Metering device for use in transferring a desired volumetric dose of a flowable substance from a storage container

A metering device, for use in transferring a desired volumetric dose of a flowable substance from a storage chamber containing the flowable substance to a location outside the storage chamber, is disclosed. An outlet conduit is arranged between the storage chamber and the location to which the dose is to be transferred. The metering device is of such size and shape as to be able to pass through the outlet conduit and includes first and second end element which, when the metering device is located inside the outlet conduit, are in a sealing engagement with the inner walls of the outlet conduit. The shape of the metering device between the first and second end elements is such that a space of the desired dose volume is defined between the first and second end elements and the intervening section of the inner walls of the outlet conduit, in which space the flowable substance from the storage chamber may be enclosed. The metering device is of particular use in a dry powder inhaler.

FIELD OF THE INVENTION 
This invention relates to a metering device for transferring a desired 
volumetric dose of a flowable substance from a storage chamber containing 
the substance to a location outside the chamber, which device is of 
particular use in an inhaler for delivering a dose of a medicament or 
other substance for inhalation into the lungs of a user. The invention 
also relates, inter alia, to an inhaler incorporating such a metering 
device; to a method for transferring a desired volumetric dose of a 
substance from one location to another using such a device; and to a 
container for containing metered doses of a substance, the container 
incorporating one or more such devices. 
BACKGROUND TO THE INVENTION 
It is often necessary to transfer an accurate volume of a substance from a 
storage chamber containing that substance to another location, but it is 
not always easy to effect the transfer accurately and efficiently. In 
particular, it is often desired to transfer a powdered medicament from a 
storage chamber to an inhalation passage in a dry powder inhaler. 
Powder inhalers, which deliver a drug in a dry, finely divided form, have 
been shown to give certain medical advantages over other forms of delivery 
system. In particular, they are more popular than inhalers which propel a 
drug in pressurised gas from an aerosol, because of environmental and 
other considerations. 
EP-079478, EP-166294 and GB-2165159 disclose examples of dry powder 
inhalers which include a medicament storage chamber and an inhalation 
passage through which air is drawn via a mouthpiece. A metering member 
provided with a metering recess takes a dose of medicament from the 
storage chamber and deposits it in the inhalation passage. 
It is considered that the accuracy of such arrangements can be very poor: 
on the one hand, by repeated indexing of the metering member it is 
possible to deposit two or more doses of medicament into the inhalation 
passage, resulting in the administration to the user of an overdose of 
medicament; on the other hand, since the medicament normally drops from 
the metering recess into the inhalation passage under gravity, particles 
of medicament can adhere to the interior of the metering recess so that an 
underdose is delivered. 
U.S. Pat. No. 2,587,215 discloses dry powder inhalers with the same 
disadvantages as those mentioned above. However, this document also 
discloses an embodiment in which the metering member presents the 
medicament in an upwardly open dispensing cup to a mixing chamber, where 
it is mixed with air before being sucked into an inhalation tube via a 
nozzle having a narrow opening. Air sucked into the inhaler passes into 
the inhalation tube either directly or through the mixing chamber and 
nozzle. Accordingly, not all the air passes over the dispensing cup. If 
medicament adheres to the surface of the dispensing cup but is not sucked 
therefrom, an underdose of medicament will be delivered to the user. Upon 
repeated use of a dispensing cup to deliver doses to the inhalation tube, 
a continually increasing amount of the medicament powder can adhere to the 
base of the dispensing cup, resulting in progressively decreased dosages 
to the user. 
This build-up of adherent powder is thought to be a source of inaccurate 
dosing in many of the inhalers previously proposed. 
Moreover, in the inhaler of U.S. Pat. No. 2,587,215, the metering member is 
a rotary sliding device journalised on a cylindrical pivot member 
extending from the bottom of the body of the device. Such an arrangement 
is susceptible to jamming due to ingress of powdered medicament between 
the cylindrical contacting surfaces of the pivot member and the metering 
member. 
Another form of inhaler which is currently available includes a metering 
member having a number of tapered metering recesses which are open at top 
and bottom. In use, finely divided medicament from a storage chamber is 
packed into the recesses, whereupon the metering member is moved to a 
dispensing position in which air can be drawn through the recesses to draw 
out the medicament. This device is considered to have a number of major 
shortcomings. Firstly, the metering recesses are prone to clogging. 
Secondly, a large amount of suction is required, so that the device is 
unsuitable for use by patients with breathing problems. Thirdly, two hands 
are required to operate the device. 
An improvement over the above described inhalers is described in our 
earlier PCT patent application, No. PCT/GB91/01147. This discloses an 
inhaler in which the metering member comprises at least one dispensing cup 
which, when filled from a storage chamber with a dose of the substance to 
be delivered, is presented to the inhalation passage in an upwardly open 
position. The substance to be delivered is removed from the dispensing 
cup, rather than by the action of gravity, by air flow through the 
inhalation passage. Thus, in normal use of the inhaler, repeated indexing 
of the metering member should not result in multiple doses of the 
substance being delivered into the inhalation passage. 
The inhaler described in PCT/GB91/01147 incorporates means for ensuring 
that the dispensing cup is substantially free from the substance to be 
delivered, before it is presented to the storage chamber to be re-filled 
with the substance. This means may comprise a specially shaped inhalation 
passage; means for moving the dispensing cup into a downwardly open 
position after it has been presented to the inhalation passage and before 
it is re-presented to the storage chamber; or means, such as resilient 
wiping means, for dislodging any remaining substance from the cup after it 
has been presented to the inhalation passage. In all cases, at least one 
of these special means must be included in the inhaler so as to prevent 
any of the substance from remaining in the dispensing cup after it has 
been presented to the inhalation passage. If any of the substance did 
remain, this could affect accuracy when the dispensing cup was refilled 
from the storage chamber ready for subsequent representation to the 
inhalation passage. 
The need to ensure that a metering member is substantially free from the 
substance to be delivered, after each presentation to the inhalation 
passage of an inhaler, arises largely from the fact that the metering 
member is constantly being re-presented to the storage chamber, re-filled 
with the substance and returned to the inhalation passage. The metering 
member is required to deliver an accurate dose of the substance each time 
it passes through the inhalation passage. 
It is an aim of the present invention to provide improved means for 
accurately transferring a dose of a substance, such as a powdered drug, 
from one location to another, which means may be used, inter alia, in an 
inhaler to transfer a dose of drug from a storage chamber to an inhalation 
passage. An inhaler incorporating such means should overcome or at least 
mitigate the above described problems associated with conventional 
inhalers, and should be capable of delivering an accurate dose of drug to 
a user each time it is used. 
STATEMENTS OF THE INVENTION 
According to a first aspect of the present invention there is provided a 
metering device for use in transferring a desired volumetric dose of a 
flowable substance from a storage chamber containing the substance to an 
outlet conduit communicating with the chamber, the device being of such 
dimensions as to be able to pass into the outlet conduit and having first 
and second end elements which, when the metering device is located inside 
the conduit in use, are in sealing engagement with the inner walls of the 
conduit, the shape of the metering device between the first and second end 
elements being such that a space of the desired dose volume is defined 
between the first and second end elements and the intervening section of 
the inner walls of the conduit, in which space substance from the storage 
chamber may be enclosed when the metering device has passed out of the 
storage chamber into the outlet conduit in use. 
