WO2007031740A1

WO2007031740A1 - Inhaler with an electronic dose counter

Info

Publication number: WO2007031740A1
Application number: PCT/GB2006/003383
Authority: WO
Inventors: Naseem Bari
Original assignee: Trumeter Company Ltd
Priority date: 2005-09-12
Filing date: 2006-09-12
Publication date: 2007-03-22
Also published as: EP1937339A1; GB0518586D0; GB2429922A

Abstract

The present invention aims to provide an inhaler device including an inhaler canister (110) having a canister body (112) for containing a substance, the canister being actuatable to deliver a dose of the substance; a casing (120) housing at least a portion of the canister; a counter (164) for storing a count derived from the number of actuations of the canister detected by first switch means, the first switch means including first and second elements (110, 128) located on the canister and casing respectively, and the first switch means being triggerable in response to relative movement of the first and second elements, without there being physical contact between the first and second elements. As such, the present invention aims to provide an inhaler with a 'non-contact' dose counter capable of detecting actuation of a canister and storing information derived from the number of actuations of the inhaler canister.

Description

INHALER WITH AN ELECTRONIC DOSE COUNTER

The present invention relates to, but is not limited to, an inhaler having a counting device for counting the number of deliveries of a medicament or drug from the inhaler.

Respiratory disorders are often treated by the application of a medicament or drug using an inhaler to provide the drug in aerosol form. Indeed, other disorders are also sometimes treated by using a drug delivered via a PMDI. A typical inhaler, of the sort used by e.g. asthma sufferers, comprises a casing for at least partially housing a canister. The canister may be made integral with the casing, but more often the canister is removable from the casing so that either (or both) the canister and casing can be cleaned, and/or so that a "refill" canister can be substituted for a spent canister, i.e. a canister containing insufficient drug to deliver an effective dose.

In most applications the drug is contained in the inhaler canister in powder or liquid form together with a propellant under suitable pressure. The canister usually includes an elongate canister body, generally cylindrical in shape, with a movable nozzle located at one end of the body. This type of inhaler is usually used by inserting the canister to the casing until the nozzle engages with a complementary seating member, or portion, i.e. a cradle, formed in the casing.

In most PMDIs, the dispensing or delivery action consists of moving the canister body relative to the nozzle sat in the cradle of the casing. At a predetermined extent of motion of the canister body, relative to the nozzle, a dose (usually a metered dose) of the medicament and propellant is released through the nozzle, together with an amount of the propellant.

In PMDIs, each canister contains enough drug for a predetermined number of doses, i.e. a metered dose of drug can be released only a set number of times before there is insufficient drug remaining in the canister for an effective dose to be delivered, and the canister is spent. However, there may remain a substantial volume of propellant to be delivered, giving the user an erroneous impression that he/she is receiving an effective dose of medicine .

This presents a serious, and potentially fatal, problem to the user of the inhaler canister, because the user cannot be sure whether there is sufficient drug remaining in the canister to effectively treat the relevant disorder, e.g. asthma, or not. Therefore, a counting device, or dose delivery register, or record, is needed to ensure that a user is given a dose delivery count, i.e. a countdown of the number of "safe" deliveries remaining in the canister (i.e. how many metered doses remain) ; or, at the least an indication ensuring that a user is made aware of the likelihood of the canister being spent, or being close to being spent.

There are a number of examples in the prior art that attempt to provide solutions to the above problems, but which themselves suffer from a range of drawbacks. In particular, many examples in the prior art include a counting device mounted on the casing of the inhaler, including e.g. a lever based switch providing means for recognising when a dose is delivered by the mechanical movement of the switch caused by the movement of the canister body, the count being stored and/or displayed accordingly.

However, such devices rarely account for removal of the canister from the casing, for e.g. cleaning of the casing. It is a problem that removal of the canister causes the stored count to change, frequently to zero. Therefore, the count reading can be erroneous for a partially used canister replaced into the housing.

Other examples in the prior art include a counter mounted on the end of the canister distal to that of the nozzle, which includes a switch simply reactive to a force applied to the canister, via the switch, by a user attempting to dispense or deliver a dose of the drug. However, the switch must be designed so that the force needed to activate it be matched as closely as possible to the force needed to move the canister body sufficiently to deliver a dose of the drug, else the counter may erroneously (or may fail to) register a dose delivery.

Matching these forces is difficult. Indeed, the particular force required to deliver a dose of drug from the canister may vary considerably over the lifetime of the canister, and even from canister to canister, thus rendering the counting device inaccurate. Moreover, many of the proposed counting devices in the prior art employ mechanical means to register that the canister body has moved the predetermined distance relative to the casing (and nozzle) required to deliver a dose of drug. However, the mechanical means suggested in the prior art seem prone to failure or missed counts due to dirt, or drug residue clogging up the mechanism. Consequently, the mechanical solutions need regular servicing, i.e. cleaning, to ensure continued reliability.

