WO2001051112A1

WO2001051112A1 - Device for dry powder inhalation

Info

Publication number: WO2001051112A1
Application number: PCT/US2001/000768
Authority: WO
Inventors: Robert Stanley Dirksing
Original assignee: The Procter & Gamble Company
Priority date: 2000-01-10
Filing date: 2001-01-10
Publication date: 2001-07-19
Also published as: CO5280234A1; AU2001229334A1; PE20010819A1

Abstract

The present invention provides a device suitable for dry powder inhalation. The particles of dry powder are fluidized with air and cause a vortex flow of the fluidized particulate material. A particle classifier permits fluidized particulate material of a predetermined size and inertia to flow from the chamber to the outlet and excludes fluidized particulate material with greater than the predetermined size and inertia from flowing from the chamber to the outlet.

Description

Device for Dry Powder Inhalation

Field of the Invention

The present invention relates to a device suitable for producing an aerosol of a dry powdered material. More particularly, the present invention relates to a device that can produce and deliver an aerosol of dry powdered medicament into the respiratory system of a user.

Background of the Invention Respiratory diseases have long been treated by the inhalation of aerosolized medicament. "Aerosolized" refers to a colloidal dispersion of a liquid or a solid in a gas. The medicament is aerosolized so that it may be transported by the inhaled air stream into the respiratory system. There are many advantages to delivering medicament via inhalation, including a rapid onset of action, avoiding drug degradation in the gastrointestinal tract, and low dosages to minimize adverse reactions.

Two predominant types of systems for aerosolizing medicament are available in the market: propellant-based inhalers and dry powder inhalers (DPIs), which do not use propellants. Propellants are undesirable as many are believed to adversely affect the ozone layer of the atmosphere, and even those propellants believed to be safe for the environment are nevertheless often associated with environmental issues, regardless. It is also desirable to minimize the introduction of any unnecessary materials in inhalation devices used for delivering active ingredients to the respiratory system to minimize the occurrence of irritation, allergic reaction, or other undesirable side effect.

DPIs are often designed such that air stream generated by the inhaled breath of a user aerosolizes the dry powder. The user takes slow deep breaths to accomplish delivery of the aerosolized powder into the lower portions of the respiratory system. Aerosolizing the dry powder with slow deep breaths can be a challenge, especially if the very ailment for which the DPI is being employed prevents the user from generating sufficient airflow to aerosolize the dry powder. Thus, it is desirable to provide an inhaler that does not solely rely on inhalation by the user to accomplish aerosolization of the dry powder.

Most inhalation devices for delivery of aerosolized dry powder medicament are intended to deliver medicament to the lower respiratory tract, primarily to the large surface and thin membranes of the lungs. The efficacy of inhalation devices is governed by quantity of medicament reaching the lower portion of the lower respiratory tract. Medicament with particle sizes that are less than 0.5 microns in diameter tend to be exhaled, whereas particle sizes larger than 10.0 microns in diameter generally deposit in the upper respiratory tract. Accordingly, inhalation devices generally are designed to deliver particles in the preferred size range from about .5 microns to about 10 microns in diameter, more preferably from about 1 to 6 microns in diameter.

Manufacturers conventionally process the dry powder medicament to the desired particle size distribution prior to market distribution. Unfortunately, many types of dry powder medicaments in the preferred particle size range tend to agglomerate during handling and storage. This tendency is aggravated if moisture is present.

Numerous approaches have been proposed to solve the problems attributable to powder agglomeration. Some devices include features that deagglomerate the dry powder at the point of use, for example, jets of gas or mechanic vibration. Other devices have one or more channels with bends through which the aerosolized medicament must pass whereby the shear and wall friction forces promote deagglomeration of the particles. In short, these devices promote particle size distribution of inhaled powder, but do not ensure that only particles of the desired particle size range are dispensed. Therefore, it is desirable to provide an inhalation device that provides both deagglomeration at the point of use and improved control of particle size distribution to within a predetermined range.