The flowable substance may be a pulverulent material, for example a 
powdered drug. 
Such a device allows the relatively simple and efficient transfer of 
precise volumetric doses of a substance from one location to another. 
Movement of the device from the storage chamber, through the outlet 
conduit, to another location causes the device to carry with it as it 
moves a precisely defined dose of substance, trapped between the first and 
second end elements of the device and the inner walls of the conduit. When 
the device exits the outlet conduit, the substance can then be released 
ready for use as desired. 
The metering device need not be large in size, complex in shape or 
cumbersome. In use, several such devices may be moved through the outlet 
conduit to transfer several successive doses of the substance. These 
factors mean that the device is of particular use in an inhaler, for 
transferring a powdered drug from its storage chamber to the inhalation 
passage of the inhaler. The device may also be used, however, to transfer 
a substance (eg, a powdered drug) from a storage chamber into a receptacle 
which is to be used to store and transport a measured amount of the 
substance for subsequent use in, for example, an inhaler. 
According to a second aspect of the invention there is provided a metering 
device in accordance with the first aspect, in combination with a storage 
chamber for containing a substance of which a volumetric dose is to be 
transferred from the chamber, and an outlet conduit communicating with the 
chamber, the shape and dimensions of the device relative to those of the 
outlet conduit being as described in accordance with the first aspect of 
the invention. 
The storage chamber may be part of an inhaler for delivering a substance to 
a user in a finely divided form, the chamber being for storing a quantity 
of that substance, and the outlet conduit then communicating between the 
chamber and an inhalation passage in the inhaler. 
Thus, according to a third aspect of the present invention, there is 
provided an inhaler for delivering a substance in a finely divided form, 
the inhaler comprising a storage chamber for storing a quantity of the 
substance to be delivered; air intake means by which air may be drawn into 
the inhaler from the atmosphere; an inhalation passage communicating with 
the air intake means, through which passage air may be drawn using the air 
intake means; a storage chamber outlet conduit communicating between the 
storage chamber and the inhalation passage; a metering device in 
accordance with the first aspect of the invention for use in transferring 
a desired volumetric dose of the substance from the storage chamber to the 
inhalation passage via the outlet conduit, the metering device being 
movable through the outlet conduit from a first position, in which it is 
presented to the storage chamber to receive the substance, to a second 
position in which the desired volumetric dose of the substance is 
presented with the metering device to the inhalation passage; and indexing 
means operable to move the metering device from its first to its second 
position. The shape and dimensions of the metering device relative to 
those of the outlet conduit are as described in accordance with the first 
aspect of the invention. 
The metering device may comprise a body in the form of a spool which may be 
located in, and preferably pass through, the outlet conduit in use. The 
device may also be one of a plurality of such devices arranged in series, 
which devices are able to pass through the storage chamber and into the 
outlet conduit in series so as to transfer a succession of metered doses 
of substance out of the storage chamber. In this case, the first end 
element of one device in the series may also serve as the second end 
element of the preceding device in the series, such that the desired 
volume is defined between two successive end elements as successive 
devices in the series pass into the outlet conduit in use. 
The invention thus also provides, according to a fourth aspect, a plurality 
of metering devices arranged in series, each device being in accordance 
with the first aspect of the invention. The devices may be releasably or 
permanently attached to one another so as to be in a chain-like 
conformation, preferably a flexible or semi-flexible chain. The design of 
metering devices in accordance with the invention makes such flexibility 
possible. 
A series of metering devices in accordance with the fourth aspect of the 
invention is ideal for use in an inhaler, because it allows sequential 
presentation of doses of a substance to the inhalation passage of the 
inhaler as the series is indexed through the inhaler. If the series is in 
the form of a flexible chain, it can then be rolled or folded up for 
compact storage in the inhaler. The series may be of any appropriate 
length. It may, for instance, be supplied in a length greater than might 
be needed for use in an inhaler, but capable of being broken up into 
usable lengths. 
An inhaler in accordance with the third aspect of the invention thus 
preferably comprises a plurality of metering devices arranged in a series, 
in accordance with the fourth aspect of the invention, the series being 
movable as a series through the inhaler by means of the indexing means 
such that each metering device in the series may be moved via the outlet 
conduit from a first position, in which it is presented to the storage 
chamber to receive the substance, to a second position in which a desired 
volumetric dose of the substance has been transferred with that device to 
the inhalation passage. 
So long as there is a sufficient number of metering devices in the series, 
a large number of doses can be delivered to the user without any 
particular metering device necessarily being re-presented to the storage 
chamber after it has reached the inhalation passage. A flexible chain in 
accordance with the invention is able to comprise a large number of 
devices without assuming undue amounts of space in an inhaler. The 
indexing means of an inhaler in accordance with the third aspect of the 
invention is thus preferably operable to move the metering device, or each 
device in a series included in the inhaler, away from the inhalation 
passage after it has reached its second position, in such a manner that 
the metering device is not re-presented to the storage chamber after 
having reached its second position. 
In use of such an inhaler, the metering device moves, via the outlet 
conduit, from the storage chamber to the inhalation passage, where it 
delivers a volumetric dose of the substance, and thence to waste. It is 
not subsequently re-presented to the storage chamber to be filled with a 
further dose of the substance. 
Since the metering device is not re-used, i.e. not used to deliver more 
than one dose of the substance to the inhalation passage, there is no need 
to incorporate in the inhaler means for ensuring that the metering device 
is substantially free from the substance after its presentation to the 
inhalation passage. 
The inhaler preferably additionally comprises a waste chamber, in which the 
metering device may be housed after having been moved, by the indexing 
means, away from the inhalation passage. 
Where the inhaler comprises a plurality of metering devices arranged in a 
series, operation of the indexing means preferably moves the series 
forward through the inhaler by the length of a fixed number of (typically 
one) metering devices, or of intervals between successive devices in the 
series, for each operation. Each metering device would thus pass in turn 
from its first to its second position, i.e. from the storage chamber to 
the inhalation passage, and preferably subsequently away from the 
inhalation passage and to a waste chamber. On passing from its first to 
its second position via the outlet conduit, each device would transfer to 
the inhalation passage a dose of substance, trapped between its first and 
second end elements and the inner walls of the outlet conduit as the 
device passes through the conduit. 
The inhaler preferably comprises a number of metering devices which is 
either equal to or greater than the number of volumetric doses, of the 
substance to be delivered, which the storage chamber of the inhaler is 
adapted to hold. Thus, a large number of consecutive doses of the 
substance can be delivered to a user, even if the metering devices are not 
re-cycled inside the inhaler. 
The metering devices in the series may be of such sizes and shapes as to 
allow delivery of different sized doses of the substance as the series is 
moved through the inhaler. For example, doses could be increased or 
decreased in volume over the length of the series, or otherwise varied in 
accordance with a course of treatment desired to be delivered by means of 
the inhaler. 