Therefore, in a first aspect, the present invention aims to provide an inhaler device including an inhaler canister having a canister body for containing a substance, such as a dry powder or liquid e.g. a medicament or drug, the canister being actuatable to deliver a dose of the substance; a casing housing at least a portion of the canister; a counter for storing a count derived from the number of actuations of the canister detected by first switch means, the first switch means including first and second elements located on the canister and casing respectively, and the first switch means being triggerable in response to relative movement of the first and second elements, without there being physical contact between the first and second elements. Preferably, the first switch means is triggerable in response to a predetermined extent of movement of the said elements. In particular, the extent of motion corresponds to actuation of the canister. Indeed, it is preferable that the first switch means is triggerable in response to the said elements moving between a first and a second relative position. As such, the present invention aims to provide an inhaler with a "non-contact" dose counter capable of detecting actuation of a canister and storing information derived from the number of actuations of the inhaler canister. Accordingly, the present invention overcomes any mechanical inconsistencies in the mechanical interaction between canister and/or casing and any mechanical gearing used for counting, such as that which can be found in the prior art .

Furthermore, there is no need for regular servicing, or cleaning, of the first switch means, the casing or the canister to facilitate normal working of the counting device, as there are no mechanical moving parts detecting actuation of the canister that can be clogged up by dirt or residue from deliveries of the content of the canister.

It is preferable that the first switch means includes transmitting means and receiving means capable of detecting a signal transmitted by the transmitted means. Preferably, the transmitting means is capable of emitting electromagnetic radiation (light) , and accordingly the receiving means is selected to be capable of detecting light at the or an emission wavelength of the transmitting means.

In a preferred aspect of the present invention, the first element includes a transmitting means for transmitting a first signal, the first signal being detectable by receiving means preferably when the first and second elements are in a predetermined position, more preferably when the first and second elements are in at least one of the first and second relative positions, most preferably the first relative position. Preferably, receiving means is included in the first element, but receiving means could be alternatively or additionally be included in the second element.

It is preferred that the signal path of the first signal is a direct path from the first element transmitter to the first element receiver when the first and second elements are in a predetermined relative position, more preferably when the first and second elements are in at least one of the first and second relative positions, most preferably the first relative position. That is, the first signal path is a straight line from the first element transmitting means to the first element receiving means. The second element may include means for interfering with the first signal along the signal path. The interfering means may be a blocking member capable of partially blocking the signal path, but preferably the interfering means is a blocking member capable of entirely blocking the signal path of the first signal, thereby preventing the first element receiving means from detecting the first signal transmitted by the first element transmitting means when the first and second elements are in a predetermined relative position. Preferably, the blocking member at least partially blocks the signal path when the elements are in the second relative position. Preferably, the blocking member does not block any portion of the first signal path when the elements are in the first relative position.

The blocking member may be arranged so that the blocking, or unblocking, (or partial blocking or unblocking) of the first signal path indicates that the first and second elements have moved relative to one another to an extent sufficient for the canister to be actuated.

In response to the first element receiving means detecting a first signal of strength below a predetermined minimum or threshold, or detecting no first signal, the first element receiving means may indicate to the counter that the canister has been actuated and the stored count is adjusted accordingly. Preferably, in this and other aspects of the present invention, the counter is included in an electric circuit, and is connected to receiving means.

The elements may be predeterminedly arranged so that when the elements are in the first relative position the canister is in a rest position (that is the canister is ready to be actuated) , whereas when the elements are in the second relative position, the canister is in the actuated position. In other words, by way of example and referring to the canister and inhaler casing described above, when the canister body is moved relative to the nozzle, engaged with the seating member formed in the canister, to such an extent that a dose is delivered from the canister, the canister body is said to be in the "actuated" position; but, when the canister body is permitted to return to its starting position, the canister body is said to be in the "rest" position.

Therefore, according to this preferred first aspect, the first signal is blocked when the said elements are in the second relative position (i.e. when the canister is in the actuated position the first element receiving means detects no first signal) ; the stored count is adjusted accordingly to reflect an actuation of the canister. On the other hand, the signal path of the first signal is not blocked when the canister is in the rest position, and the said elements are in the first relative position.

For clarity, and to avoid unnecessary repetition, we refer herein to the elements being in the first relative position when the canister is in the "rest" position and the elements being in the second relative position when the canister is in the "actuated" position.

However, it should be clear to a skilled person that the elements could alternatively be arranged so that the first relative position is the relative position of the elements when the canister is in the "actuated" position, and the second relative position is the relative positions of the elements when the canister in the "rest" position, i.e. the first element receiving means could be incapable of detecting a signal above a predetermined threshold when the canister is in the second position (rest position) , but when the canister is in the actuated position (first position) , the first element receiving means may be capable of detecting a signal.

Reference is also made herein to receiving means detecting no signal. However, it is to be understood that the detection of no signal means the receiving means detects no signal strength above a minimum predetermined threshold; a signal strength below the minimum predetermined threshold (including no detectable signal strength at all) is indicative of the elements being in the second relative position, e.g. the canister is in the actuated position. Accordingly, referral to the detection of a signal is to be understood as meaning the detection of a signal above a predetermined threshold.

