Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Patent
1995-06-01
1998-11-03
Weiss, John G.
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
12820018, 12820312, A61M 1500
Patent
active
058294341
DESCRIPTION:
BRIEF SUMMARY
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 the respiratory tract, but instead, will be deposited in the mouth or pharynx and thence enter the digestive tract. As an example, preferred particles can have a diameter of 1 to 5 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 With such devices, the powder is automatically withdrawn during inspiration so there is less need to be concerned with synchronizing release of medication with the exact start of inspiration to insure quality of the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.
U.S. Pat. No. 4,524,769 to Wetterlin, the entire disclosure of which is incorporated herein by reference, describes a dosing unit of the above type that includes a storage chamber for holding the active compound, a perforated membrane rotatably positioned under the storage chamber and a holder for the membrane. Introduction of the active compound into perforations in the perforated membrane is accomplished with elastic, spring-loaded scrapers, mounted in a holder in the storage chamber. With this arrangement, the membrane is movable between a first position where active compound is introduced by the scrapers in part of the area of the perforated membrane, and a second position where the part of the area of the loaded membrane has been inserted into the air conduit in the dosage inhalator. Thus, the active compound contained in the perforations is entrained at inhalation and brought through the nozzle to the respiratory tract and the lungs of the patient.
With this arrangement, a coil spring is used to bias the scrapers into engagement with the perforated membrane. The coil spring is interposed in the storage chamber between the casing and the scraper assembly. Alternatively, it is disclosed that the coil spring can be arranged so that the membrane is pressed against the scrapers, and thereby mounted in the base or maneuvering unit. In addition to the coil spring, Wetterlin uses spring loaded pins beneath the membrane to engage the ratcheted bottom of the membrane in order to provide distinct positions for the perforated membrane when it is advanced by the base or maneuvering unit. See also U.S. Pat. Nos. 4,907,583; 4,534,345; 4,667,668; and 4,805,811; all to Wetterlin.
U.S. Pat. No. 4,668,218 to Virtanen discloses a dispenser substant
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Ambrosio Thomas J.
Ashley Charles R.
Bilanin Alan J.
Huck Charles M.
Kaufman Andrew E.
Franks Robert A.
Schering Corporation
Srivastava V.
Weiss John G.
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