Summary of the Invention

More particularly, the device of the present invention can comprise a housing having an inlet, an outlet, and a chamber suitable for containing a particulate material, a particle fluidizer for providing a fluidized flow of the particulate material with a gas in the chamber upon operation of the device, wherein the flow in the chamber is a vortex flow, and a particle classifier in fluid communication with the fluidized flow of the chamber between the chamber and the outlet. Brief Description of the Drawings

While the specification concludes with claims which particularly point out and distinctly claim the present invention, it is believed that the present invention will be

80 better understood from the following description of preferred embodiments, taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements and wherein

FIG 1 is a partially sectioned side elevational view of an embodiment of an inhalation device of the present invention having a conduit particle classifier, 85 FIG 2 is an enlarged cross-sectional \ ιew thereof, taken along section line 2-2 of

FIG 1 showing an upward view into the interior of the chamber according to the embodiment of Figure 1,

FIG 3 is a cross-sectional side elevational view of an alternate embodiment of an inhalation device of the present invention having a conical particle classifier, 90 FIG 4 is a partially sectioned front view of the embodiment of FIG 3, and

FIG 5 is an enlarged sectioned top plan view of the conical particle classifier of FIG 3

95 Detailed Description of the Invention and Preferred Embodiments

Typically, inhalation devices are conveniently divided into category types of unit dose, bulk powder multi-dose and pre-metered multi-dose Unit dose generally refers to a device that usually the user inserts a single dose of the medicament into the device before operation Bulk powder multi-dose generally refers to a de\ιce that contains a

100 bulk quantity of medicament for many doses Pre-metered multi-dose generally refers to a device that is designed to deliver a metered dose of the drug multiple times Examples of pre-metered multi-dose de\ ιces include, but are not limited to, capsule and blister package types The inhalation device of the present invention can comprise any one of the above types of inhalation devices or others known in the art

105 Referring now to the drawings, Figures 1-2 depict an embodiment of the present invention having a bulk powder, which pro ides an inhalation device 10 that produces and dispenses an aerosol of a fine powdered particulate material Device 10 generally comprises a housing 20, a particle fluidizer, and a particle classifier In the configuration shown in Figures 1-2, the particle fluidizer is an impeller 50 and the

110 particle classifier is an egress conduit 37, as will be discussed hereafter

Housing 20 generally comprises a chamber 60, a support frame 30, an inlet and an outlet Housing 20 is arranged to provide air passage from the inlet, through the chamber, and then through the outlet Chamber 60 comprises peripheral wall 21, base wall 22, and upper chamber wall 31. Chamber 60 is suitable for containing dry powder

115 or other particulate material. Preferably, the chamber 60 may also be used to store unfluidized particles. Alternatively, a separate storage container for particulate material may be provided.

Tube 32 extends from upper chamber wall 31 In the configuration shown m Figures 1-2, the inlet comprises ingress conduit 33, having external ingress port 34 and

120 internal ingress port 36 Ingress conduit 33 permits ambient air external to device 10 to enter chamber 60 Tube 32 contains at least a portion of the ingress conduit 33. The ingress conduit 33 is arranged such that internal ingress port 34 is located m proximity to the axis of rotation of impeller 55.

The particle classifier is in fluid communication with chamber 60 The particle

125 classifier can be any means for separating particles, including, but not limited to. preventing particles above the desired size from entering the classifier or permitting only particles less than and including the predetermined size and inertia to exit the device and others being redirected back into the flow for further de-agglomeration or particle size reduction.

130 The particle classifier in the embodiment shown in Figures 1-2 comprises egress conduit 37, having internal egress port 38 and external egress port 39. The egress conduit particle classifier 37 is arranged so that air flows from the chamber 60, through internal egress port 38, through egress conduit 37, and then exits the housing 20 through the egress port 39. Internal egress port 38 and external egress port 39 can be sized as

135 desired to control the rate of flow of the air through chamber 60, wherein reducing the restriction through the ports, e.g. increasing the size of the ports, increases the rate of flow The internal dimension of the internal egress port 38 can be substantially larger than the predetermined particle size In the configuration shown in figures 1-2, the outlet further comprises external egress port 39 Additionally, the egress conduit 37 is

140 placed such that the internal egress port 38 is axially located within the upper portion 61 of the chamber 60 between ingress port 36 and peripheral wall 21, as will be described m further detail below

As stated above, in Figures 1-2 the particle fluidizer is an impeller drive 50 Preferably, the fluidizer is a device that mechanically intermixes gas and the particles to

145 create a flow of the mixture, referred to herein as fluidized particles or fluidized particulate material. However, the particle fluidizer may be any type of device capable of fluidizing dry powder known in the art. For example, without limitation, the particle fluidizer may be an irregular disk or a blade The impeller drive 50 can be powered by an electrical source comprising motor 51, battery 52, button 53, drive shaft 54, and