In another aspect of the present invention, the first element may include both transmitting means and receiving means, the first signal being indirectly detectable by the first element receiving means, e.g. by reflection from, for example, a surface of the casing. Preferably, the first element receiving means detects the reflected first signal at a predetermined relative position of the said elements, preferably when the said elements are in the first relative position, that is, preferably when the canister is in the rest position.

Accordingly, the second element may include a reflecting face for reflecting the first signal to the first element receiving means; preferably, the face includes a region of high reflectivity, and the face is positioned to guide the first signal to the first element receiving means. The reflecting face may be positioned so that the first signal is guided to the first element receiving means when the elements are in the second relative position.

Alternatively, and more preferably, the casing may be modified so that the first signal is indirectly receivable by the first element receiving means, by e.g. reflection of the first signal from a surface of e.g. the casing, when the elements are in the first relative position. However, when the elements are in the second relative position, the first signal may not be guided to the first element receiving means by a portion of the casing. For example, the casing may be modified to define an aperture through which the first signal is transmittable when the canister is in the actuated position, i.e. when the elements are in the second relative position, the first signal therefore not being guidable by a portion of the casing to the first element receiving means .

The electronic counter may be located on the canister. Indeed, when the counter is located on the canister, the counter is preferably connected, e.g. via an electric circuit, to the first switch means, and preferably to the first element, so as to be capable of adjusting the stored count in response to the first switch being triggered. Of course, a skilled reader appreciates that any such electric circuit herein described may include other electronic components, for example a power source, such as a battery, whether the electronic circuit is located on the canister or the casing.

In an alternative aspect of the present invention, the first element includes receiving means, but it may be that the first element does not include transmitting means, and the second element includes transmitting means for transmitting a second signal. The first element receiving means may accordingly be capable of detecting the second signal transmitted by the second element transmitting means preferably when the elements are in the second relative position.

Preferably, where the counter is located on the canister, a display is also located on the canister, the display being capable of displaying information derived from the stored count.

However, in another aspect of the present invention, a display may alternatively, or additionally, be located on the casing. The casing display may be connected to the second element by e.g. an electronic circuit, the second element preferably including receiving means, and the first element preferably including transmitting means.

The counter may also be located on the casing, and the counter may be connected to the second element and a casing display. The first element transmitting means may transmit a first signal detectable by the second element receiving means when the elements are in the second relative position. As such, the first element may not necessarily include receiving means. Rather, receiving means may be included with the second element, the receiving means being capable of detecting the first signal when the elements are in the second position, so that on such detection the counter suitably connected to the second element and located on the casing can adjust the stored count accordingly.

In another aspect of the present invention, the counter may be located on the canister, and the first element further includes receiving means. The second element receiving means may be capable of detecting the first signal transmitted by the first element transmitting means, when the elements are in the second position. Preferably, in at least this aspect, the first signal includes information derived from the stored count. Preferably, a transmitter included with one of the elements may be in communication with the counter, and is capable of transmitting a signal including information derived from the stored count. Preferably, such a transmitter transmits a signal including such information to allow a display, suitably configured, to display information derived from the stored count. In particular, in at least this aspect, the casing display is therefore capable of displaying information derived from that information included in the first signal about the count stored in the counter located on the canister.

The second element may include reflecting means for reflecting a suitable proportion of the first signal to the first element receiving means, when the elements are in the second relative position. However, it is envisaged that the first element receiving means may alternatively be capable of detecting the first signal by reflection from a portion of the casing when the elements are in the first relative position, and that the first element receiving means may be incapable of detecting the first signal when the elements are in the second relative position. The detection of no signal may indicate that the canister is in the actuated position.

Alternatively, the second element may further include a transmitting means for transmitting a second signal to be detected by the first element receiving means when the elements are in the second relative position. The second signal may be derived from the first signal, received by the second element receiving means.

Indeed, where the counter is located on the canister and the display is located on the housing, this arrangement may advantageously provide a feedback loop, in that: the first element transmitting means transmits a first signal, detectable by the second element receiving means when the elements are in the second relative position, the first signal including information about the stored count for display by the housing display, if present; the second element transmitting means transmitting a second signal, detectable by the first element receiving means preferably when the elements are in the second position, preferably indicating the second element has received the first signal. Preferably, the second signal includes information derived from the first signal, more preferably, the second signal additionally or alternatively includes information about the count information being displayed by the casing display, if present. It is therefore envisaged that comparison means could be further included in communication with the counter for comparing the displayed count with the stored count and issuing a warning if there is a discrepancy. If the display count and the stored count match, or satisfy some predetermined criterion or criteria, then the counter may be adjusted to indicate that an actuation has been effected.

Alternatively, the second signal may, of course, be a signal independent of the first signal.

