U.S. patent application number 10/105370 was filed with the patent office on 2002-08-08 for inhaler.
This patent application is currently assigned to AstraZeneca AB. Invention is credited to Christrup, Soren, Geert-Jensen, Anders, Jorgensen, Mikael, Rasmussen, Jorgen, Schmidt, Hugo Dines.
Application Number | 20020104532 10/105370 |
Document ID | / |
Family ID | 8102180 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020104532 |
Kind Code |
A1 |
Christrup, Soren ; et
al. |
August 8, 2002 |
Inhaler
Abstract
An inhaler such as a breath-actuated inhaler for delivering
medicament by inhalation, comprising a housing for receiving a
canister of medicament actuatable to deliver a dose of medicament,
a detector for detecting actuation of a received canister, a timer
responsive to the detector to measure the elapsed time from
actuation of the canister, and an indicator means responsive to the
timer to indicate when a predetermined time has elapsed during
which the user should maintain inhalation or delay exhalation. This
allows the inhaler to provide an indication of how the user should
breath to properly receive a dose of medicament. The indicator
means may be further responsive to the timer to indicate when a
second predetermined time has elapsed.
Inventors: |
Christrup, Soren; (Struer,
DK) ; Geert-Jensen, Anders; (Hojbjerg, DK) ;
Jorgensen, Mikael; (Arhus C, DK) ; Rasmussen,
Jorgen; (Struer, DK) ; Schmidt, Hugo Dines;
(Arhus C, DK) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
8th Floor
1100 North Glebe Road
Arlington
VA
22201-4714
US
|
Assignee: |
AstraZeneca AB
|
Family ID: |
8102180 |
Appl. No.: |
10/105370 |
Filed: |
March 26, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10105370 |
Mar 26, 2002 |
|
|
|
09873385 |
Jun 5, 2001 |
|
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|
09873385 |
Jun 5, 2001 |
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09424336 |
Nov 22, 1999 |
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Current U.S.
Class: |
128/200.23 ;
128/200.14; 128/203.12 |
Current CPC
Class: |
A61M 2205/582 20130101;
A61M 15/009 20130101; A61M 2205/6045 20130101; A61M 15/0068
20140204; A61M 2205/581 20130101; A61M 2205/43 20130101; A61M
15/0083 20140204; A61M 15/0091 20130101 |
Class at
Publication: |
128/200.23 ;
128/200.14; 128/203.12 |
International
Class: |
A61M 011/00; A61M
015/00; A61M 016/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 24, 1998 |
DK |
1988 01207 |
Sep 24, 1999 |
SE |
PCT/SE99/01684 |
Claims
1. An inhaler for delivering medicament by inhalation, comprising:
a housing for receiving a canister of medicament actuatable to
deliver a dose of medicament; a detector for detecting actuation of
a received canister; a timer responsive to the detector to measure
the elapsed time from actuation of the canister; and an indicator
means responsive to the timer to indicate when a predetermined time
has elapsed during which the user should maintain inhalation or
delay exhalation.
2. An inhaler according to claim 1, wherein the period of time is
from 0.2 to 15 seconds.
3. A inhaler according to claim 1 or 2, wherein the indicator means
is a display for displaying a visual indication the predetermined
time has elapsed.
4. An inhaler according to claim 3, wherein the display is arranged
in normal use to display a representation of the number of doses
remaining in the canister and to alter that representation when
said predetermined time has elapsed.
5. An inhaler according to any one of claims 1 to 3, wherein the
indicator means is arranged to generate an audible indication of
the predetermined time has elapsed.
6. An inhaler according to any one of claims 1 to 3, wherein the
indicator means physically moves the inhaler.
7. An inhaler according to any one of the preceding claims, wherein
the indicator means is further responsive to the timer to indicate
when a second predetermined time has elapsed.
8. An inhaler according to claim 7, wherein the first mentioned
predetermined time is a time during which the user should maintain
inhalation and the second predetermined time as a time during which
the user should delay exhalation.
9. An inhaler according to any one of the preceding claims, wherein
the inhaler further comprising an actuation mechanism operatable to
actuate the canister and the detector is arranged to detect
operation of the actuation mechanism.
10. An inhaler according to claim 9, wherein the actuator mechanism
is breath actuated.
