Source: https://patents.justia.com/patent/8820324
Timestamp: 2019-11-13 07:15:53
Document Index: 764765587

Matched Legal Cases: ['art 2', 'art 4', 'art 2', 'art 2', 'art 4', 'art 2']

US Patent for Hinged dry powder inhaler comprising a circulating airflow chamber Patent (Patent # 8,820,324 issued September 2, 2014) - Justia Patents Search
Justia Patents Means Broken Or Pierced To Supply Treating AgentUS Patent for Hinged dry powder inhaler comprising a circulating airflow chamber Patent (Patent # 8,820,324)
Jun 13, 2007 - Cambridge Consultants Limited
A dry powder inhaler comprises two parts (2, 4) connected by an integrally molded, e.g. living hinge (6), so as to be moveable from an open position to a closed position. At least one of the parts (2, 4) defines at least part of a circulating airflow chamber (12), wherein when said parts (2, 4) are in said closed position, the inhaler comprises an airflow path including the circulating airflow chamber (12).
Furthermore, there is a tendency for the respirable particles to aggregate during storage. The DPI should there to de-aggregate these fine (respirable) particles. Despite this, known DPIs are rather inefficient at de-aggregating the drug particles. The number of particles of respirable size as a proportion of the total output of the inhaler is known as the Fine Particle Fraction (FPF). In typical conventional inhalers, the Fine Particle Fraction can be as low as 30% and 40-50% is typical. Moreover, in many devices the FPF is dependent upon the inhalation flow rate of the user so that performance is inconsistent both between users and from one use to the next. Of course, a low FPF also leads to much of the drug being wasted. The additional problem with the FPF being inconsistent is that it is then impossible to control the dose actually being received by the user.
Conventional DPIs are usually susceptible to moisture which can affect both the FPF and the delivered dose consistency. Even if the inhaler is provided with a cover, it must be opened to use and/or refill the inhaler.
Even more beneficially though, a single dose inhaler may be found particularly suitable for one-off treatment of medical conditions, for example in administering an antidote, vaccination or immunisation, especially where it is necessary to carry this out for a large number of people, such as in the event of an outbreak of a health epidemic.
It will be understood that what is meant by a circulating airflow chamber is any kind of chamber which creates a circulating, swirling or turbulent airflow that acts to de-aggregate entrained powder particles. However, in particularly preferred embodiments the circulating airflow chamber has an air inlet and is so shaped that at least a part of the chamber decreases in cross-sectional area in a direction away from the air inlet, so as thereby in use to set up a reverse flow cyclone in the chamber.
Firstly, the flow pattern in a reverse flow cyclone—with an outer, downwardly spiralling “free” vortex and an inner, upwardly spiralling “forced” vortex—gives rise to a substantial fluctuation in tangential velocity across the width of the chamber. The steep velocity gradient encountered in the flow cause efficient de-aggregation of the particles. Moreover, the particles are subjected to these relatively high shear forces both as they travel downwardly to the base of the chamber and also as they travel back up the chamber in the inner, forced vortex. This relatively long flow path over substantially the whole of which de-aggregation can take place leads to a significantly increased proportion of fine particles within the entrained airflow as it travels towards the exit of the cyclone chamber.
Secondly, the central, forced vortex, which travels up from the base of the chamber is relatively tight and well defined. As is known in the art, the mean radius of circulation of a particle is dependent upon its weight and therefore size. Thus by careful selection of a particular circulation radius, a very sharp cut-off threshold of particle sizes may be achieved. By selecting a radius equivalent to 5 microns or less, an even higher Fine Particle Fraction may be achieved. Such selectivity can be obtained for example, by a “vortex finder” comprising a tube projecting some way into the cyclone chamber, which provides the outlet to the chamber.
Thirdly, the reversal of vertical direction of travel of the particles at the base of the chamber causes the de-aggregated carrier particles, and any drug or combination particles which are too large, to be trapped within the cyclone and thus not be inhaled by the user. This substantially reduces the deposition of large particles on the user's throat with the attendant problems referred to previously. The separation of the large particles retained in the inhaler from the finer particles which are inhaled is seen as an important benefit which may be achieved in accordance with some preferred embodiments.
When viewed from a further aspect the invention provides a dry powder inhaler comprising: an airflow path including a cyclone chamber having an air inlet and being so shaped that at least a part of the chamber decreases in cross-sectional area in a direction away from the air inlet, so as thereby in use to set up a reverse flow cyclone in the chamber; said inhaler comprising two parts connected together by an integrally moulded hinge defined by a line of weakness.
