HK1169060B - Dry-powder inhaler - Google Patents

Description

Dry powder inhaler

Technical Field

The present invention relates to a dry powder inhaler for delivering dry powder medicament doses to a patient. More particularly, the present invention relates to an inhaler of the type in which the medicament doses are stored in a medicament carrier in the form of a blister pack.

Background

Inhalers for delivering a medicament to a patient by inhalation are known. Such devices include metered dose inhalers and dry powder inhalers.

Metered dose inhalers typically comprise a container containing at least a pressurised propellant and medicament together with a metering valve and some form of actuator for dispensing a dose of liquid medicament as an aerosol. In contrast thereto, dry powder inhalers comprise a supply of dry powder medicament and means for anti-agglomeration aerosolisation of the medicament into a form suitable for delivery to a patient.

Dry powder inhalers are generally considered easier to use than metered dose inhalers due to the difficulty in coordinating the actuation of the metering valve of a metered dose inhaler with the inspiratory effort of the patient. Also, dry powder inhalers do not require a propellant as the medicament is aerosolized and delivered using the patient's inspiratory airflow.

It has been recognized that in order to aerosolize and deliver consistent doses of dry powder drug in an effective manner, the moisture content of the drug must be carefully controlled. In dry powder inhalers this can conveniently be achieved by storing the medicament dose in a blister pocket of a sealed blister pack. In using such devices, the medication dose is typically released by piercing, abruptly fracturing or peeling a portion of the cover sheet of the blister pack just prior to delivery of the dose to the patient for inhalation.

One known dry powder inhaler of this type is disclosed in us patent No.5590645, in which medicament doses are stored in blister packs. The blister pack of the inhaler is formed as a flexible elongate strip and comprises a base sheet having a plurality of recesses spaced along its length and a cover sheet hermetically but peelably sealed to the base sheet to define a plurality of blisters each containing an identical dose of medicament.

The inhaler of us patent No.5590645 includes a medicament dispensing mechanism arranged such that on each actuation of the inhaler, the medicament dispensing mechanism peels a portion of the cover sheet of the blister pack away from the base sheet, thereby opening the blister. The medicament dispensing mechanism comprises a blister strip indexing means for moving an open blister into alignment with a medicament aperture formed in a manifold of the inhaler, the manifold being in fluid communication with a mouthpiece through which a patient can inhale. The unused portion of the blister strip and the used portions of the base and cover sheets are stored in the body of the inhaler.

In use of the inhaler described above, the patient exposes the mouthpiece by rotating the cap relative to the inhaler body and operates the trigger to actuate the medicament dispensing mechanism. The patient then inhales through the mouthpiece to inhale air from within the inhaler body through the manifold. The airflow through the mouthpiece and manifold carries the dry powder medicament contained within the open blister pocket, which is delivered to the patient in the form of an aerosol. The trigger and cover of the inhaler are then returned to their initial positions to reset the medicament dispensing mechanism ready for subsequent use.

Although dry powder inhalers of the type disclosed in us patent No.5590645 have improved consistency in the amount of dose delivered to a patient, there is still a need for inhalers with improved dose consistency. In particular, there is a need for an inhaler that minimizes the risk of overdosing or under-dosing.

Disclosure of Invention

According to a first aspect of the present invention there is provided an inhaler for delivering dry powder medicament to a patient from an open blister pocket of a blister pack, the blister pack being in the form of a flexible elongate strip comprising a base sheet having a plurality of recesses spaced along its length and a cover sheet peelably sealed to the base sheet to define a plurality of blister pockets each containing a measured dose of medicament, the inhaler comprising:

a medicament dispensing mechanism for opening a blister of the blister pack, the medicament dispensing mechanism comprising peeling means for peeling a cover sheet from a base sheet of the blister pack;

a housing for enclosing used and unused portions of the blister pack together with the medicament dispensing mechanism; and

a manifold through which air can be inhaled when using the inhaler, the manifold comprising: an air inlet for receiving outside air; at least one medicament aperture for communicating with an open blister of the blister pack to enable medicament to be carried by air drawn through the manifold; and an air outlet for delivering the entrained medicament to a patient;

wherein the medicament dispensing mechanism comprises a driven cover sheet winding wheel for winding up and applying tension to a used portion of the cover sheet, and a guide surface for guiding the cover sheet of an unused portion of the blister pack, the ends of the guide surface being disposed adjacent to an outside surface of the manifold and defining a peeling edge,

such that, in use, the cover sheet is peeled away from the base sheet at the peel edge and a used portion of the cover sheet passes between the peel edge and the outside surface of the manifold and the opened blister pocket is moved into alignment with the at least one medicament aperture of the manifold,

wherein the manifold and the guide surface are defined by separate components of the inhaler.