150 impeller 55 In assembly, impeller drive 50 is affixed to housing 20. Drive shaft 54 is inserted through tube 32 An end of drive shaft 54 extends beyond the lower end of tube 32 so that impeller 55 may be press fit or otherwise fastened to the lower end of drive shaft 54 The axis of rotation of impeller 55 is substantially concentric about the longitudinal axis of the chamber Motor 51 is snap fit or otherwise fastened to a mating recess m support frame 30 Further, motor 51 is electrically connected to batten 52 button 53, and drive shaft 54 (which is connected to impeller 55), such that when button 53 is depressed, electrical current passes through motor 51 Thus, drive shaft 54, and thereby impeller 55, is caused to rotate rapidly in a direction indicated by arrow 71 m Figure 2 If a specific life span of the dispensing device 1 10 is desired, a zinc air battery that is activated upon first use may be employed Also, means other than button 153 ma> be employed to activate the device 110, such as a pressure switch in the inhalation tube 143 that activates upon inhalation by the user

Base wall 22 is affixed to peripheral wall 21 The upper edge of peripheral wall 21 of housing 20 is press fit or otherwise fastened to a mating ring about upper chamber wall 31, thereby forming enclosed chamber 60 A charge of particulate material 15 is introduced into chamber 60 before enclosing said chamber Base wall 22 is conical in shape, such that particulate material 15 tends to settle near the axis of rotation of impeller 55 Consequently, the starting moment is reduced as impeller 55 begins to rotate within particulate mateπal 15, relative to a flat bottom configuration of base wall 22

As impeller 55 rotates rapidly, particulate material 15 is fluidized with the air in the chamber to form a vortex flow of fluidized particulate material The vortex flow hereof can be characterized as a flow in a circular path or otherwise having an angular velocity The vortex flow of the device as shown m Figure 1 generates a cyclonic or centrifugal condition within the chamber such that a relative low pressure region forms near the center, l e near the axis of impeller 55, with regions having progressively higher pressure radially outward toward peripheral wall 21 The low pressure region has a pressure lower than the ambient air at atmospheric pressure m preferred embodiments The high pressure region has a pressure higher than the ambient air at atmospheric pressure in preferred embodiments The pressure differential is generally a function of the rate of rotation, diameter and frontal area of the impeller 55, amount of particulate material 15, and the diameter of chamber 60

Alternatively, gases other than the ambient air may be introduced to fluidize the particulate material, including, but not limited to other gases, such as oxygen and nitrogen, or a propellant, such as halogenated hydrocarbons like dichlorodifluoromethane Most preferably, ambient air is used The low pressure region near the axis of impeller 55 is in fluid communication with the ingress conduit 33 via internal ingress port 36, which is located m proximity to the

190 axis of rotation of impeller 55, such that upon rotation of the impeller 55, ambient air from outside device 10 is drawn through said ingress conduit 33 The high pressure region near peripheral wall 21 is in fluid communication with the egress conduit 37 \ιa internal egress port 38, which is located m an upper portion of chamber 60 between the axial location of ingress port 36 and peripheral wall 21, such that upon rotation of the

195 impeller 55. air inside the chamber 60 is expelled through said egress conduit 37 These pressure differentials cause airflow through the ingress conduct 33, through chamber 60, and out through egress conduit 37

Further, interior egress port 38 is oriented such that it faces a direction similar to the direction of the vortex flow formed withm chamber 60, as indicated by arrow 71 m

200 Figure 2 Thus, the air stream that exits through egress conduit 37 must deviate from the direction of the vortex flow prior to entering into the interior egress port 38, as indicated by arrow 73 Generally, the size and inertia of the rapidly rotating fluidized particulate material prohibits the particulate material particles from deviating direction and entering interior egress port 38 Abrasion, fracturing, or the like of particulate

205 material 15, either from impact with impeller 55, rubbing against peripheral wall 21 of the chamber, or between the particles of particulate material 15 themselves, produces finer particles of the particulate material 15. Consequently, a broad distribution of particle sizes of particulate material 15 will be produced within the chamber. As finer and finer particles of particulate material are produced, the finer particles have

