Unit dose cartridge and dry powder inhaler

Description of equivalent WO 2005023348 A2

UNIT DOSE CARTRIDGE AND DRY POWDER INHALER

Field of the Invention The present invention is in the field of drug administration inhalers having improved control over system volumetric air flow rate, medicament particle transport, particle dispersion, particle metered dosimetry and patient compliance. Background of the Invention In the early 1970's it was found that certain medicines could be administered in dry-powder form directly to the lungs by inhalation through the mouth or inspiration through the nose. This process allows the medicine to bypass the digestive system, and may, in certain cases, allow smaller dosages to be used to achieve the same results as orally ingested or injected medicines. In some cases, it provides a delivery technique that reduces side effects for medicines and interactions with other prescribed medicines, as well as providing a more rapid drug medication uptake. Inhaler devices typically deliver medicine in a liquid droplet mist or as a dry powder aerosol. Deposition of particulate matter within the human lungs is a very complex and not fully understood phenomenon. People breathe over a relatively broad tidal volume. It is known that lower transport velocities of gas-entrained particles entering the mouth avoid impaction better within the oropharyngeal cavity. This is particularly true of particles greater than one to two microns in diameter. In order for particles to remain suspended in a gas stream, their superficial transport velocity must be greater than their gravity settling velocity. For example, a 100 micron particle must have a transport gas velocity of approximately 7 ft/sec or greater for the 100 micron particle to remain in a particle/gas entrainment state. The required transport velocity for smaller particles is much less. High speed particles have a greater propensity to impact and deposit on the tissue lining of the oropharyngeal cavity, as noted above. Thus, a significant number of particles are lost and will not enter the lungs, if those particles are not transported at the correct velocity. Another common problem with inhalers is that the particles agglomerate, causing clumping of particles that then adhere to the inhaler or the oral cavity, rather than entering the lungs. Most approaches to this problem have been to include a surfactant in, on or with the particles to decrease the adhesion between particles. Importantly, it should not be difficult for a patient to load the inhaler with medicine, and to easily and properly use the inhaler so that the correct dosage is actually administered. Many current dry particle inhalers fail in one or more of these important criteria. It is therefore an object of the present invention to provide inhalers which are easy to properly use, and which deliver drug powders so that the powder enters the lungs instead of adhering to the back of the throat. It is an object of the invention to provide an inhaler which will operate effectively with dry powder medicaments having particles ranging in size from about 0.5 to about 10 microns, and preferably from about 1 to about 5 microns in size. It is a further object of the present invention to provide an inhaler that can operate effectively over a broad inhalation tidal volume range of human breath. It is a still further object of the present invention to provide an inhaler which controls the volume and velocity of air flow so as to provide effective and desirable colimation, de-agglomeration and entrainment of the inhaled drug. A related object is to provide an inhaler which creates a high-shear air flow field and controlled circulating gas action to break up particle agglomeration during proper inhaler usage. A more specific object is to provide an inhaler mouthpiece which is sized and shaped to develop an air flow which will air stream entrained medicament particles through the oropharyngeal cavity. Another specific object is to provide a medicament-containing inhaler cartridge which will supply medicament for complete air entrainment and proper dispersion into the air stream. Yet another object is to provide an inhaler air-flow-controlling check valve which will straighten the air flow and limit the air flow volume and velocity to values between pre-determined maxima and minima so as to properly entrain, de-agglomerate and deliver medicament particles to the inhaler user. Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings. Throughout the drawings, like reference numerals refer to like parts. Summary of the Invention A dry powder inhaler (DPI) includes an air intake and check valve section; a mixing and cartridge section; and a mouthpiece, all designed to control the volume and velocity of the inhaled air and aerosolized drug. This inhaler can be operated over a very broad inhalation tidal volume range of human breath. Several features of the inhaler provide advantageous properties, most significantly with respect to using carefully designated aerodynamic forces to dilute and de-agglomerate the medicament particles, rather than using broad high pressure forces that would contribute to relatively great particle losses in the oropharyngeal region. The inhaler intake chamber mounts a check valve bulb, which in the preferred embodiment has a tapered bulb, bulb travel rod and biasing spring, and one or more perimeter chutes or Venturis on the bulb to modulate and control the flow of air through the device. The intake further optionally includes a feedback module (not shown) to generate a tone indicating to the user when the adequate inhalation air-flow rate has been achieved. The inhaler mixing section preferably holds a cartridge containing a dry powder medicament. In the preferred embodiment, the cartridge has two telescopically assembled halves, and each half has an air inlet hole or orifice- port and an air outlet hole or orifice-port. When the halves are rotated so as to align the air holes, the air stream from the check valve enters the cartridge and then picks up, fluidizes and de-agglomerates the medicament powder in the cartridge. The airflow entraining the particles then exits the cartridge and flows through the mouthpiece to the inhaler user. In the preferred embodiment, the cover on the mixing section can open only when the mouthpiece is at an appropriate pre-determined angle to the intake conduit. The mixing section helps to impart a cyclonic flow to air passing through the mixing chamber and cartridge. An important feature of the inhaler is the mouthpiece. In a preferred embodiment, the mouthpiece is integrated with the swivel j oint of the mixing section, and can be rotated back into the inhaler intake section and then enclosed by a cover for storage. A mouthpiece transport conduit has the ability to expand the cross-section of the air flow, which in turn reduces the velocity of approach of the drug powder into the oral cavity. As shown in figures 10, 18, 19, 21 and 23, the mouthpiece is offset with respect to the centerline of the mixing cavity and mounted cartridge. The airflow inlet from the check valve mechanism into the mixing chamber and cartridge is also offset. These tangential offsets encourage a helical airflow around the cartridge, as explained in further detail below. Initially, the tangential mouthpiece exit tube increases the velocity of the transport gas, which in turn inducts the discharged particles into the exit tube. The mouthpiece exit tube then expands in one dimension and the transport gas slows while the particle concentration per unit volume becomes more dilute. Flow is expanded to create a secondary shear flow, which helps to further de-agglomerate particles. This also creates a horizontal aspect ratio and therefore aerosol discharge path that is more effective in negotiating and streaming the aerosol through the convoluted pathway of the oral pharynx. The mouthpiece expansion wall divergence angle is important for stable particle transport conditions to exist. An optimum divergence angle is between 14 and 16 degrees. However, a slightly larger 17 degree divergence angle can be used to achieve a horizontal aerosol discharge path with a 3: 1 aspect ratio closely approximating the aspect ratio at the rear of the human throat. Once the expansion divergence has reached a specified limit, the continuing slot discharge tube maintains the proper collimation of the particles for controlled particle injection speed and direction of the path of the particles into the oral cavity. In a preferred embodiment, the mouthpiece includes a tongue depressor, and a tactile protrusion to contact the lips of the user to tell the user that the Dry Powder Inhaler (DPI) is in the correct position. The cartridge halves can be rotated into and out of positions in which the air inlet holes and the air outlet holes are respectively aligned. The cartridge can only be inserted into the mixing chamber when a cartridge alignment boss is aligned with a receiving recess at the bottom of the mixing chamber, and a cartridge collar engages a mating mixing chamber collar (Figure 2). In the preferred embodiment, each cartridge has a unique key on each half that fits only with a particular part of the inhaler, thereby insuring that the proper cartridge containing the proper medicament is preselected, and further insuring that the cartridge is installed properly in the inhaler. Brief Description of the Drawings Figure 1 is an isometric view of the inhaler embodying the invention. Figure 2 is an exploded view of the inhaler shown in figure 1. Figure 3, including figures 3a, 3b and 3c, is a front isometric view of the medicament containing cartridge used with the inhaler, showing cartridge outlet hole or orifice port alignments. Figure 4, including figures 4a, 4b and 4c, is a rear isometric view of the medicament-containing cartridge used with the inhaler shown in figure 3, showing inlet hole or orifice port alignments. Figure 5 is a front elevational view of the cartridge shown in figures 3 and 4. Figure 6 is a rear elevational view of the cartridge shown in figures 3, 4 and 5. Figure 7 is a sectional view taken substantially in the plane of line 7 -