In a further aspect of the present invention, it may be that an inhaler device according to the present invention be provided with a display attached to both the canister body and the casing. In such an embodiment, it may be that one of the displays is able to be disabled. In an appropriate arrangement, the first or second signal may contain information instructing permanent or temporary disablement of the respective display.

The display may include a liquid crystal display (LCD) , one or more light emitting diodes (LED) , an organic light emitting polymer, or other display means known in the art. Preferably, the display gives a representation of the stored count (or information derived therefrom) , in the form of e.g. Arabic numerals or other alphanumeric representation . In an alternative, the display may give an indication of the approximate number of doses remaining in the canister by virtue of different colours produced by e.g. an LED or a plurality of coloured LEDs; i.e. the display may include a green, an amber and a red LED, only one LED preferably being capable of illumination at any one time, in accordance with the stored count. For example, a green LED may be illuminatable to indicate that there is e.g. more than a week's worth of metered doses remaining, say 100 doses, an amber LED may be illuminatable to indicate that the number of metered doses remaining is e.g. less than a week's worth, say 30 doses, and a red LED may be illuminatable to indicate that there is insufficient drug left in the canister for an effective metered dose to be delivered, i.e. zero doses.

For clarity, in this application reference is made to the counter recording, storing and registering the number of doses, in particular metered doses, delivered by the canister, however it should be recognised that the counter may record, store or register the remaining number of metered doses left in the canister, i.e. the number of metered doses contained in the canister at manufacture, less the number of metered doses already delivered. Additionally, where reference is made to a dose delivered by a canister, this reference encompasses a metered dose.

Preferably, the first element is a part of a canister attachment for location on the canister. Preferably, the canister attachment is detachable from the canister, but alternatively, the attachment may be permanently fixable to the canister. Preferably, the canister attachment is located, or locatable, on a portion of the canister, i.e the canister body, projecting from the casing when the canister is in the rest position. Preferably, at least a portion of the attachment remains outside the casing when the canister is in the actuated position. Preferably, the attachment includes the electronic counter, and preferably a display for displaying information derived from the stored count. Preferably, the counter and/or display are not locatable in the housing, either when the canister body is in the "actuated" or the "rest" position.

Preferably, the attachment is a self-contained unit, preferably a hermetically sealed unit, but more preferably, it is sealed to be splash-proof, more preferably water-proof, and most preferably water-proof to a depth of 1 metre (i.e. the device is provided with IP67 sealing) . The transmitting means, whether included with the first or second element, preferably includes a light emitting device, preferably a solid-state light emitting device, and most preferably a semiconductor light emitting device, such as an LED or a laser diode.

The receiving means, whether included with the first or second element, preferably includes a light detecting device or photodetector, preferably a solid-state photodetector, and most preferably a semiconductor photodetector, such as photodiode.

The transmitter and receiver mounted on the canister are preferably discrete devices, alternatively, the transmitter and receiver may be part of a transceiver. If a transmitter is included with a casing display, then the transmitter and receiver are preferably discrete devices, but they may be parts of a transceiver.

In a preferred embodiment the canister attachment is in the form of a cap, mountable to the end of the canister projecting from the inhaler casing. An attachment, or cap, according to the present invention aims, therefore, to be usable with any shape of inhaler housing or casing. Preferably, an inhaler according to the present invention further includes second switch means for enabling and disabling the first switch means. Preferably, the second switch means is located on the canister, and is capable of disabling at least a part of the first element, however it is also envisaged that the second switch means might be located on the casing, and may be capable of disabling the second element, or a part thereof.

It is preferred that the second switch means be included in an electronic circuit together with the first element transmitting and/or receiving means. Preferably, the second switch means is capable of breaking the power supply to first element transmitting means or to first element receiving means, or both.

It is preferred that the second switch means be triggerable by the user, so that when the user actuates the canister, the second switch means is closable and power is suppliable to the first element transmitting means and/or the first element receiving means so that the first switch is triggerable. During actuation of the canister, the second switch means maintains the first switch enabled and thus triggerable during the actuation cycle . Preferably, on restoration of the canister to the rest position, the second switch means disables the first switch means .

Preferably, the second switch means is located on a portion of the counting device that is easily accessible by the user when the counting device is mounted on the canister and the canister inserted to the casing. In particular, it is preferred that such a switch be located on the axis along which the canister is compellable to deliver a dose by application of a suitable force. In other words, the second switch means is preferably located at the end of the canister projecting from the housing, and is located in a region of the canister that the user pushes to actuate the canister.

The second switch means may include a switch member such as a membrane switch or a rocker switch.

Alternatively, or additionally, the second switch means may include a switch member such as a conductive rubber switch or a rubber keypad.

Thus, application of pressure to the second switch means compels the canister to deliver a dose, and causes the second switch means to enable the first switch means. Removal of pressure from the canister and second switch means restores the canister to the "rest" position and preferably causes the second switch means to disable the first switch means.