Where a reverse-cyclone chamber is provided, the decreasing cross-sectional area could be achieved in a number of ways. To give one example, the chamber could be generally cylindrical with a conical or frusto-conical inward protrusion from the base thereof to give the reducing internal cross-sectional area which gives rise to the reverse-cyclone flow pattern described previously. Preferably, however, the outer wall of the chamber tapers towards the base. This could be a curved taper, but preferably the shape is generally frusto-conical. This has been found to give the most efficient reverse-cyclone flow pattern.
The air inhaled by a user may all be drawn through the circulating airflow/reverse cyclone chamber. However in accordance with preferred embodiments of the invention the inhaler comprises a main airflow path which passes through the chamber and a bypass airflow path bypassing the chamber; wherein the main and bypass airflow paths communicate with the mouthpiece.
In accordance with such embodiments, only a proportion of the air inhaled by a user is drawn through the circulating airflow chamber. The remainder is drawn through the bypass airflow path into the mouthpiece without passing through the chamber. The Applicant has found that such bypass airflow can be important in limiting the flow rate through the chamber, and controlling the overall device airflow resistance as felt by the user. Particularly where, as is preferred, the circulating airflow chamber is a reverse cyclone chamber. If there is too great a flow rate through the circulating airflow chamber, then the velocity of the particles is too great and so even the fine respirable particles are separated and hence retained in the cyclone. Therefore the cyclone must be sufficiently large to allow the respirable particles to escape for a given flow rate. In practice this could mean that the chamber would be too large to be incorporated in an easily portable device such as can be carried in a pocket or handbag.
In accordance with all embodiments of the invention, the dose of powder could be arranged to be introduced into and entrained by the inhaled air at any convenient point in the system. For example, the powder could be stored within the circulating airflow chamber and released at the appropriate time into the chamber. Alternatively, the powder could be introduced into the chamber by the vortex finder where such is provided. Preferably, however, the powder is stored within the circulating airflow chamber and exposed to an entraining airflow in the chamber upon inhalation.
In other arrangements the powder could be entrained prior to entry into the circulating airflow chamber. In some arrangements this could take place in a conduit leading to the chamber, although in an advantageous arrangement a further ante-chamber is provided upstream of the swirl or cyclone chamber into which the powder is delivered. Preferably this ante-chamber is arranged to encourage a circulatory airflow therein. This has the advantage of providing a “scouring/scrubbing” flow to collect powder efficiently from the inner surface of the chamber. It is of particular benefit in applications where the powder particles do not flow very well.
FIG. 1 is a perspective view of an inhaler in accordance with the present invention, in its open position;
FIG. 2 is a side view of the inhaler in its open position;
FIG. 3 is a top view of the inhaler in its open position;
FIG. 4 is a perspective view of the inhaler in its closed position;
FIG. 5 is a perspective view of one side of the inhaler;
FIG. 6 is a perspective view of the other side of the inhaler;
FIG. 7 is a perspective view of the front of the inhaler;
FIG. 8 shows the reverse cyclone airflow in a frusto-conical chamber;
FIG. 9 shows five different cyclone chamber configurations A-E used to test the performance of a reverse flow cyclone; and
FIG. 10 shows the performance test results for the cyclone chambers A-E of FIG. 9 compared to two conventional dry powder inhalers.
With reference to FIGS. 1-8, the general construction and operation of a dry powder inhaler in accordance with the invention will be described.
The inhaler 1 is integrally moulded in two parts from a plastics material such as polypropylene in what is essentially a box-frame structure that gives good strength for minimum amount of material. The bottom part 2 and the top part 4 are connected by a living hinge 6. The hinge 6 is formed by a thinned section of plastic joining the two parts, as is best shown in FIG. 2. The joining section is thinned enough that the two parts can be flexed open and closed, but is strong enough that it retains its mechanical integrity.
In the bottom part 2 of the inhaler there is formed a dose storage and entrainment system 8 which comprises a relatively shallow entrance channel 10 and a circulating airflow or cyclone chamber 12. The entrance channel 10 and cyclone chamber 12 are formed as an integral recess in the bottom part 2. The cyclone chamber 12 is generally cylindrical at its upper end with a frusto-conically shaped base. As can be seen from FIG. 3, the entrance channel 10 is wider at one end and then tapers in towards the point where it connects with the cyclone chamber 12. The entrance channel 10 is configured so as to provide a tangential air inlet into the cyclone chamber 12 at its upper end. The cross-sectional shape and area of the channel 10 at its outlet into the cyclone chamber 12 is chosen so as to promote a well-defined grade efficiency curve in the cyclone chamber 12. This would be optimized on the basis of a specific application.
