Inhaler for medicament

The invention relates to inhaler products, such as medicaments, and particularly to an inhaler for transferring to a patient a metered dose of medicament contained in a pressurized dispensing container. The inhaler includes a housing for receiving a pressurized dispensing container of medicament and a mouthpiece for insertion into the mouth or a user of the inhaler. An outlet in the housing communicates with the mouth piece via a duct ending in an outlet. At least one air inlet is provided for allowing air into the inhaler. The air inlet(s) being positioned downstream relative to the duct outlet. A restricted airflow passage is provided between the air inlet(s) and a location adjacent to the outlet of the duct. The inhaler also includes a vortex generating arrangement positioned in the restricted airflow passage, such that, in use, when a user inhales through the mouthpiece, a swirling airflow is created from the inlet(s) to the mouthpiece along the passage towards the duct outlet. The swirling airflow exits the restricted airflow passage to create a swirling airflow in the neck region of the duct outlet that swirls about a central axis of the duct outlet and the swirling airflow has a component directed in reverse to the airflow form the duct outlet of the mouthpiece for reducing the velocity of medicament dispensed from the pressurized dispensing container via the duct and duct outlet.

FIELD OF THE INVENTION 
The invention relates to an inhaler for products such as medicaments and 
particularly to an inhaler for transferring to a patient a metered dose of 
medicament contained in a pressurised dispensing container. 
BACKGROUND OF THE INVENTION 
In known metered dose inhalers, the aerosol stream from a pressurised 
dispensing container is fired towards a patient or user of the inhaler 
into an air flow travelling in the same direction. In known devices, a 
user inhales through a mouth piece of the inhaler and creates an air flow 
through the container from air inlet holes which are generally at a part 
of the inhaler well spaced from the mouth piece. The medicament is then 
released into this air flow at a point between the air inlet holes and the 
mouth piece so that it is travelling in the same direction as the air 
flow. Typically in such devices, there is no restriction in the air flow 
between the air inlet holes and the mouth piece. Because of this, a 
substantial air flow may be created by a user of the device and, because 
the medicament is fired into the air flow in the same direction as the air 
flow, the effect is that particles of medicament can attain quite 
substantial velocities. As inhalers of this type are normally designed to 
be as small as practical for the convenience of users, the distance 
between the point at which the medicament is fired into the air flow and 
the patients mouth is usually quite small so that there is little distance 
to reduce the inertia of the particles of medicament with the result that 
the particles may impact in the oro-pharynx of a user with quite high 
velocity. This can be a problem with some medicaments. 
In an effort to overcome this problem, devices have been produced in which 
the medicament is fired into a holding volume which allows the velocity of 
the medicament to be reduced and also allows some evaporation to occur. 
U.S. Pat. No. 5,435,297 discloses a medical device for inhaling a metered 
aerosol comprising a cylindrical housing with a receiving chamber and 
first main air channels extending axially within the housing. A mouthpiece 
is co-axially connected to the housing. An atomising and vortexing chamber 
is delimited by the housing and the mouthpiece. Second main air channels 
extend within the mouthpiece and communicate with the first main air 
channels. Branch air channels extend at a slant to an axial direction 
within a partition positioned between the receiving chamber and the 
atomising and vortexing chamber. The branch air channels are connected to 
the first main air channels and open into the atomising and vortexing 
chamber. Inhaled airflow through the branch channels aids the atomisation 
of the aerosol. However, the branch channels do not slow the velocity of 
the dispensed medicament. Rather, they tend to increase the velocity of 
the medicament particles. 
Devices such as those disclosed in U.S. Pat. No. 5,435,297, with a holding 
volume tend to be of significantly larger size than the standard metered 
dose inhalers and therefore less convenient and attractive to users. 
One solution proposed in GB-A-2279879 uses a reverse flow. In this inhaler 
the air inlets are provided at a location axially between the air outlet 
of the duct means connecting an outlet of the container with the mouth 
piece and the mouth piece, and a passage is provided connecting the inlets 
to a location adjacent the outlet of the duct means. Thus when a user 
inhales through the mouth piece, an air flow is created from the inlet 
means to the mouth piece, the air flow having a component directed away 
from the mouth piece towards the outlet of the duct means. 
SUMMARY OF THE INVENTION 
The present invention seeks to provide an inhaler which allows delivery of 
medicament to a user at reduced velocity without significantly increasing 
the size of the inhaler. 
The invention therefore provides an inhaler for medicament comprising a 
housing adapted to receive a pressurised dispensing container of 
medicament, a mouth piece for insertion into the mouth of a user of the 
inhaler, duct means connecting an outlet of the container with the mouth 
piece and air inlet means for allowing air into the inhaler when a user 
applies suction to the mouth piece in which the air inlet means are 
provided at a location axially between the air outlet of the duct means 
and the mouth piece, and passage means are provided connecting the inlet 
means to a location adjacent the outlet of the duct means, further 
comprising vortex generating means in the passage means so that, in use, 
when a user inhales through the mouth piece, a swirling air flow is 
created from the inlet means to the mouth piece.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 provides a cross-sectional view of one embodiment of an inhaler 10 
according to the present invention. 