We refer herein to the second switch means being open and closed. By open it should be understood that the second switch means is in a state capable of disabling the first switch means, whereas by closed it should be understood that the second switch means is in a state capable of disabling the first switch means. However, a skilled reader also understands that the second switch means is not merely a mechanical switch that is openable and closable to physically break a circuit.

Preferably, an inhaler according to a further aspect of the present invention includes circuit break delay means. The circuit break delay means may allow the first switch means to remain functional, i.e. enabled, for a predetermined length of time after the second switch means has been opened when the canister body is returned to the "rest" position, and pressure may have been removed from the second switch means.

As such, it is possible that the circuit break delay means permits the supply of power to continue to the first switch means, and preferably the counter and display where applicable, for several seconds after the second switch means is opened, and the canister is in the "rest" position. For example, the circuit break delay- means may permit power to be supplied to the first switch means for one second after the second switch means is opened, more preferably three seconds, even more preferably five seconds, and most preferably ten seconds. Therefore, should the user require two or more metered doses, the first switch means remains in the ready state awaiting actuation of the canister. After the predetermined length of time has expired, the first switch means is permitted to enter the "standby" stage, in that one of the transmitter and receiving means, or indeed both of the transmitter and receiving means, is disabled. It is preferable, that when the first switch means is disabled, either with or without the circuit break delay means being used, that the receiver is disabled before the transmitter, to prevent the receiver erroneously reading that the signal emitted by the transmitter is blocked, and perhaps registering an additional count in the counter, in an appropriate embodiment .

The pressure required to close the second switch means is less than the pressure required to actuate the canister, thereby ensuring that the first switch means is enabled when the canister is urged to actuate.

It is possible that in a further aspect of the present invention, each canister is provided with means for unique self-identification, readable or communicatable by identifying means located on the casing. The casing may include storage means for storing information derived from the unique self-identification means to uniquely identify the canister. Additionally, the storage means may be capable of storing information about the number of actuations of that particular canister. On recognising a particular canister, by the unique self-identification means, the display can display information derived from the number of actuations of that particular canister. The identifying means may include transmitting and receiving means as described above.

In a further aspect, the present invention may provide a counting device for attachment to an inhaler canister for use in a complementary inhaler casing, the device including a counter, for registering, or recording, the number of times the canister has delivered a dose, e.g. a metered dose; and a first switch element locatable on the canister for interaction with a second switch element located on the casing; the first switch element and the second switch element forming first switch means without physical contact between the said switch elements; the first switch means being triggerable by relative motion of the first and second switch elements.

In an aspect of the present invention,- at least one of the first and second elements may include a reed switch. Preferably, a magnet may be included in the first or second element not including a reed switch, for actuation of the reed switch.

The present invention will now be described, by way of example, with reference to the accompanying figures in which:

Fig 1 is a partial exploded view of an inhaler according to at least one aspect of the present invention.

Fig 2 is a view of an inhaler according to at least one aspect of the present invention.

Fig 3 is a partial exploded view of a cap for inclusion in an inhaler according to at least one aspect of the present invention.

Fig 4 is a view of a cap for inclusion in an inhaler according to at least one aspect of the present invention. Fig 5 includes a cross-section, a cutaway view, and a schematic view of the operation of a transmitter and receiver according to at least one aspect of the present invention.

Fig 6 shows a cross-section, a cutaway view and a schematic representation of operation of an inhaler according to at least one aspect of the present invention.

Fig 7 shows a partial exploded view of an inhaler according to at least one aspect of the present invention.

Fig 8 shows a cap for use in an inhaler according to at least one aspect of the present invention.

Fig 9 shows an inhaler according to at least one aspect of the present invention.

Fig 10 shows a partial exploded cap for use in an inhaler according to at least one aspect of the present invention.

Fig 1 is a partial exploded view of an inhaler according to the present invention, showing a cap 100 locatable on the canister 110, which in turn is locatable in, and in this example to be partially contained by, the inhaler casing 120. The canister 110 and casing 120 may be of standard type, in that the canister 110 includes a canister body 112 for containing a substance such as medicament or drug in the form of a dry powder or liquid, and a nozzle 114 projecting from the canister body, and in that the canister body 112 is movable relative to the nozzle to deliver a dose of the substance contained within the canister.

Usually, a canister such as that shown in Fig. 1 is under pressure, and the relative movement of the nozzle 114 to the canister body 112 opens a valve to deliver a dose. Normally, the opening of the valve delivers a predetermined dose, i.e. a metered dose of the substance.

The inhaler case 120 is suitable for use with the canister 110, in that the casing 120 has a recess 122 at least partly defined by the casing 112 for receiving the canister 110. Although not shown, a casing such as this usually includes a cradle, or seating member, on which the nozzle 114 is locatable i.e. statically locatable, whereas the canister body 112 is movable relative to the casing 120. Therefore, by application of a suitable force to the canister body 112 to cause it to move relative to the casing 120 (supporting the nozzle 114), a measured dose can be dispensed. Often, the cradle seating member includes a conduit for passing the dose delivered by the canister through to the mouthpiece 126. The embodiment shown in Fig. 1, also includes a cap 100 that is removably locatable on the canister 110. Fig. 2 shows an inhaler according to the present invention with the canister positioned in the recess 122 of the casing 120 and the cap 100 mounted on top of the canister, i.e. distal to the nozzle 114.

