Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Patent
1996-10-10
1999-11-02
Weiss, John G.
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
12820312, 12820319, A61M 1500, A61M 1600, B05D 714, B65D 8306
Patent
active
059750766
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to inhalers for use in inhaling medicaments in the form of a dry powder.
Numerous inhaler designs have been devised, some for the inhalation of medicaments dispensed as an aerosol spray and others for use in inhaling medicaments dispensed as a dry powder. Dry powder inhaler designs may either be for inhaling a single dose of medicament which is placed by the user into the inhaler on each occasion of its use or else they may incorporate a multidose dispensing mechanism having a reservoir from which a single dose is dispensed within the inhaler or a series of unit doses separately held on a carrier such as a tape or disc.
In either type of dry powder inhaler, the dose is placed between the inlet and the outlet of an air passage through which the user inhales through the mouth and the dry powder is entrained into the resulting air-flow to be conducted into the lungs of the user. The medicament may either be dispensed directly as particles of medicament, optionally in the presence of an inert diluent, or else the particles of medicament may be held on the surface of larger diluent particles from which the medicament particles must be shaken loose as the medicament is entrained into the air-flow.
Difficulties arise in producing a sufficiently vigorous flow of air and a sufficiently turbulent flow of air properly to entrain the medicament and to carry it as far as a patient's lungs. The problem is obviously more acute where the patient has a restricted peak flow.
Generally, inhalers of this kind have an air inlet passage leading to a dispensing chamber in which the medicament is located prior to inhalation, and an inhalation passage leading from the dispensing chamber and terminating in a nozzle which is placed in the patient's mouth prior to inhalation. The present invention relates to a number of refinements of the design of these components to produce improved penetration of the medicament into the lungs of the patient, particularly where the patient's peak flow is low.
U.S. Pat. No. 3,938,516 discloses an inhalation device having the basic layout described above. The medicament is inserted into the inhalation device in one half of a conventional medicament capsule which has been opened. The medicament lies below the flow-path for air through the device constituted by the air inlet passage and the inhalation passage and in order to promote the entraining of the medicament, an additional air passage is provided in the form of a tube extending at right angles to the main air passage and dipping into the opened capsule. Negative pressure produced by the venturi effect in the main air passage is used to draw air through this auxiliary air passage into the capsule to lift the medicament up into the main air-stream. This design lacks versatility in that it cannot readily be adapted for operation in conjunction with a multiple dose dispensing mechanism and is heavily reliant upon sufficient flow rate being generated in the main air passage to produce the necessary negative pressure to draw air in through the auxiliary air passage.
The present invention provides in a first aspect a dry powder inhaler comprising a dispensing chamber for receiving a charge of powder to be dispensed, said chamber having a floor upon which said charge lies prior to inhalation, an air inlet passage having at its outlet end a nozzle protruding into said dispensing chamber directed towards said floor thereof and an inhalation passage exiting from said chamber through which said powder may be inhaled entrained in air drawn into the inhaler through said air inlet passage, wherein said air inlet passage terminating in said nozzle is the principal or sole route for air to enter said dispensing chamber in use.
Preferably, the nozzle of the air inlet passage at its outlet end is directed transversely with respect to the exit of the inhalation passage from the dispensing chamber as well as being directed toward the floor of the dispensing chamber. This configuration of the direction of the nozzle at the outlet end of
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Ganderton David
Lee Ka-lok Carroll
Marriott Christopher
Martin Gary Peter
Suen Kwok-On
King's College London
Weiss John G.
Weiss, Jr. Joseph F.
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