Preferably, in use, the outer side surface of the manifold separates the base sheet from the cover sheet.

During assembly of the inhaler, a portion of the cover sheet passes through the gap between the peel edge and the side surface of the manifold and then engages the cover sheet winding wheel. By providing an inhaler in which the guide surface and the manifold are defined by separate components, the width of the gap between the stripping edge and the manifold in the assembled inhaler can be minimised. For example, the used portion of the cover sheet may be passed through the gap before assembly of the components, when the gap is relatively wide, and then the components may be assembled with the blister pack into the inhaler with the gap having a reduced width, for example only slightly wider than the thickness of the cover sheet. Typically, in use, the outside surface of the manifold and the peel edge are arranged to define a gap sufficient to enable the cover sheet to pass therethrough, the gap being less than or equal to about 1 mm, preferably less than or equal to about 0.8 mm, more preferably less than or equal to about 0.4 mm. Preferably, the gap is from about 0.1 mm to about 0.8 mm, preferably from about 0.2 mm to about 0.6 mm, more preferably from about 0.2 mm to about 0.4 mm. Preferably, the gap is less than half, more preferably less than a quarter, even more preferably less than an eighth of the respective width of the recesses in the substrate. By minimizing the width of the gap, the risk of medicament being lost from an open blister pocket when the blister pack is moved from the peeling edge into alignment with the at least one medicament aperture of the manifold during use of the inhaler is minimized. In this way, under-dosing (and possible subsequent overdosing) can be avoided, the likelihood of the device becoming clogged is also reduced, and the device can be more easily adjusted to accommodate different formulation characteristics.

The housing may include an inner housing member disposed within at least one outer housing member. The manifold may be defined by the at least one outer housing component. The guide surface including the peeling edge may be defined by the inner housing member. The used portion of the cover sheet may penetrate into the gap between the peeling edge and the outside surface of the manifold when the gap is relatively large, either before or during assembly of the inhaler. The components can then be brought together in the assembled inhaler to reduce the size of the gap.

The at least one outer housing member may comprise a pair of outer housing members defining an outer shape of the inhaler.

In some embodiments, the inner housing member and the at least one outer housing member may comprise positioning means for positioning the inner housing member relative to the at least one outer housing member. The positioning means enables an accurately controllable and repeatable gap to be provided between the stripping edge and the outside of the manifold. The positioning means may comprise engagement projections and recesses formed in the inner housing member and the at least one outer housing member, the engagement projections and recesses being arranged to engage with each other to fix the positioning of the inner housing member relative to the at least one outer housing member.

In some embodiments, the inner housing member defines an inner transverse wall extending in a width direction of the blister pack for separating a used portion of the cover sheet from an unused portion of the blister pack. Since the used portion of the cover sheet may carry residual amounts of medicament left over due to a previous actuation of the medicament dispensing mechanism, the risk of overdosing may be reduced by separating the used portion of the cover sheet from the unused portion of the blister pack to prevent contamination of the unused portion of the blister pack. Loose medication may also cause the inhaler to not work smoothly and may cause the user to think that the inhaler is clogged.

By "spaced apart" it is meant that the inner transverse wall serves to make it more difficult for the medicament of the used portion of the cover sheet to contaminate the unused portion of the blister pack.

The medicament dispensing mechanism may further comprise a driven basesheet winding wheel for winding up a used portion of the basesheet, and the inner housing member may further define an inner transverse wall extending in a width direction of the blister pack for separating the used portion of the basesheet from an unused portion of the blister pack. Similar to the used portion of the cover sheet, the used portion of the base sheet may also carry residual medicament, and it is therefore advantageous to separate the used portion of the base sheet from the unused portion of the blister pack.

