DOSAGE DISPENSING DEVICES

Abstract: A dosage dispensing device is described having means for recording the number of times the device is used. Such means are provided by an electronic counting assembly.

Description: DOSAGE DISPENSING DEVICES The present invention relates to dosage dispensing devices having means for recording the number of times the devices are used. Examples of dosage dispensing devices include metered dose inhalers and nasal sprays. Dosage dispensing devices are often used in the treatment of respiratory disorders such as asthma, both for relief of bronchospasm and for prophylactic treatment of acute attacks. To be effective, therapy often needs to be taken regularly, especially when used prophylactically. Many asthmatics are not aware of the need for regular inhaler use, particularly when they are free of symptoms of asthma. Doses of regular medications are often missed, which may account for so-called treatment failures. In long term clinical trials assessment of compliance is a very important factor in the assessment of a drug's efficacy, particularly with prophylactic agents. It is possible that potentially useful respiratory compounds may have failed through poor compliance, rather than lack of efficacy. Assessment of patient compliance is therefore important both in routine clinical practice and in the clinical stages of drug dev 1opment. Another problem with dosage dispensing devices is that a patient may not become aware that a device is empty until it is required for use, for example for relief of severe bronchospasm. A dosage dispensing device with means for recording the number of times it has been used would be useful in the assessment of compliance by a physician, clinical researcher or patient and to let a patient know that the medicament is about to be exhausted so that a new dosage UBSTITUTESHEET dispensing device can be obtained in good time. Dosage dispensing devices with such recording means have been described in WO86/02275, US-A-4668218 and ϋS-A-4817822. In these devices the recording means comprise complicated mechanical systems such as : ° a multiple digital wheel counter, ° a rotatable disc with a central portion having a spiral groove that can engage with peripheral teeth on an indicator wheel, or ° a ratchet wheel with a ratchet driving member, the ratchet wheel driving an indicating member in the form of a linear rack or rotatable wheel. It has now been surprisingly found that the recording means can be more simply and conveniently provided by an electronic counting assembly. Accordingly the present invention provides a dosage dispensing device comprising a housing for holding a medicament container from which measured amounts of medicament can be dispensed and having means for recording the number of times medicament is dispensed from the container characterised in that the recording means comprise an electronic counting assembly. Suitably the dosage dispensing device is an inhaler of the dry-powder type, for example as disclosed in US Patent 4524769, but having an electronic counting assembly. Alternatively the dosage dispensing device comprises a housing which can support a medicament container having a discharge valve, the electronic counting assembly being actuated by relative movement between the container and the discharge valve whenever a measured amount of medicament is discharged. A dosage dispensing device can suitably be designed for oral, nasal, rectal or vaginal delivery. Suitably the electronic counting assembly comprises a power source, an electronic counter, a switch which is actuated by the relative movement between the container and the discharge valve to record a count on the electronic counter, and means for allowing a variable, but preset, delay-time between counts so that repeated actuations within said delay-time are not recorded. By the term switch is meant any device or assembly for completing or interrupting an electronic circuit. Thus the circuit can be designed such that either completion or interruption of it records a count on the electronic counter. Suitably the switch has a contact arm which is normally in an open position but which is releasably closed by the relative movement between the container and discharge valve. Alternatively the contact arm is normally in a closed position but is releasably opened bysaid relative movement. In one embodiment the switch is an assembly having a separate moveable conducting member so positioned such that said relative movement effects contact closure. For example the separate moveable conducting member can be an elastomeric switch of known type. It is desirable to have means for allowing a delay-time since otherwise rapid vibrations of the switch, which can occur when it is actuated, would cause a plurality of counts to be incremented on the electronic counter, instead of a single count. S TUTE HEET The means for allowing the delay-time can be provided by a suitable RC (resistor/capacitor) network which can be designed by one skilled in the art to give a delay-time of for example 0.05 to 60 