Description
[0001] Known inhalers receive a canister of medicament which is
actuatable to deliver a dose of medicament. For various
medicaments, the user is required to synchronise inhalation and
exhalation with the actuation of the canister. Normally it is
recommended that the user inhales for a given period of time after
delivery of a dose. However, in practice this can be difficult for
the user who will often breath incorrectly resulting in inhalation
of an incorrect dose or in a dose not properly reaching the user's
lungs or throat. This can be particularly a problem for the user in
an emergency when it may be more vital than usual to deliver a dose
properly.
[0002] It is known to provide a breath-actuated inhaler which
includes an actuation mechanism operatable to actuate the canister
upon inhalation by the user. This ensures that the dose of
medicament delivered on actuation of the canister is supplied
whilst the user is inhaling. However, there remains the problem of
the user needing to synchronise the rest of his inhalation with the
delivery of a dose, in particular as to how long the user should
maintain inhalation or delay exhalation. This is particularly
difficult in the case of a breath-actuated inhaler because the user
does not always recognise what point during inhalation the
breath-actuated mechanism actuates the cannister to deliver a dose
of medicament.
[0003] The present invention is intended to assist the user in
synchronising breathing with delivery of a dose.
[0004] According to the present invention there is provided an
inhaler for delivering medicament by inhalation, comprising:
[0005] a housing for receiving a canister of medicament actuatable
to deliver a dose of medicament;
[0006] a detector for detecting actuation of a received
canister;
[0007] a timer responsive to the detector to measure the elapsed
time from actuation of the canister, and
[0008] an indicator means responsive to the timer to indicate when
a predetermined time has elapsed during which the user should
maintain inhalation or delay exhalation.
[0009] As a result, the user is provided with an indication of the
time for which he should maintain inhalation or delay exhalation
which allows the user to fully synchronise his breathing with the
delivery of a dose. This assists in assuring that the dose is
properly inhaled by the user. The present invention is advantageous
because it overcomes the difficulties for the user in determining
when the actual actuation of the of the canister occurred,
especially in a breath-actuated inhaler. As the inhaler detects
inhalation and indicates when the predetermined time has elapsed
relieves the user from this task and enables the user to breath
correctly to ensure proper delivery of a dose.
[0010] Typically the period of time is from 0.2 to 15 seconds.
[0011] The indicator means may comprise means for indicating the
period of time by visual indication, audible indication or by
physically interacting with the user.
[0012] To provide a visual indication, the indicator means may be a
display. The display may be arranged to alter the information
displayed, such as a representation of the number of doses, after
the predetermined time has elapsed.
[0013] Another manner of providing a visual indication is for the
indicator means to comprise means for automatically re-setting the
actuation mechanism, for example by moving buttons or other means
for mechanically introducing energy into the inhaler.
[0014] The indicator means may be arranged to physically move the
inhaler for example by vibrating the inhaler.
[0015] The indicator means may be arranged to generate an audible
indication. A sound may be generated after the elapsed time or the
generation of a sound of the entire predetermined elapsed time
followed by change of or cessation in the sound.
[0016] Naturally, the different manners of indication may be
combined.
[0017] Advantageously the indicator means is further responsive to
the timer to indicate when a second predetermined time has elapsed.
Thus, the first predetermined time may be a time during which the
user should maintain inhalation and the second predetermined time
may be a time during which the user should delay exhalation. This
allows the inhaler to provide further information for assisting the
user in correctly breathing when using the inhaler.
[0018] To allow a better understanding, an inhaler which embodies
the present invention will now be described by way of
non-limitative example with reference to the accompanying drawings,
in which:
[0019] FIG. 1 is a front view of the inhaler held in a hand;
[0020] FIG. 2 is a side view of the inhaler,
[0021] FIG. 2A is a side view of the inhaler without a closure
element fitted;
[0022] FIG. 3 is a side view of the inhaler with a lower housing
portion being removed;
[0023] FIG. 4 is a side view of an upper housing portion of the
inhaler with a canister being removed;
[0024] FIG. 5 is a side view of an alternative form of collar for
connecting the closure element to the canister,
[0025] FIG. 6 is a cross-sectional view taken along line VI-VI in
FIG. 5;
[0026] FIG. 7 is a side view of the canister mounting arrangement
and actuation mechanism;
[0027] FIG. 8 is a view from the rear and side of the actuation
mechanism;
[0028] FIG. 9 is a view from the rear and the opposite side from
FIG. 8 of the actuation mechanism;
[0029] FIG. 10 is a front view of the arrangement for loading the
actuation mechanism;
[0030] FIG. 11 is a side view of an alternative form of button
arrangement for loading the actuation mechanism;
[0031] FIG. 12 is a view of certain parts of the actuation
mechanism from the front and side;
[0032] FIGS. 13 to 16 are schematic views of the actuation
mechanism illustrating respective states over a complete cycle of
operation; and
[0033] FIG. 17 is a view of the electronic timer circuit.