The inner transverse walls of the inner housing member may define separate compartments for receiving the used portion of the cover sheet and the used portion of the base sheet, and the separate compartments are arranged to receive loose medicament, that is to say to prevent loose medicament from contaminating the unused portion of the blister pack. The inner transverse wall of the inner housing member may further define a separate compartment for accommodating an unused portion of the blister pack.

The inner transverse wall may extend in a vertical direction from a base surface of the inner housing member, the base surface of the inner housing member being arranged to support a side edge of an unused portion of the blister pack, which may be rolled up. Thus, the inner housing member may actually be in the form of a tray having respective compartments for receiving used and unused portions of the blister pack.

One of the pair of outer housing members may be arranged to support opposite side edges of an unused portion of the blister pack. The outer housing member and the inner housing member may be arranged to substantially enclose an unused portion of the blister pack. In this way, the unused portion of the blister pack may be protected from contamination by the used portions of the base sheet and the cover sheet.

In some embodiments, the manifold and one of the pair of outer housing members may be provided as a one-piece moulded plastics component, such that the one-piece moulded plastics component defines, in use, at least a portion of an outer surface of the inhaler in which the air inlet is arranged. By providing the manifold with the air inlet and the part of the housing defining the outer surface of the inhaler, in which the air inlet is arranged, as a unitary component, the risk of air within the inhaler housing being drawn into the manifold can be minimized. It is desirable to avoid air within the housing being drawn into the manifold as such air may carry loose medicament remaining in the housing due to previous actuation of the medicament dispensing mechanism, e.g. medicament that has not been inhaled or medicament that has not been completely inhaled.

Preferably, the air inlet of the manifold defines the only location for external air to enter the inhaler, and/or the manifold is arranged such that, in use, air is drawn into the manifold only through the air inlet, that is to say air cannot be drawn through any part of the inhaler other than the unitary part (including, of course, the open blister pocket of the blister pack).

The unitary component defines, in use, at least a portion of the outer surface of the inhaler surrounding the air inlet of the manifold, and may in fact define the entire outer surface of the inhaler surrounding the air inlet. In some embodiments, the outer surface surrounding the air inlet may be defined in part by other components such as a cap, mouthpiece insert, and the like.

The air inlet of the manifold may have an elongated cross-sectional shape, and the cross-sectional area of the manifold may decrease in the direction of airflow. With this arrangement, the air flow velocity within the manifold is lowest at the air openings, which may reduce the risk of loose powder or other contaminants being carried around the air inlets.

The manifold may comprise at least two medicament apertures arranged sequentially in the direction of airflow of the manifold, namely a first medicament aperture for the flow of air from the manifold into an open blister pocket and a second medicament aperture for the flow of entrained medicament from an open blister pocket into the manifold. In this case, the geometry of the manifold may be particularly configured to direct air from the air inlet to the open blister pocket through a first medicament aperture and to direct entrained medicament from the open blister pocket to the manifold through a second medicament aperture.

The geometry of the manifold may be configured to provide the required flow by providing an air flow restriction means for restricting air flow between the first and second medicament apertures within the manifold, for example by providing a local reduction in the cross-sectional area of the manifold. Such a local reduction in the cross-sectional area of the manifold may take the form of a protrusion on the wall of the manifold opposite the medicament aperture.

The integrally moulded plastics component may further define a mouthpiece arranged, in use, to receive entrained medicament from the air outlet of the manifold. The end of the mouthpiece may be provided with a mouthpiece cover or insert having a surface around which the patient can seal his lips comfortably.

The manifold and mouthpiece may be arranged such that the direction of airflow in the mouthpiece is substantially perpendicular to the direction of airflow in the manifold and a turn of the airflow is adjacent the at least one medicament aperture, such that entrained medicament can be delivered from the open blister pocket to the patient along a substantially straight path.