seconds, preferably 0.1 to 10 seconds. For example when a 3 volt power supply is used, a 1 megohm resistor and a 3.3 microfarad capacitor can be used to provide a delay-time of about 3 seconds. In order to maximise the efficacy of respiratory compounds physicians often recommend that a minimum time e.g. 10 seconds should elapse before a patient should receive a subsequent dose. Patient compliance can be simply assessed by using a dosage dispensing device of the present invention, having a RC network providing a suitable delay-time of 10 seconds, for example, which would only record dosages administered according to the recommended regimen. The electronic counting assembly may further comprise a second electronic counter and further means for allowing a variable, but preset, delay-time between counts so that repeated actuations within said delay-time are not recorded on the second electronic counter. Suitably such means for allowing the delay-time is an RC network as hereinbefore described. The electronic counting assembly may therefore have a first electronic counter with an RC network providing a delay-time of between 3 and 60 seconds, for example 10 seconds, and a second electronic counter with an RC network providing a delay-time of between 0.05 and 0.5 seconds, for example 0.1 seconds. The second counter would record all actuations and would therefore be of use in checking the quantity of medicament remaining whilst the first counter would be of use in assessing patient SUBSTITUTESHEET compliance as hereinbefore described. The means for providing the delay-time(s) can alternatively be provided by a suitable electronic logic circuit. Preferably the electronic counting assembly further comprises a reset switch which when it is closed resets the electronic counter to zero. This facilitates the resetting of the electronic counter whenever an aerosol container is replaced. Conveniently the electronic counter is a low power consumption electro-mechanical counter or preferably is a liquid crystal display counter. Suitably the components of the electronic counting assembly are contained within an assembly housing which can be tailored releasably to fit commercially available dosage dispensing devices. Preferably the assembly housing is made of moulded plastics material and is integrally formed with the housing for the medicament container. It will be understood by the person skilled in the art that the design of the assembly housing should allow easy fitting of the assembly components and replacement of a battery if one is used as a power source. Preferably the dosage unit comprises a cover for preventing unauthorised access to the electronic counting assembly in particular to the electronic counter(s) and the reset switch. Thus the cover may be provided with a seal which would be broken whenever the cover is SUBSTITUTE SHEET removed. This would be advantageous should a physician want to assess usage of a dosage dispensing device without the knowledge of a patient. Embodiments of the present invention will now be described with reference to the accompanying drawings : Figure 1 is an exploded view of a dosage inhaler. Figure 2 is a side view, partially in section, of an aerosol container resting in the dosage inhaler. Figure 3 is a side view, partially in section, of an aerosol container depressed fully into the dosage inhaler. Figure 4 is a circuit diagram of the electronic counting assembly having one electronic counter. Figure 5 is a circuit diagram of the electronic counting assembly having two electronic counters. Figure 6 is an exploded view of a nasal dosage dispenser. Figure 1 indicates how an electronic counting assembly can be attached to a commercially available dosage inhaler comprising a housing 1 with an aerosol container 2 containing for example at least 200 doses of medicament. Protruding through the housing 1 is attached a switch 3 which is part of the electronic counting assembly further comprising a liquid crystal display counter 4, battery 5 and resistor, capacitor and reset switch as more fully described in the circuit diagram of Figure 4. The electronic counting assembly is contained within an assembly housing comprising two parts 6a and 6b suitably made of perspex secured with screws as shown in SUBSTITUTE SHEET Figure 1. A cover 7 made for example of black perspex can be secured to the assembly housing 6a by further screws which if desired can be sealed for example with wax to prevent unauthorised access to the electronic counting assembly. As shown in Figure 2 the switch 3 is positioned such that it's contact arm 8 is in an open position when the aerosol container 2 is resting within the housing 1. In order to cause relative movement between the aerosol container 2 and the discharge valve 9 and so to discharge a measured amount of medicament therefrom, the aerosol container 2 is depressed into the housing 1 as shown in Figure 3. Downward movement of the aerosol container 2 causes the contact arm 9 of the switch 3 to be closed which results in a count being registered on the liquid crystal