[0034] An inhaler 1 which embodies the present invention is
illustrated in FIGS. I and 2, respectively showing the front view
of the inhaler 1 held in a user's hand and a side view of the
inhaler.
[0035] The inhaler has a housing 2 comprising an upper housing
portion 3 and a lower housing portion 4 which are coupled together.
The upper and lower housing portions 3 and 4 have outer walls which
are hollow to define a space accommodating a canister 5 of
medicament and an actuation mechanism 6 operatable to actuate the
canister 5 to deliver a dose of medicament
[0036] The upper housing portion 3 has opposed side walls 7 joined
by a flat front wall 8, a curved rear wall 9 and a top wall 10. The
lower housing portion 3 has opposed side walls 11 fitting flush
with the side walls 7 of the upper housing portion 3 and a curved
rear wall 12 fitting flush with the rear wall 9 of the upper
housing portion 3. The rear walls 12 and 9 together form a curved
surface comfortably received in the palm of the users hand as
illustrated in FIG. 1. A mouthpiece 13 protrudes from the lower
housing portion 4 and may be protected by a cap 14 hinged to the
lower housing member 4 to be openable as illustrated in FIG. 2.
[0037] The front of the lower housing member 4 between the side
walls 11 is open to define a vent in the outer surface of the
housing 2 adjacent the mouthpiece 13 between the upper and lower
housing portions 3 and 4. The vent 15 is closed by a closure
element 16 fitting flush with the front wall 8 of the upper housing
portion 3 to form part of the outer wall of the housing 2.
[0038] The upper and lower housing members are coupled by a
coupling 17 allowing the lower housing member 4 to be slid off as
illustrated in FIG. 3.
[0039] The canister 5 fits in the upper housing portion 3 and may
be slidably removed for replacement as illustrated in FIG. 4.
[0040] The canister 5 comprises a generally cylindrical body 18 and
a valve stem 19 which are compressible together to deliver a dose
of medicament from the valve stem 19. The canister is of a known
type including a metering chamber which captures a defined volume
of medicament from the body 18 of the canister 5, which volume of
medicament is delivered as a metered dose from the valve stem 19 on
compression of the valve stem 19 relative to the body 18 The valve
stem 19 is weakly biassed outwardly to reset the canister 5 after
compression for refilling the metering chamber. The valve stem 19
is received in a nozzle block 20 which is arranged to direct a dose
of medicament delivered from the valve stem 19 out of the inhaler 1
through the mouthpiece 13.
[0041] The closure element 16 is connected to the canister 5 by a
collar 21 fitted around a necked portion 22 of the canister body
18. The collar 21 is permanency fixed to the closure element 16 and
may be integral therewith. The collar 21 is restrained by the
necked portion 22 of the canister 5 such that the closure element
16 is removed and replaced together with the canister 5 as
illustrated in FIG. 4. The canister 5 and collar 21 have a small
degree of relative movement along the axis of the canister 5. This
allows actuation of the canister by compression of the canister
body 18 towards the valve stem 19 when the stem 19 is fixed
relative to the inhaler I in the nozzle block 20 and the collar 21
is also fixed by the closure element 16 fitting as part of the
housing 2 of the inhaler 1.
[0042] FIGS. 5 and 6 respectively illustrate a side view and
cross-sectional view and alternative collar 23 for connecting the
closure element 16 to the canister 5. The collar 23 includes a
cylindrical portion 24 held on the necked portion 22 of the
canister body 18 by a protrusion 25 formed in the cylindrical
portion 24 by a U-shaped cut-out 26. The cylindrical portion 24 has
an extension 27 extending beyond the end of the canister body 18 to
protect the valve stem 19. The extension 27 is of reduced diameter
relative to the remainder of the cylindrical portion 24 of the
collar
[0043] The collars 21 and 23 are both formed with a weak portion
constituted by two rupture lines 28 disposed on opposite sides of
the collar 21 or 23 and arranged to be broken preferentially to the
remainder of the collar 21 or 23 on application of a force to
separate the closure element 16 from the canister 5. After the
rupture lines 28 have been broken or at least deformed to enable
removal of the canister 5, it is impossible to connect the collar
21 or 23 to a different canister.