The cross-sectional area of the mouthpiece may increase in the direction of airflow and the tapered wall of the mouthpiece may be provided with a plurality of airflow diversion apertures. The airflow diverter aperture is preferably in fluid communication with the manifold such that: in use, air from the manifold is drawn through the airflow diverting apertures. The airflow diverting apertures may be arranged such that: in use, air is drawn through the airflow diverting holes in a direction substantially parallel to the central axis of the mouthpiece (at an acute angle to the mouthpiece wall) for preventing excessive lateral diffusion of the entrained medicament in the mouthpiece.

The at least one drug aperture may be provided with at least one barrier for preventing agglomeration of the carried drug. The obstruction may in effect act as a divider to divide each orifice into a plurality of sub-orifices. In use, the agglomerated drug particles collide with the separator, which results in fragmentation of the agglomerated drug particles.

In some embodiments, the unitary component is a molded component and may be formed of plastic. Suitable materials for the unitary component are formed from materials selected from the group consisting of: polyolefins, including polyethylene, particularly High Density Polyethylene (HDPE), polypropylene; polyesters, including polyethylene terephthalate; polyamides, including nylon; thermosetting polymers including urea formaldehyde, melamine, epoxy and polyimide; and mixtures or copolymers of the above materials.

The inhaler may further comprise a dose counter, wherein the dose counter comprises:

a display aperture formed in one of the pair of outer housing members;

a display element having a plurality of dose counting indicia, the display element being rotatably mounted within the housing such that a series of dose counting indicia are sequentially visible through the display aperture as the display element is rotated about an axis of the exterior shape of the inhaler; and

drive means for progressively rotating the display element in response to actuation of the medicament dispensing mechanism.

Such a dose counter may enable the patient to reliably determine how many times the medicament dispensing mechanism has been actuated, which helps to avoid overdosing or inhalation of multiple doses.

The display aperture formed in the outer housing part may be provided with a magnifying lens arranged to magnify the dose counting indicia of the display element. In this way, the patient may more easily see the information on the dose counter and/or may be provided with a greater number of indicia. The magnifying lens may be a convex lens formed of, for example, a transparent plastic.

Since the dose counting indicia of the display element is enlarged, the actual size of the indicia may be relatively small, thereby enabling the display element to be provided with a large number of indicia and making it possible to require only one display element. In this case, a complicated mechanism for connecting a plurality of rotatably mounted display elements can be avoided.

The dose counting indicia of the display element may comprise a unique indicia which is displayed after each actuation of the medicament dispensing mechanism. At least 50, preferably at least 60, unique dose counting indicia may be provided and may comprise arabic numerals. Each dose counting indicium may represent the number of doses dispensed by the inhaler or the number of doses remaining within the inhaler.

In some embodiments, the medicament dispensing mechanism may comprise indexing means for longitudinally indexing the blister pack in response to each actuation of the medicament dispensing mechanism, the blister pack being indexed by a distance equal to the pitch between the blisters such that each actuation aligns a blister with the at least one medicament aperture of the manifold. The indexing means may comprise a driven indexing wheel having a recess adapted to receive the base sheet of the blister pack, the recessed indexing wheel being arranged to rotate a predetermined angle in response to each actuation of the medicament dispensing mechanism. The indexing wheel may be arranged to face a guide surface of the medicament dispensing mechanism.

The inhaler may comprise a trigger for actuating the medicament dispensing mechanism, and/or a lid rotatable between an open position in which the inhaler can be used and a closed position in which the inhaler cannot be used.

According to a second aspect of the present invention there is provided a method of assembling an inhaler as described above, the method comprising:

passing a portion of the cover sheet between the peeling edge and an outer side surface of the manifold before components of the inhaler defining the peeling edge and the manifold are assembled into the inhaler and when a gap between the peeling edge and the manifold is relatively large; and

assembling the components of the inhaler defining the peeling edge and the manifold into the inhaler together with the portion of the cover sheet passing between the peeling edge and the manifold such that the size of the gap between the peeling edge and the manifold is reduced.

Other features and/or advantages of the present invention will become apparent from the following detailed description.