Preferably, only one metering device of the series is presented to the 
inhalation passage at a time. Preferably, each time the indexing means is 
operated by a user, the metering device which has last transferred a dose 
of the substance to the inhalation passage is moved forward and replaced 
in the passage by the next metering device in the series. Thus, the 
metering devices are used one after another, and preferably not re-used 
after presentation to the inhalation passage. 
Where the inhaler comprises a series of metering devices, these are 
preferably arranged together in the form of a flexible or semi-flexible 
chain. This chain may then be wound around itself inside the inhaler, 
allowing a relatively large number of metering devices to be stored inside 
the inhaler. The inhaler preferably comprises a metering device housing, 
in which the or each metering device may be housed prior to being 
presented to the storage chamber. A series of metering devices may be 
stored in the housing, used devices then conveniently being housed in a 
waste chamber in the inhaler. 
Alternatively, the metering devices may be housed in the storage chamber 
itself, prior to their being moved via the outlet conduit to the 
inhalation passage. 
The inhaler may comprise more than one series of metering devices, which 
series are moveable through the inhaler in parallel with one another. The 
indexing means of the inhaler would conveniently be operable to move a 
metering device in one series from its first to its second position, and 
at the same time a metering device in another series from its first to its 
second position, such that both metering devices are presented 
simultaneously to the inhalation passage. This inhaler may comprise more 
than one storage chamber to correspond to the respective more than one 
series of metering devices, such that each series delivers, in use, a 
different substance to the inhalation passage. Such an arrangement might 
be of use, for instance, in delivering two drugs which are to be 
administered together but which should be stored separately prior to 
administration. Alternatively, one of the series might be used to deliver 
a placebo and another a drug, relative amounts of the drug and placebo 
delivered being varied as the series are moved through the inhaler in use. 
The metering devices are preferably joined together in the series, either 
permanently or releasably. They are preferably spaced at equal intervals 
along the length of the series, so as to transfer repeated doses of the 
same volume, although the devices may be spaced at intervals if it is 
desired to vary the volume of substance to be transferred by each device. 
In particular, however, the series is preferably continuous, in the sense 
that as the series passes through the outlet conduit, the only substance 
transferred with it is that trapped between the end elements of each 
successive device, there being no spaces between an end element of one 
device and the next end element of the next device in the series. 
Each metering device of the series must have at least a first end element, 
the simplest form being a disc or flange having the same cross-sectional 
size and shape as that of the outlet conduit. Doses of the substance to be 
delivered are thus carried between the end elements of adjacent devices in 
the series. However, the metering devices may comprise bodies of any 
desired size and shape, so as to define an appropriate dosage volume 
between two successive metering devices passing through the outlet conduit 
of the storage chamber. Effectively, the end elements act as "spacers" to 
define dose volumes as the series passes through the outlet conduit. 
The shape of each metering device is preferably also such that, when air is 
drawn through the inhalation passage past a metering device present in the 
passage, substantially no part of the region of the metering device 
between its first and second end elements, which region defines the dose 
of the substance to be delivered, is sheltered from the air flow. 
Thus, in the region of each device between end elements, as large a 
proportion as possible of the outer walls of the device should be parallel 
to the direction of air flow through the inhalation passage, when the 
metering device is presented to the inhalation passage in use. 
The or each metering device, in an inhaler in accordance with the third 
aspect of the invention, may be disposable after it has been moved away 
from the inhalation passage. Alternatively, once all the metering devices 
of a series of devices have been passed through the inhaler, the series 
may be removed, as a chain, cleaned and inserted back into the metering 
device housing. The storage chamber of the inhaler would then be re-loaded 
with a fresh supply of the substance to be delivered, and the inhaler 
operated in the usual way to achieve movement of the cleaned metering 
devices through the inhaler, via the storage chamber and outlet conduit to 
the inhalation passage. 
Where the inhaler comprises a series of metering devices arranged in a 
chain-like conformation, it may also comprise cutting means by which 
individual metering devices, or groups of metering devices, may be severed 
from the series after passing through the outlet conduit. The individual 
devices or groups of devices are more easy to house in the inhaler after 
use. The cutting means may comprise any appropriate arrangement, eg, a 
cutting blade and anvil, preferably linked to the indexing means so as to 
sever a metering device of the series after that metering device has 
passed through the outlet conduit. 
The inhalation passage of the inhaler is preferably so shaped that a dose 
of the substance to be delivered, transferred to the inhalation passage by 
means of the metering device, is subjected to substantially the entire air 
flow through the inhalation passage when air is drawn in via the air 
intake means. In this way, whether air is drawn into the inhaler through a 
single opening or several openings, the air flow through the inhaler is 
such that all of the air flows along a single duct at the point where the 
metering device is presented to the inhalation passage. This helps to 
ensure that the entire dose of the substance is removed from the metering 
device when a user inhales via the air intake means. 
The air intake means may comprise, for instance, a mouthpiece, so that a 
user may suck air into the inhaler using his mouth. Alternatively, it may 
comprise a fitting capable of being inserted into the nostril, allowing a 
user to inhale from the inhaler through his nose. A baffle, of an 
appropriate size and shape, may be included within the mouthpiece or other 
fitting. This, together with the contours of the inhalation passage 
itself, assists in breaking up the substance to be delivered and mixing it 
with air flowing through the passage. 
The indexing means of the inhaler may comprise a ratchet-like mechanism, 
which allows the passage of metering devices in a series through the 
outlet conduit and into the inhalation passage, say, one at a time. This 
will then allow each metering device a "stepped" movement, rather than 
continuous movement, from its first to its second position and 
subsequently away from the inhalation passage. 
For instance, the indexing means may comprise first engaging means for 
engaging a first metering device in the series and conveying it to its 
next position; and biasing means for subsequently urging the first 
engaging means back into engagement with a second metering device in the 
series, thus releasing the first device for subsequent passage through the 
inhaler. A second engaging means preferably engages the series of metering 
devices following release of the first metering device by the first 
engaging means, so that the series is fixed in position whilst the first 
engaging means moves back into engagement with the second metering device. 
The engaging means will need to be appropriately shaped to interact with 
the metering devices, preferably in such a way that substance is not 
released from a metering device, during its movement through the inhaler, 
until that device is in a position to present its dose of substance to the 
inhalation passage. 
The indexing means is preferably operable by pushing down a single button 
or handle on the inhaler to cause appropriate movement of the indexing 
means. For instance, such a button or handle might be connected to a 
piston moveable within the inhaler, which piston comprises at least the 
first engaging means of the indexing means. Preferably, the indexing means 
is linked to the operation of any cutting means in the inhaler, so that a 
single action by the user causes drug delivery, indexing and severance of 
the next used metering device. 
In use, the storage chamber of the inhaler is preferably positioned above 
the inhalation passage, which in turn is positioned above any waste 
chamber included in the inhaler. The metering device is thus moved 
downwardly through the inhaler in normal use, and the substance to be 
delivered flows downwardly with it through the outlet conduit. 