[0044] The outer surface of the closure element 16 carries an
indication of the type of medicament in the canister 5 to which the
closure element 16 is connected. The indication may be printed
information, an embossed or indented pattern or the colour of the
closure element 16.
[0045] An inlet opening 29 is formed in the upper housing portion
3, in particular in its top wall 10 and front wall 8. The outer
walls of the housing defined by the upper and lower portions 3 and
4 and the closure element 16 seal together to define a closed space
which constitutes an air flow path extending from the mouthpiece 13
through the housing 2 to the inlet opening 29. Inhalation at the
mouthpiece 13 draws air in through the inlet opening 29 through
that air flow path around the canister 5 and actuation mechanism 6
encased in the housing 2. The actuation mechanism 6 (described in
detail below) has a trigger disposed in the upper housing portion 4
which, in response to a flow through the air flow path, triggers
the actuation mechanism 6 to actuate the canister 5.
[0046] If a canister without a closure element connected thereto is
inserted into the housing 2, then the vent 15 will remain open as
illustrated in FIG. 2A. Consequently, when a user inhales at the
mouthpiece 13, the flow resistance through the vent 15 will be much
lower than the flow resistance through the remainder of the air
flow path above the vent 15 from the inlet opening 29. Accordingly,
the vent 15 will vent most of the flow through the mouthpiece,
thereby reducing the flow in the remainder of the air flow path in
the upper housing portion through. The positioning of the vent in
the air flow path inside the housing 2 between the mouthpiece 13
and the trigger reduces the air flow across the trigger. The vent
15 is positioned and dimensioned such that the flow at the trigger
is reduced below the threshold needed to operate the trigger and
therefore prevents operation of the actuation mechanism 6. To
assist in assuring that the vent 15 sufficiently vents the flow,
the vent 15 is provided with a larger opening area and hence a
lower flow resistance than the inlet opening 29. The vent 15 is
dimensioned so that the actuation mechanism is not operated on a
flow through the mouthpiece 13 at a level above the maximum
expected inhalation, for example at an inhalation of at least eight
times a standard inhalation flow rate. The triggering mechanism for
the actuation mechanism 6 is designed taking into account the flow
generated by a standard inhalation selected by the designer.
[0047] The actuation mechanism 6 for actuating the canister 5 to
deliver a dose of medicament is illustrated in FIGS. 7 to 9. The
elements illustrated in FIGS. 7 to 9 are accommodated in the
housing 2 but are illustrated separately for clarity. The canister
5 is held with its valve stem 19 in a nozzle block 20' connected to
the mouthpiece 13, both fixed relative to the lower housing portion
4. A nozzle block 20' has a slightly different structural form from
the nozzle block 20 illustrated in FIGS. 3 and 4 but performs the
same function. The body 18 of the canister 5 is supported by a
guide block 30 fixed to the upper housing portion 3 and having a
curved inner surface engaging the cylindrical surface of the
canister body 18 to allow axial movement of the canister body 18
within the housing 2. The actuation mechanism 6 operates to
compress the canister body 18 relative to the valve stem 19 held in
the nozzle block 20 to deliver a dose of medicament.
[0048] The structure of the actuation mechanism 6 is as
follows.
[0049] The actuation mechanism 6 includes a pre-loading mechanism
for loading a resilient loading element in the form of a coiled
loading spring 3 1. The pre-loading mechanism includes the loading
member constituted by a shaft 32 encircled by the coils of the
loading spring 31. The shaft extends and is movable in a direction
parallel to the cylindrical axis 80 of the canister body 18. The
loading member shaft 32 has an enlarged head 33.
[0050] As illustrated in FIG. 1, two buttons 34a and 34b,
constituting contact members to be manually depressed, are mounted
opposite one another in the side walls 7 of the upper housing
portion 3 on either side of the axis 80 of the canister 5 held in
the housing 2. The buttons 34 are manually depressible in a
direction substantially perpendicular to the axis 80 of the
cannister 5 which makes them easy to grip and move by a finger and
thumb, as can be seen in FIG. 1. The buttons 34 load the loading
member 32 and loading spring 31 through the arrangement illustrated
in FIG. 10 comprising two torsion springs 35a and 35b fixed inside
the upper housing portion. The torsion springs 35a and 35b engage
the enlarged head 33 of the loading member 32 and respective ones
of the buttons 34 to convert sideways force applied to the buttons
34 to a downwards force along the axis of the loading member shaft
32.
