GB2110543A

GB2110543A - Inhalers

Info

Publication number: GB2110543A
Application number: GB8136920A
Authority: GB
Inventors: Dr Richard Alexander Lewis
Original assignee: University of Southampton
Current assignee: University of Southampton
Priority date: 1981-12-04
Filing date: 1981-12-04
Publication date: 1983-06-22
Also published as: GB2110543B

Abstract

An inhalation chamber for use with a supply of aerosol-propelled medication, comprises a mouthpiece 15 and a set of clear plastics, telescoping rings 7A to 7J, and 6, which define, in their extended position, the inhalation chamber. The medication is admitted to the inhalation chamber through the smallest ring 7A e.g. from an aerosol. The user may then draw on the mouthpiece 15 to open a non-return valve in an end wall 5 of the chamber, and inhale the medication. The chamber may be collapsed, the rings then adopting their nested position within a casing formed by the end wall 5 and the outermost ring 6. A detachable cover is engaged over the open end of the latter. The inhaler components may thus fit readily into the user's pocket or handbag. <IMAGE>

Description

SPECIFICATION Inhalers This invention relates to inhalers for delivering therapeutic substances to the respiratory systems of patients.

One form of hand-held inhaler which is available for the relief of asthma attacks comprises a mouthpiece attached to a moulded plastics body which holds a small aerosol can containing a drug (in powder form) and a propellant (usually a mixture of chlorinated hydrocarbons). The base of the can is exposed through an opening in the body and effectively forms an operating button for the inhaler. To operate, the patient presses on the can end (against the action of a spring in the delivery valve of the can) and slides the can body further into the inhaler body. The delivery valve nozzle tube of the can is in contact with an abutment surface surrounding an atomising passage in the body through which the drug and propellant are discharged.

Such an inhaler is compact, occupying a space of about 70 mm x 50 mm x 30 mm and can thus be readily carried in the patient's pocket or handbag. However, the mixture discharged from the inhaler travels at high speed of the order of 100 Km per hour, and includes large droplets of the higher-boiling point fractions of the propellant.

As a result, a high proportion of the drug is deposited at the back of the patient's mouth and does not enter the respiratory system. This proportion is thus wasted and may further cause unpleasant side effects. To diffuse and disperse the mixture into an acceptible aerosol requires a dispersion chamber of about 200 mm in length and 870 mm in diameter which to too bulky for carrying in the pocket or handbag.

According to the present invention, an inhaler comprises a supply of therapeutic substance and a propellant therefor, a mouthpiece and a set of rings of substantially the same axial length and progressively increasing diameter, each ring being axially movable relative to the next larger ring between retracted position in which it lies within the next larger ring and an extended position in which the exterior of one end of the ring engages the interior of the opposite end of the next larger ring, the inhaler including means for applying the substance and propellant through the smallest ring and an end wall associated with the largest ring and being arranged to carry the mouthpiece.

Preferably a non-return valve prevents return flow from the mouthpiece through the end wall.

The set of rings in their retracted state fit within a casing formed by the end wall and the outermost ring, preferably with a detachable cover engaged over the open end of the latter. In this state, the assembly fits readily into a pocket or handbag. In their extended positions, the rings define, together with the end wall, a dispersion chamber interposed between the mixture source and the mouthpiece.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which:~ Figure 1 is a side view of an inhaler with its components in a retracted state suitable for carrying in a pocket or handbag; Figure 2 shows a longitudinal section through the dispersion chamber of the inhaler in its extended state ready for use; and Figure 3 shows a detail of Figure 2 on an enlarged scale.

The assembly shown in the drawings comprises a conventional hand-held pocket-size inhaler 1 having an outlet portion 2 which can be used directly as a mouthpiece or have an appropriately shaped mouthpiece attached to it, and an aerosol can 3 inserted into the body 1. When the can 3 is pushed upwards (as seen in Figure 1) to open the valve of the aerosol can, a mixture of drug and propellant is ejected from the outlet 2.

A dispersion chamber assembly 4 is shown in its collapsed condition in Figure 1 and its extended position in Figures 2 and 3. The dispersion chamber comprises an end wall 5 with which is integrally moulded the outermost ring 6 of a set of telescopically nested rings 7A to 7J. Each ring 7 is frusto-conical with the angle of taper of both its inner and its outer walls being about 20 to the axis. As can be seen in Figure 2, the end marginal portion of the outer surface of the larger end of each ring makes jamming contact with the end marginal portion of the inner surface of the smaller end of the next larger ring in the extended state of the dispersion chamber.

The end wall 5 and each of the rings 7 are conveniently moulded from a suitable plastics material, for example transparent polycarbonate, thereby rendering the whole assembly easily washable.

The centre of the end wall 5 contains a nonreturn valve 9, formed in this case by openings 10 through a spider portion of the end wall 5 and a rubber disc 1 1 held captive by a headed pin portion 12.

An annular flange 13 on the end wall 5 forms a detachable mounting for a moulded mouthpiece 14 formed with an exhalation outlet hole 1 5.

A cover 1 6 fits over the opposite end of the outermost ring 6 to the end wall 5.

As shown in Figure 3, the larger end of each ring 7 is preferably chamfered or rounded on its inner surface as shown at 17. In order to prevent the smaller rings such as 7A and 7B from falling loosely into the largest rings, it may be found desirable to mould each ring with an outer flange 18 and with an inner rebate 19 to form a seating for the outer periphery of the flange 1 8 of the next smaller ring.

It will be noted that the dispersion chamber shown in the drawings in its extended form can readily have a length of 200 mm and a diameter at its larger end of 80 mm but, when packed into its retracted form need only have an overall length, including the flange 13, of only 35 mm.

The inner diameter of the smaller ring 7A is sufficient to receive the outlet 2. When the inhaler is in its retracted form, the mouthpiece 14 may be engaged over the upper end of the body 1 and aerosol cannister.

According to another aspect of the invention, the collapsible dispersion chamber is formed by a flexible envelope reinforced by stiffening rings which may be formed integral stiffer portions of the envelope (for example thicker rings, or annular pleats) or by inserted rings or a resilient helix defining the required shape for the dispersion chamber.

Claims

1. An inhaler comprising a supply of therapeutic substance and a propellant therefor, a mouthpiece and a set of rings of substantially the same axial length and progressively increasing diameter, each ring being axially movable relative to the next larger ring between a retracted position in which it lies within the next larger ring and an extended position in which the exterior of one end of the ring engages the interior of the opposite end of the next larger ring, the inhaler including means for applying the substance and propellant through the smallest ring and an end wall associated with the largest ring and being arranged to carry the mouthpiece.

2. An inhaler according to claim 1 wherein the set of rings and the end wall are moulded from a transparent plastics material.

3. An inhaler according to claims 1 or 2, and including a non-return valve to prevent return flow of therapeutic substance and propellant from the mouthpiece through the end wall.

4. An inhaler according to any one of claims 1 to 3 wherein each ring is frusto-conical, the end marginal portion of the outer surface of the larger end of each ring making jamming contact with the end marginal portion of the inner surface of the smaller end of the next larger end, in the extended position of the rings.

5. An inhaler according to any previous claim wherein a detachable cover is engageable over the open end of the outermost ring, in the retracted position of the rings, the cover, outermost ring and end wall then providing a casing for the other rings.

6. An inhaler according to claim 4 or 5 wherein each ring is moulded with an outer flange which comprises a seating for the flange of the next, smaller ring, in the retracted position of the rings.

7. An inhaler substantially as hereinbefore described with reference to the accompanying drawings.