Drawings

Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a known blister package for use with a dry powder inhaler;

FIG. 2 is an exploded view of a known dry powder inhaler including the blister pack shown in FIG. 1;

FIG. 3 is a cut-away plan view of the dry powder inhaler shown in FIG. 1 for illustrating the principles of operation;

FIG. 4 is an exploded view of a dry powder inhaler according to the present invention, with some components of the inhaler omitted for clarity;

FIG. 5 is a cut-away plan view of the dry powder inhaler shown in FIG. 4 for illustrating the principle of operation;

FIGS. 6 and 7 are different perspective views of the outer housing component of the dry powder inhaler shown in FIG. 4;

FIG. 8 is an enlarged partial cross-sectional side view of the outer housing component shown in FIGS. 6 and 7;

FIG. 9 is a front view of the outer housing component shown in FIGS. 6 and 7;

FIG. 10 is an enlarged fragmentary section of a cross-sectional plan view of the outer housing component shown in FIGS. 6 and 7;

fig. 11 is a perspective view of some components of the dry powder inhaler shown in fig. 4, illustrating a method of assembling the same.

Detailed Description

The present invention provides an inhaler for delivering dry powder medicament from an open blister pocket of a blister pack (blister pack) to a patient. The blister package is in the form of a flexible elongate strip comprising: a substrate having a plurality of recesses spaced along a length thereof; and a cover sheet peelably sealed to the base sheet to define a plurality of blisters each containing a measured dose of the medicament. The inhaler comprises a medicament dispensing mechanism for opening a blister of a blister pack. The medicament dispensing mechanism comprises peeling means for peeling the cover sheet of the blister pack away from the base sheet. The inhaler further comprises: a housing for enclosing, together with the medicament dispensing mechanism, a used portion and an unused portion of the blister pack; and a manifold through which air can be drawn in use of the inhaler. The manifold includes: an air inlet for receiving outside air; at least one medicament aperture for communicating with an open blister of the blister pack to enable medicament to be carried by means of air drawn through the manifold; and an air outlet for delivering the entrained medication to the patient.

The medicament dispensing mechanism comprises a driven lid sheet winding wheel for winding up and applying tension to the used portion of the lid sheet. The mechanism further includes a guide surface for guiding the cover sheet of the unused portion of the blister package, an end of the guide surface being disposed adjacent to the outside surface of the manifold and defining a peeling edge. In use of the inhaler, the cover sheet is peeled from the base sheet at the peel edge, the used portion of the cover sheet passes between the peel edge and the outer side surface of the manifold, and the opened blister pack is moved into alignment with the at least one medicament aperture of the manifold. According to the invention, the manifold and the guide surface are defined by separate parts of the inhaler.

Fig. 1 shows a known blister package 1 suitable for use in connection with a known dry powder inhaler and a dry powder inhaler according to the invention. The blister pack 1 is in the form of a flexible elongate strip defining a single row of blisters 3 spaced along its length. The blister pack 1 may have, for example, a total of sixty or one hundred blisters.

The blister pack 1 comprises: a base sheet 5 in which respective recesses corresponding to the blisters 3 are formed; and a lid sheet 7 hermetically but preferably peelably sealed to the surface around the recess of the base sheet 5. The base sheet 5 and the cover sheet 7 are generally formed of a laminate including a plastic film and an aluminum film. The base sheet 5 is more rigid than the lid sheet 7 and preferably has a rigidity sufficient to maintain the predetermined shape of each shaped recess. The recesses formed in the base sheet 5 are elongate in shape, with their length direction corresponding to the width direction of the blister pack 1.

The cover sheet 7 is hermetically but peelably sealed to the base sheet 5 by a heat seal lacquer. The lid sheet 7 is sealed to the base sheet 5 over its entire surface (except for those portions which overlap the recesses in the base sheet 5, and the leading edge portions 9, 11 of the base sheet 5 and lid sheet 7). The leading edge portions 9, 11 of the base sheet 5 and the cover sheet 7 lengthen as the blister pack 1 is used, and these portions are referred to herein as "used portions". The portion of the blister pack 1 where the cover sheet 7 has not been peeled away from the base sheet 5 is referred to herein as the "unused portion". The blister pack 1 is arranged so that the cover sheet 7 can be peeled away from the base sheet 5 in a progressive manner so that one blister 3 can be opened at a time.

