AEROSOL INHALATION DEVICE

Abstract: An aerosol inhalation device (1) suitable for use in association with a pressurised medicament container (3) having a valve stem (4) has a spray head (5) adapted to receive the valve stem (4). The spray head (5) has an outlet orifice which is provided with a spout (12). The device is especially useful in the administration of hygroscopic medicaments, for example sodium cromoglycate or nedocromil sodium.

Description: This invention relates to an aerosol inhalation device, more particularly to a device for the dispensing of hygroscopic medicaments for inhalation. US-A-3913842, EP-A-132352 and FR-A-2603809 disclose aerosol dispensing devices in which the outlet orifice is provided with a spout. The use of aerosol inhalation devices for the administration by inhalation of medicaments in the form of powder aerosols is well known. Such devices generally comprise a housing which receives a canister of pressurised medicament. The canister is provided with a dispensing metering valve including a metering chamber and a hollow valve stem which locates in a spray head within the housing. Medicament is discharged by moving the canister relative to the valve stem. This changes the dispensing metering valve from an inoperative state in which the metering chamber is isolated from the atmosphere to an operative state in which the metering chamber communicates with the atmosphere via the valve stem and an outlet orifice provided in the spray head. Thus, in the operative state medicament can pass from the chamber through the valve stem, the spray head and the outlet orifice into the housing from where it can be inhaled by a user via a mouthpiece formed in the housing. A problem which can occur with devices of this type when they are used to dispense hygroscopic medicaments is blockage of the outlet orifice. Also, medicament may build up around the outlet orifice and form a plug which may subsequently be dislodged and inhaled by the user. We have now surprisingly found that these problems can be eliminated or substantially mitigated by providing the outlet orifice with a generally frusto-conical spout whose curved outer surface is concave and whose length is less than 5mm. Thus, according to the present invention there is provided an aerosol inhalation device comprising a pressurised medicament container having a valve stem; and a spray head in which the valve stem is received, the spray head having an outlet orifice provided with a generally frusto-conical spout whose curved outer surface is concave, the spout extending from a wall of the spray head in a direction substantially transverse to the axis of the spray head; characterized in that the spout is less than 5mm in length and the medicament is hygroscopic. The spout may be, for example, 2mm in length. The ratio of the length of the outlet orifice to the length of the spout is preferably less than 2:1. The spray head includes an internal cavity which is open at one end to receive the valve stem and closed at the other end. The cavity may extend beyond the outlet orifice. We prefer the outlet orifice to be of uniform cross section throughout its length. We further prefer the outlet orifice to be circular in cross section. By "hygroscopic medicament" we mean a medicament which takes up significant amounts of water when in a moist atmosphere, for example one which at 90% relative humidity (being approximately a lower value for the relative humidity found in human breath) takes up more than 8% of its own weight of water. Examples of such medicaments include sodium cromoglycate and nedocromil sodium. The aerosol inhalation devices of the invention have the advantages that they do not become blocked or block less frequently, so that a canister of medicament can be exhausted without the danger of the device being discarded prematurely because the patient mistakenly believes that the canister is empty or because it cannot readily be unblocked; there is a greatly reduced risk of plugs of medicament forming in the devices which are subsequently inhaled by the patient - such inhalation may lead to over-dosing or a coughing spasm which is especially dangerous for patients who have breathing difficulties and who are most likely to be using aerosol inhalation devices; the devices are more hygienic because there are fewer or no medicament accretion surfaces which bacteria may colonize; and they need to be cleaned less frequently - cleaning being a difficult task for patients who have unsteady hands. A preferred embodiment of a device according to the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view in partial section of an aerosol inhalation device according to the invention including a pressurised medicament container, Figure 2 is an expanded view of the spray-head of the device shown in Figure 1 (also here in cross-section) and; Figure 3 is a view of the spray-head shown in Figure 2 along the line III-III. Referring first to Figure 1, an aerosol inhalation device comprises a generally cylindrical housing 1 having a mouthpiece 2. The housing 1 receives a container 3 of pressurised medicament, the container being provided at one end with a metering valve including a valve stem 4. The valve stem 4 is seated in a spray head 5. The spray head 5 includes an internal cavity 6 provided with an outlet orifice 7. The internal cavity 6 has a lower portion 8 which extends below the outlet orifice 7. As can be seen more clearly from Figure 2, the outlet orifice 7 passes through a spout 12 which has a generally frusto-conical shape with a concave outer wall. The spout 12 rises out of a flat front surface 9 of the spray head 5, the flat surface being at an angle such that the spout 12 is directed towards the mouthpiece 2. To use the device, a patient inhales at the mouthpiece 2 while simultaneously urging the medicament container 3 towards the spray head 5. The relative motion of the container 3 and the valve stem 4 causes the metering valve to open and medicament to be discharged into the valve stem 4. The medicament then passes through the internal cavity 6 of the spray head, and finally through the outlet orifice 7 after which it is inhaled by the patient through the mouthpiece 2.

Claims: An aerosol inhalation device comprising a pressurised medicament container (3) having a valve stem (4); and a spray head (5) in which the valve stem (4) is received, the spray head (5) having an outlet orifice (7) provided with a generally frusto-conical spout (12) whose curved outer surface is concave, the spout (12) extending from a wall (9) of the spray head (5) in a direction substantially transverse to the axis of the spray head (5); characterized in that the spout is less than 5mm in length and the medicament is hygroscopic. An aerosol inhalation device according to claim 1, wherein the spray head (5) includes an internal cavity (6) which is open at one end to receive the valve stem and closed at the other end, the cavity extending beyond the outlet orifice (7). An aerosol inhalation device according to claim 1 or claim 2, wherein the outlet orifice (7) is of uniform cross section throughout its length. An aerosol inhalation device according to any one of the preceding claims, wherein the medicament is sodium cromoglycate or nedocromil sodium.

Inventors: BLOWER, ANDREW WILLIAM, CLARKE, MICHAEL JOHN, CORBETT, JOHN STUART
Applicants: FISONS PLC
Application year: 1989
Main classification: A61M15
IPC codes: A61M13, A61M15, A61M11, B05B9