Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Patent
1995-09-15
1999-03-30
Asher, Kimberly L.
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
12820312, 12820315, 600529, 600532, A61M 1610, A62B 700, F16K 3102, A61B 508
Patent
active
058875867
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/SE95/00590 filed May 24, 1995.
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring a dose of a drug in aerosol form inhaled by an animal as well as a system for implementing the measuring method. The present invention also relates to a method for administering a predetermined dose of a drug in aerosol form to an animal and a system for implementing the administering method.
When performing animal experiments for testing a new drug, it is often desirable to administer a predetermined dose of the drug to each animal.
A method known in the art for administering a dose of a drug inhaled by an experimental animal in aerosol form is the fixed time administration method. The experimental set-up of this method is schematically shown in FIG. 1. An aerosol generator 1 is connected to one end of a tube 2, the other end of which is connected to a nose mask 3, through which the animal is to inhale during the experiment. The tube 2 is provided with an air inlet 4, comprising a one-way flap valve 5 and a filter 6, as well as an air outlet 7, also comprising a one-way flap valve 8 and a filter 9.
In a preparatory phase of the method, the exposure time required for administering a desired dose of the drug is calculated from the following relation concentration.times.respiratory minute volume) predetermined particle concentration in the flow of aerosol generated by the aerosol generator, and the respiratory minute volume is calculated in a predetermined way according to a theory or empirical knowledge. Then, the aerosol generator 1 is adjusted so as to generate, in the tube 2, a fixed volumetric flow of aerosol of the predetermined concentration.
In the measurement phase, the animal inhales the aerosol through the nose mask 3 during the predetermined exposure time. If the animal needs more air than what is provided by the aerosol generator 1, additional air is supplied through the air inlet 4. Exhaled air and any air not inhaled by the animal leaves the system through the air outlet 7. The filters 6, 9 prevent contamination of the air outside the system.
However, it has been found that this prior-art fixed time administration method is not sufficiently accurate for use in certain experiments where the doses actually delivered must be in keeping with the planned doses.
SUMMARY OF THE INVENTION
Thus, a first object of the present invention is to provide a more accurate method and system for measuring the dose of a drug inhaled by an experimental animal in aerosol form.
A second object of the present invention is to provide a more accurate method and system for administering a predetermined dose of a drug in aerosol form to an experimental animal.
These objects are achieved by methods and systems having the features recited in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the present invention will now be described in more detail with reference to the accompanying drawings, in which
FIG. 1, which already has been discussed, is a schematic view of a prior-art experimental set-up for carrying out the fixed time administration method; and
FIG. 2 is a block diagram of a system for administering a dose of a drug in the form of a dry-powder aerosol to an experimental animal and measuring the size of the dose.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The system shown in FIG. 2 for administering a dose of an aerosol essentially consists of an administration section and a measurement section.
The administration section, which is similar to the system shown in FIG. 1, comprises a dry-powder aerosol generator 20, which is connected to a removable nose mask 21 via a conduit system 22.
The aerosol generator 20, which is a modified Wright Dust Feeder from Adams Ltd., London, Great Britain, comprises a scraping mechanism, by means of which powder can be scraped off a tablet of compressed powder, as well as means for aerosolising the scraped-off powder in an air flow. The scraping speed, and thus the concentration of the generated dry-powde
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Dahlback Magnus
Fagerstrom Per-Olof
Marchner Hans
Nerbrink Ola
Asher Kimberly L.
Astra Aktiebolag
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