210 sufficiently low size and inertia to permit deviation from the vortex flow into the air stream caused by the pressure differential and exit the housing through the egress conduit 37 via interior egress port 38, as indicated by arrow 73 In this way, egress conduit serves as a classifier of particle size to insure that only particles of a predetermined size and less are permitted to flow from the chamber to the outlet and

215 particles with greater than the predetermined size are excluded from flowing from the chamber to the outlet As this is an ongoing process, a stream of aerosolized particles will be dispensed

Figures 3-5 depict an alternate embodiment of the present invention having a bulk powder, which provides an inhalation device 110 that produces and dispenses an aerosol

220 of a fine powdered particulate material Device 1 10 generally comprises housing 120, a particle fluidizer, and a particle classifier In the configuration shown m Figures 3-5, the particle fluidizer is an impeller drive 150 and the particle classifier is a conical particle classifier 140, as will be discussed hereafter Housing 120 generally comprises a chamber 160, a motor housing 123, a battery 225 housing 124, an inlet and an outlet. Housing 120 is arranged to provide air passage from the inlet, through the chamber 160, through the particle classifier 140, and then through the outlet.

Chamber 160 comprises a peripheral wall 121 , a base wall 122, and upper chamber wall 131. Chamber 160 is suitable for containing dry powder or other 230 particulate material. Preferably, the chamber 160 may also be used to store unfluidized particles. Alternatively, a separate storage container for particulate material may be provided.

Tube 170 extends from upper chamber wall 131. In the configuration shown in

Figures 3-5, the inlet comprises ingress conduit 172 having external ingress port 174 235 and internal ingress port 176. Ingress conduit 172 permits ambient air external to device 110 to enter chamber 160. Tube 170 contains at least a portion of the ingress conduit 172. The ingress conduit is arranged such that internal ingress port 176 is located in proximity to the axis of rotation of impeller 155.

Housing 120 further includes fins 146 located adjacent the external ingress port 174. 240 Fins 146 improve the grasp of the user's fingers in holding device 110 and prevent blockage of external ingress port 174 by the user's fingers.

The particle classifier is in fluid communication with chamber 160. The particle classifier can be any means for separating particles, including, but not limited to, preventing particles above the desired size from entering the classifier or permitting 245 only particles less than and including the predetermined size and inertia to exit the device and others being redirected back into the flow for further de-agglomeration or particle size reduction.

The particle classifier of the alternate embodiment is a conical particle classifier 140.

The conical classifier 140 comprises conical fitment 148, cone 181, and egress conduits 250 177. In assembly, the conical particle classifier 140 is arranged such that the cone 181 is inserted into the conical fitment 148, whereby egress conduits 177 are formed.

Preferably, egress conduits 177 are helical. Subsequent to assembly, egress conduits

177 further comprise internal egress ports 178 and intermediate egress ports 179. The interior egress ports 178 are located in an upper portion of chamber 160 between the 255 axial location of ingress port 176 and peripheral wall 121. The conical particle classifier 140 is arranged so that air flows from the chamber 160, through internal egress ports 178, through egress conduit 177, through intermediate egress ports 179, and then exits the housing 120 through the outlet. Internal egress ports 178 and intermediate egress ports 179 can be sized as desired to control the rate of flow of the air through 260 chamber 160, wherein reducing the restriction through the ports, e.g. increasing the size of the ports, increases the rate of flow. The internal dimension of the internal egress port 38 can be substantially larger than the predetermined particle size. In this configuration, the outlet comprises inhalation tube 144 having mouthpiece 143. Alternatively, the present invention may be designed for use for inhalation through a

265 nose.

Tube 172 is inserted into and fastened to upper chamber wall 131. The cone 181 is integrally molded about tube 172 and conical fitment 148 is integrally molded to upper chamber wall 131.

As discussed above, in Figures 3-5 the particle fluidizer is an impeller drive 150.

270 However, the particle fluidizer may be any type of device capable of fluidizing dry powder. For example, without limitation, the particle fluidizer may be an irregular disk or a blade. The impeller drive 150 is powered by an electrical source and comprises motor 151, battery 152, button 153, drive shaft 154, impeller 155, and conductors 156 and 157. In assembly, impeller drive 150 is affixed to housing 120. Drive shaft 154 is

275 inserted through an opening in base wall 122 so that an end of drive shaft 154 extends beyond the lower surface of base wall 122. Impeller 155 is press fit or otherwise fastened to the upper end of drive shaft 154. The axis of rotation of the impeller 155 is substantially concentric about the longitudinal axis of the chamber. Motor 151 is snap fit or otherwise fastened within supports 125 of motor housing 123. Battery 152 is

280 located within the battery housing 124. The components of the impeller drive 150 are electrically connected, such that when button 153 is depressed, electrical current passes through battery 124 and conductors 156 and 157 to motor 151. Thus, drive shaft 154, and thereby impeller 155, is cause to rotate rapidly in a direction indicated by an arrow 190 in Figure 5.