7 in figure 5. Figure 8 is a sectional view taken substantially in the plane of line 8 -

8 in figure 7. Figure 9 is a sectional view taken substantially in the plane of line 9 -

9 in figure 7. Figure 10 is a top plan view of the inhaler shown in figures 1 and 2. Figure 11 is a sectional view taken substantially in the plane of line 11 - 11 in figure 10. Figure 12 is a sectional view taken substantially in the plane of line 12 - 12 in figure 10. Figure 13 is an isometric view of the inhaler shown in figures 1 and 2 but configured for the insertion or removal of a medicament-containing cartridge. Figure 14 is an isometric view similar to figure 13 but configured as it appears when a medicament-contaimng cartridge has been inserted in the inhaler. Figure 15 is a sectional view taken substantially in the plane of line

15 - 15 in figure 13. Figure 16 is a sectional view taken substantially in the plane of line

16 - 16 in figure 14. Figures 16a, 16b and 16c are fragmentary sectional views taken substantially in the plain of line 16a - 16c in figure 16. Figure 17 is an isometric view showing the inhaler of figures 1 and 2, parts being broken away to permit the diagramming of air flow through the inhaler. Figure 18 is an isometric view similar to figure 17 diagramming air flow through and around the inhaler check valve, mixing section, cartridge and mouthpiece. Figure 19 is an isometric view similar to figure 18 diagramming air flow through and around the inhaler check valve, inside the cartridge, and through the mouthpiece. Figure 20 is an isometric view similar to figures 1, 2, 17, 18 and 19 showing the inhaler, the inhaler flow-control/check- valve, and the flow- control/check-valve sub-housing. Figure 21 is a top plan view of the inhaler shown in figure 20. Figure 22 is a sectional view taken substantially in the plane of line

22 - 22 in figure 21. Figure 23 is a top plan view substantially similar to figure 21. Figure 24 is a sectional view taken substantially in the plane of line 24 - 24 in figure 23. Figure 25 is an isometric view of the flow-control/check- valve and sub-housing shown on figures 17, 18, 19, 20, 22 and 24. While the invention will be described in connection with several preferred embodiments and procedures, it will be understood that it is not intended to limit the invention to these embodiments and procedures. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. Detailed Description of the Invention An improved dry powder inhaler ("DPI") has been developed which has several features optimizing performance. Medicament particles can be delivered/administered over a broad range of inhalation velocity and tidal volume of human breath. An inhaler mouthpiece exit tube dilutes, expands, and collimates the particle dispersoid so that the particles do not re- agglomerate during delivery. This inhaler provides the means to effect a process whereby particles are fluidized, suspended, then scavenged from the walls by re-circulating scrubbing air, as well as higher speed-flow-through air, followed by a high-shear flow field discharge into an expanded, slower- moving mass of air that disperses and meters the particle concentration expelled from the unit dose cartridge upper outlet port. Inhaler Overview Figure 1 shows an embodiment of a dry powder inhaler 10 described and claimed herein. In broad conceptual terms, an inhaler housing 15 includes an intake section 20, a mixing section 30 and a mouthpiece 40. In the preferred embodiment, this inhaler housing 15 is approximately 93 mm long, 38 mm high, and 22 mm thick. The other parts illustrated and described here are of proportionate size. The mouthpiece 40 can be swiveled from a stored position within the housing 15 to a cartridge installation position in which the mouthpiece 40 is oriented at 90 degrees to the long dimension of the housing. When a cap 352 is closed, the mouthpiece can then be further rotated into an operating position in which the mouthpiece is located at a 180 degree position to the long dimension of the housing. When the