The inhaler may comprise a body made up of two separate components, the 
body defining the storage chamber, inhalation passage, air intake means 
and, where applicable, the waste chamber and the metering device housing. 
The two components of the body are conveniently arranged one at least 
partly inside the other and capable of a degree of telescopic movement 
relative to one another, with the inhaler comprising biasing means to urge 
the two components in a direction away from one another. 
The internal construction of these body components, and the arrangement of 
the metering device(s) inside them, is preferably such that movement of 
the two components in a direction towards one another, against the action 
of the biasing means, releases the metering device(s) for movement from 
one position to the next. In this way, movement of the two components 
relative to one another constitutes operation of the indexing means of the 
inhaler. The biasing means (which may take the form of, for instance, a 
spring) will then urge the two components of the inhaler body away from 
one another again, to a "rest" position in which the metering device which 
has last been presented to the inhalation passage is "captured" in its 
second position until the next operation of the indexing means. 
Preferably, one of the body components defines the storage chamber (and 
preferably also the metering device housing), the other a waste chamber. 
The inhalation passage is preferably defined inside that component which 
also defines the storage chamber. 
An inhaler in accordance with the present invention may also include a 
moisture-absorbent material stored inside the storage chamber, together 
with the substance to be delivered, to ensure that the substance remains 
dry at all times. 
The inhaler preferably includes display means, operable by the indexing 
means so as to display an item of information to a user. The display means 
may, for instance, comprise counter means for indicating to the user the 
number of times that a dose of the substance has been presented to the 
inhalation passage, and/or the number of metering devices still remaining 
to be so presented. Display means of this general type are already known 
for use in conventional inhalers. 
The inhaler may additionally comprise a timer (eg, an electronic or 
mechanical timer) and associated control means for ensuring that the 
substance may only be transferred to the inhalation passage at a desired 
dosage rate and that the user is unable to inhale the substance more often 
than is medically desirable over a given time period. The control means 
may comprise locking means, by which the indexing means is prevented from 
further operation until a predetermined period of time has elapsed since 
its last operation. 
According to a fifth aspect of the present invention there is provided a 
method for transferring a desired volumetric dose of a flowable substance 
from a storage chamber containing the substance to an outlet conduit 
communicating with the chamber, the method comprising the step of passing 
a metering device in accordance with the first aspect of the invention 
from the storage chamber into the outlet conduit so as to cause substance 
surrounding the device in the storage chamber to pass with the device into 
the conduit, in the space defined between the end elements of the device 
and the intervening section of the inner walls of the conduit, the shape 
and dimensions of the device relative to those of the outlet conduit being 
as described in accordance with the first aspect of the invention. 
Such a method may involve the use of an inhaler in accordance with the 
third aspect of the invention, in which case the method may be used to 
transfer the substance from the storage chamber into the inhalation 
passage of the inhaler, via the outlet conduit. 
A metering device according to the first aspect of the invention may in 
particular be used to transfer a desired volumetric dose of a substance 
from a supply to a receptacle in which that dose is to be stored, for 
instance for subsequent use. The receptacle may be part of, for instance, 
a container for carrying one or more doses of a medicament for subsequent 
administration to a patient. The receptacle or container may be for use in 
an inhaler. 
Thus, according to a sixth aspect of the present invention, being an 
embodiment of the fifth aspect, there is provided a method for use in 
loading a receptacle with a desired volumetric dose of a flowable 
substance, the method comprising the steps of providing a storage chamber 
containing the substance and an associated outlet conduit communicating 
with the chamber, and passing from the storage chamber into the outlet 
conduit a metering device according to the first aspect of the invention, 
the shape and dimensions of the device relative to those of the outlet 
conduit being as described in accordance with the first aspect of the 
invention. In this way, substance enclosed between the first and second 
end elements of the metering device and the intervening section of the 
inner walls of the conduit, may be transferred to the receptacle when the 
metering device is passed into the receptacle from the outlet conduit. 
Preferably, the receptacle is itself of such shape and dimensions (ie, 
typically in the form of a conduit passing through a body) that the 
metering device may pass into the receptacle and be located therein with 
its first and second end elements in sealing engagement with the inner 
walls of the receptacle. A dose of substance may then be enclosed in the 
receptacle, trapped by means of the metering device. The relative 
dimensions of the metering device and receptacle are preferably such that 
the device, once located in the receptacle, has a tendency to remain 
therein unless actively urged out of it. Thus, the receptacle and metering 
device together provide a sealed enclosure in which a metered dose of 
substance is or may be contained until such time as the device is urged 
fully or partially out of the receptacle (eg, pushed out) by appropriate 
means. 
According to a seventh aspect of the present invention, there is provided a 
receptacle in combination with a metering device located therein, as 
described above, the space defined by the device and the inner walls of 
the receptacle having been loaded (preferably using the method of the 
sixth aspect of the invention) with a desired volumetric dose of a 
flowable substance. The combination may be used to store and transport the 
dose of substance prior to its use. 
The receptacle may form part of a container including a plurality of such 
receptacles, in each of which a desired dose of a desired substance may be 
held. Preferably, each receptacle in the container includes a metering 
device located inside the receptacle and is loaded with the desired 
flowable substance. The container may be adapted for use, for instance, in 
an inhaler, each dose of substance contained in its receptacles being 
presented to the inhalation passage of the inhaler at an appropriate point 
during use. Thus, the container may be in the form of a drug-carrying 
"magazine" or cartridge. 
According to an eighth aspect, the invention provides a container including 
a plurality of receptacle-metering device combinations in accordance with 
the seventh aspect, as described above. 
In the method according to the sixth aspect of the invention, the 
receptacle is preferably placed adjacent the outlet conduit in such a way 
that one forms a continuation of the other and the substance and metering 
device are able to pass from the outlet conduit into the receptacle 
without the possibility of escape of the substance into the atmosphere. 
Once the metering device has been passed fully into the receptacle, the 
latter may be removed from its position adjacent the outlet conduit. 
Alternatively, the receptacle may itself serve as the outlet conduit, 
communicating directly with the storage chamber, if it is of appropriate 
dimensions relative to the metering device that the desired volume of 
space is defined between the end elements of the device and the 
intervening section of the inner walls of the receptacle as the device is 
passed from the storage chamber into the receptacle. 
For use in a method according to the fifth aspect of the invention, the 
metering device may comprise a body in the form of an appropriately shaped 
spool. However, the method preferably involves passing through the storage 
chamber a plurality of metering devices in accordance with the fourth 
aspect of the invention, each device transferring as it is passed from the 
chamber into the outlet conduit its own metered dose of substance. 
Preferably, in the method according to the sixth aspect, each device is 
passed to a separate respective receptacle, for instance in a container 
comprising several receptacles, so as to load each of the receptacles in 
turn with a desired dose of the substance. 
