Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Reexamination Certificate
1998-05-08
2001-12-11
Weiss, John G. (Department: 3761)
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
Reexamination Certificate
active
06328032
ABSTRACT:
BACKGROUND
The present invention relates to a powder inhaler and a method of constructing the same.
A number of powder inhalers are known which use different systems for introducing a dose of powder into an air stream. Typically, the powder is inhaled into the lungs of a patient in order to treat, for example, asthma.
One such powder inhaler is disclosed in EP-A-0237507. This inhaler comprises an inhalation channel and a mouthpiece comprising an air chamber and an outlet nozzle, which together define a flow path through which a stream of air is drawn during inhalation by a user. This inhaler further comprises means for introducing powder into the inhalation channel. During inhalation, air is first drawn into and through the inhalation channel so as to pick up powder. The stream of air containing powder is then drawn through the air chamber and out of the outlet nozzle of the mouthpiece.
Powder inhalers are, however, particularly susceptible to the effects of moisture and should therefore include a desiccant, such as silica gel, to absorb any moisture. It will of course be appreciated that it is a requirement that the desiccant be contained entirely separate from the powder to be inhaled so as to avoid contamination of the powder.
In powder inhalers of the kind which comprise an inhaler body and a grip portion at one end thereof, which grip portion is rotatable relative to the inhaler body so as to provide a dose of powder for inhalation, it has been proposed to provide a chamber in the grip portion for containing desiccant. In one proposed construction the grip portion comprises first and second parts which fit together to define a chamber; the first and second parts having cooperating splines to lock the same in the rotational sense. There is, however, one major drawback with this proposed construction in that, when fitting together the first and second parts, particles of desiccant may become lodged between the splines and prevent correct assembly.
It is thus an aim of the present invention to provide a powder inhaler having a construction which allows the parts thereof that define the chamber for containing desiccant to be fitted in a sure and reliable manner when enclosing desiccant.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides an inhaler for administering powder by inhalation which comprises a member that defines a chamber for containing desiccant, the member comprising first and second parts which when fitted together define the chamber for containing desiccant, wherein the first part has an outer surface provided with at least one of an internal or external spline and the second part has an inner surface provided with at least one of the other of an internal or external spline, the splines being dimensioned and/or spaced so as, on fitting together the first and second parts, rotationally to fix the same and define spaces therebetween.
Preferably, the splines are dimensioned and/or spaced so as rotationally to fix the first and second parts irrespective of the relative angular relationship therebetween on fitting.
More preferably, the splines are defined by a plurality of projections provided to the outer and inner surfaces respectively of the first and second parts, and, compared to notional surfaces complete with projections, the outer surface of the first part provided with one of external or internal splines has n
1
notional projections missing between adjacent projections, n
1
being an integer greater or equal to one, and the inner surface of the second part provided with one of the other of external or internal splines has n
2
notional projections missing between adjacent projections, n
2
being an integer greater than n
1
and satisfying the relationships (n
1
+1).k
1
+1=(n
2
+1).k
2
and (n
1
+1).k
3
=(n
2
+1).k
4
, where k
1
, k
2
, k
3
and k
4
are zero or integers greater than zero and k
2
is less than k
4
.
Preferably, the at least one external spline and the at least one internal spline are of different radial dimension.
Preferably, the first and second parts comprise cooperating detent means for holding the same together on fitting and the splines are dimensioned and/or spaced relative to the cooperating detent means such that, when the first and second parts are fitted together, the at least one external spline is engaged within the at least one internal spline before any resistance to further insertion is caused by the cooperating detent means.
Preferably, the splines are dimensioned and/or spaced such that the axes of the first and second parts are substantially relatively angularly immovable before any resistance to further insertion is caused by the cooperating detent means.
Preferably, the at least one internal spline extends from a position sufficiently near to the peripheral edge of the surface in which the same is provided that, on fitting together the first and second parts, the splines engage before any resistance to further insertion is caused by the cooperating detent means.
Preferably, the relative lengths and positions of the splines are such that at least one-third of the length of each of the external and internal splines is engaged before any resistance to further insertion is caused by the cooperating detent means.
Preferably, the cooperating detent means comprise an at least part circumferential groove and an at least part circumferential ridge which is configured to engage therewithin.
Preferably, the at least part circumferential ridge is provided on the outer surface of the first part and the at least part circumferential groove is provided in the inner surface of the second part.
More preferably, the at least part circumferential groove is provided in the inner surface of the second part between the peripheral edge of the inner surface and the at least one spline provided to the inner surface.
Preferably, the at least one external spline is about three-quarters of the length of the at least one internal spline.
Preferably, the outer surface of the first part is provided with at least one external spline and the inner surface of the second part is provided with at least one internal spline.
Preferably, the inhaler further comprises an inhaler body and a mouthpiece from which powder is in use inhaled, the inhaler body housing a dosing mechanism for providing a dose of powder for inhalation.
More preferably, the member comprises a grip portion for operating the dosing mechanism.
Yet more preferably, the grip portion is rotatably mounted to the inhaler body.
Still yet more preferably, the inhaler body comprises one of an at least part circumferential ridge or an at least part circumferential groove and the grip portion comprises the other of the at least part circumferential ridge or at least part circumferential groove, the at least part circumferential ridge being configured to engage within the at least part circumferential groove.
Preferably, at least a part of a wall of the chamber adjacent the inhaler body is permeable to moisture.
Preferably, an outer surface of the second part has a knurled or ridged surface which can be gripped by a user.
Preferably, the one of the first and second parts which is provided with the at least one internal spline includes at least one element which is disposed so as to be abutted by at least one of the at least one external spline when the first and second parts are fitted together.
Preferably, at least one of the at least one internal spline is bridged at the forward end in the direction of fitting by an element at least one of which is abutted by the at least one external spline when the first and second parts are fitted together.
More preferably, each element is formed of a material which is deformed by the respective external spline.
The present invention also provides a method of constructing an inhaler for administering powder by inhalation which comprises a member that defines a chamber for containing desiccant, the method comprising the steps of: providing first and second parts having respectively an outer surface and an i
Astra Aktiebolag
Fish & Richardson P.C.
Weiss John G.
Weiss, Jr. Joseph F.
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