Each blister 3 of the blister pack 1 comprises a packaging volume defined by the surfaces of the cover sheet 7 and the base sheet 5. The enclosed volume defined by the blister is generally constant and filled with a predetermined amount of dry powder medicament suitable for inhalation by a patient. When the blister pack 1 is used, the leading edge 11 of the cover sheet 7 is peeled away from the base sheet 5 to open the blister 3. The leading edge of the cover sheet 7 is provided with a loop 13 for applying a tension capable of peeling the cover sheet 7 from the base sheet 5.

A more detailed description of blister package 1 can be found in us patent No.5590645, the entire contents of which are incorporated herein by reference.

Fig. 2 and 3 show a known dry powder inhaler 21 comprising the blister pack 1 shown in fig. 1. Fig. 2 is an exploded view of the inhaler 21, and fig. 3 is a sectional plan view of the inhaler 21 for explaining the working principle thereof.

The inhaler 21 has a disc-like outer shape with rounded edges and has a thickness sufficient to accommodate the width of the blister pack 1. In correspondence with the blister pack 1, the inhaler 21 comprises: a housing for enclosing used and unused portions of the blister pack 1; a medicament dispensing mechanism for opening a blister 3 of the blister pack 1; and a manifold through which air can be drawn in using the inhaler 21; and a dose counter for counting the number of doses dispensed by the inhaler 2 and the number of doses remaining in the inhaler 21.

The inhaler housing comprises a pair of housing components, namely an upper housing component 23 and a lower housing component 25, which snap-fit together to define a major portion of the outer surface of the inhaler 21. The upper and lower housing components 23, 25 also define an interior chamber. The inhaler 21 is additionally provided with a cover 27, the cover 27 being pivotally mounted to the housing components 23, 25 and arranged to rotate about the housing between an open position of the inhaler 21 (as shown in figure 3) and a closed position of the inhaler 21 (not shown).

The medicament dispensing mechanism of the inhaler 21 is largely housed within a housing and comprises essentially: peeling means for peeling the cover sheet 7 of the blister pack 1 from the base sheet 5 to open the blister 3; and indexing means for indexing the longitudinal position of the blister pack 1 by a distance equal to the longitudinal spacing between blisters 3, so as to align the newly opened blisters 3 containing dry powder medicament with a manifold (described below) to enable inhalation by a patient.

The medicament dispensing mechanism comprises: a pivotally mounted trigger 29 having a finger engaging tab; a blister pack indexing wheel 31 mounted around an indexing ratchet 33; a substrate winding wheel 35; flap winding wheels 37a, 37 b; and a guide surface 39 for guiding the cover sheet side of the blister pack 1. The guide surface 39 is defined by a moulded plastic part 41 and comprises a peeling edge for separating the cover sheet 7 from the base sheet 5 of the blister pack 1.

The medicament dispensing mechanism further comprises a pawl 43 attached to the housing for engaging the teeth of the substrate winding wheel 35 to prevent counter-clockwise rotation (inversion).

The lid sheet winding wheels 37a, 37b include: a first part in the form of a toothed wheel 37a having a projecting and parallel axially extending shaft and a non-axially extending shaft; and a second portion in the form of a wheel 37b having a hollow shaft provided with resilient wings extending outwardly from the hollow shaft. The protruding axle of wheel 37a engages the hollow axle of wheel 37b so that the two wheels cannot rotate relative to each other.

The manifold is defined by the same moulded plastics component 41 that defines the guide surface 39 of the medicament dispensing mechanism. The manifold includes: an air inlet 45 for receiving air from the interior of the housing; a drug port 47 for communicating with the lumen defined by the housing through which the carried drug is inhaled; an air outlet 49 for delivering the entrained medicament to the patient. The air outlet 49 communicates with a mouthpiece (mouthpiece) provided with a mouthpiece insert 51.

The dose counter of the inhaler comprises a display aperture 55 formed in the lower housing part 25 and a display element in the form of a display ring 53 provided with dose counting indicia and arranged such that when the display ring 53 is rotated about the axis of the disc-like outer shape of the inhaler 21, the sequence of indicia is sequentially visible through the display aperture. The inner edge of the display ring 53 is provided with teeth for rotationally driving the display ring 53.