mouthpiece 40 is stored within the inhaler 15, a sliding dirt shield cover 16 slidably mounted stored on the housing can be slid upwardly to protect the mouthpiece 40 and the air intake conduit entrance of the inhaler. The housing 15 can be formed of a gamma radiation-proof polycarbonate plastic for the rapid sterilization of the inhaler in mass production, as well as in clinical- hospital use. An air passage 50 (Fig. 17) extends through the intake section 20, the mixing section 30 and the mouthpiece 40. A swivel joint 80 (Figs. 2 and 17) connects the mouthpiece 40 to the mixing section 30. In the preferred embodiment, the mouthpiece and mixing section are one unit, and are connected by a swivel joint to the main housing. The cap 352 is pivotally attached to the mixing section 30, and an interlock mechanism 355 prevents the mouthpiece 40 from being swung into an operating position unless the cartridge 301 is properly seated and installed. A cartridge 301 shown in Figs. 3, 4 and 5 contains a medicament powder, and it can be installed in and removed from the mixing chamber 30. Aerosolized powder is drawn from the cartridge 301 and mixing section 30 through the mouthpiece 40 to the users' oropharyngeal cavity via the mouthpiece 40. As air and powder travel through the mouthpiece, the velocity of the travel slows, thus preparing the powder for effective delivery to the inhaler user's broncheal tract and lungs. So that writing or identifying indicia on medicament-containing cartridge 301 can be read easily, the mixing section 30 has a cover 352 which may be configured as a transparent magnifying lens. An arrow 460 (Fig. 17) shows the direction of aerosolized medicament powder discharge from the cartridge and through the mouthpiece. Air-Flow Control/Check Valve System Air is caused to enter the inhaler by an inhalation effort which the inhaler user exerts on and in the mouthpiece 40. As shown particularly in Figure 17 and as suggested by the air-flow arrows 460 in Figures 17 and 18, ambient air enters the air control system 171 through air intake ports 172 and is directed to an air flow-control/check-valve 180. As shown in Figures 17, 18, and 25, this check valve system 180 includes a conical head 181 mounted upon a bulb rod 182. A bulb 184 is slidably mounted upon the rod 182 for reciprocation between a stagnant air-flow position and a dynamic air-flow- inhibiting position. The rod 182 also serves to maintain the annular gap between the bulb 184 and the bore in which the bulb is located. The bulb 184 is drawn into a normal relatively downstream air-flow position, by the force of air flow acting to overcome the bulb reactive force of a conical tension spring 185, as suggested particularly in figure 19. The spring 185 allows selection of the strength of the bias of the bulb towards normal and avoids the requirement for vertical orientation. This spring is preferably formed of medical grade stainless steel. In a preferred embodiment, chute-like recesses 186 in the surface 187 of the bulb 184 control and direct the flow of air over the bulb 184, thereby acting as venturies. In another preferred embodiment, air-flow straightening vanes 189 mounted on the conical head 181 engage a confronting conical venturi formation or seat 191 (figure 22). Air flowing between the head 181 and seat 191 is accelerated and the air-flow straightened, in accordance with known characteristics of gaseous air-flow. The venturies, by virtue of changes in their length and depth, can be used to alter flow rate as well as sheer and air flow direction. When the inhaler user draws air through the mouthpiece 40, air flows to and around the bulb 184, and the imbalance of air pressure forces acting upon the reciprocating bulb 184 pushes the bulb in a downstream direction along the rod 182 into a position which inhibits air-flow. Because the bulb 184 is connected to the tension spring 185, increasing amounts of force are required to draw the bulb 184 into increasingly air-flow-restricting positions. Additional bulb movement control can be provided, if desired, by an opposing second spring (not shown) forming a high-sensitivity push-pull system. This bulb and spring mechanism allow the inhaler user to generate a slight partial vacuum in his lungs before the bulb is drawn away from the seating arrangement. Thus, by the time significant vacuum is generated, a slight velocity increase of air-flow through the inhaler assists in drawing the medicament from the cartridge (Figures 1 and 17-19), through the inhaler and into the bronchial region and lungs of the user. As suggested particularly in Figure 20, the check valve arrangement 180 can be mounted in a sub-housing 20, and both components 20 and 180 can be removed from the inhaler housing 50 