[0051] An alternative means for converting the sideways force
applied to the buttons 34 is illustrated in FIG. 11. This consists
of a double knee joint 36 fixed at its upper end 37 to the upper
housing portion 3, fixed at its lower end 38 to the enlarged head
33 of the loading member 32 and fixed at its intermediate joints
39a and 39b to the respective buttons 34a and 34b.
[0052] The pre-loading mechanism further includes a lever 40
pivoted relative to the housing about a pivot 41. The lever 40 has
a planar canister engagement portion 42 contacting the canister
body 18 adjacent the pivot 41 with a pair of arms 43 and 44
extending therefrom. One arm 43 is engaged by the loading spring 31
so that the loading spring 31, when loaded, biasses compression of
the canister through the lever 40 coupled to the canister 5 by the
canister engagement portion 42. As the loading spring 31 is further
away from the pivot 41 than the cannister engagement portion 42,
this provides leverage between the loaded actuation force and the
force applied to the cannister 5. The arm 43 has a hole through
which the loading member shaft 32 extends. The other arm 44 of the
lever 43 has a similar hole through which extends a further shaft
78 for preventing lateral displacement of the lever 40.
[0053] The actuation mechanism further includes a triggering
mechanism for holding the lever 40 against compression of the
canister under the biassing of the spring 31 and to release the
lever 40 in response to inhalation at the mouthpiece. The
triggering mechanism is constructed as follows.
[0054] The triggering mechanism comprises a first knee joint 45
having two links 46 and 47 connected pivotally to one another by a
central pivot 50. The upper link 46 is pivotally connected both
arms 43 and 44 of the lever 40 by a pivot 48. The lower link 47 is
pivotally connected to the upper housing portion 3 by a pivot
49.
[0055] Accordingly, the first knee joint 45 has a locked position
illustrated in FIGS. 7 to 9 in which it holds the lever 40 against
compression of the canister 5. In the locked position of the first
knee joint 45, the central pivot 50 is substantially aligned with
the pivots 48 and 49 at the ends of the links 46 and 47. As the
first knee joint 45 is connected to the lever at a position further
away from the pivot 41 then the cannister engagement portion 42,
this provides leverage between the locking force provided by the
first knee joint and the force applied to the cannister 5. This
leverage enhances the locking and triggering action of the
triggering mechanism.
[0056] The triggering mechanism further includes a second knee
joint 51 comprising two links 52 and 53 connected by a central
pivot 54. One link 57 of the second knee joint 51 is pivotally
connected to the upper housing portion 3 by a pivot 55 and extends
laterally so that it constitutes a trigger vane which is moved by a
flow of air thereover. The trigger vane 52 has a counterweight
portion 79 (illustrated only in FIG. 7) fixed to the opposite side
of pivot 55 from the laterally extending surface. The counterweight
balances the trigger vane so that its centre of mass is positioned
on the axis of the pivot 55.
[0057] The other link 53 of the second knee joint 5 extends from
the trigger vane 52 between the arms 43, 44 of the lever 40 to the
upper link 46 of the first knee joint 45 where it is pivotally
connected by a pivot 56.
[0058] Accordingly, the second knee joint 51 has a locked position
illustrated in FIGS. 7 to 9. In the locked position of the second
knee joint, the central pivot 54 is substantially aligned with the
pivots 55 and 56 and the ends of the links 52 and 53.
[0059] The actuation mechanism 6 further includes a reset mechanism
which is constructed as follows.
[0060] The reset mechanism employs a locking element constituted by
a third knee joint 57 comprising an upper Link 58 and a lower link
59 pivotally connected together by a central pivot 60. The upper
link 58 is pivotally connected to the upper housing portion 3 by
the pivot 49 in common with the first knee joint 45. The lower link
59 is pivotally connected to the loading member shaft 32 by a pivot
61. The third knee joint 57 has a locked position illustrated in
FIGS. 7 to 9 in which it holds the loading member shaft 32 in its
loaded position as illustrated in FIG. 7. In the locked position of
the third knee joint 57, the central pivot 60 is aligned with the
pivots 48 and 61 at the end of the links 58 and 59. The third knee
joint 57 is also biassed into its locked position by a biassing
spring 67 connected to the upper housing portion 3. Hence the third
knee joint constitutes a locking element which holds the canister
in a compressed state through spring 31 and lever 40 after the full
movement of the lever 40 to compress the canister 5.