Thus, such a method may comprise the steps of moving into position adjacent 
the outlet conduit a first receptacle in a series of receptacles; 
transferring a dose of the substance to the first receptacle by passing a 
first metering device from the storage chamber into the first receptacle; 
replacing the first receptacle with a second receptacle in the series of 
receptacles; and transferring a dose of the substance to the second 
receptacle by passing a second metering device (for instance, in a series 
of such devices) from the storage chamber into the second receptacle. 
These steps may be repeated as often as desired. 
Preferably, each metering device of a series of devices passed through the 
storage chamber is separated from the next device in the series after the 
former has been passed out of the storage chamber. The product of such a 
method is a receptacle containing a single metering device and a dose of 
substance transferred with that device, the combination of receptacle and 
device being in accordance with the seventh aspect of the invention. 
According to a ninth aspect of the invention there is provided an inhaler 
for delivering a substance in a finely divided form, the inhaler 
comprising air intake means by which air may be drawn into the inhaler 
from the atmosphere; an inhalation passage communicating with the air 
intake means, through which passage air may be drawn using the air intake 
means; a receptacle and metering device in combination in accordance with 
the seventh aspect of the invention; indexing means operable to move the 
receptacle into a position in or adjacent the inhalation passage; and 
means for urging the metering device at least partially out of the 
receptacle so as to release into the inhalation passage the dose of 
substance contained in the receptacle between the end elements of the 
metering device, when the receptacle occupies its position in or adjacent 
the inhalation passage. 
This inhaler preferably comprises a plurality of such pre-loaded 
receptacle-metering device combinations, the receptacles forming part of a 
larger container. The container may comprise, for instance, a cartridge 
(conveniently circular) adapted for rotation inside the inhaler, by the 
indexing means, so that each receptacle may be positioned in turn in or 
adjacent the inhalation passage. Alternatively, the container may be in 
the form of a chain of receptacles arranged together in a series and 
adapted for linear movement through the inhaler. 
The means for urging the metering device out of the receptacle may 
comprise, for instance, a plunger operable in association with the 
indexing means to push the metering device out of the receptacle.

DETAILED DESCRIPTION OF THE DRAWINGS 
The invention is described firstly by reference to inhalers in accordance 
with the third aspect, which incorporate metering devices in accordance 
with the first aspect. 
Referring firstly to FIG. 1, the body of the inhaler shown comprises two 
components, 1 and 2, arranged one partly inside the other and capable of a 
degree of telescopic movement relative to one another. Component 1 is 
urged in a direction away from component 2 by the action of spring 16 
located within component 2 (here shown in its fully extended 
conformation). 
Component 2 is provided with a mouthpiece 20, seen in the part section 
shown in FIG. 2. Through mouthpiece 20, a user is able to draw air into 
the inhaler and through the inhalation passage 8. Air enters the inhaler 
through an appropriately positioned inlet in the body of the inhaler (not 
shown as such in the Figures). 
Component 2 is also connected to a set of pawls 11. 
Inside component 1, there is defined a metering device housing 4 and a 
storage chamber 21, as well as the inner part of inhalation passage 8. The 
component has an associated set of pawls 12. 
Inside storage chamber 21 is stored a quantity of the substance 6 to be 
delivered to a user via the inhaler. This might be, for example, a 
medicament, and will typically be in a dry, finely powdered form. A 
suitable dessicant may also be stored in chamber 21, to keep substance 6 
dry. 
Running through the inhaler is a flexible chain 3 of metering devices. The 
chain is coiled round on itself and stored in housing 4, and then passes 
downwardly through the inhaler, through opening 5, the storage chamber 21, 
channel 7, the inhalation passage 8, the opening 9, two sets of pawls 11 
and 12 and thence into the waste chamber 13 defined in body component 2. 
In waste chamber 13, the free end of chain 3 is once more coiled round 
upon itself for economy of storage space. 
Each metering device of the chain 3 comprises a solid metering body 15 
having an upper edge ("end element") 15a. These bodies are of such a size 
and shape that, when two successive metering devices in the chain pass 
through the storage chamber outlet channel 7, the space defined between 
the end elements of the two devices and the internal wall of channel 7 is 
of the desired volume to define a dose of substance 6 to be delivered to a 
user of the inhaler. Each body 15 is thus dimensioned as to be able to 
pass through channel 7 with the outer edges of the end elements 15a flush 
with the internal wall of the channel, so as to prevent escape of 
substance 6 between each body and the internal wall. 
The metering devices 15 are typically made from a moulded plastics 
material. A side view of part of chain 3 is shown in FIG. 4. An enlarged, 
perspective view of chain 3, having metering devices 15, is shown in FIG. 
5. One dose of substance 6 is represented by volume V.sub.1. 
In FIG. 2, 17 is a baffle fitted inside mouthpiece 20. 18 is a conical 
recess positioned at the lower end of inhalation passage 8. The conical 
shape of this recess, complementing the shape of the metering devices and 
sloping downwardly, ensures that a metering device passing through it 
carries waste powder downwardly with it and away from the inhalation 
passage 8, preventing subsequent overdosing. 
The inhaler shown in FIGS. 1-3 might typically be used as follows. 
The inhaler would normally be supplied as a sealed unit, storage chamber 21 
being pre-filled with an appropriate quantity of a medicament or other 
substance to be delivered, 6. This substance would be in the form of a 
dry, finely divided powder. 
The inhaler would also be pre-loaded with a chain 3 of metering devices 15, 
stored inside housing 4 and projecting downwardly through chamber 21 and 
inhalation passage 8, with its free end engaged by pawls 11 and 12. 
In use, the inhaler is held vertically upright, i.e. in the orientation as 
depicted in FIG. 1. Substance 6 then "floods" around the metering devices 
15 in storage chamber 21, such that as two successive metering devices in 
the chain pass down through channel 7, the space between their end 
elements is packed with a predetermined quantity (volume V.sub.1) of the 
substance. Thus, each metering device passing into inhalation passage 8 
through channel 7 will also have passed through chamber 21 and received a 
dose of substance 6. 
To release this dose, the user sucks air into the inhaler via mouthpiece 
20. The air passes through the inhalation passage 8, collecting the dose 
of substance 6 from between the metering device 15 currently positioned in 
the inhalation passage and the next metering device in the chain. The air 
then passes out of the mouthpiece past baffle 17, which encourages breakup 
of substance 6 and its mixing with the air flow. 
The inhalation passage 8 is internally contoured such that the substance 6 
held by a metering device inside the passage is subjected to substantially 
the entire air flow through the passage and into the mouthpiece 20. 
Accordingly, the air flow through the passage 8 is along a single duct at 
the point where metering device 15 is presented to the air flow. All of 
the substance 6 should thus be removed from the metering device by the air 
flow. 
To operate the inhaler so as to move the chain of metering devices through 
the inhalation passage 8, the procedure is as follows. Upper body 
component 1 is depressed in a direction towards lower body component 2, 
against the action of spring 16 (see FIG. 3), such that one further 
metering device 15 of chain 3 is pushed through the pawls 11 which are 
connected to lower component 2. When the user releases upper component 1, 
spring 16 urges this component away from lower component 2. Chain 3 now 
remains fixed in position relative to component 2, being gripped by pawls 
11, but moves downwardly by one metering device through pawls 12, which 
are connected to component 1. Pawls 11 and 12 then engage with the 
undersides of the next metering devices in the chain 3. Spring 16 is 
thereby allowed to return to its decompressed length (as in FIG. 1). 