for cleaning, repair or replacement. A lock device 196 of known design can be used to secure the sub-housing 20 and contained components within the inhaler housing 50. When air is being drawn through the inhaler 10 and the bulb 184 is drawn along the rod 182 so as to impact the conical head 181, a clicking sound may be produced. This clicking sound indicates to the inhaler user that he or she is drawing properly upon the mouthpiece and operating the inhaler correctly. If desired, a vibratory mechanical reed (not shown) can be mounted in the air-flow path to produce an audible signal to the user. Alternatively, an electronic flow or pressure sensor can trigger an audible or visual signal indicator to tell the user that proper air flow has been established. This air flow-control/check-valve system 180 serves to deliver air at a predetermined volume and velocity to downstream inhaler parts. The airflow, at this predetermined volume and velocity, acts to pick-up, fluidize, de- agglomerate and deliver entrained medicament particles to the inhaler user in a dispersed form and at a proper location to enter the user's bronchial system. Venturi and Mixing Section As suggested particularly in Figures 12, 17 and 18, the air flow is then drawn through a venturi passage 201 of restricted size, thus increasing the velocity of the air-flow, and into the inhaler mixing section 30. As shown in Figures 10-17, this mixing section 30 comprises a fixed support 31 upon which is joumaled a cup 32. It will be noted that the mouthpiece 40 is attached to the swivel cup 32 and can thus act as a handle for pivoting the cup member 32 and mouthpiece to the configurations shown in figures 1, 14 and elsewhere and as more fully described below. In general, the mixing section 30 is provided with shapes on its interior surface to encourage air flow acceleration so as to suspend medicament particles in the air-flow and to de-agglomerate them. Within the cup 32 a medicament-containing cartridge 301 can be mounted. As more fully described below, the cartridge 301 is provided with air inlet and outlet holes (Figures 5 -9), the cup 32 is sized and shaped to direct air into the cartridge through the lower inlet hole. The air then generally flows up through the cartridge in an upward direction while producing a dual counter- rotating helical motion, and out of the cartridge and down the mouthpiece as particularly suggested in figure 19. As suggested in Figure 18, excess volume of air can flow around the outside of the cartridge but within the mixing chamber to again mate with the emerging medicament-laden air discharged from the cartridge and flowing into the mouthpiece. Thus, air flowing into the mixing chamber feeds the cartridge inlet holes, helps to extract air flowing out from the cartridge discharge holes, dilutes the medicament-laden air flow, and provide controlled, even concentrations of medicament particles into the mouthpiece air flow. The particle entrainment and dilution in the mouthpiece are provided primarily by the cartridge bypass air. As suggested in Figures 11, 12, 15 and 16, the mixing chamber inlet port 33 provides vortex shedding which, aided by the top and bottom internal mixing chamber internal swirl toroids 34 and 35, fluidizes, suspends and scrubs the powder in the cartridge. The upper semi-toroid shape 35 changes air flow direction from dispersion chamber to mouthpiece, thus aiding further de-agglomeration of the medicament particles in the entrained powder stream. To reduce powder cohesion, a modest gas expansion velocity with subsequent air shearing forces (and flow resistance) act to support a fully dispersed flow through 40. Alternatively, a chamber which includes internal protrusions or spiral shapes can be provided. The interior surfaces of the mixing chamber can be shaped to provide one or more helical flows of air around and within the cartridge, if desired. Cartridge The cartridge 301 is shown in further detail in Figures 3-9. In the illustrated embodiment, the cartridge 301 comprises an upper half 302 and a lower half 303, each preferably formed of transparent plastic material. To encourage medicament particle dispersion, the preferable plastic material is provided with ultra smooth surfaces, is capable of being molded into the cartridge components which have and which maintain great dimensional accuracy, does not absorb or otherwise interact with water or moisture, and has electrostatically neutral characteristics such that the medicament powder in the cartridge 301 is not retained by cartridge static charge, and does not adhere to the cartridge halves 302, 303. One such material which can be used for the lower half 303 is the Topaz brand of cyclicolephin co-polymer plastic offered by Ticonia