[0061] The reset mechanism further includes a release member 62
mounted on the loading member shaft 32 by having an aperture
through which the shaft 32 extends. The release member 62 is
movable relative to the shaft 32 between limits defined by a pin 63
protruding from the shaft 32 engaging in a track 64 formed in the
release member 62. A timer spring 65, the coils of which encircle
the shaft 32, is connected between the arm 43 of the lever 40 and
the release member 62. The timer spring 65 is in a relaxed state in
FIG. 7 and is provided for biassing the release member 62 when
loaded by movement of the lever 40 to compress the canister 5.
[0062] A protrusion 66 extends from the release member 62 (as best
seen in the partial view of FIG. 12) to engage with the lower link
59 of the third knee joint 57 when the release member 62 is moved
down the shaft 32. Such engagement of the protrusion 56 with the
third knee joint 57 moves the knee joint 57 against the biassing
spring 67 to break the third knee joint 57 thereby releasing
locking effect of the third knee joint 57.
[0063] The shaft 32 is biassed upwardly by a reset spring 68 acting
between the shaft 32 and upper housing portion 3 to move the shaft
32 upwardly upon breaking of the third knee joint 57.
[0064] The downwards movement of the release member 62 is damped by
a damping element 69 consisting of a stator 70 fixed to the upper
housing portion 3 and a rotor 71 rotatable through viscous fluid
provided between the rotor 71 and stator 70. The rotor 71 is driven
by a toothed rack 72 connected to the release member 62.
[0065] Operation of the actuation mechanism 6 will now be described
with reference to FIGS. 13 to 16 which illustrate the various parts
of the actuation mechanism 6 in schematic form for ease of
understanding.
[0066] FIG. 13 illustrates the neutral state in which the loading
member shaft 32 is in its uppermost position, so that the loading
spring 31 is relaxed. In this state, the first and second knee
joints 45 and 51 are both in their locked positions. The timer
spring 65 and the reset spring 68 are relaxed.
[0067] Upon depression of the buttons 34, the loading member shaft
32 is moved downwardly to a second position illustrated in FIG. 14
loading the loading spring 31 which therefore biasses the lever 40
towards compression of the canister 5. However, the first knee
joint 45 is its locked position where it holds the lever 40 against
compression of the canister 5. The first knee joint 45 is held in
its own locked position by the second knee joint 51 being in its
locked position.
[0068] Movement of the loading member shaft 32 downwards also loads
the reset spring 68 and brings the third knee joint 57 into its
locked position where it is held by the spring 67. In this loaded
state illustrated in FIG. 14, the inhaler I is loaded ready for
delivery of a dose of medicament.
[0069] Inhalation by the user at the mouthpiece 13 generates an air
flow through the air flow path defined inside the housing 2 from
the inward opening 29 to the mouthpiece 13. This air flow acts on
the trigger vane 55 of the second knee joint 51 causing it to move
upwardly due to pressure drop created by the flow inside the
housing 2 to the position illustrated in FIG. 15 where the second
knee joint is broken. This breaks the first knee joint 45 into its
broken position illustrated in FIG. 15 which releases the lever 40
and allows it to compress the canister 5 under the biassing of the
loading spring 31.
[0070] During compression of the canisters, the shaft 32 remains
locked in position by the third knee joint 57. This causes the
canister to be held in its compressed state by the shaft 32 acting
through the spring 31 and lever 40, the spring force of the spring
31 far exceeding the internal reset biassing of the canister 5.
[0071] However, movement of the lever 40 loads the timer spring 65
which accordingly biasses the release member 62 downwards. Movement
of the release member 62 is delayed by the damping action of the
damping element 69. The protrusion 66 of the release element 62
engages the third knee joint 57 after a predetermined period of
time after actuation of the canister 5. This time is determined by
the strength of the timer spring 65 and the damping properties of
the damping element 69 and is at least 100 ms or 200 ms and up to
1000 ms or 5000 ms to allow the full dose of medicament to be
delivered from the cannister 5. Such engagement breaks the third
knee joint 57 into its broken position as illustrated in FIG. 16.
Subsequently the reset spring 68 moves the loading member shaft 32
upwardly to the neutral position illustrated in FIG. 13. At the
same time the shaft 32 lifts the release member 62, itself still
damped by the damping element 69 so that the reset movement is
damped.