The mouthpiece 20 is shown more clearly in FIG. 7. One channel of the mouthpiece 20a is blocked off apart from an air inlet hole 22. This air inlet 22 provides an airflow directly into the mouth from the exterior, i.e. bypassing the cyclone chamber 12. The other half of the mouthpiece 20b communicates with the plenum portion 19.
As shown in FIG. 1, the inhaler is provided with a snap-fitting arm 24 on the top part 4 and a corresponding recess 26 on the bottom part 2. The inhaler is shown in its closed position in FIG. 4 with the arm 24 snap-fitted into the recess 26 to hold the top and bottom parts together.
The airflow pattern in the reverse cyclone chamber 12 is shown in FIG. 8. The tangentially entering air and cylindrical upper wall portion set up a bulk circulation of air around the periphery of the chamber 12. The inlet from the communicating channel 10 is also angled down slightly so that the air flow forms a shallow downward spiral known as a “free” vortex 17a. Due to conservation of angular momentum, the rotational velocity of the free vortex increases as the airflow is constricted by the tapering inner surface of the frusto-conical portion of the chamber 12a. As the free vortex 17a hits the base of the chamber 12b it is reflected to form a tight “forced vortex” inside the free vortex and travelling back up the axis of the chamber.
The form and dimensions of the bypass air inlet 22 are designed to set the inhaler overall resistance and the proportion of an average breath air flow which passes through the cyclone relative to the bypass air flow. In further embodiments (not shown) the bypass air inlet 22 can include a variable resistance valve such as a resilient star valve which reduces in resistance as air flow through it increases so as substantially to maintain air flow through the cyclone chamber constant. Alternatively, one or more resiliently biased flaps may be provided in the bypass air inlet 22, the extent of opening of the flaps increasing with an increasing rate of inhalation.
By the time the powdered drug enters the user's respiratory system it will generally contain a high proportion of particles of 5 μm or less (i.e. a high Fine Particle Fraction). These can be inhaled into the deep part of the lungs where they will be most effective. Furthermore very little of the drug or carrier is deposited on the back of the user's throat which is beneficial medically and from the point of view of user comfort.
FIG. 9 shows five different cyclone chamber configurations A-E used in a performance test. The cyclone chamber diameters range from 10 to 20 mm. FIG. 10 shows the performance test results for the cyclones A-E compared to two conventional dry powder inhalers. The fine particle fraction achieved using the cyclones A-E is seen to be over 69%, and as much as 81%, compared to only 30-40% for conventional dry powder inhalers. This results from the deposition of large particles above the cut-off size in the base of the cyclone chamber, so that the fine particle fraction is greatly enhanced. The size of the particles separated by the cyclones A-E was also reduced to 2-3 μm in all configurations. Thus cyclone chambers of these configurations separate out particles of a much finer, respirable size than can be achieved by conventional dry powder inhalers, therefore concentration of fine particles in the emitted dose is increased compared to the conventional formulation.
Some key features of the preferred embodiment include the following. Firstly, a reverse flow cyclone to efficiently de-aggregate the respirable (fine) drug particles from coarse carrier fraction (e.g. lactose). This is achieved by increasing the residence time of the particles (therefore a greater number of opportunities for separation), and by maximizing the shear forces for a given energy input. Secondly, the reverse flow cyclone separates and retains the coarse carrier fraction—i.e. only respirable (fine) drug particles are emitted upon inhalation. Thirdly the use of bypass airflow to control the separation efficiency of the reverse-flow cyclone, and to tailor the airflow resistance of the device. Fourthly the cyclone geometry being on a disposable device, to maximize Dose Content Uniformity (DCU), by preventing carry-over of drug particles between doses. Fifthly, formulation is pre-metered into a moisture-proof chamber, therefore accurate dose mass, and performance independent of environmental conditions. Finally, a disposable device which retains the non respirable fraction aerodynamically during inhalation and mechanically after inhalation.