Referring to FIG. 1, an actuator or inhaler 10 for a product such as a 
medicament, comprises a housing 11 for receiving a pressurised dispensing 
container 12 of medicament, a mouth piece 14 for insertion into the mouth 
of a user of the inhaler 10 and a cover 15 for the mouth piece 14. 
The container housing 11 is generally cylindrical and open at its upper 
end. A lower wall 17 of the housing 11 includes a socket 18 defining a 
seat for receiving the tubular valve stem 13 of the container 12. The 
socket 18 communicates, via a duct 16 ending in an orifice 19, with the 
mouth piece 14. 
The mouth piece 14, which may be generally circular or shaped to fit the 
mouth, is connected to the housing 11 through a generally frusto-conical 
wall portion 20. The wall portion 20 includes inner and outer walls 21, 
22, the inner wall 21 being an extension of the mouth piece 14. The outer 
wall 22 forms, with the inner wall 21, a restricted air flow passage from 
inlet air holes 23 provided in the outer wall 22 around the periphery of 
the mouth piece 14 to a restricted air inlet 25 adjacent a neck portion 24 
of the device 10. On the inner surface of outer wall 22 are formed means 
for generating a vortex (i.e., the inhaler includes a vortex generator). 
An example of a preferred vortex generator can be seen in FIG. 1 (and in 
greater detail) in FIGS. 4 and 5 comprises four raised vanes 30 located 
around the inner surface of the outer wall 22 at an angle of incidence to 
the air flow. When the mouth piece 14 is fitted in the housing 11, the 
inner wall 21 seals against the top surfaces of the vanes 30 and forms the 
above noted restricted airflow passage. 
The cover 15 of the device 10 which fits over the open mouth piece 14 is 
connected by a flexible hinge portion 27 to a cover attachment 28 which 
fits in the lower part of the housing 11 to attach the cover 15 to the 
housing 11. All of the components of the inhaler 10 may be plastics 
mouldings. 
It will be appreciated that the lower wall formation 17 of housing 11 forms 
a barrier between the open end of the housing 11 and the mouth piece 14 so 
that there is no air flow passage from around the container 12, or the 
left side of the housing 11 (as viewed in the drawing), to the mouth piece 
14. 
In use of the inhaler 10, a patient or user holds the inhaler 10, usually 
in one hand, and applies his mouth to the mouth piece 14. The user then 
inhales through the mouth piece 14 and this creates an air flow from inlet 
air holes 23 along the channels created between the vanes 30, and the 
inner and outer walls 21, 22, via the restricted air inlet 25 to the mouth 
piece 14. It will be appreciated that the inlet air holes 23 are arranged 
downstream of the orifices 19 relative to the mouth piece 14, that is to 
say the inlet air holes 23 are axially closer to the mouth piece 14 than 
the neck portion 24 and orifice 19. This ensures that when a user inhales 
through the mouth piece 14, the air flow is not directly from a position 
upstream of the orifice 19 to the mouth piece 14 but has at least a 
component of reverse flow towards the orifice 19. The effect of the 
reverse air flow and vortex generator 30 is to create a swirling air flow 
in the neck portion 24. After the user has started inhaling through the 
mouth piece 14, the container 12 is depressed downwardly on to its stem 13 
to release a dose of medicament from the container. The dose of medicament 
is projected by the pressure in the container 12 through the orifice 19 
and then mixes with the swirling air flow in the neck portion 24 and 
thence is inhaled by the user. 
The reverse flow component of air flow and the vortex created by the vortex 
generator ensure that the velocity of medicament particles is relatively 
low when they enter the oro-pharynx region of the patient. The spray 
pattern formed during use of a prior art inhaler is shown in FIG. 2. This 
spray is a high velocity, narrow cone, downwardly angled spray shown by 
the shaded envelope. The spray pattern formed during use of the inhaler of 
the present invention is illustrated in FIG. 3. The spray pattern is much 
wider and more upwardly angled as the product is dispersed with a greater 
volume of air. Thus the inhaler 10 is more effective and more comfortable 
to use. 
When not in use, the cover 15 is placed over the mouth piece 14 in the and 
when the inhaler is to be used, the cover is removed by hinging it away 
from the mouth piece 14. 
An alternative construction of vortex generator for use in the present 
invention is illustrated in FIGS. 8 and 9. In this arrangement the vanes 
31 are curved. 
Although only four vanes are shown in the foregoing embodiments, other 
numbers of vanes can be used which provide sufficient swirl to the air 
flow.