NZ204430A - Telescopic dispersion chamber for inhaler - Google Patents

Description

204430 Priority Date(s): Complete Specification Filed: Class: fl (\! ti: J. > )..F.h P.l .., Publication Date: . ....Bl.JUL.iM I P.O. Journal, No: ...!.?&$ Patents Form No. 5 NEK ZEALAND PATENTS ACT 195 3 COMPLETE SPECIFICATION "INHALERS" -I-WE THE UNIVERSITY OF SOUTHAMPTON, incorporated in England of Highfield, Southampton S09 5NH, England hereby declare the invention, for which -I-/ve pray that a patent may be granted to irre-/us, and the method by which it is to be performed, to be particularly described in and by the following statement -1- (followed by page I 204430 - lfl- INHALERS This invention relates to inhalers and to dispersion chambers for use therewith, for delivering therapeutic substances to the respiratory systems of patients.

One form of hand-held inhaler which is available s 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 fluorinated 10 hydrocarbons). The base of the can is exposed through v 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 15 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 25 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 a 30 unpleasant side effects. Moreover, some patients find difficulty in developing the necessary co-ordination of respiratory inhalation and the pressing of the aerosol can to use such inhalers effectively. 2 044 3 These problems can be lessened by using a dispersion chamber, commonly known as a spacer, between a standard inhaler and the patient's mouth. One such dispersion chamber on the market is a rigid, 5 pear-shaped plastics envelope of about 750 ml internal capacity. The envelope has an inlet hole at one end and an outlet hole at the other. The envelope widens from the inlet to the outlet. The size and taper of the dispersion chamber results in the aerosol passing 10 through the inlet, and slowing down and dispersing along the envelope, so that when the patient draws on the outlet he inhales a diffuse stream of therapeutic substance, which can penetrate deeply into the bronchial tree. Moreover, the degree of co-ordination 15 needed between pressing the can and inhalation is much less than with the standard inhaler alone. However, the dispersion chamber is too bulky to be conveniently carried in the patient's pocket or handbag.

It is an object of the present invention to 20 provide a dispersion chamber which diffuses and disperses therapeutic spray from a can into an acceptable aerosol, a high proportion of which enters the respiratory system, which is readily collapsible to a size which can be accommodated in a pocket or small 2 5 handbag, and which can be easily maintained in a hygienic condition.

According to the present invention there is provided a collapsible dispersion chamber for use with a medicament dispersion comprising: a set of rings of 30 progressively increasing diameter, the diameter of at least the largest ring of said set of rings exceeding the axial length of each ring of said set of rings, each said ring being axially movable relative to the next larger ring between a retracted postion in which 3 5 it lies within said next larger ring and an extended position in which the exterior of one end of said ring 20443' engages the interior of the opposite end of said next larger ring; and an end wall associated with said largest ring, the end wall being formed with an outlet aperture of 5 said dispersion chamber.

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 10 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 15 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 20 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 downwards (as seen in Figure 1) to open the valve of the aerosol can, a mixture of drug and propellant is ejected from the 25 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 30 moulded the outermost ring 6 of the set of telescopically nested rings 7A to 7J. Each ring 7 is of the same axial length and is frusto-conical with the angle of taper of both its inner and its outer walls being about 2° to the axis. As can be seen in Figure 35 2, the end marginal portion of the outer surface of the larger end of each ring makes jamming contact with the 204430 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 diameter of each ring exceeds its axial 5 length, so that the dispersion chamber, when retracted, forms a thick disc suitable for carriage in a pocket or handbag.

The end wall 5 and each of the rings 7 are conveniently moulded from a suitable plastics material, 10 for example transparent polycarbonate, thereby rendering the whole assembly easily washable.

The centre of the end wall 5 contains a non-return valve 9, formed in this case by openings 10 through a spider portion of the end wall 5 and a rubber disc 11 15 held captive by a headed pin portion 12.