Repeated operation of the inhaler in this way causes the chain 3 to 
progress in a stepwise manner from the upper to the lower component, one 
metering device 15 passing through inhalation passage 8 at a time. In 
effect, the two sets of pawls 11 and 12 act together, hand-over-hand, to 
move the chain 3 as one might pull a rope. Each depression of component 1 
places a new metering device 15 in position in passage 8. A user can then 
inhale through mouthpiece 20 to release the dose of substance 6 
transferred by the metering device. Subsequent depression of component 1 
moves the now discharged metering device out of passage 8 towards opening 
9, and the next metering device in the chain passes into passage 8, 
carrying a fresh dose of substance 6. 
The discharged metering devices are moved downwardly, in this ratchet-like 
manner, into waste chamber 13. They are not re-presented to storage 
chamber 21 for re-use. 
If the user fails to inhale a dose of substance 6 after operating the 
inhaler, that dose should fall into the conical recess 18, from whence 
subsequent operation of the inhaler will cause it to be carried through 
opening 9 and into waste chamber 13. 
In one embodiment of the invention, means (not shown in the figures, but 
for instance an electrically operated drive means) may be provided to 
assist the user in effecting movement of the chain 3 through the inhaler, 
against the resistance provided by spring 16 and pawls 11 and 12. 
For the inhaler of FIGS. 1-3, it is intended that when the entire length of 
the metering device chain 3 has passed through the inhalation passage 8, 
the complete inhaler, including enclosed metering devices, is discarded. 
An alternative, and often preferred, type of metering device, for use in 
the inhaler of FIGS. 1-3, is shown in perspective view in FIG. 6. In this 
case, chain 30 is made up of metering devices 31, each being a solid body 
with an upper end element 32, again of such a size and shape that a 
desired volumetric dose, V.sub.2, of substance 6 can be retained between 
two successive devices in the chain as they pass through channel 7 of the 
inhaler. 
Each metering device 31 has an upper, disc-like portion 32 (the end 
element), of diameter such that its outer edges sit flush with the inner 
wall of channel 7. It also has a lower, narrower portion 33, having 
straight sides parallel to the longitudinal axis of chain 30. Such a 
straight-sided portion means that air flow past the metering devices in 
inhalation passage 8 is more likely to dislodge all of the dose of 
substance 6 held between two adjacent metering devices 31 and being 
presented to the inhalation passage. There is no region of volume V.sub.2 
which is "sheltered" from the air flow, as there might be in the case of 
the metering devices 15 shown in FIGS. 4 and 5. 
This is illustrated more clearly in FIGS. 7 and 8. FIG. 7 shows a section 
taken along the line VII--VII in FIG. 4, and illustrates how air would 
flow past the metering device 15 when the device was presented to the 
inhalation passage and a user inhaled through mouthpiece 20. Most of the 
dose of substance 6, held between the metering device and the next device 
in the chain, and defined as the two devices passed through channel 7, 
would be dislodged by the air flow and pass to the user. However, an area 
34 would be sheltered from the air flow and substance 6 could remain 
lodged around the metering device, resulting in an underdose to the user. 
The corresponding situation for metering devices 31, of FIG. 6, is shown in 
FIG. 8. Here, there is no area sheltered from the air flow and all of a 
dose of substance 6 presented to the inhalation passage is likely to be 
dislodged and delivered to the user. Naturally, the devices 31 must be 
positioned in use such that the sides of the narrower portions 33 are 
parallel to the normal direction of air flow through the inhalation 
passage 8. 
Metering devices 31 are also easier to produce than are devices 15. 
FIGS. 9A, 9B, 10A, 10B, 11A, 11B, and 11C show inhalers in accordance with 
the third aspect of the invention which incorporate cutting means for 
severing individual metering devices from a chain after use, for ease of 
storage of the discarded devices. 
The inhaler shown in FIG. 9A (in longitudinal cross-section in FIG. 9A and 
transverse cross-section in FIG. 9B) comprises a metering device housing 
40, in which a chain 41 of metering devices is wound spirally around a 
central cylindrical core 42, as shown, ready for use. Core 42 is able to 
rotate about axle 51. Chain 41 passes over a roller 43 through drug 
storage chamber 44 and then into inhalation passage 45, movement of lower 
devices in the chain being drawn by piston 46 acting against spring 47, in 
a similar manner to that in which the inhaler of FIGS. 1 and 3 functions. 
At its upper end, piston 46 is connected to a push button control (not 
shown) operable by the user to index metering devices through the inhaler. 
At its lower end, the piston is fixed to a blade 48. 
Each time the user presses the push button down, the chain of metering 
devices moves downwards through the inhaler by one device. The blade 48 
also moves downwards, severing one more metering device from the end of 
the chain 41 as it passes below the blade. The severed metering devices 
are stored in waste chamber 49. 
Circle 50 indicates where an anvil might be positioned, against which blade 
48 would rest in each cutting movement. 
In the inhaler shown in FIG. 10A, a horizontal blade 55 is mounted below 
piston 56, opposite an anvil 57 (in the form of a metal insert in the side 
wall of the inhaler). FIG. 10B shows how movement of the piston 56 
downwards (operated by a push button control, as is piston 46 in FIG. 9A) 
causes blade 55, mounted in a slide 58, to move out and strike the anvil. 
The slide 58 is pushed in this direction, against the action of spring 59, 
because of the interaction between the shaped lower portion 60 of the 
piston 56 and slot 61 in the slide 58. The slide is mounted within the 
inhaler casing. 
Severed metering devices such as 62 are stored in waste chamber 49, as seen 
in FIG. 10A. Other structural and operational features of the FIG. 10 
inhaler are the same as those of the FIGS. 9A, 9B and 9C inhaler. 
In another similar inhaler, part of which is shown in FIG. 11A, two 
horizontally oriented blades 66 are mounted in a piston 67, the two 
flexible legs 68 of which when pushed downwardly by the user flex inwardly 
due to the presence of rollers 69. As the blades 66 come together, a 
metering device is cut from the end of chain 41 and falls to waste into 
chamber 49. 
Operation of the piston 67 is shown in FIG. 11B, the top drawing showing 
the piston in its "at rest" position and the bottom drawing the piston 
when pressed down by the user. 
Note that in the FIGS. 11A, 11B and 11C inhaler, the piston 67 comprises 
upper flexible legs 70 to prevent the chain 41 from pulling back and 
effecting a double dose. This in turn allows a reduction in the space 
below the inhaler mouthpiece 71, labelled x in FIG. 11A. Because of this, 
a spring performing an equivalent function to spring 47 in FIGS. 9A, 9B 
and 9C must be positioned elsewhere in the inhaler other than cavity 72 
(eg, directly below the user-operated push button, not seen in FIG. 11A). 