285 Base wall 122 is affixed to peripheral wall 121. The upper edge of peripheral wall

121 of housing 120 is press fit or otherwise fasted to a mating ring about upper chamber wall 131, thereby forming enclosed chamber 160. Prior to assembly of housing 120, a charge of friable particulate material 115 is introduced into chamber 160 before enclosing said chamber. Base wall 122 is conical in shape, such that the particulate

290 material 115 tends to settle near the axis of rotation of impeller 155. Consequently, the starting moment is reduced as impeller 155 begins to rotate within particulate material 15, relative to a flat bottom configuration of base wall 122.

As impeller 155 rotates rapidly, particulate material 115 is fluidized with the air in the chamber to form a vortex flow of fluidized particulate material. The vortex flow

295 generates a cyclonic or centrifugal condition within the chamber such that a relative low pressure region forms near the center, i.e. near the axis of impeller 155, with regions having progressively higher pressure radially outward toward peripheral wall 121. The low pressure region has a pressure lower than the ambient air at atmospheric pressure in preferred embodiments The high pressure region has a pressure higher than the

300 ambient air at atmospheric pressure m preferred embodiments The pressure differential is generally a function of the rate of rotation, diameter and frontal area of the impeller 155, amount of particulate material 1 15, and the diameter of chamber 160

Alternatively, gases other than the ambient air may be introduced to fluidize the particulate material, including, but not limited to other gases, such as oxygen and

305 nitrogen, or a propellant, such as halogenated hydrocarbons like dichlorodifluoromethane Most preferably, ambient air is used

The low pressure region near the axis of impeller 155 is in fluid communication with the ingress conduit 172 via internal ingress port 176, which is located near the axis of rotation of impeller 155, such that upon rotation of the impeller 155, ambient air from

310 outside device 110 is drawn through said ingress conduit 172 The high pressure region near peripheral wall 121 is in fluid communication with the interior egress ports 178, which are located in an upper portion of chamber 160 between the axial location of ingress port 176 and peripheral wall 121, such that upon rotation of the impeller 155, air inside the chamber 160 is expelled though the egress conduits 177 These pressure

315 differentials cause airflow through ingress conduit 172 though the chamber 160, through the conical particle classifier 140, and exit through the outlet

Further, interior egress ports 178 of particle classifier 140 face a direction similar to the direction of the vortex flow withm chamber 160, as shown by arrow 190 in Figure 5 Thus, the air stream that exits through egress conduit 177 must deviate from its general

320 direction prior to entering into the interior egress ports 178, as indicated by arrow 191 Generally, the size and inertia of the rapidly rotating fluidized particulate material prohibits the particulate material particles from deviating from the direction of the vortex flow and entering interior egress ports 178 Abrasion, fracturing, or the like of granular particulate material 1 15, either from impact with impeller 155, rubbing against

325 peripheral wall 21 of the chamber, or between the granules of particulate mateπal 115 themselves, generates finer particles of the granular particulate material 1 15 Consequently, a broad distribution of particle sizes of particulate material 115 will be produced withm the chamber As finer and finer particles of particulate material 1 15 are formed withm the chamber, the finer particles have sufficiently low size and inertia

330 to permit deviation from the general cyclonic airflow into to the exiting air stream through particle classifier 140 into inhalation tube 144 of mouthpiece 143 via intermediate egress port 179 In this way, the conical particle classifier serves to insure that only particles of a predetermined size and less are permitted to flow from the chamber to the outlet and particles with greater than the predetermined size are 335 excluded from flowing from the chamber to the outlet As this is an ongoing process, a stream of aerosolized particles will be dispensed

The user of the present device for dispensing an aerosol of a fine powdered particulate material 1 10 places his or her lips about mouthpiece 143 and while depressing button 153, inhales the fluidized particulate material through inhalation tube