An annular flange 13 on the end wall 5 forms a detachable mounting for a detachable moulded mouthpiece 14 provided with a one-way valve 15 formed again by a captive rubber disc 15A over an aperture 15B. The 2 0 final exhalation prior to inhalation of therapeutic substance may take place with the mouthpiece in the patient's mouth, aiding patient s with co-ordination problems. As an alternative to the one-way valve 15, a simple aperture 15B may be provided. 2 5 A cover 16 fits over the opposite end of the largest ring 6 to the end wall 5, the cover, largest ring and end wall providing a casing for the retracted dispersion chamber.

As shown in Figure 3, the larger end of each ring 30 7 is preferably chamfered or rounded on its innter 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 35 inner rebate 19 to form a seating for the outer periphery of the flange 18 of the next smaller ring. 2O4430 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 5 only have an overall length, including the flange 13, of only 35 mm. The dispersion chamber can be between 0.1 and 2 litres in volume, most commonly 0.5 to 2 litres.

The inner diameter of the smallest ring 7A is 10 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 canister.

The device may be used to alleviate asthmatic 15 conditions with therapeutic medicaments such as salbutamol, a selective beta2 - adrenoceptor stimulant or a corticosteriod such as beclomethasone dipropionate. The dose may be tailored to suit the circumstance. However, one or two inhalations can 20 usually be taken up to four times a day as required.

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Claims (14)

- 6 - 204430 -CLAIM &- WHAT n.AIM IS>

1. A collapsible dispersion chamber for use with a medicament dispenser comprising: a set of rings of 5 progressively increasing diameter, the diameter of at least the largest ring of said set of rings exceeding the axial length of each ring of said set of rings, each said ring being axially movable relative to the next larger ring between a retracted position in which 10 it lies within said next larger ring and an extended position in which the exterior of one end of said ring engages the interior of the opposite end of said next larger ring; and an end wall in said largest ring, 15 the end wall being formed with an outlet aperture of said dispersion chamber.

2. A dispersion chamber according to claim 1 wherein the rings of said set of rings are all of substantially 2 0 the same- axial length.

3. A dispersion chamber according to claim 1 or 2 wherein the diameter of the smallest ring exceeds the axial length of each said ring. 25

4. A dispersion chamber according to any preceding claim including a one-way valve fitted at said outlet aperture to allow gas to leave the dispersion chamber through said outlet aperture. 30

5. A dispersion chamber according to any preceding claim, further comprising a detachable mouthpiece carried by said end wall. r23HAYi986 "Cpe I 2044IQ 7

6. A dispersion chamber according to claim 5 including an outlet aperture in the side wall of said mouthpiece.

7. A dispersion chamber according to claim 6,*;including a one-way valve fitted at said mouthpiece' aperture to allow exhaled air to leave the mouthpiece through said aperture.;

8. A dispersion chamber according to any preceding claim, in which said rings of said set of rings and said end wall are moulded from transparent plastics material.;

9. A dispersion chamber according to any preceding claim, wherein each said ring of said set of rings is frusto-conical, the end marginal portion of said exterior of the larger end of each said ring making jamming contact with the end marginal portion of said interior of the smaller end of the next larger ring, in said extended positon of said set of rings.;

10. A dispersion chamber according to any preceding claim and further including a detachable cover engagable over the open end of said largest ring, in said retracted position of said set of rings, said cover, largest ring and end wall then defining a casing for the other rings.;

11. A dispersion chamber according to any preceding claim, wherein each said ring is moulded with an outer flange which comprises a seating for the flange of the next, smaller ring, in said retracted position of said set of rings.;

12. A dispersion chamber according to any preceding.;claim wherein the volume of said chamber;0.1 and;2 litres;*04430 - 8 -

13. A dispersion chamber according to claim 12 wherein said volume is between 0.5 and 2 litres.

14. A dispersion chamber substantially as hereinbefore described with reference to the accompanying drawings.