Corporation. The upper cartridge half 302 defines an air inlet hole 306 and an outlet hole 307, and the cartridge lower half defines a corresponding air inlet hole 308 and an air outlet hole 309. This upper half can be made of a clear very low water absorbent nylon. As shown particularly in Figure 7, and as suggested in Figure 3 a, the halves 302 and 303 interengage through a telescopic fit. A circumferential ring and groove arrangement 310 retain the halves 302 and 303 in their assembled configuration. As suggested particularly in Figures 5,6, 8, and 9, the inlet holes 306 and 308 formed at the lower portion of the cartridge are preferably beveled, and the outlet holes 307, 309 are likewise beveled at an angle of substantially 60 degrees so as to encourage air ingress and egress but to discourage electrostatic adhesion and agglomerate deposition of 10 or larger micron- sized medicament particles on the plastic defining the hole edges. To enable air flow and particle pickup action, the inlet holes 306 and 308 are arranged to overlap or register with one another when the cartridge halves are rotated (as suggested by the arrow A in Figure 4c) into the appropriate cartridge open position, and the holes 306, 308 are elongated in a vertical direction. Similarly, the outlet holes 307, 309 are arranged to overlap and provide free air egress when the cartridge halves are appropriately aligned, and the holes are elongated in a horizontal direction so as to orient the air outflow for delivery to the horizontally elongated channel in the mouthpiece 40. This cartridge 301 is approximately one-quarter inch in diameter and its body is approximately 1 inch in axial length. To facilitate easy installation and extraction from the inhaler 10, a handle or manipulator structure 314 is provided atop the cartridge 301. Here, the handle structure 314 comprises four web extensions 315 which extend from the cartridge body to a finger disk 316 which may have a coined or serrated periphery. A pointer or dial indicator 317 is formed atop the disk 316 and is further discussed below. At the bottom of the cartridge 301, a cartridge installation check boss 319 is formed. This check boss can have a unique, non-circular shape of any desired form such as those shown in figures 16a, 16b and 16c. These unique embossments are designed to fit within a closely mating relief 39 formed in the base 31 of the mixing section. These unique embossed shapes will be uniquely associated with particular medicaments, so that a cartridge containing an incorrect medicament cannot be installed in a particular patient's inhaler. Cartridge Mounting Mechanism To properly mount the cartridge 310 in the inhaler 10, a mounting mechanism 350 is provided as especially shown in Figures 1, 2, 13-16 and 17. This mounting mechanism 350 takes the form of a cap 352 formed of clear plastic, pivotally mounted to cover the mixing section cup 32. See especially Figure 16. A pivot pin 353 interconnects the cap 352 with an extension 354 of the mount 31. To facilitate reading indicia marked upon the top of the cartridge pointer 317, the top of this cap 352 is curved so as to act as a magnifying lens. This dome shape also provides strength to the cover structure. The cartridge can be installed and the cap 352 secured in place when the mouthpiece 40 and cartridge are pivoted into their operating positions. To this end, a radially outwardly biased lock pin 356 (Figure 2) depending from the cap mount 31 pushes the cap 352 upwardly and into an open position when the mouthpiece 40 and cap mount 31 are swiveled into a position so that the mouthpiece is located at approximately 90 degrees to the long or greater dimension of the inhaler body 15. In this configuration, the lock pin 356 is pushed radially outwardly and the cap 352 is rotated upwardly when the lock pin 356 is pushed into a relief 359 defined in a skirt 360 of the cover 358 (Figure 2). This arrangement acts as a safety and user prompting feature. After the cartridge is inserted into the inhaler and the cap is closed, the mouthpiece 40 can be pivoted out of its cartridge installation and cap release position as shown in Figures 13-16 and into the user medication inhalation configuration shown in Figures 1, 17 and 20-24. This mouthpiece pivoting motion can occur only when the cap skirt 360 is pushed down into its closed position and the lock pin 356 is radially depressed to permit mouthpiece 40 swiveling action. Thus, when the inhaler user moves the mouthpiece from its stored position within the housing 15 to the cap unlocked position, the cap springs open as shown in Figures 13 and 15, and thereby indicates to the inhaler user that he or she should inspect and, if necessary, replace or insert a new cartridge 301.