340 144

The present invention is suitable for a wide range of particulate materials, including but not limited to medicaments, drugs, biologically actrv e substances and the like Additionally, the particulate material may be comprised of more than one active, excipients, enhancers, or the like Alternatively, the granules or beads of a different

345 composition than the desired dispensed particulate material maybe added to the particulate material to facilitate agitation of the particulate material in operation or pπoi to operation, as by shaking The initial particle size of the particulate material can also range widely, particularly in view o the benefits provided by the invention of excluding particles that are too large and de-agglomeratmg or otherwise reducing particle sizes as

350 described above

The present invention is presently of interest for dispensing sodium chloride In general, without limitation, it is contemplated that particle sizes ranging from as low as 0.5 (or other lower limit as may be desired) to 500 microns may be used Preferably, a quantity of larger particles is used for two reasons First, smaller particles tend to

355 adhere to the walls of the chamber and are not affected by gravity The larger particles impact the small particles that are adhered to the walls and free them of adhesion thereby allowing the smaller particles to exit the chamber Second, the larger particles maintain the vortex flow within the chamber When large particles are used, preferabh they will be in the form of agglomerations of smaller particles or be a frangible material

360 that is capable of being reduced m size upon operation of the device

If immediate output of an aerosol is desired, an initial small quantity of fine particulate material may be mixed with a granular particulate material, preferably 5 to 20% b weight of the particles are 10 microns or less m diameter and about 80-95% by weight of the particles are between 300 to 400 microns in diameter Generally, the impeller ma)

365 rotate from about 1000 to 5000 rpm, depending upon desired flow rate, which depends on particle size and density Also, if desired, a separate particle size reducer, such as an impeller, blender, grinder, mixer, etc may be included

High degrees of dispensing particulate material with the desired size can be obtained, including levels as high as 99% by weight In general, particle sizes delivered

370 will preferably be between about 5 and about 10 microns m diameter, more preferably between about 2 and 6 microns in diameter, though it is not intended to limit the present invention to exclude particle sizes outside of this range if such larger or smaller sizes are determined to be desirable

375 Examples

Example 1

An example of a highly preferred embodiment generally corresponding to the type ot design shown in Figures 1-2 the particulate material is granular sodium chloride hav ing a typical cubic dimension of about 300 to 400 microns The chamber has a diameter of

380 about 25 mm and depth from upper wall to the bottom of base wall of about 40 mm The included angle of the conical form of base wall is about 90° The impeller is about 22 mm across and the clearance between impeller and base wall is about 1 5 mm The impeller rotates at about 3000 rpm The interior egress port 38 and exterior egress port 39 of egress conduit 37 both have an internal diameter of about 2 5 mm

385 In this exemplary embodiment, sodium chloride particles between 2 to 6 microns generally have sufficiently low size and inertia as to be classified and carried by the exiting fluidized stream through the conduit With a chamber initially containing 1 gram of sodium chloride, approximately 1 milligram per minute of fine particles are dispensed, and of the particles dispensed as an aerosol of a fine powder, over 99 % of

390 the particles dispensed are between 2 to 6 microns

Example 2

An example of a highly preferred embodiment generally corresponding to the type of design shown in Figures 3-5. the particulate material is granular sodium chloride having

395 a typical cubic dimension of about 300 to 400 microns The chamber has a diameter of about 27 mm and depth from upper wall to the bottom of base wall of about 36 mm The included angle of the conical form of base wall is about 110° The housing, uppei support frame, and tube insert are injection molded of LUSTRAN 348 ® acrylonitπle butadiene styrene produced by the BAYER CORPORATION POLYMERS DIVISION

400 100 Bayer Road, Pittsburgh, PA, 15205 The impeller is about 22 mm across and the clearance between the impeller and base w all is about 1 5 mm The impeller is molded of Vectra ® liquid crystal polymei produced by HOECHST TECHNICAL POLYMERS, 90 Morris A\e . Summit, NJ, 07901 The impeller rotates at about 3000 rpm The impeller is driven by an electric motor A suitable permanent magnet electric