Fig. 2 shows the cap 100, and therefore the canister 110, in the "rest" position. The rest position is the position in which the canister body 112 rests when no compressive force is applied to it compelling it to move relative to the nozzle 114.

In contrast, when sufficient force is applied to the canister 112 to compel it to move relative to the nozzle 114 sufficiently to cause a delivery of a dose, then the canister body is said to be in the "actuated" position, once the dose is delivered.

Fig. 3 shows an exploded view of the cap 100 which includes a transmitter 140 and a receiver 150, both of which are electrically connected to an electrical circuit 168, which is mounted on electric circuit board 160. In this preferred embodiment, the transmitter 140 is an LED, a light emitting diode, and the receiver 150 is a photodiode. The photodiode is selected to be responsive to the electromagnetic radiation emitted by the light diode 140. Preferably, the LED 140 emits in a region of the electromagnetic spectrum outside the visible region, to minimise interference with visible background radiation. Preferably, the LED 140 emits in the infrared region of the electromagnetic spectrum. Consequently, it is preferred that the photodiode's detection bandwidth encompasses the infra-red region of the electromagnetic spectrum.

In this particular embodiment, the LED 140 may be driven by a modulated signal, therefore, the signal emitted by the LED 140 (to be received by the photodiode 150) is a modulated signal, e.g. a pulse train. This modulation has the advantage that the received modulated signal can be isolated from background noise by appropriate electronics, located for example on the electronic circuit 160.

In the present embodiment, as shown in Fig. 3, LED 140 is able to transmit a signal directly to receiver 150. The LED 140 and receiver mounted on the electronic circuit board 168 and the transmitter 140, receiver 150 and circuit 160 are all locatable within the cap body 132. The LED 140 and receiver 150 are received in the cap body 132 such that the receiver 150 is capable of detecting a signal if emitted by the transmitter 140.

The cap body 132 includes a slit 130 defined such that a member can be inserted to the slit to be locatable between the transmitter 140 and receiver 150, so as to at least partially block the signal path between transmitter 140 and receiver 150.

As can be seen with reference to Fig. 1, the inhaler casing 120 according to the present embodiment, of the present embodiment, is adapted to include a rib 128 capable of being received by the slit 130. Thus, when the cap 100 is mounted on the canister 110, the rib is locatable in a portion of the slit 130. In the "rest" position, the rib is not blocking a significant portion of the signal path between a transmitter 140 and the receiver 150. However, when the canister body is depressed to actuate the canister, the cap body moves relative to the rib, and the rib is inserted between the transmitter 140 and receiver 150 to at least psrtially block this signal.

In this embodiment the receiver 150 responds to losing the signal transmitted by transmitter 140, by sending a signal to counter 164 to adjust the stored count. The counter 164 is an electronic counter connected to the electronic circuit 160. The electronic circuit 160 in the present embodiment, also includes a power source 162, for supplying current to the counter 164 and the transmitter 140 and the receiver 150.

The cap 100 also includes display means 170, which in the present embodiment, includes a tri-colour LED arrangement for indicating that there is sufficient dose left in the canister for, say, thirty metered doses (say a green LED) , an amber LED indicating that there is less than thirty doses and a red LED for indicating that the canister should be changed because it is spent. The display means is supplied with power via the electrical connections 166. A cap cover portion 113 is then included to the cap 100 to provide a secure fixing.

However, the display means 170 may include an LCD display or an organic light entity polymer or other display known in the art .

Thus, it can be seen that when the inhaler according to the present invention is assembled according to Fig. 2, the transmitter and receiver pair and rib act as a switch. When the cap is moved towards the mouthpiece end of the casing 120, the rib 128 is effectively inserted between the transmitter 140 and receiver 150 and the transmitted signal between is cut off. This is equivalent to opening (or closing) a switch. The counter, being responsive to the switch comprising the transmitter 140, receiver 150 and rib 128 then adjusts the count to reflect an actuation of a canister.

Fig. 4 shows the cap in close up, and shows that the cap includes a flange 135 defining a recess 137 allowing the cap to be locatable at the nozzle-free end of the canister. However, it is envisaged that the cap could be permanently locatable on the canister, for example by spot welding or the use of adhesive.

Figs 5 and 6 show in more detail the operability of the present embodiment. Figs. 5 (a) and 5 (b) show the inhaler in the rest position, in that the rib 128 is not inserted between the transmitter 140 and receiver 150. Fig. 5(c) shows a representative view of the arrangement, showing the transmitter 140 communicating directly with the receiver 150. The rib 128 is clearly shown well outside the signal path of the signal transmitted from the transmitter 140 to the receiver 150. Fig. 6, however, shows the inhaler according to the present invention in the actuated position. The cap 100 and canister body 112 have been moved relative to the casing 120, in a direction towards the mouthpiece end. The rib 128 is now clearly seen to be located between the transmitter 140 and receiver 150, and in Fig. 6(c) the representative image shows the rib 128 blocking the signal path between the transmitter 140 and receiver 150. In response to this signal blocking, the counter, in the present embodiment, responds by increasing the count by one. Of course, in an alternative embodiment, the count could be decreased by one, or indeed the count could be adjusted in any way suitable to indicate an actuation of the canister.

