Note: Descriptions are shown in the official language in which they were submitted.
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POWDER INHALER
This is a divisional application of CA 2,190,031.
The invention relates to a device for dispensing of a powdered
drug preparation by inhalation. The device is in particular a
multiple-dose device without propellant gas, equipped with a
metering means which dispenses doses from a powder container. A
device such as this is usable, for e'ample, in the treatment of
asthma.
The administering of powdered drug preparation by inhalation
from an inhaler is commonly known. Multiple-dose type powder
inhalers comprising a powder container and a metering member
which measures and dispenses a unit dose are also known, for
example from patent publications GH 2165159, EP 79478, and EP
166294. In these devices, a series of dosing recesses are
notched into the surface of a cylindrical metering member, and
the said member is disposed in a chamber of precisely the same
shape. When the metering member is rotated, the dosing recesses
in turn will move first to a position in alignment with the
powder container for being filled and thereafter to a position
in alignment with the inhalation channel, whereupon a unit dose
will fall by gravity from the dosing recess into the inhalation
channel. Thereafter the dose of medication is inhaled from the
inhalation channel. These devices have the drawback that they
make overdosing of the medication possible by allowing the
dispensing of a plurality of doses in succession into the
inhalation channel, whereby a multiple dose may be drawn by one
inhalation.
Inhalation devices having a metering plate movable between
filling and dispensing position are described e.g. in patent
publications WO 92/10229, US 5113855, US 2587215, EP 546996, W0
94/04210 and US 5161524. However, also these devices suffers
from a drawback that they make overdosing possible by allowing
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the dispensing of a plurality of doses into the inhalation channel.
Attempts have been made to solve this problem by using dispens-
ing systems in which the dosing recess will not be emptied into
the inhalation channel by gravity but, instead, the dose of
medication is inhaled directly from the dosing recess, such
recesses having been notched into the surface of a metering
member having the shape of a cylinder, a cone or a truncated
cone, as disclosed in patent publications WO 92/00771 and WO
92/09322. Also in these devices, a metering member having the
shape of a cylinder, a cone or a truncated cone is disposed in a
chamber having precisely the same shape. When the metering
member is rotated, the dosing recesses will move first to a
position in alignment with the flow container for_filling, and
then to the inhalation channel, which is shaped so that the
dosing recess will be emptied under the effect of the air flow
being inhaled, and thereafter, having rotated through a full
360'; back to a position in alignment with the flow container.
The lower surface of the chamber wall may also have an emptying
aperture from which any powdered medication possibly left in the
dosing recess will fall out during the said rotation.
In the rotating dispensing devices described above, the distance
from the filling position to the inhalation position is less
than 90' of a circle arc. Since the metering member is, for
purposes of metering precision, disposed within a chamber of the
same shape, and since it has to be rotated through 360', of
which at least 270' are useless for the actual function of the
inhaler, in these devises particles will inevitably fall onto
the slide surface between the metering member and the chamber.
Thereby the rotation of the highly sensitive metering member
will be disturbed and may even be completely obstructed. The
metering member jamming in the chamber will hinder the
functioning of the whole device. Vigorous shaking or tapping
will only increase the jamming, as more powder flows into the
gap between the chamber and the metering member.
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An object of the present invention is to provide a powder inhaler comprising a
powder container, an air channel through which air is drawn via a mouthpiece,
and a metering strip equipped with a dosing recess having a bottom, the strip
being disposed on a flat surface and being movable in its longitudinal
direction
along the flat surface between a first position, in which the dosing recess is
filled
with powder coming from the container, and a second position, in which the
filled
dosing recess is brought into the air channel, the powder being maintained in
the recess by the support of the recess bottom, and the air channel being
directed to introduce the air flow in the bottom of the dosing recess during
inhalation whereby the powder is released directly from the dosing recess,
characterized in that the flat surface, in the normal position of use of the
inhaler, is downwardly inclined.
The invention relates to a powder inhaler which has the following properties:
1) it can be operated with one hand;
2) the dosage may be easily set for different powder
quantities;
3) the device will dispense only one dose at a time;
4) the surfaces rubbing against each other are small,
whereby the risk of their jamming is reduced;
5) the track of movement on which the surfaces will rub
against each other is small;
6) if desired, any remnants of powder left on the rubbing
surfaces and in the inhalation channel can be removed
automatically by gravity, without any further steps to be
taken or tracks of movement.
The principle of the device according to the invention is
illustrated below by way of example, with reference to
Figures 1-4.
