Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Patent
1993-02-16
1994-03-22
Burr, Edgar S.
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
12820323, A61M 1500
Patent
active
052954790
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a section of a powder inhalator required for the inhalation of a powdered medicament, said section containing powdered medicament as well as a mechanism required for measuring its dosage and delivering it out of a reservoir.
The dosage of a medicament for inhalation is generally effected by using a propellant-pressurized dosage aerosol or powder inhalator. With dosage aerosol, the metering of a dose is accurate based on the determination of liquid volume in a dosage valve with external moisture having no effect on the procedure. With powder inhalators, the metering is inaccurate for several reasons. Measuring or metering a dose is based on two prior known principles. The powder may be contained as measured portions in small dosage containers, e.g. capsules, from which it is metered and delivered into the inhalation air of a patient. A larger amount of powdered medicament can also be contained in a reservoir included in an inhalator, wherein a special mechanism is used for delivering a measured amount of powder into the inhalation air of a patient. Such multi-dosage inhalators are more convenient to a patient by virtue of their easy operation.
The medicament doses to be inhaled with powder inhalators may vary within the range of tenths of a milligram to tens of milligrams. The smaller the doses in question, the more difficult it is to effect a sufficiently accurate measuring of the dose and the greater a detrimental effect of extraneous disturbing factors on measuring accuracy. The most significant disturbing factor is external moisture . If a powdered medicament is moistened, e.g. during storage, it may form lumps for impaired measuring accuracy. The penetrability of moisture into a medicinal substance depends on the tightness of a medicament reservoir, the water-vapour permeability of a structural material as well as on the moisture absorbency of a medicament itself. It is prior known to alleviate the moisture trouble by means of a dehydrating agent associated with a medicament reservoir.
Moisture has also another effect on the accuracy of a medicament dose discharging from an inhalator. If those internal surfaces of an inhalator, which are in contact with discharging medicament powder, become moist, the delivered amount of medicament will be reduced to a fraction of the normal. The moistening may be a result of exhalation through an inhalator or of bringing the device from a cold place to a warm one. This moisture trouble could be inhibited by fitting the inhalator with a one-way valve preventing exhalation and other air-flows occurring through the device.
On the basis of what is stated above, a medicament reservoir and a dose measuring mechanism included in a multi-dosage inhalator should fulfil the following conditions: inhalator.
Further, in terms of total medication costs, it would be preferable to use a replaceable medicament reservoir.
Thus, with multi-dosage powder inhalators, the design of a medicament reservoir and a dose measuring mechanism is highly important not only in terms of dose measuring accuracy and stability of a powdered medicament but also a preferred inhalator structure. No prior art multidosage powder inhalator is provided with a medicament reservoir and a dose measuring mechanism that would fulfil all the above-mentioned conditions.
Finnish Patent publication No. 69963 discloses a multidosage dispenser provided with a medicament container and a dose metering device. The medicament container has a conical lower section and its bottom is provided with a shaft rotatable around its longitudinal axis. The shaft is fitted with one or a plurality of dosage recesses, into which the powder is flowing upon rotating said shaft. The container can be fitted with a dehydrating agent and a vibrator for an intensified flow of the powder upon rotating said shaft. After rotating the shaft through half a turn, the dosage recess has rotated so as to reach an inhalation conduit, which is located below the container and into which the powder drops.
The powdered medicam
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Derwent's Abstract, No. 90-73 613/10, SU 1, 503 827, publ. week 9010 (Gorki Paediatrics).
Burr Edgar S.
Leiras Oy
Lewis Aaron J.
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