Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Patent
1996-01-02
1997-10-21
Lewis, Aaron J.
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
12820321, A61M 1500
Patent
active
056785380
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a device for the administration of powdered medicaments by inhalation, more particularly to a multiple-dose inhalation device with metering means for dispensing pre-determined doses from a medicament reservoir.
European Patent Application 407028 (Fisons plc) discloses a multiple-dose inhalation device in which a dose of medicament is metered by abrading a fixed volume from a compacted body of powdered medicament. The metered dose is then entrained in a through-going pathway of the device and is inhaled by the patient, the means for abrading being, for example, a helical blade. Other devices which use the principle of abrading a compacted body of powdered medicament are disclosed in International Patent Applications WO 92/04067 (Boehringer Ingelheim KG) and WO 93/24165 (GGU Gesellschaft fur Gesundheits- und Umweltforschung mbH & Co. Vertriebs KG).
Such devices may offer improved dose consistency when compared to multiple-dose devices which rely on gravitational force to meter a dose of medicament from a reservoir. However, inaccuracies in dosing may still occur due to incomplete removal of the abraded dose from the compacted body, or by the removal of additional quantities of powder from the body during inhalation by the patient. Furthermore, if such devices are inadvertently dropped quantities of medicament could break off from the compacted body and enter the through-going pathway of the device, resulting in a multiple dose being administered when the patient next uses the device.
We have now found that these disadvantages can be overcome or substantially mitigated by providing a shuttering system in the device which is capable of isolating the compacted body of medicament from the through-going pathway of the device.
Thus, according to the invention, there is provided a medicament inhalation device including a housing having a through-going pathway connecting an air inlet with an air outlet, a medicament reservoir adapted to receive a compacted body of powdered medicament, and metering means for dispensing a predetermined dose of medicament from the reservoir into the through-going pathway, the metering means including means for abrading the compacted body; characterised in that the device is provided with a shutter movable between a first position in which the compacted body is isolated from the through-going pathway and a second position in which the compacted body is in communication with the through-going pathway such that a dose of medicament can be dispensed from the reservoir into the through-going pathway.
The means for abrading the compacted body preferably includes a blade which cuts, planes, scrapes or otherwise erodes a surface of the compacted body by relative rotation or sliding between them. For example, the blade may have a helical shape, in which case the dose abraded from the compacted body of medicament will depend inter alia upon the pitch of the helix, the diameter of the blade, the density of the compacted body, and the angle through which the blade is rotated. Alternatively, the means for abrading the compacted body may include a brush or other abrasive surface.
The shutter is preferably biassed into the first position in which the compacted body is isolated from the through-going pathway.
The shutter may be mounted on a carrier, the carrier being adapted to move within the housing of the device, e.g. in an axial direction. Movement of the shutter between the first and second positions may then be effected by the action of a cam on the carrier. The carrier is preferably kept in contact with the cam surface by biassing means, e.g. a cantilever, provided on the carrier which bears against a stationary part of the device. The cam is preferably arranged such that the shutter moves from the first position to the second position prior to the metering of a predetermined dose of medicament from the reservoir, and returns to the first position once the predetermined dose of medicament has been metered. In addition, the shutter preferably returns to the first positi
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Fisons plc
Lewis Aaron J.
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