In the inhalers of FIGS. 9A, 9B, 10A, 10B, 11A, 11B and 11C, a single 
operation of the push button effects not only dose delivery, but also 
reindexing of the metering devices and their severance for storage in 
waste chamber 49. 
It can also be seen in the inhalers of FIGS. 9A, 9B, 10A, 10B, 11A, 11B and 
11C that the relevant parts of the pistons 46, 56 and 67 are level with 
the metering devices that they convey into the inhalation passages, so 
that in each case the metering device and piston move downwardly together. 
This prevents any powder, from the metering device being conveyed, from 
falling to waste during movement of the metering device from the drug 
storage chamber to the inhalation passage. 
FIGS. 12A and 12B shows how a chain 75 of metering devices may be stored in 
an inhaler according to the invention, in a housing 76 located adjacent 
the drug storage chamber 77 and above the inhalation passage 78. Parts 
only of the inhaler are shown, schematically, in FIGS. 12A and 12B, by 
means of longitudinal cross-sections viewed from the side (FIG. 12A) and 
from the front (FIG. 12B). 
The chain 75 is wound spirally around a cylindrical core which may have 
lugs on its outer surface for accurate location of the chain. The core is 
able to rotate about a central axle to allow the chain to unwind in a 
controlled fashion over a freewheeling roller 82, as the metering devices 
are pulled through the inhaler by indexing means (not shown). 
FIGS. 13 and 14 show an inhaler which incorporates a preferred form of 
indexing means consisting primarily of a piston 90 (manually operated by 
means of a handle 91 protruding through the side wall of the inhaler) and 
a spring 92. A chain 93 of metering devices (sequentially numbered, for 
clarity) is shown passing through drug storage chamber 94, its outlet 
conduit 99 and inhalation passage 95. 
FIG. 13 shows the indexing means in its "at rest" position. A dose of 
powder, 96, is held in readiness for delivery between metering devices 4 
and 5 and the inner walls of outlet conduit 99. Piston 90 is held in 
position by the upward action of spring 92. 
When the user wishes to release the dose of powder 96, he does so by 
pushing handle 91 downwardly, against the action of spring 92 (FIG. 14). 
Piston 90 moves down, its legs carrying chain 93 with it, and the dose 96 
is released into the inhalation passage 95, as shown, as the user inhales 
(the user must continue to hold the handle 91 down as he inhales). The 
direction of air flow is indicated by the arrows. 
When the user releases handle 91, piston 90 returns to its "at rest" 
position under the action of spring 92, but chain 93 is prevented from 
returning by the legs 97 of the inhaler body. A fresh dose 98 is now 
trapped between metering devices 5 and 6 in the outlet conduit 99, and the 
inhaler is ready for re-use. 
One particular use for an inhaler according to the third aspect of the 
present invention, to provide a programmed dose variation, might be as 
follows. In some therapies it is desirable to vary the dose of drug 
delivered to a recipient from a dry powder inhaler during a course of 
treatment. A typical example of this is a course of treatment for 
individuals wishing to give up smoking cigarettes. Here the principal 
difficulty is the smoker's addiction to nicotine inhaled in cigarette 
smoke. It is believed that the addiction can be overcome by taking a 
course of nicotine that reduces the smoker's craving by gradually reducing 
the amount of nicotine absorbed over a controlled period of time. 
A number of products are currently available which purport to do this, one 
such product being an adhesive patch containing a nicotine formulation 
which is placed on the body so that the nicotine may be absorbed into the 
blood stream through the skin. Patches are placed on the body at regular 
intervals, usually every 24 hours, and over a period of time (typically 
three months) the size of the patch or strength of formulation is reduced 
to zero. 
There are a number of problems with this approach, but it is believed that 
the principle drawback is that the rate of nicotine absorption into the 
blood stream is slow and varies between recipients. 
The perceived benefit of smoking is that nicotine enters the blood stream 
almost immediately the smoke is inhaled. Delivering a nicotine formula 
directly to the lungs by inhalation may give a similar immediate effect. 
However, the drawbacks to the use of inhalers (dry powder or aerosol type) 
of designs presently available are two fold: 
1. the current designs generally deliver a consistent amount of formulation 
on each operation of the device; 
2. there is no feature that limits the number of deliveries over a time 
span. 
An inhaler in accordance with the present invention may be used to overcome 
either or both of these drawbacks. 
By altering the dimensions and shape of each metering device of a series, 
the volume of substance transferred by that device can be altered. If this 
alteration takes place progressively from one end of the series of 
metering devices to the other, the volume of substance carried, and hence 
the amount the patient inhales, can be progressively altered. In the 
circumstances of a dose of nicotine formulation, discussed above, this 
would mean making the volume of substance progressively smaller as the 
series passes through the inhaler in use. 
An example of such a series of metering devices is shown in FIG. 15, in 
which successive devices 101-105 are shaped so as to carry progressively 
(in this case) smaller doses 106-110 of a substance to be delivered. Such 
a chain of metering devices could be used, for example, in any of the 
inhalers shown in FIGS. 1-3 or 9-12. The chain effectively incorporates a 
"programme" of dose deliveries. 
In practice, it may be found that at some stage in a course of treatment 
the volume of substance delivered becomes too small for the user to 
taste/sense, if the substance is flavoured for example. If this proves to 
be the case, an inhaler having two flexible chains of metering devices 
indexed in parallel could be constructed, one chain (a) passing through a 
storage chamber containing a drug formulation and the second chain (b) 
passing through a second chamber containing a placebo. The chain (a) would 
be arranged to dispense a maximum amount of drug at the beginning of a 
course of treatment and a minimum amount of drug at the end of the chain; 
the chain (b) would be arranged to dispense a minimum amount of placebo at 
the beginning and a maximum amount of placebo at the end of the chain. 
Thus, with the metering devices indexing in parallel through the inhaler, 
the total volume dispensed from a pair of metering devices on each 
inhalation remains consistent throughout the life of the inhaler. 
This arrangement could also be used in circumstances requiring the 
dispensing of two type of drugs that may not be suitable for storing in 
one chamber. 
In order to overcome the potential problem of a user inhaling more 
frequently than is desirable, the inhaler may be fitted with a timing 
mechanism. This could comprise a simple light, an electrically operated 
flag or a mechanically operated flag operated by a clockwork mechanism, or 
a more sophisticated electronic timing device operating a lock mechanism. 
FIGS. 16 and 17 are perspective views of drug-carrying containers in 
accordance with the eighth aspect of the invention. Each container 
comprises a plurality of receptacles in accordance with the seventh aspect 
of the invention, in each of which receptacles a desired volumetric dose 
of a substance, in this case a drug, is held. The two containers are for 
use in an inhaler in accordance with the ninth aspect of the invention. 
The container 120 shown in FIG. 16 is in the form of a "bandolier" made up 
of a series of units 121. Each unit, or receptacle, 121 is in the form of 
a cuboid body having an open-ended cylindrical conduit 122 running through 
it. A metering device 123, in the form of a spool, is located inside each 
conduit 122. Each spool 123 has upper and lower flanges 124 and a narrower 
neck portion 125. The flanges (end elements) 124 are a tight but slidable 
fit inside the conduit 122 and the overall length of the spool 123 is more 
or less the same as the overall length of the conduit 122. 