display counter 4. Figure 4 shows a circuit diagram of an electronic counting assembly comprising a 3 volt lithium manganese dioxide battery (e.g. DL 1620, Duracell®) , a liquid crystal display (LCD) counter (e.g. RS 343-442, supplied by RS Components Ltd. , Corby, England) , a contact to record counts, a contact for resetting the LCD counter and a RC network comprising a 1 megohm resistor and a 3.3 microfarad tantalum capacitor. The RC network ensures that after the initial count, further counts are inhibited by approximately 3 seconds. A current consumption of 15 microamps gives a life expectancy of the battery of 120 days, far in excess of the time in which 200 doses in the aerosol container are expected to be used under normal circumstances. The battery may be simply replaced when necessary. Figure 5 shows a circuit diagram of an electronic counting assembly having two electronic counters. The SUBSTITUTE SHEET components of this assembly are as described in Figure 4 but further comprise a second LCD counter and another RC network comprising a 1 megohm resistor and a 100 nanofarad ceramic capacitor. This RC network ensures that after the initial count further counts on the second LCD counter are inhibited by approximately 0.1 seconds. The device described in Figures 1 to 4 has been tested by discharging an aerosol container therein and at the same time pressing a tally counter to assess independently the number of actuations. To take account of the time constant in the circuit, actuations were at least 5 seconds apart. This experiment showed that for each of five inhalers discharged until empty, i.e. in excess of 200 actuations, the device read within 99% of the reading on the tally counter. Figure 6 shows a medicament container 2 to which can be attached a discharge valve 9. Placed around the discharge valve is a metallic seal which forms part of the switch 3 of the electronic counting assembly. The medicament container 2 can be placed within a housing 1 suitably designed for nasal delivery. Placed within the housing 1 is a ring containing contacts which forms the remaining part of the switch 3. In operation the relative movement between the discharge valve 9 and the medicament container 2 brings the metallic seal into contact with the ring containing contacts which effects contact closure thereby causing a count to be registered on the LCD counter 4 which is contained in an assembly housing 6. SUBSTITUTE SHEET

Claims: Claims 1. A dosage dispensing device comprising a housing for holding a medicament container from which measured amounts of medicament can be dispensed and having means for recording the number of times medicament is dispensed from the container characterised in that the recording means comprise an electronic counting assembly. 2. A dosage dispensing device according to claim 1 wherein the housing can support a medicament container having a discharge valve; the electronic counting assembly being actuated by relative movement between the container and the discharge valve whenever a measured amount of medicament is discharged. 3. A dosage dispensing device according to claim 2 wherein the electronic counting assembly comprises a power source, an electronic counter, a switch which is actuated by the relative movement between the container and the discharge valve to record a count on the electronic counter, and means for allowing a variable, but preset, delay-time between counts so that repeated actuations within said delay-time are not recorded. 4. A dosage dispensing device according to claim 3 wherein the means for allowing the delay-time between counts comprise a resistor and a capacitor which result in a delay-time of 0.05 to 60 seconds. 5. A dosage dispensing device according to claim 3 or 4 wherein the electronic counting assembly further comprises a second electronic counter and SUBSTITUTE. SHEET further means for allowing a variable, but preset, delay-time between counts so that repeated actuations within said delay-time are not recorded on the second electronic counter. 6. A dosage dispensing device according to any one of claims 3 to 5 wherein the electronic counting assembly further comprises a reset switch which when it is closed resets the electronic counter to zero. 7. A dosage dispensing device according to any one of claims 3 to 6 wherein the electronic counter is a liquid crystal display counter. 8 « dosage dispensing device according to any one of claims 1 to 7 wherein the electronic counting assembly is contained within moulded plastics material which is integrally formed with the housing for the medicament container. 9. A dosage dispensing device according to any one of claims 1 to 8 which comprises a cover for preventing unauthorised access to the electronic counting assembly.

Inventors: BURNS COLIN PETER, HARE JOHN FRANCIS, O'CONNOR STEPHEN ANTHONY PETER, BURNS, COLIN, PETER, HARE, JOHN, FRANCIS, O'CONNOR, STEPHEN, ANTHONY, PETER
Applicants: SMITH KLINE FRENCH LAB, SMITH KLINE & FRENCH LABORATORIES LIMITED
Application year: 1990
Main classification: A61M15
IPC codes: A61M15