Method and system for measuring a dose of drug inhaled

• US 5,887,586 A
• Filed: 09/15/1995
• Issued: 03/30/1999
• Est. Priority Date: 06/23/1994
• Status: Expired due to Fees

• Current Assignee: Astra AB (Astrazeneca PLC)
• Original Assignee: Astra AB (Astrazeneca PLC)
• Inventors: Marchner, Hans, Fagerstrom, Per-Olof, Dahlback, Magnus, Nerbrink, Ola
• Primary Examiner(s): Asher, Kimberly L.
• Application Number:
  US08/525,535
• Time in Patent Office: 1,292 Days
• Field of Search: 128/203.12, 128/203.14, 128/203.15, 128/204.22, 128/204.21, 128/204.26, 128/204.23, 128/716, 128/719, 128/724, 128/725, 600/529, 600/532
• US Class Current: 128/204.22
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
• CPC Class Codes: A61D 7/04 Devices for anaesthetising animals by gases or vapours; Inhaling devices
• CPC Class Codes: A61M 15/0065 Inhalators with dosage or measuring devices A61M15/0028 takes precedence; dosage devices incorporated in aerosol cans B65D83/52
• CPC Class Codes: A61M 15/008 Electronic counters
• CPC Class Codes: A61M 15/009 using medicine packages with incorporated spraying means, e.g. aerosol cans pocket atomiser of the injector type A61M11/08
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2202/064 Powder

Abstract

In a method for measuring a dose of a drug inhaled by an animal, the momentary concentration of the drug in an aerosol supplied to the animal and the momentary inhalation flow rate of the animal are determined. An inhaled partial dose is calculated from each determined inhalation flow rate value and a corresponding concentration value. The calculated inhaled partial doses are added to obtain the total dose inhaled by the animal.

Claims

1. A method for measuring a dose of a drug inhaled by an experimental animal, the drug being supplied to the animal in the form of a flow of aerosol, characterised by the steps of

(a) determining the momentary concentration of the drug in said flow of aerosol;

(b) determining the momentary inhalation flow rate of the animal a plurality of times during each inhalation by the animal;

(c) calculating an inhaled partial dose for each determined momentary flow rate;

the total dose of the drug inhaled by the animal being obtained by summation of all inhaled partial doses,

wherein the aerosol flow rate at the point where the momentary concentration of the drug is determined, is known or is determined, characterised in that the calculation of an inhaled partial dose is based on the aerosol flow rate at said point if the determined inhalation flow rate exceeds the aerosol flow rate at said point, and otherwise based on the determined momentary inhalation flow rate.

2. A method for measuring a dose of a drug inhaled by an experimental animal, the drug being supplied to the animal in the form of a flow of aerosol, characterised by the steps of

(a) determining the momentary concentration of the drug in said flow of aerosol;

(b) at a frequency of at least 50 Hz, determining the momentary inhalation flow rate of the animal a plurality of times during each inhalation by the animal;

(c) calculating an inhaled partial dose for each determined momentary flow rate;

the total dose of the drug inhaled by the animal being obtained by summation of all inhaled partial doses.

3. A system for measuring a dose of a drug inhaled by an experimental animal, the drug being supplied, via a conduit system, to the animal in the form of a flow of aerosol from an aerosol generator, characterised by

means for determining the momentary concentration of the drug in said flow or aerosol;

means for determining the momentary inhalation flow rate of the animal;

calculating means for calculating an inhaled partial dose for each determined inhalation flow rate as well as for adding up a plurality of inhaled Partial doses of obtaining the total dose inhaled by the animal,

characterised by an air inlet for supplying additional air to the conduit system and an air outlet from the conduit system, said air inlet and said air outlet being located down-stream from the means for determining the concentration.

4. A system according to claim 3, characterised in that the means for determining the inhalation flow rate are arranged to determine the air flow rate in the air outlet.

5. A system according to claim 3, characterised in that the air outlet is connected to the conduit system upstream of the means for determining the momentary concentration of the drug in said flow of aerosol.

6. A method for administering a predetermined dose of a drug to an experimental animal, comprising the steps of aerosolishing the drug and supplying it in the form of a flow of aerosol to the animal, characterised by the further steps of

(a) determining the momentary concentration of the drug in said flow of aerosol;

(b) determining the momentary inhalation flow rate of the animal a plurality of times during each inhalation by the animal;

(c) calculating an inhaled partial dose for each determined momentary flow rate;

(d) successively cumulating the calculated inhaled partial doses to a cumulated inhaled dose;

(e) interrupting the generation of aerosol when the cumulated inhaled dose is approximately equal to the predetermined dose,

wherein the aerosol flow rate at the point where the momentary concentration of the drug is determined, is known or is determined, characterised in that the calculation of an inhaled partial dose is based on the aerosol flow rate at said point if the determined inhalation flow rate exceeds the aerosol flow rate at said point, and otherwise based on the determined momentary inhalation flow rate.

7. A method for administering a predetermined dose of a drug to an experimental animal, comprising the steps of aerosolishing the drug and supplying it in the form of a flow of aerosol to the animal, characterised by the further steps of

(a) determining the momentary concentration of the drug in said flow of aerosol;

(b) at a frequency of at least 50 Hz, determining the momentary inhalation flow rate of the animal a plurality of times during each inhalation by the animal;

(c) calculating an inhaled partial dose for each determined momentary flow rate;

(d) successively cumulating the calculated inhaled partial doses to a cumulated inhaled dose;

(e) interrupting the generation of aerosol when the cumulated inhaled dose is approximately equal to the predetermined dose.

8. A system for administering a predetermined dose of a drug to an experimental animal in the form of a flow of aerosol, comprising an aerosol generator which is connected to a conduit system for supplying the aerosol generated by the aerosol generator to the experimental animal, characterised by

means for determining the momentary concentration of the drug in said flow of aerosol;

means for determining the momentary inhalation flow rate of the animal;

calculating means for calculating an inhaled partial dose for each determined momentary inhalation flow rate as well as for successively cumulating the calculated inhaled partial doses to a cumulated inhaled dose;

comparing means for comparing the cumulated inhaled dose with the predetermined dose; and

means for turning off the aerosol generator when the cumulated inhaled dose is approximately equal to the predetermined dose;

characterised by an air inlet for supplying additional air to the conduit system and an air outlet from the conduit system, said air inlet and said air outlet being located downstream from the means for determining the concentration.