line Y-Y in Figure 6; Figure 8 is an exploded view of the embodiment shown in Figures 6 and 7; and Figure 9 is an exploded perspective view, partly cut away, showing the dose indicator mechanism of the embodiment shown in figures 6 to 8. The inhalater device herein is suitable for dispensing medicament which is suitable for inhalation. Many such medicaments are well known to those skilled in the art, for example for the treatment of asthma. Powdered medicaments suitable for this purpose include salbutamol, beclomethasone, salmeterol, fluticasone, formoterol, terbutaline, budesonide and flunisolide, and physiologically acceptable salts, solvates and esters or any combination thereof. Preferred medicaments are salbutamol, salbutamol sulphate, salmeterol, salmeterol xinafoate, fluticasone propionate, beclomethasone dipropionate and terbutaline sulphate. Individual isomers, such as R-salbutamol, can also be used. It is to be understood that the medicament powder may consist purely of one or more active ingredients, or there may additionally be a carrier, for example lactose powder. The device shown in cross section in Figures 1 and 2 comprises a main body portion 5 which defines a reservoir 6 and a reservoir cover or end cap 2. The reservoir 6 contains a supply of medicament in the form of a powder (not shown). The reservoir cover 2 may be provided with a desiccant cartridge (not shown) to absorb moisture and reduce the risk of the powder in the reservoir absorbing moisture and undergoing agglomeration of the particles thereof. The cover 2 may be removably secured to the body 5 by any known means, for example by means of a screw thread or a snap fit, to enable refilling of the reservoir 6 with powder. In this case a pharmaceutical grade rubber sealing ring 4 may be incorporated between the cover 2 and body 5 to prevent ingression of moisture into the reservoir 6. Alternatively, the device may be intended to be disposable after exhaustion of the supply of powder in the reservoir, in which case the cover 2 may be permanently secured to the body 5 by use of an adhesive, ultrasonic welding or any other method. At its lower end the main body portion 5 is fitted with a base 10 which together with body 5 defines an aperture 11 which is offset from the vertical axis of the device and through which powder can pass from the reservoir to the dosing member 3. Powder is guided to the aperture by the walls of the reservoir which form a hopper. Extending laterally from the lower end of main body 5 is mouthpiece 7. If, however, the device were intended for nasal inhalation this would be replaced by a nosepiece. Dosing member 3 is mounted upon lower body portion 9 which is pivotally connected to main body 5 such that it may rotate about the vertical axis of the device. As explained in more detail below, lower body portion 9 serves to allow rotation of the dosing member 3 whilst maintaining the same in axial alignment with base 10. It also urges the dosing member 3 into close contact with base 10. Dust cover 33 is attached to lower body portion 9 through pivot 34. A weight 31 in the form of a ring encircles the reservoir 6 and is slidable longitudinally thereof. The locus of movement of the weight 31 is defined towards the top of the reservoir by an end stop 32 formed as an integral part of the body 5, and towards the bottom of the reservoir by base 10 which behaves as an anvil. It is to be understood that whilst the device described herein incorporates a weight for the purpose described below, the weight is not an essential element of the invention and it might be chosen to omit the incorporation of the weight. The lower face of base 10 is provided with a highly polished smooth and flat surface as is the contacting upper face of dosing member 3. These surfaces are ground and polished to render a surface finish giving a flatness which does not undulate over its area by more than 0.003mm and a surface texture having a roughness average value (Ra) of 0.2 microns as internationally designated under ISO/R468, meaning that the average height of the irregularities constituting surface texture is 0.2 microns. These highly polished flat faces provide contacting surfaces between which there is substantially no clearance. It has been found that by providing such highly polished flat faces, the faces adhere to each other yet slide over each other as they are wrung together during assembly and use in the same way as mechanical slip gauges adhere to each other when wrung together. Air and powder are thus excluded from the interface between the base 10 and dosing member 3. When assembled the faces adhere firmly together but may be slid over eachother without affecting the closeness of the interfacial contact. Such contacting surfaces have been found to provide excellent sealing characteristics both in the static state and during the sliding motion of one face over the other preventing both loss of powder from and ingression of moisture into the reservoir 6 through the interface between the base 10 and dosing member 3. This type of kinetic or sliding seal obviates the need for any additional sealing means between base 10 and dosing member 3. The contacting surfaces of base 10 and dosing member 3 are made of a hard rigid material, and suitable materials include acetal resins, ceramics and metals. In the