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The powder inhaler according to the invention includes a powder
container (1), an air channel (2) through which air is drawn via
a mouthpiece, and a metering strip (4) equipped with a dosing
recess (3), the strip being disposed on a flat surface (S) and
being movable in its longitudinal direction along the flat
surface between a first position, in which the dosing recess is
filled with powder coming from the container, and a second
position, in which the filled dosing recess is brought into the
air channel, wherein while the metering strip is in a second
position the powder is maintained in the recess by the support
Qf the recess bottom before the inhalation and the air channel
is adapted to introduce the air flow into the bottom of the
dosing recess during inhalation whereby the powder is released
directly f rorn the dosing recess. In the metering strip the
metering recess preferably extends through the metering strip,
in which case, in an inhaler ready for use the said flat surface
constitutes the bottom of the metering recess. Such a metering
recess may, for example, simply be drilled through the metering
strip.
For the removal of any powder possibly left between the surfaces
rubbing against each other, the inhaler may additionally have an
aperture for remnants. The aperture for remnants may be
constructed so that, when moving along the flat surface between
the first and the second positions, the metering strip will
travel over the aperture (6) for remnants, at which time any
powder possibly remaining between the metering strip and the
flat surface will, in normal use of the device, automatically
fall via the aperture for remnants into a chamber for remnants.
The movement of the metering strip between the first and the
second positions can be implemented in a number of ways. Figure
1 depicts an embodiment in which there is, locked to a moving
outer casing (7), a lever member (8) which is attached
eccentrically to the body and in which articulations (9) and
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(10) can be effected, for example, by thinning the elastic
plastic in the area of the articulation. The metering strip (4)
and the lever member may, when so desired, be made as one in-
tegral piece. The figure shows how the metering recess is
shifted from the filling position to the inhalation position by
a depression of the outer casing. When the depressing of the
outer casing is discontinued, a return spring (11) will return
the casing and the whole mechanism to the initial position. The
return spring may be disposed as shown in the figure, or it may
be disposed directly in connection with the lever member.
The moving of the metering strip between the two positions may
also be implemented in the manner depicted in Figure 2. This
mechanism is straight and simple. By a depression of a button
(12) in the back wall of the inhaler, the metering strip (4)
will be moved to the inhalation position. In this case the
depressible outer casing is unnecessary, and the powder con-
tainer (1) may as a construction be detachable from the body of
the device. In such a refill embodiment the powder container may
be attachable to the body, for example, by a snap-fit or by
means of threading. The inhaler is thus composed of a body and a
powder container attachable thereto. A filled powder container
closed with a cap may thus be an independent sales item, which
the user can himself connect to the body part. In this case the
size of the powder container can be varied widely. Furthermore,
problems of shelf life will be reduced, since the combining of
the powder container and the metering part will take place only
in connection with the device being taken into use.
In the figures referred to above, the flat surface has been
depicted as being horizontal when the device is in the normal
position for use. It is, however, to be noted that the flat
surface (5) need not necessarily be horizontal; the flat surface
may also be constructed, for example, so as to be downwardly
inclined, in which case also the metering sheet will move
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slantedly downwards in the normal position for use. This will
facilitate the removal of powder from between the flat surface
(5) and the metering strip (4).
Many users are accustomed to using conventional aerosol in-
halers, which are actuated by depressing from the top. The best
aspects of the embodiments depicted in Figures 1 and 2 can be
combined, whereby a refill inhaler is obtained which is operated
in the manner of an aerosol by depressing from the top. Such an
embodiment is depicted in Figure 3. There is no depressible
outer casing but, instead, an attachable powder container (1)
which is depressed like an aerosol container. The flat surface
(5) is constructed so that it is not fixed but, for example,
spring-actuated. A depression of the container will cause the
lever member (8) to move the metering sheet (4) to the
inhalation position. On the other hand, the inhaler of Figure 2
can be modified so as to have an outer casing, in which case the
outer surface of the push button is bevelled so that, when
depressed, the outer casing will cover the push button and push
it in. In this case the outer casing must have its own return
spring.
Figure 4 depicts an example of an inhaler according to the in-
vention, in which the metering strip (4) and the flat surface
(5) are downwardly inclined. This simple inhaler is assembled by
snap-fitting the upper and lower pieces together, for example,
by means of a snap tabs, after the spring (13) and the metering
strip (4) have been placed iri their slot. The inhaler may be
disposable, in which case the container (1) is filled at the
factory and is closed with a cap from above. The inhaler may
also be of the refill type, in which case, for example, a drug-
containing cylinder having a bottom is installed in the powder
container while the device is upside down. In this case the
inhaler cap can thus be repeatedly opened and closed. The powder
container of the inhaler may, of course, also consist of only
the said drug-containing cyJ.irider, which is in this case
attached to the body of the inhaler by means of, for example,
threading.
