WO1991000117A1

WO1991000117A1 - Aerosol holding chamber

Info

Publication number: WO1991000117A1
Application number: PCT/GB1990/001036
Authority: WO
Inventors: Andrew William Blower; John Stuart Corbett; Andrew Reginald Clark; Michael John Clarke
Original assignee: Fisons Plc
Priority date: 1989-07-05
Filing date: 1990-07-04
Publication date: 1991-01-10
Also published as: GB8915420D0

Abstract

An aerosol spacer device or holding chamber comprises a chamber (1) provided at one end with an inlet to receive an aerosol cloud and at the other end with an outlet including a one-way valve comprising a support grid (7, 8) and a membrane (3), characterised in that the membrane has a central flap (10) supported at its periphery by the support grid (7, 8) such that, when the flap is lifted out of the plane of the rest of the membrane, the passage of air through the central portion of the valve is unimpeded by the support grid.

Description

Aerosol Holding Chamber

This invention relates to improvements in devices for the inhalation of medicaments, in particular to an aerosol r-acer device or holding chamber with an improved respiratory valve.

One of the ways in which medicaments are administered by inhalation is by means of a pressurised metered dose inhaler. For some patients, however, notably the very young or the old, the use of such devices is difficult due to the necessary coordination of inhalation and actuation of the device. For such patients, this problem may be alleviated by the use of an extension tube or spacer device. Such devices provide a temporary reservoir for the aerosol cloud released from the inhaler which may then be inhaled by the patient.

Commonly used types of spacer comprise a 'pear-shaped' or cylindrical chamber provided at one end with an inlet to receive the inhaler and at the other end with a mouthpiece including a respiratory valve. The respiratory valve typically comprises a rubber membrane with two crossed slits forming four flaps in the centre of the membrane which are lifted upon inhalatory effort by the patient, thereby permitting the aerosol cloud contained within the chamber to be inhaled. The flaps are supported by an X-shaped grid, the limbs of the 'X' extending along the lines of the slits.

We have now surprisingly found that modification of the respiratory valve in a spacer device of the type described above such that the support grid does not impede the passage of air through the centre of the valve when the valve is opened substantially improves the performance of the device.

Accordingly, this invention provides an aerosol spacer device comprising a chamber provided at one end with an inlet to receive an aerosol cloud and at the other end with an outlet including a one-way valve comprising a support grid and a membrane, characterised in that the membrane has a central flap supported at its periphery by the support grid such that, when the flap is lifted out of the plane of the rest of the membrane, the passage of air through the central portion of the valve is unimpeded by the support grid.

The spacer device according to the invention is advantageous principally in that the quality of the aerosol cloud inhaled, in terms of the proportion of aerosol particles which are sufficiently fine to penetrate deep into the lung, is better than that achieved using comparable known spacer devices. The device is also advantageous in that the valve is more easily actuated by the breath of children than is the case with other, known devices. Furthermore, the need for accurate coordination of inhalation and dispensing of a dose of medicament is reduced.

The flap is preferably of partially circular shape. The flap may, for example, be formed by an arcuate slit in the membrane, the slit preferably describing approximately 300° of arc. In this case, the support grid conveniently includes an annular portion of similar diameter to that of the flap such that the flap is supported at its edge by the annular portion and air is able to flow unimpeded through the annulus when the flap is lifted. This arrangement has the added advantage that the inhalatory effort required to open the valve is relatively low and the time taken for the valve to fully open is relatively small. The annular portion of the support grid is preferably connected to the walls of the outlet by a plurality of radial members spaced angularly, preferably equiangularly, around the annulus. There are preferably provided further radial slits in the membrane extending outwardly from the _Q flap along the lines of some or all of the radial members. This arrangement provides supplementary flaps which open on strong inhalatory effort by the patient.

The membrane is preferably of elastomeric material and is preferably circular. The diameter of the membrane is preferably less than about 6cm, eg about 5cm. The flap, when it is of partially circular form, is preferably of diameter from about 1 to 2.5cm, eg about 2cm.

The outlet is preferably provided downstream of the membrane with one or more bleed outlets which permit egress of air should the user mistakenly exhale into the outlet. This helps to prevent the membrane being deformed, eg by the flap being blown back into the chamber.

We have also found that the performance of the device may be substantially improved by appropriate choice of the shape of the device.

Another feature of the present invention is therefore the provision of an aerosol spacer device comprising a chamber having a frustoconical portion having at its smaller end an inlet to receive an aerosol cloud, characterised in that the angle of taper of the frustoconical portion is between 10° and 25° per side and the length of the frustoconical portion is between 0.50 and 0.65 of the total length of the chamber.

The angle of taper of the frustoconical portion is preferably greater than 15 ° .

The angle of taper of the frustoconical portion is preferably less than 20°.