embodiment described, the two faces are formed by the surfaces of flat discs. It will be appreciated that disc shapes are not essential. Contact faces may be formed by the surfaces of a frusto-cone and a correspondingly frusto conical socket, by the contacting surfaces of two co-axial cylinders or by two correspondingly partially spherical contacting ball and socket surfaces. In operation, the user initially shakes the device in a generally upward and downward motion while maintaining the device in a generally upright orientation as shown in Figure 3. Weight 31 is thereby caused to travel up and down the reservoir, so repeatedly striking end stop 32 and base 10. The jolts which this produces causes the powder in the reservoir to be urged downwardly and to enter the metering recess 22. The user then opens dust cover 33, as shown in Figure 4, and rotates the cover which is connected to lower body portion 9 through 90° to move the dust cover 33 away from the mouthpiece 7 to allow access thereto and to bring the recess 22 into alignment with the aperture 8 leading to the mouthpiece 7. The user knows when this position has been reached as the lower body portion 9 engages a stop (not shown) and will not move any further. The user then inhales through mouthpiece 7. After inhalation the user returns the lower body portion 9 to its initial position and closes the dust cover 33. In the device shown in Figures 1 and 2 the aperture 11 is radially offset by an angle of 90° about the vertical axis of the device from the aperture 8 at the inner end of the mouthpiece to allow the dust cover and lower body portion 9 to be moved through 90° for ease of access to the mouthpiece. However, it will be appreciated that this angle can be substantially increased or slightly decreased according to the desired angle of rotation of the dust cover, lower body portion and dosing member. Further possible modifications to the device described include incorporation of a suitable dose counting mechanism to give the user an indication of the amount of powder remaining in the device. A further embodiment of the invention is shown in Figures 6 to 9. As in the previous embodiment, the device shown in cross section in Figures 6 and 7 and in exploded view in figure 8 comprises an elongate main body portion 55 which defines a reservoir 56 and a reservoir cover or end cap 52. The reservoir 56 contains a supply of medicament in the form of a powder (not shown). The reservoir cover 52 is secured to the body 55 by a snap fit and a pharmaceutical grade rubber sealing ring 54 is incorporated between the cover 52 and body 55 to prevent ingression of moisture into the reservoir 56. At its lower end the main body portion 55 is fitted with a base member 60 which together with body 55 defines an aperture 51 which is offset from the vertical axis of the device and through which powder can pass from the reservoir to a recess 65 in dosing member 53. The lower face of base member 60 is provided with a similarly highly polished smooth and flat surface to that described with reference to the embodiment shown in Figures 1 to 5 as is the upper face of dosing member 53. Powder is guided to the aperture by the walls of the reservoir which form a hopper. Extending laterally from the lower end of the main body 55 is mouthpiece 57. Dosing member 53 is mounted upon lower body assembly 59 which is pivotally connected to main body 55 such that it may rotate about the vertical axis of the device. Lower body assembly 59 serves to transmit rotational movement thereof to the dosing member 53 whilst maintaining the same in axial alignment with base member 60. It also urges dosing member 53 into close contact with base 60 by means of spring 61. Dust cover 63 (not shown in figures 6 and 7) is attached to lower body portion 69 through pivot 64. The wall of the main body 55 is provided with three longitudinal bores 58 substantially equidistantly spaced around the reservoir 56. A cylindrical weight 67 is slideably received in each of the bores 58. The weights 67 may be made of a rust resistant metal such as stainless steel or other hard material such as acetal resin. The bores are each blind at their upper ends and closed by a pressed-in stainless steel ball bearing 68 at their lower ends which also act as anvils against which weights 67 may impact as described later. A dose indicator drive means comprising a shaft 70 provided with a screw thread over much of its length, a sprung lug 71 at the base of the thread and a sprocket 72 with inclined teeth positioned below the lug is rotatably mounted within a bore 73 in the wall of the main body 55 (see figure 9). An indicator nut 77 is threaded onto the shaft with a projection protruding through an indicator window 74 in the wall of bore 73 which prevents the indicator nut 77 from rotating with shaft 70. Sprung lug 71 engages with teeth 75 formed within bore 73 to form a ratchet allowing shaft 70 to rotate in one direction only. Sprocket 72 is located adjacent the periphery of dosing member 53 which is provided with a second sprung lug 76. Operation of the device is similar to that described with reference to the embodiment shown in Figures 1 to 5. The user initially shakes the device in a generally upward and downward motion while maintaining the device in a generally upright orientation as shown in