Fig. 7 shows an alternative embodiment, indeed an alternative preferred embodiment, of an inhaler according to the present invention. The canister 110 is substantially as previously described, and the basic operation of the canister by interaction with the casing 220 is also as previously described.

However, as can be seen from Fig. 7, both the cap 200 and the detail of the casing 220 differs from that shown in Figs. 1 to 6. The cap 200 is shown in close up in Figs. 8 (a) and (b) and shows a transmitting light pipe 212 and a receiving light pipe 214. The light pipes 212 and 214 are arranged so that the light pipe 214 is incapable of directly receiving light transmitted by light pipe 212 through its aperture shown in Fig. 8 (a) . The cap 200 includes a transmitter (not shown) associated with the transmitting light pipe 212 for transmitting light along the light pipe 212; and, a receiver (not shown) capable of receiving radiation at the emission frequency of the transmitter, the receiving associated with the receiving light pipe 214 for detecting light channelled along the light pipe 214. The rest of the cap 200 is substantially similar to the cap 100 previously described. In this embodiment, the cap 200 is locatable on the canister 110, the cap and canister being arranged relative to the casing 220 as shown in Fig. 9. In this particular embodiment, the transmitting light pipe 212 channels or guides light to be reflected by the inner surface of the casing 220, so as to be received by the light pipe 214 for guidance to the receiver. When the cap 200 and canister 410 are in the rest position, the receiver is capable of detecting light emitted by the transmitter, the light being guided by transmitting light pipe 212 and reflected by the casing to the receiving light pipe 214. However, when the cap 200 and canister 110 are depressed so as to actuate the canister i.e. the canister body and cap are in the "actuated position", the transmitting light pipe 212 is aligned with an aperture 250 defined in a wall of the casing 220. As such, the signal emitted by the emitter and guided by the transmitting light pipe 212 is transmitted through the aperture, and the receiving light pipe 214 does not receive any significant portion of the signal emitted by the transmitting light pipe 212. As such, the counter 164, shown in Fig 10, configured to be responsive to a receiver not detecting the signal adjusts the stored count to register an extra actuation.

Fig 10 also shows a preferred embodiment for a cap implementing the present invention, in which the display 170 includes a preferred display means, coloured LEDs for indicating the count, stored in the counter 164. As can be seen, the transmitting and receiving means 140, 150 are locatable adjacent, or in, the corresponding light pipes or light guides 212, 214 so that the light emitted from the transmitting means is guidable along the corresponding light guide.

It will be apparent to the skilled person from the teaching herein that the invention can be achieved in ways other than those specifically described in the examples, which do not necessarily limit the appended claims .

Claims

1. An inhaler device including an inhaler canister having a canister body for containing a medicament, the canister being actuatable to deliver a dose of medicament; a casing at least partially housing the canister; first switch means for detecting when the canister body is in the actuated position relative to the casing; and an electronic counter, in which a count is storable, the count being derived from the number of actuations of the canister detected by the first switch means; wherein the first switch means includes first and second elements located on the canister and casing respectively, the first switch means being triggerable by relative movement of the first and second elements, without physical contact between the said elements .

2. An inhaler device according to claim 1 wherein at least one of the first and second elements includes receiving means capable of detecting a signal, the signal being indicative of the relative positions of the first and second elements.

3. An inhaler device according claim 1 or claim 2 wherein at least one of the first and second elements includes transmitting means for transmitting a signal, detectable by said receiving means.

4. An inhaler device according to claim 2 or claim 3 wherein the strength of the signal detectable by the receiving means is indicative of the relative positions of the said elements.

5. An inhaler device according to any one of the preceding claims, wherein movement of the first and second elements between a first and a second relative position is capable of triggering the first switch means.

6. An inhaler device according to claim 5 wherein no signal is detectable by the receiving means in one of the first and second relative positions.

7. An inhaler device according to claim 5 or 6 wherein the first element includes transmitting means for transmitting a first signal, and receiving means capable of detecting the first signal in at least one of the first and second relative positions.

8. An inhaler device according claim 7 wherein the signal path of the first signal between the first element transmitter means and the first element receiving means is a direct path.

9. An inhaler device according to claim 7 or claim 8 wherein the second element includes interfering means capable of interfering with the first signal, in at least one of the first and second relative positions.

10. An inhaler device according to claim 9 wherein the interfering means obstructs at least a part of the signal path of the first signal in at least one of the first and second relative positions.