[0072] Release of the shaft 32 causes the spring 31 to raise the
lever 40 which has two effects. Firstly it allows the canister to
reset itself. Secondly, it causes the first and second knee joints
45 and 51 to straighten, returning them to their locked position in
the neutral position of the actuator mechanism illustrated in FIG.
13. The loading spring 31 and the timer spring 65 are pre-loaded
and do not work against the reset movement, so that the reset
spring 68 has only to overcome friction and the weight of the
component.
[0073] The buttons 34a and 34b protrude from the inhaler when the
actuation is in its relaxed state as shown in FIG. 1 and are
depressed to a position flush with the side walls 8 of the upper
housing portion 3. Accordingly, the distance between the
extremities of the buttons before depression is less than the
maximum length of the inhaler 1 in the direction parallel to the
axis 80 of the canister 5 and less than the overall length of the
canister 5 including the body 18 and the valve stem 19. Also, the
total distance over which the two buttons 34 are moved relative to
one another is greater than the distance by which the body 18 and
the valve stem 19 of the canister 5 are relatively compressed. This
is achieved by the leverage obtained by the loading spring 31
engaging lever 40 at a point further away from the pivot 41 than
the canister engagement portion 42.
[0074] The actual flow recommended in order to correctly deliver a
drug will depend on the manner operation of the drug, the position
where it should be deposited in the mouth, lungs of the user and
the manner of dispensing the drug. Some drugs are inhaled as a fine
mist and transported all the way to the lungs whereas others are
inhaled like a jet of liquid deposited in the mouth of the person.
These different types of drugs require different types of
inhalation and therefore different inhalation flows and different
actions by the user.
[0075] It is possible to adapt each of a number of different
inhalers for use with a number of different types of drug by giving
each inhaler a vent with a different shape and giving different
closure elements shapes which conform with a single type of
inhaler. For example, a possible different shape is illustrated by
the dotted line in FIG. 1. Thus canister with differently shaped
closure elements are for use exclusively with the inhaler having a
conforming vent. The different shapes may prevent a closure element
from being fitted in an inhaler of the inhaler having a conforming
vent. Alternatively, the closure element may fail to close the vent
of an inhaler having a differently shaped vent such that the
remaining opening vents the flow sufficiently to prevent operation
of the triggering mechanism.
[0076] FIG. 17 illustrates an electronic system for indicating to
the user how long inhalation should be maintained or exhalation
should be delayed.
[0077] A switch 73 is fixed to the inside of a side wall 7 of the
upper housing portion 3 to be physically switched by movement of
the lever 40 compressing the canister 5. The signal from the switch
73 is passed to a microprocessor 74 to indicate when the canister
is actuated. At that point, the microprocessor 74 starts a timing
count to measure the elapsed time from actuation of the
canister.
[0078] When a predetermined elapsed time has elapsed, the
microprocessor 74 sends an operation signal to operate three
different indicator means, namely a display 75, a buzzer 76 and a
vibrator 77.
[0079] The display 75 is arranged in the front wall 8 of the upper
housing portion 3 as illustrated in FIG. 1. On receiving the
operation signal from the microprocessor 74, the display is changed
to provide a visual indication that the predetermined time has
elapsed. The microprocessor 74 may also send control signals to the
display 75 in response to actuation of the canister 5 detected by a
switch 73 to cause the display 75 to display the number of doses
remaining in the canister. In this case, the visual indication that
the predetermined time has elapsed may be to alter the disclosed
number of doses, for example, by blanking or flashing the displayed
count.
[0080] The operation signal sent from the microprocessor 74 to the
buzzer 76 causes it to generate a buzzing sound as an audible
indication that the predetermined time has elapsed. Similarly, the
signals sent from the processor 74 to the vibrator 77 causes the
vibrator to shake the inhaler 1, for example by moving a mass
within the vibrator 77.
[0081] Similarly, the microprocessor may be programmed to send an
operation signal to operate the indicator means 75, 76 and 77 when
a second predetermined time has elapsed from actuation of the
canister.
[0082] The first and second elapsed times are selected to be timed
during which the user should maintain inhalation or delay
exhalation for proper delivery of a medicament in the canister 5,
typically between 0.2s and 15s. In this way, the user is provided
with an indication of how to breathe correctly which assists in
ensuring a proper delivery of a dose.
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