Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Reexamination Certificate
1998-03-02
2001-09-11
Weiss, John G (Department: 3761)
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
C128S203210, C128S203230
Reexamination Certificate
active
06286507
ABSTRACT:
BACKGROUND
The present invention relates to a disposable inhaler, particularly for administering powder by inhalation.
Previously, as described in WO93/17728 and illustrated in
FIGS. 1
to
3
of the accompanying drawings, there was known a disposable inhaler constructed from two parts
1
and
2
. The lower part
2
includes a recesses
3
in which a dose of powder is stored and the two parts together define a channel through which a stream of air may be drawn by a user from an air inlet
4
to a mouthpiece
5
. A tape
6
is provided to cover the recesses
3
and is additionally bent around the outside of the part
2
to cover an aperture
8
in the bottom of the recess
3
. In use, the tape
6
is pulled away from the lower part
2
so as to expose both the aperture
8
and the recess
3
. Projections
7
are provided to keep the loose tape out of the way of the air flow and a depression
9
directs the air flow to pick up the powder in the recess
3
more effectively. The channel defined by parts
1
and
2
also includes a deagglomeration section
10
having a section inlet
11
, a section outlet
12
and a divider
13
. The divider
13
splits the stream of air into two flow paths and powder is caused to impact on internal surfaces. In this way, powder is effectively deagglomerated.
In use, a patient inhales through the mouthpiece
5
causing an air stream to pick up the powder stored in recess
3
. As the air/powder mixture flows through the inhaler, powder is deagglomerated then passes out of the mouthpiece
5
and into the lungs of the patient.
SUMMARY OF THE INVENTION
An object of the present invention is to provide improved deagglomeration of powder, in other words to increase the fine particle fraction and fine particle dose.
Another object of the present invention is to minimize retention of powder within the inhaler.
With regard to these two objects, the prior art of
FIGS. 1
to
3
included an inhalation channel which directed the air flow along a path with walls that change direction. The changes in the direction of the walls results in powder impacting with those walls and a generally turbulent air flow which assists in deagglomeration of powder.
The present invention is based on the realization that the effects of deagglomeration of powder by the channelling surfaces or any of the surfaces facing downstream of the surfaces of the divider
13
are relatively insignificant.
According to the present invention there is provided an inhaler for administering powder by inhalation, the inhaler comprising:
a channel through which a stream of air may be drawn by inhalation of a user; and
a powder dispenser for providing said powder in said stream of air for inhalation by the user; wherein
said channel includes at least one deagglomeration section with a section inlet, a section outlet downstream of said section inlet and a divider between said section inlet and said section outlet for dividing said stream of air either side of said divider; and wherein
said divider has a surface opposite said section inlet and said surface is oriented at an angle substantially perpendicular to the flow of said stream of air passing through said section inlet.
In this way, powder carried in the air stream is more effectively deagglomerated and the final air/powder mixture inhaled by the user has a higher fine particle fraction and fine particle dose. By providing a perpendicular surface to the divider, there is greater impact of powder with the surface of the divider causing improved deagglomeration throughout the air/powder mixture. Furthermore, impact of the powder with the surface of the divider, together with the air flow past the surface prevents undue retention of powder on the surface. When a large powder particle impacts with the surface, it breaks into smaller particles which rebound back into the airflow and are carried on through the inhaler by that air flow.
Preferably, the surface of the divider extends over at least the area corresponding to a projection of the section inlet on to said divider.
By providing a perpendicular surface over the entire width of the section inlet, the effects and advantages discussed above are maximised.
According to the present invention there is also provided an inhaler for administering powder by inhalation, the inhaler comprising:
a channel through which a stream of air may be drawn by inhalation of a user; and
a powder dispenser for providing said powder in said stream of air for inhalation by the user; wherein
said channel includes at least one deagglomeration section with a section inlet, a section outlet downstream of said section inlet and a divider between said section inlet and said section outlet for dividing said stream of air either side of said divider, said divider having a surface substantially opposite said section inlet for dividing the air flow entering through said section inlet and affecting deagglomeration of powder in the air flow; and wherein
surfaces of the at least one deagglomeration section are shaped and spaced apart so as substantially not to cause any restriction to or turbulence in the stream of air through the inhaler.
According to the present invention, it has been recognized that most of the deagglomeration occurs on the surface of the divider opposite the section inlet and that, with the same size of inhaler and same fine particle fraction/dose, the shape of the walls defining the channel through the inhaler may be modified to reduce the flow resistance and retention of the inhaler.
In particular, with a particular shape and size of divider surface opposite the section inlet for deagglomeration of powder, the remaining surfaces of the deagglomeration section should be shaped to follow the natural flow path of the air deflected either side of the divider. Clearly, this results in reduced deagglomeration effects in the rest of the inhaler other than the deagglomeration surface. However, as mentioned above, the present invention recognizes that the effects of deagglomeration in these parts are relatively insignificant. The advantages of the present invention are that, with reduced disturbance, restriction, turbulence etc. of the stream of air, there is less opportunity for powder to be deposited in the inhaler and the flow resistance experienced by the user inhaling through the inhaler is minimized.
Each section inlet may be fed by one or more substantially straight sections or channels.
The advantage of this is that the powder particles carried in the stream of air then have a well defined momentum towards the facing surface of the deagglomeration divider. This maximizes the number of larger powder particles which leave the direction of flow of the stream of air and which continue straight on to impact with the divider.
Preferably, two deagglomeration sections are provided with the section outlet of one deagglomeration section being in fluid connection with the section inlet of the other deagglomeration section.
The channels formed either side of the divider of one deagglomeration section may feed directly into the section inlet of the next deagglomeration section or they may first join to form a single straight section feeding that section inlet.
The use of two deagglomeration sections provides further improvement in deagglomeration with further increases in the fine particle fraction and fine particle dose. In particular, the fine particles in the air/powder mixture will be carried by the airstream around the surface of the divider. However, those larger heavier particles which escaped deagglomeration by the first divider will have sufficient momentum to leave the flow of air and impact with the surface of the second divider. As with the first divider, the particles break into smaller particles which rebound back into the airstream and are carried on through the inhaler. Of course, the exact shape and size of the second deagglomeration section may differ from that of the first deagglomeration section.
According to the present invention, there is also provided a method of optimizing the characteristics of an
Astra Aktiebolag
Fish & Richardson P.C.
Srivastava V.
Weiss John G
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