When the bandolier 120 is ready for use in an inhaler, each conduit 122 
contains one spool such as 123, and is filled with a powdered drug which 
occupies the space defined between the flanges 124, the neck portion 125 
and the inner walls of the conduit 122. The spool 123 and the conduit 122 
are of such dimensions that this space is of the precise volume of the 
dose of drug to be delivered in use. Because the flanges 124 are a tight 
fit inside conduit 122, they provide seals at the open ends of the 
conduit, to prevent escape of the drug contained in it. The spools may, 
however, be pushed out of either of the open ends of the conduits by 
suitable means provided in the inhaler, at the time when the dose of drug 
contained in the conduit is to be delivered to the user. 
The container 128 shown in FIG. 17 is in the form of a disc which carries 
around its periphery a series of conduits 129 similar to conduits 122 
shown in FIG. 16. When the container is ready for use, each conduit 129 
contains a metering device of similar form to spool 123 shown in FIG. 16, 
with a desired quantity of drug trapped between the outer flanges of the 
metering device and the inner walls of the conduit 129. Each of the 
conduits in the container thus contains one dose of the drug, each to be 
delivered to a user in turn when the container is used in an inhaler. The 
doses may be of the same or differing amounts in the conduits of the 
container; if they are of differing amounts, this may be achieved by using 
metering devices of differing shapes and sizes. 
FIG. 18 shows schematically how the container 128 of FIG. 17 may be loaded 
with a drug prior to use in an inhaler. The method being used is in 
accordance with the sixth aspect of the present invention, and would be 
equally applicable to loading a container such as 120 shown in FIG. 16. 
A supply of the desired drug 132 is contained in storage chamber 133. A 
chain of metering devices (spools) 134 is arranged to run downwardly 
through the storage chamber 133 and its outlet conduit 135. The container 
128 is positioned so that one of its conduits 129 sits directly below the 
outlet conduit 135. 
The drug 132 in chamber 133 "floods" around the spools 136 in chain 134. 
The chain is moved downwardly by appropriate means (not shown in FIG. 18) 
so that the next spool at the lower end of the chain is pushed firstly 
down through the outlet conduit 135 and then into conduit 129. The two 
conduits 135 and 129 are of the same dimensions. Thus, as a spool 136 
enters outlet conduit 135, it carries with it the desired quantity of drug 
132 in the space bound by its upper and lower flanges and the inner walls 
of the outlet conduit 135. This accurately defined dose of the drug is 
also transferred to conduit 129 in the container 128, as the chain 134 is 
moved further down and the spool enters the conduit 129. 
By appropriate means (again not shown in FIG. 18), the container 128 is 
then rotated so that the next conduit 129 moves into position below outlet 
conduit 135, and the chain 134 is moved downwardly once more by the length 
of one metering device 136. As this happens, the next device 136 in the 
chain enters the next conduit 129, again carrying with it the required 
dose of drug 132. In this way, by moving in a stepwise fashion both the 
conduits 129 and the chain 134 of metering devices, each of the conduits 
129 in container 128 may be loaded with a spool 136 and a dose of drug 132 
of an appropriate amount, ready for subsequent use of the container. 
A number of storage chambers such as 133, each containing a different drug, 
may be appropriately mounted relative to the container being filled, so 
that different receptacles in the container may be filled with different 
drugs. If different receptacles are to contain different sized doses of a 
drug, the chain 134 should be made up of appropriately positioned metering 
devices of the necessary sizes and shapes. 
FIGS. 19A, 19B and 19C, shows an inhaler in accordance with the ninth 
aspect of the present invention, in various stages of its use. The exact 
construction of most parts of the inhaler 140 is not critical to the 
invention, although it can be seen that it comprises a cover 141 which is 
removed prior to use (FIGS. 19B and C) and a mouthpiece 142 through which 
the user may suck air which enters the inhaler as shown at 143 and passes 
through the inhalation passage 144. 
The inhaler 140 contains a disc-like magazine 145, similar to the container 
shown in FIG. 17 and having a plurality of drug-carrying receptacles 
around its periphery. Suitable indexing means, including a push button 146 
and a ratchet mechanism 147, engages with the upper surface of disc 145. 
As shown in FIG. 19B, depression of the push button 146 (as shown by the 
arrow) pushes spool 148 downwards and almost fully out of a first 
receptacle, positioned adjacent the inhalation passage 144, into the 
inhalation passage (FIG. 19B). As the spool 148 is pushed into the 
inhalation passage, it carries with it the measured quantity of drug which 
it has been used to contain inside the magazine 145. The user can then 
inhale through the mouthpiece 142 so as to take up the drug now released 
into the inhalation passage. The upper flange of the spool remains, 
however, held by the lower part of the receptacle. 
When the user then releases push button 146, the ratchet mechanism 147 
causes disc 145 to rotate by one step so that the next receptacle is 
brought into register with the inhalation passage 144. The inhaler is thus 
reset and ready for delivery of another dose of drug. The "empty" spool 
148, not having been pushed fully out of the first receptacle, continues 
to move round with the first receptacle, supported by the lower guide 150. 
In an inhaler such as that shown in FIGS. 19A, 19B, and 19C, the metering 
devices may alternatively be pushed upwardly towards an inhalation passage 
positioned above the drug-filled receptacles in use. 
FIG. 20 shows an exploded perspective view of the components of the inhaler 
140 shown in FIG. 19. It can be seen that the upper surface of disc 145 is 
specially profiled so as to engage with the ratchet mechanism 147 provided 
on the underside of push button 146. The inhaler is also provided with 
conventional display means (not shown) for displaying to the user, through 
window 149, an indication of the number of doses already taken or 
alternatively of the number of doses remaining in magazine 145. 
It will be understood that an inhaler such as that shown in FIGS. 19A, 19B 
and 19C and 20 is only one example of an inhaler according to the ninth 
aspect of the invention. Other examples, comprising different types of 
drug container, different ways of mounting the container, different types 
of indexing means, etc are also possible. The container may, for instance, 
take the form of a chain of receptacles such as the bandolier 120 shown in 
FIG. 16. Each receptacle in the container may carry more than one metering 
device, if necessary to increase the capacity of the container overall. 
The inhaler may be provided pre-loaded with a container carrying the 
required number of drug doses. The container may be removable and 
refillable or replaceable once empty. 
The advantages of using a metering device in accordance with the present 
invention, particularly in a powder inhaler, are that the volume of 
substance transferred with each metering device can be accurately 
controlled. In a drug-carrying container in accordance with the invention, 
the type of substance carried may be different in each of its receptacles. 
In an inhaler in accordance with the third or ninth aspect of the 
invention, the use of a metering device in accordance with the first 
aspect ensures that the accurately defined dose of drug carried with the 
metering device is entirely transferred to the inhalation passage and may 
then be subject ed to substantially all the air flow, thus reducing the 
risk of the user receiving an incorrect dosage.