Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Reexamination Certificate
1997-02-20
2001-06-05
Lewis, Aaron J. (Department: 3761)
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
C128S203120
Reexamination Certificate
active
06240918
ABSTRACT:
INTRODUCTION TO THE INVENTION
The present invention relates generally to powder dispenser assemblies and, more particularly, is directed to a powder dispenser assembly used for inhalation of a metered dose of a powdered medicament.
When delivering medicaments, that is, pharmacologically active compounds, in solid form to the respiratory tract and to the lungs, careful attention to the accuracy of the dosage, which can be smaller than 0.1 milligram, must be made. This is because such medicaments are often quite potent, and the administration of excessive amounts thereof could be harmful to the patient. Further, if the dosage that is delivered is too small, it will not serve its purpose.
It is also necessary that the particles leaving the dispenser assembly be substantially within a particular size range, since particles of the medicament which are too large may not enter a desired lower portion of the respiratory tract, such as the bronchial tree or lungs, but instead will be deposited in the mouth or pharynx and thence enter the digestive tract. As an example, preferred particles usually are considered as having a diameter less than about 10 micrometers.
Various devices have been used in order to dispense a metered dose of powdered medicament, including pressurized aerosol devices, nebulizing devices, pump inhalators and the like. With the current concern over environmental issues, however, aerosol devices, which constitute a large part of the devices now on the market, are less favored. Further, with aerosol devices, the medicament is dissolved or suspended in a liquid propellant mixture, which results in the introduction of unneeded chemical substances into the body and further adds to the complexity of the devices.
In addition to the aforementioned types of dispenser assemblies, powder dispenser assemblies are also known. Studies have shown that there are virtually no significant differences in bronchodilator responses with equivalent amounts of medicinal substances administered either by powder dispensing devices or aerosol devices. Accordingly, there is now an ever-growing demand for powder dispensing devices which can dispense metered doses of powdered medicament. With such devices, the powder is automatically withdrawn during inspiration so there is less need to be concerned with synchronizing release of medication with the exact start of inspiration to insure quality of the product delivery.
One such device has been described in published International Patent Application No. WO 94/14492. However, it has been discovered that various enhancements thereto are possible and desirable, as will now be described.
In the first place, when agglomerates comprised of hard particles are used, for example, having a bulk density of 0.29 to 0.36 g/ml, in contrast to standard agglomerates having a bulk density of approximately 0.27 g/ml, the respirable fraction, that is, the portion of the particles that can enter the lower airway, may be less than that which is desirable. For example, experiments have shown that the respirable fraction from the powder dispenser of the aforementioned international application for a formulation of mometasone/lactose agglomerates having a component weight ratio of 1:5.8 provides only about 10% of total particles having diameters less than about 6.8 micrometers. It has been determined that one of the likely reasons for this is the swirl nozzle design which does not sufficiently break up the hard agglomerates.
Another potential problem with such design is that the screw threads on the cap and adapter provide a condition in which the cap may be prematurely pulled off due to the tolerances of the screw threads. As a result, the dispenser may not be turned a full 180°, as required. Thus, the proper dosage may not be provided, and the counter mechanism may not be activated. Further, by prematurely pulling the cap off, it may not be possible to easily reapply the cap to the dispenser to close the same.
Also, positioning of the cap for the rotating operation may not always result in accurate alignment.
Another possible problem is that of securing the powder retainer to the metering dose plate. If a hot melt adhesive is used, the adhesive may leak into the mesh, so that quality and consistency is not obtained. Further, by heating the same, there may be a distortion in the flatness and/or damage to the mesh.
A yet further potential problem is that the pawl used in the counter mechanism of the primary embodiment thereof requires an additional metal spring to be inserted therein. This increases the number of parts, makes assembly more difficult, provides a pawl assembly that is not totally moldable and does not always provide a totally reliable counter mechanism. Although a totally molded spring and pawl assembly is disclosed in a later embodiment thereof, such totally molded spring and pawl assembly is more difficult to mold and is not as satisfactory in use to that of the primary embodiment.
A still further potential problem relates to the indicia on the continuous and intermittent counter rings of the counter mechanism, that is, the dispenser must be tipped to a horizontal position to read the numbers, rather than providing the indicia for reading while the dispenser remains in its normal upright position.
Lastly, the swirl nozzle and mouthpiece can be fairly easily disengaged from the drive body during inhalation, possibly resulting in swallowing of the same or choking. The same considerations are not applicable to disengagement of the mouthpiece from the swirl nozzle because of the inclined sides of the mouthpiece.
SUMMARY OF THE INVENTION
In accordance with an aspect of the present invention, a powder dispenser includes a supply for holding a supply of powdered material to be dispensed; an inhalation conduit extending in a first direction and positioned in displaced relation to said supply; means for carrying a predetermined amount of said powdered material from said supply to said inhalation conduit; and a nozzle for reducing particle sizes of agglomerates of powdered material from the inhalation conduit to form micronized powdered material and for mixing said micronized powdered material with suction air, said nozzle including a cavity for changing the direction of flow of said powder from said first direction of said inhalation conduit to a second direction different from said first direction, said cavity being defined by a top wall and a skirt connected to a periphery of said top wall, said top wall having an opening therein; a swirl wall for substantially continuously changing the direction of flow of the powder in the second direction in the cavity; and a chimney extending from the top wall in surrounding relation to the opening for changing the direction of flow of the powder from the second direction of the cavity substantially back to the first direction, the chimney extending along an axial direction thereof and including an inner tubular wall surface having irregularities extending in the axial direction.
Preferably, the irregularities are formed by a plurality of flutes on the inner tubular wall surface, and the flutes are formed by a plurality of first concave wall sections extending in the axial direction and having an arc of a first radius in a direction transverse to the axial direction, and a plurality of second wall sections extending in the axial direction and interconnecting the first concave wall sections, the second wall sections being of a concave configuration having an arc of a second radius in a direction transverse to the axial direction, the second radius being greater than the first radius.
The top wall has a circular shape and the opening is centrally located in the top wall, and the swirl wall includes a curved wall extending from the opening to the skirt, the curved wall extending in a substantially spiral manner and being connected with the top wall.
In accordance with another aspect of the present invention, a powder dispenser includes a powder housing for holding a supply of powdered material to be dispensed, the powder hous
Ambrosio Thomas J.
Benson, Jr. Warren A.
Dao Kim C.
Kenyon David J.
Kreiseder Walter J.
Franks Robert A.
Lewis Aaron J.
Schering Corporation
Weiss, Jr. Joseph F.
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