figure 3. Weights 67 are thereby caused to travel up and down bores 58 next to the reservoir, so repeatedly striking anvils 68. The vibrations which this produces are transmitted through base member 60 and body 55 to the powder in the reservoir, and this encourages powder to flow downwardly and enter metering recess 65 within dosing member 53. The user then opens dust cover 63, as shown in Figure 4, and rotates the cover which is connected to lower body assembly 59 through 90° to move dust cover 63 away from mouthpiece 57 to allow access thereto and to bring recess 65 into alignment with the aperture at 66 leading to the mouthpiece 57. As the dosing member 53 rotates with the lower body assembly 59, lug 76 engages an inclined tooth presented by sprocket 72 of the dose indicator drive means. The dose indicator drive means is prevented from turning in the direction urged by lug 76 by virtue of the ratchet mechanism formed by teeth 75 and lug 71. As a result, lug 76 rides over the inclined tooth and out of engagement with sprocket 72. The lower body assembly 59 engages a stop (not shown) and will not move any further when the recess 65 is correctly aligned with aperture 66. The user now inhales through mouthpiece 57. Air is drawn through grill 80 and passage 81, defined by body 55 and hole 82 in base member 60, and entrains the powder in recess 65 of dosing member 53. The airflow draws the entrained powder through the mouthpiece 57 and is inhaled by the user. Further air is drawn into the mouthpiece through holes 82 on either side of mouthpiece 57 and this creates turbulence which helps to break-up any agglomerates of powder entrained. After inhalation the user returns lower body assembly 59 to its initial position and closes the dust cover 63. As dosing member 53 rotates, lug 76 again engages sprocket 72 of the dose indicator drive means. As the ratchet mechanism formed by teeth 75 and lug 71 allows movement of the dose indicator drive means in the direction as now urged by lug 76, the dose indicator drive means is rotated by one tooth pitch through engagement with lug 76 as it passes sprocket 72. Rotation of the dose indicator drive means causes the captive dose indicator nut 73 to travel down threaded shaft 70. The pitch of the thread and the number of teeth on sprocket 72 are selected to ensure that the dose indicator nut travels from the uppermost "full" position to the lowermost "empty" position when the device has been used sufficiently to deliver its prescribed number of doses, so indicting to the user that the device is empty.

Claims: An inhalation device comprising a body (1) forming a reservoir (6) for medicaments in the form of a powder, an outlet (7) through which a user can inhale, and a dosing member (3) with at least one metering recess (22) formed therein, the dosing member (3) being moveable between a position in which the at least one metering recess (22) communicates with the reservoir (6) to receive a dose of powder therefrom and a position in which the at least one metering recess (22) communicates with the outlet (7) to permit the user to inhale the dose, the at least one metering recess (22) being formed in a face of the dosing member (3), the said face being mounted in contact against a similar mating face of the body (1), characterised in that the said face of the dosing member (3) and the said mating face of the body (1) have highly polished smooth surfaces with a roughness average value (Ra) of 0.5 µm or less which form a contacting face to face kinetic seal which excludes substantially all air from the interface. An inhalation device according to claim 1, wherein the kinetic seal is a shiding seal. A device according to either of claims 1 or 2, characterised in that the sealing faces adhere to each other. A device according to claim 3, characterised in that the sealing faces have a roughness average value (Ra) of 0.2 microns or less. A device according to either of claims 3 or 4, characterised in that the sealing faces are flat. A device according to claim 5, characterised in that the sealing faces have a flatness of 0.005 mm or less. A device according to claim 6, characterised in that the sealing faces have a flatness of 0.003 mm or less. A device according to either of claims 3 or 4, characterised in that the sealing faces are cylindrical. A device according to either of claims 3 or 4, characterised in that the sealing faces are spherical. A device according to any of claims 1 to 9, characterised in that the sealing faces are made of a hard rigid material. A device according to claim 10, characterised in that the sealing faces are made of acetal resin. A device according to claim 10, characterised in that the sealing faces are made of ceramics. A device according to claim 10, characterised in that the sealing faces are made of metal. A device according to any preceding claim, further comprising a dose indicating means adapted to display to a user the quantity of medicament remaining within the reservoir (6).

Inventors: SCHAEFFER ALAIN EMILE EDOUARD, SEGUELAS ETIENNE, SCHAEFFER, ALAIN EMILE EDOUARD, SEGUELAS, ETIENNE, Schaeffer, Alain Emile Edouard, Laboratories Glaxo, SEGUELAS, ETIENNE, APE MEDICAL
Applicants: GLAXOSMITHKLINE LAB SAS, LABORATOIRE GLAXOSMITHKLINE S.A.S.
Application year: 1995
Main classification: A61M15
IPC codes: A61M15