1. A dry powder inhaler comprising two parts connected by an integrally moulded hinge configured to hinge the two parts of the inhaler from an open position to a closed position, at least one of said parts defining at least part of a circulating airflow chamber, wherein when said parts are in said closed position, the inhaler comprises an airflow path including the circulating airflow chamber, the inhaler further comprising a dose to be inhaled which is sealed in the at least part of the circulating airflow chamber by a frangible membrane and being arranged such that the frangible membrane is broken by an action of closing the inhaler prior to use and the dose is exposed to an entraining airflow in the circulating airflow chamber upon inhalation, and
wherein the circulating airflow chamber having air and entrained substance particles circulate further comprises an axis and being elongate along said axis, an air inlet, a closed base and a vortex finder, said chamber being shaped wherein at least a part of the chamber decreases in cross-sectional area in a direction away from the air inlet,
wherein the air inlet is configured to direct air to circulate around the periphery of the chamber, and the vortex finder is configured such that air exits therethrough after a reversal of axial direction at the base of the chamber to set up a reverse flow cyclone in the chamber wherein air circulates in two generally concentric overlapping columns in opposite axial directions.
3. An inhaler as claimed in claim 1 wherein the outer wall of the chamber tapers towards the base.
4. An inhaler as claimed in claim 1 wherein said chamber is generally frusto-conical.
5. An inhaler as claimed in claim 1 wherein the circulating airflow chamber is formed integrally with or permanently attached to one of the inhaler parts.
6. An inhaler as claimed in claim 1 comprising a mouthpiece formed integrally with one of the hinged parts.
7. An inhaler as claimed in claim 1 wherein the whole inhaler is integrally moulded in one piece.
8. An inhaler as claimed in claim 1 arranged such that an inhalation airflow path through the inhaler is only formed when the two parts are closed together.
9. An inhaler as claimed in claim 1 comprising one or more piercers on one of the parts; and the at least part of the circulating airflow chamber on the other part; wherein the dose is released by the act of closing the two parts of the inhaler together.
10. An inhaler as claimed in claim 1 comprising a main airflow path which passes through the circulating airflow chamber and a bypass airflow path bypassing the circulating airflow chamber; wherein the main and bypass airflow paths communicate with a mouthpiece.
11. An inhaler as claimed in claim 10 comprising a divided mouthpiece, with one channel for the main airflow and the other channel for the bypass airflow, such that the main and bypass airflows do not meet at all inside the inhaler.
12. An inhaler as claimed in claim 1 comprising a single dose of medicament powder.
13. An inhaler as claimed in claim 1 wherein an outlet pipe projects into the circulating airflow chamber to form the vortex finder.
14. An inhaler as claimed in claim 13 wherein the vortex finder is integrated with a piercer.
15. An inhaler as claimed in claim 1 wherein the diameter of the circulating airflow chamber is between 5 and 100 mm.
16. An inhaler as claimed in claim 1 comprising a snap fit closure.
17. An inhaler as claimed in claim 1 wherein the diameter of the circulating airflow chamber is between 5 and 50 mm.
18. An inhaler as claimed in claim 1 wherein the diameter of the circulating airflow chamber is between 8 and 20 mm.
19. A dry powder inhaler comprising two parts connected by an integrally moulded hinge configured to hinge the two parts of the inhaler from an open position to a closed position, at least one of said parts defining at least part of a circulating airflow chamber, wherein when said parts are in said closed position, the inhaler comprises an airflow path including the circulating airflow chamber, the inhaler further comprising a dose to be inhaled which is sealed in the at least part of the circulating airflow chamber by a frangible membrane and being arranged such that the frangible membrane is broken by an action of closing the inhaler prior to use and the dose is exposed to an entraining airflow in the circulating airflow chamber upon inhalation, the inhaler further comprising, at least when in its closed position: said circulating airflow chamber having an outlet extending substantially axially therefrom; a mouthpiece channel having a central axis; and a plenum portion connecting said outlet and said mouthpiece channel, the mouthpiece channel axis being offset from, and making a non-parallel angle with, an axis of the outlet such that air exits the outlet at least partly tangentially into the mouthpiece via the plenum portion.
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Patent Publication Number: 20100000531
Inventors: Simon James Smith (Hertford), David Stuart Harris (Milton)
Assistant Examiner: Kathryn E Ditmer
Application Number: 12/304,900
Current U.S. Class: Means Broken Or Pierced To Supply Treating Agent (128/203.21); Means For Mixing Treating Agent With Respiratory Gas (128/203.12); Particulate Treating Agent Carried By Breathed Gas (128/203.15)
International Classification: A61M 15/00 (20060101); B65D 83/06 (20060101);