Mouthpiece As suggested above, the mouthpiece 40 discharges particle-laden air to the oropharyngeal cavity of the user. In addition, the mouthpiece diverges the air and particle stream to slow down the particles, and then converges the particle stream to collimate and aim the particles at the rear of the user's mouth. The mouthpiece is long enough so that it extends approximately midway into most users' mouths. To encourage correct inhaler and mouthpiece usage, the inhaler mouthpiece is oriented to extend diagonally upwardly at approximately a 3 degree angle X as suggested in Figures 22 and 24. As suggested in Figures 21 and 23, the horizontally spaced walls of the mouthpiece diverge at an angle Y of approximately 5 to 8 degrees. As suggested by a comparison of Figures 21 and 22, the ratio of the height H of the mouthpiece air passage page to the width W of the air passage is approximately 3:1. If desired, a tooth and lip placement embossment 411 can be provided to depend from the distal end 412 of the mouthpiece 40. The mouthpiece is preferably made of Delrin or Celcon co-polymer acetyl plastic so as to provide proper strength, swivel bearing self-lubricity, and smooth internal and external finish. In use, the inhaler employs a regulated flow of air to fluidize and aerosolize medicament particles and transport them to the desired rear region of the oropharyngeal cavity. To accomplish this, air is first drawn into the interior of the inhaler housing 15 and through the intake ports 172 as suggested in Figures 17 and 18, to a predetermined volumetric air flow which is controlled by the flow-control/ check- valve mechanism 180. The airstream then enters into the cartridge interior through the vertically elongated and aligned inlet ports 306, 308. The air entering the cartridge interior immediately impinges upon the opposite cylindrical cartridge wall. The impacted air jet then redistributes itself into several portions. One of the portions flows downwardly into the medicament powder bed, and strips the powder from the cartridge surface and begins to fluidize it into an airborne dust cloud. Another portion of the impingement jet is directed laterally in both directions, which creates dual counter-rotating vertical spinning helical columns. The majority of the fluidized medicament powder is retained in these two columns, where the first deagglomeration action is achieved. Yet another portion of the impingement jet is directed vertically, which creates a vertical high-speed air jet along the cartridge wall into the cartridge discharge port or holes 307, 309. Particles in the helical aerosolized columns are scavenged into the Jetstream and then discharged from the cartridge. This scavenging effect results in particles being metered out or discharged from the cartridge at a relatively steady particle distribution rate. Particle agglomerations are further broken down by the discharge process. Large agglomerates impinge upon the opposing mixing chamber wall, and are further reduced into smaller agglomerates. Single particles and smaller agglomerates are carried forward through the mixing chamber and into the mouthpiece discharge tube. The remaining agglomerates are pulled apart in the high-shear and shock flow field produced by the mouthpiece tangential entry port. Thus a steady flow of a individual medicament particles emerge from the mouthpiece and into the users oropharyngeal airway. These airstream flows and the sub-stream flows thus result in complete air entrainment of all medicament particles in the cartridge, and delivery of a complete, closely metered medicament dose to the patient.