The length of the frustoconical portion is preferably greater than 0.55 of the total length of the chamber. The length of the frustoconical portion is preferably less than 0.60 of the total length of the chamber.

The total length of the chamber is preferably between 15cm and 25cm, and the volume of the chamber is preferably between about 500 and 1000cm³. The spacer device may be manufactured from any suitable material, with plastics, especially clear plastics such as polycarbonate, being particularly convenient.

A further disadvantage of known aerosol spacer devices is that they can be used only with metered dose inhalers having a particular shape of outlet. This means that when a patient uses two different medications, eg a prophylactic drug and a bronchodilator, he requires two different spacer devices which are bulky and inconvenient to carry. In another preferred aspect of the invention, therefore, there is provided an aerosol spacer device comprising a chamber provided at one end with an inlet and at the other end with a mouthpiece, characterised in that the inlet is so shaped as to accept and retain more than one shape of metered dose inhaler outlet. preferred embodiment of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 is an exploded side view of an aerosol spacer device according to the invention, Figure 2 is a view along line II-II¹ in Figure 1, Figure 3 is a plan view of a membrane forming part of a respiratory valve used in the device of Figures 1 and 2, and

Figure 4 is a side view of the assembled device of Figures 1 and 2.

Referring first to Figure 1, an aerosol spacer device comprises a first chamber portion (1) , a second chamber portion (2) , a valve membrane (3) and a mouthpiece (4) .

First chamber portion (1) is provided at one end with an inlet to receive a metered dose inhaler (shown by the dashed lines) . The inlet is so shaped as to accept more than one kind of metered dose inhaler. Second chamber portion (2) has a flange (5) at its larger end, flange (5) fitting closely inside the larger end of first chamber portion (1) to form a chamber. At its smaller end, second chamber portion (2) has a second flange (6) . Mouthpiece (4) fits closely over second flange (6) , holding valve membrane (3) captive between mouthpiece (4) and second chamber portion (2) . ^As can be seen from Figure 2, the mouth of second flange (6) facing mouthpiece (4) carries a support grid (7,8) comprising a central annular portion (7) linked to the walls of second flange (6) by four radial members (8) . An arcuate slit (9) describing approximately 300° of arc defines a central flap (10) in valve membrane (3) (see Figure 3) . Slit (9) terminates in two small holes (11) which prevent tearing of membrane (3) beyond the ends of slit (9) . Three radial slits (12) extend outwardly from slit (9) to points approximately halfway between slit (9) and the edge of membrane (3) .

The assembled device is shown in Figure 4. A frustoconical portion extends from the inlet towards mouthpiece (4) . The angle of taper of the frustoconical portion is 17° and its length (indicated by A in the Figure 4) is 105mm. The total length of the chamber (indicated by B) is 185mm.

In use, the device is assembled as described above with radial slits (12) aligned with radial members (8) . A metered dose inhaler is inserted into the smaller end of first chamber portion (1) and actuated, dispensing a dose of medicament into the device. Inhalation by the patient at mouthpiece (4) opens flap (10) , allowing air and the cloud of medicament to pass through the valve. Upon expiration by the patient, flap (10) is pressed back against support grid (7,8) preventing exhaled air entering the chamber. Small bleed holes (not shown) in mouthpiece (4) permit the escape of exhaled air thereby relieving the pressure exerted on membrane (3) .

Claims

1. An aerosol spacer device comprising a chamber provided at one end with an inlet to receive an aerosol cloud and at the other end with an outlet including a one-way valve comprising a support grid and a membrane, characterised in that the membrane has a central flap supported at its periphery by the support grid such that, when the flap is lifted out of the plane of the rest of the membrane, the passage of air through the central portion of the valve is unimpeded by the support grid.

2. A device according to Claim 1, wherein the the flap is formed by an arcuate slit in the membrane and the support grid includes an annular portion of similar diameter to that of the flap.

3. A device according to Claim 2, wherein the annular portion of the support grid is connected to the walls of the outlet by a plurality of radial members spaced angularly around the annulus.

4. A device according to Claim 3, wherein there are provided further radial slits in the membrane extending outwardly from the flap along the lines of some or all of the radial members.

5. A device according to any one of the preceding claims wherein the membrane is of elastomeric material.

6. A device according to any one of the preceding claims, wherein the outlet is provided downstream of the membrane with one or more bleed outlets to permit egress of air should the user mistakenly exhale into the outlet.

7. A device according to any one of the preceding claims, wherein the chamber comprises a frustoconical portion having at its smaller end an inlet to receive an aerosol cloud, the angle of taper of the frustoconical portion being between 10° and 25° per side and the length of the frustoconical portion being between 0.50 and 0.65 of the total length of the chamber.

8. A device according to any one of the preceding claims, wherein the inlet is so shaped as to accept and retain more than one shape of metered dose inhaler outlet.