11. An inhaler device according to claim 9 or claim 10. wherein the interfering means blocks the signal path of the first signal, preventing the first element receiving means detecting the first signal.

12. An inhaler device according to claim 7 or one of claims 9 to 11 wherein the first signal is indirectly receivable by the first element receiving means by reflection of the fist signal from a surface of the casing in at least one of the first and second relative positions .

13. An inhaler device according to claim 7 or one of claim 7 to 12 wherein the second element includes a reflecting face for guiding the first signal to the first element receiving means in one of the first and second relative positions.

14. An inhaler device according to claim 13 wherein the reflecting face includes a region of high reflectivity positioned on the casing so that the signal is incident upon the high reflectivity region in either the first or the second relative position, the face having a high reflectivity relative to a portion of the casing surface on which the signal is incident when it is not incident on the reflecting face.

15. An inhaler device according to any of claims 12 to 14 wherein the casing is adapted to be incapable of guiding the first signal to the first element receiving means in one of the first and second relative positions.

16. An inhaler device according to any one of claims 12 to 15 wherein the casing defines an aperture, the first signal being transmittable therethrough, in one of the first and second relative positions.

17. An inhaler device according to any one of the preceding claims wherein the second element includes receiving means for detecting the first signal transmitted by the first element transmitting means, in at least one of the first and second relative positions.

18. An inhaler device according to claim 17 wherein the signal path between the first element transmitting means and the second element receiving means is direct, in at least one of the first and second relative positions.

19. An inhaler device according to claim 17 or 18 wherein the casing is adapted to define an aperture through which a signal is transmittable in at least one of the first and second relative positions.

20. An inhaler device according to any one of the preceding claims wherein the electronic counter is located on the canister.

21. An inhaler device according to any one of the preceding claims wherein a display is located on the canister, for displaying the stored count.

22. An inhaler device according to any one of the preceding claims wherein the first signal includes information about the stored count.

23. An inhaler device according to any one of claims 2 to 22 wherein a display is connected to the second element receiving means to be capable of displaying the received information.

24. An inhaler device according to any one of claims 2 to 23 wherein the second element includes transmitting means for transmitting a second signal, the second signal being detectable by the first element receiving means in at least one of the first and second positions.

25. An inhaler device according to claim 24 Wherein the second signal is derived from the first signal.

26. An inhaler device according to claim 24 or claim 25 wherein the signal path of the second signal between the second element transmitting means and the first element receiving means is direct, in at least one of the first and second relative positions.

27. An inhaler device according to any one of claims 24 to 26 wherein the casing is adapted to define an aperture through which the second element transmitting means can transmit a second signal detectable by the first element receiving means, in one of the first and second relative positions .

28. An inhaler device according to any one of the preceding claims wherein the counter is located on the housing.

29. An inhaler device according to any one of the preceding claims wherein the interfering means includes a rib projecting from the casing to be insertable between the first element transmitting and receiving means.

30. An inhaler device according to any one of the preceding claims wherein the electronic circuit further includes second switch means capable of disabling and enabling the first switch means, in one of the first position and the second position.

31. An inhaler device according to claim 30 wherein at least a portion of the second switch means is located on an axis of actuation of the canister, the axis of actuation of the canister being the axis along which a force is applied by a user to actuate the canister.

32. An inhaler device according to any one of the preceding claims, wherein when the canister is in the actuated position, the said first and second elements are in the second relative position.

33. An inhaler device according to any one of the preceding claims, wherein when the canister is in the rest position, the said first and second elements are in the first relative position.

34. An inhaler device according to any one of claims 30 to 33 wherein compulsion, by a user, of the canister from the rest position to the actuated position triggers the second switch means to enable the first switch means.

35. An inhaler device according to any one of claims 30 to 34 wherein restoration of the canister to the rest position triggers the second switch means to disable the first switch means.

36. An inhaler device according to any one of claims 30 to 35 wherein the second switch means is a pressure sensitive switch

37. An inhaler device according to any one of claims 30 to 36 wherein the pressure required to trigger the second switch means is less than the pressure required to compel the canister to actuate.

38. An inhaler device according to any one of claims 30 to 37 wherein the electric circuit further includes delay means, responsive to the second switch means, for delaying the disablement of the first switch means when the canister is restored to the rest position.

39. An inhaler device according to any one of the preceding claims, wherein the transmitting means includes light emitting means.

40. An inhaler device according to any one of the preceding claims, wherein the light emitting means includes a semiconductor light emitting device.

41. An inhaler device according to any one of the preceding claims, wherein the receiving means includes a photodetector .

42. An inhaler device according to any one of the preceding claims, wherein the receiving means includes a photodiode .

43. A canister for an inhaler including a first element according to any one of the preceding claims .

44. An inhaler casing for use with a canister having a first element, the inhaler casing including a second element according to any one of claims 1 to 42.

45. A kit comprising an inhaler casing and a canister including a first switch means according to any one of claims 1 to 42.

46. An inhaler substantially as described herein, with reference to, and as illustrated in the associated figures .