405 motor is model SU-020RA-1665 supplied by MABUCHI MOTOR AMERICA CORP of 3001 West Big Beaver Road, Troy, MI The battery is a standard AAA such as a DURACELL Alkaline Battery produced by Duracell, Inc , Bethel, CT, 06801 The ingress conduit has an internal diameter of about 2 5 mm The egress conduits are about 1 3 mm by 1.3 mm In this exemplary embodiment, sodium chloride particles between 2 to 6 microns generally have sufficiently low mass and sufficienth large aerodynamic surface as to be carried by the exiting air stream through the classifier With a chamber initially containing 1 gram of sodium chloride, approximately 1 milligram per mmute of fine particles are dispensed, and of the particles dispensed as an aerosol of a fine powder, over 99 % of the particles dispensed are between 2 to 6 microns

While particulai embodiments of the present

have been illustrated and described, it will be obvious to those skilled m the art that vaπous changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended to cover in the appended claims all such modification that are withm the scope of the invention

Claims

What is claimed is

1 A dry powder inhalation device, comprising

(a) a housing having an inlet for a gas, an outlet, and a chamber suitable for containing a particulate material,

(b) a particle fluidizer for providing a fluidized flow of said particulate material with said gas m said chamber upon operation of the device, and

(c) a particle classifier in fluid communication with said fluidized flow between said chamber and said outlet

T The device of claim 1, wherein said particle fluidizer causes a vortex flow of said fluidized particulate material, and said particle classifier permits particles withm said fluidized particulate mateπal with less than and including a predetermined size and inertia to deviate from said vortex flow and exit said chamber, and excludes particles withm said fluidized particulate material with greater than said predetermined size and inertia from exiting said chamber

3 The device of claim 2, wherein said vortex flow generates

(a) a low pressure center region withm said chamber, wherein said low pressure center region is m fluid communication with said inlet, whereby said gas flows into said chamber; and

(b) a high pressure outer region withm said chamber, wherein said high pressure outer region is in fluid communication with said outlet, whereby said gas flows from said high pressure outer region and exits through said outlet

4 The device of claim 3, wherein said particles withm said fluidized paniculate material with less than and including a predeteπmned size and inertia that deviate from said vortex flow and ex t said chamber, exit said device with said gas that flows from said high pressure outer region and exits through said outlet

5 The device of claim 1, wherein said device is one of the following unit dose, bulk powder, or multi-dose

6 The device of claim 1, wherein said particle fluidizei comprises an impeller

7 The device of claim 6, wherein said impeller has an axis of rotation substantially concentric about the longitudinal axis of the chamber The device of claim 3, wherein said mlet comprises an external ingress port, an ingress conduit, and an internal ingress port, and said internal ingress port is located near said low pressure center region

The device of claim 3 wherein said particle classifier comprises a ingress port and an egress port, and said particles withm said fluidized particulate material with less than and including a predetermined size and inertia that deviate from said vortex flow and exit said chamber enter said particle classifier through said ingress port

The device of claim 9, wherein said ingiess port of said particle classifiei faces m a direction similar to said vortex flow

The device of claim 10, wherein said said particles withm said fluidized particulate mateπal with less than a predetermined size and inertia that deviate from said vortex flow flow m a direction opposite said vortex flow

The device of claim 1, wherein said particle classifier is a conduit

The device of claim 1, wherein said particle classifier is a conical particle classifier

The device of claim 1, said particle fluidizer fluidizes said particulate material by one of the following abrasion, fracturing, impact with said particle fluidizer, causing particulate material to impact with said chambei, or causing impact between said particulate material

The device of claim 2, wherein said particle classifier is sized such that at least 90% of said fluidized particulate material that passes though said outlet has an average particle size of about 5 to about 10 microns in diameter

The device of claim 15, wherein said particle classifier is sized such that at least 99% of said fluidized particulate material that passes though said outlet has an average particle size of about 2 to about 6 microns in diameter

The device of claim 1, wherein approximately 1 milligram per mmute of fluidized particulate material is dispensed

18. The device of claim 1, wherein said device further comprises a mouthpiece whereby said portion of fluidized particulate material that exits said outlet can be inhaled through

19 The dev ice of claim 1. wherein said particle fluidizei is electrically powered

20 The device of claim 1, wherein said device comprises a self-contained power source

21 The device of claim 20, wherein said power source is a battery

22 The device of claim 1, wherein said particulate material is sodium chloride.

23. A method of dispensing an aerosolized particulate material for inhalation, comprising: providing a housing having an mlet for a gas, an outlet, and a chamber suitable for containing a particulate material; fluidizmg a flow of said particulate material with said gas in said chamber; classifying said fluidized flow; and dispensing said classified fluidized flow.