The blister pack 1 is arranged within the inhaler 21 such that the unused portion is loosely coiled within the cavity defined by the housing. The leading edge of the lid sheet 7 is attached by the loop 13 thereon to the non-axially extending shaft of the lid sheet winding wheel 37a and the used portion of the lid sheet 7 is wound around the elastic wings of the lid sheet winding wheel 37 b. The used portion of the base sheet 5 is loosely wound around the base sheet winding wheel 35.

The portion of the blister pack 1 where the cover sheet 7 is spaced from the base sheet 5 is arranged so that the recesses of the base sheet 5 (which are projections as viewed from the other side of the base sheet 5) are received in circumferentially spaced recesses on the surface of the indexing wheel 31. The recesses of the base sheet 5 are held in the recesses of the index wheel 31 by the guide surfaces 39 acting on the cover sheet side of the blister pack 1. The used portion of the base sheet 5 extends in front of the medicament aperture 47 of the manifold in a direction towards the base sheet winding wheel 35 and the used portion of the cover sheet 7 passes between the peeling edge of the guide surface 39 and the outer side surface of the manifold in a direction towards the cover sheet winding wheels 37a, 37 b.

In use of the known inhaler 21, the patient moves the cap 27 to an open position exposing the mouthpiece insert 51, as shown in figure 3. The patient then presses the finger engaging tab of the trigger 29 to rotate a set of teeth formed on the arcuate surface of the trigger. The teeth of the trigger 29 engage circumferential teeth formed on the indexing ratchet wheel 33, the rotation of which causes rotation of the indexing wheel 31. Rotation of the indexing wheel 31 also causes rotation of the base sheet winding wheel 35, the cover sheet winding wheels 37a, 37b, and the display ring 53 of the dose counter.

Rotation of the cover sheet winding wheels 37a, 37b applies a tension to the used portion of the cover sheet 7 sufficient to peel a portion of the cover sheet 7 from the base sheet 5 of the blister pack, thereby opening a blister 3 containing a dose of dry powder medicament. At the same time, the indexing wheel 31 is rotated through an angle sufficient to longitudinally index the blister pack 1 by a distance equal to the spacing between blisters 3, thereby moving the opened blisters 3 into alignment with the medicament apertures 47 of the manifold.

Rotation of the display ring 53 of the dose counter causes the dose counting indicia to be advanced, thereby informing the patient that a dose has been dispensed.

The patient may then inhale the dose of dry powder medicament by inhaling through the mouthpiece to draw air through the air inlet 45 of the manifold (the air passing through the medicament aperture 47 to carry the medicament and being delivered to the patient through the air outlet 49).

After use of the inhaler 1, the cover 27 is rotated back to the closed position (not shown) to reset the medicament dispensing mechanism for the next use.

Inhalers of the above type are described in more detail in the above mentioned us patent No. 5590645.

The known inhaler described above is satisfactory in many respects. In particular, the use of a peelable blister pack allows the moisture content of the dry powder medicament to be carefully controlled and which, in combination with a peelable medicament dispensing mechanism, provides a consistent number of doses. However, there is a need for an improved dry powder inhaler.

Fig. 4-11 show a dry powder inhaler 101 according to the invention comprising the blister pack 1 shown in fig. 1. Fig. 4 is an exploded view of the inhaler 101, with some components of the inhaler omitted for clarity. Fig. 5 is a sectional plan view of the inhaler 101. Fig. 6 and 7 are different perspective views of the outer housing part of the inhaler 101. Fig. 8 is an enlarged portion of a cross-sectional side view of the outer housing component. Fig. 9 is a front view of the outer housing member. Fig. 10 is an enlarged part of a sectional plan view of the outer housing member. Fig. 11 is a perspective view of some components of the inhaler 101.

The inhaler 101 according to the present invention is similar in many respects to the known inhaler 21 described above. Aspects of the inhaler 101 not described in detail below are to be understood as being the same as or similar to those described above.

Thus, with particular reference to fig. 4 and 5, the inhaler 101 according to the invention has an outer shape with rounded edges and a thickness sufficient to accommodate the width of the blister pack 1. The inhaler comprises the blister pack 1 described above, a housing for enclosing used and unused portions of the blister pack 1, a medicament dispensing mechanism for opening a blister 3 of the blister pack 1, a manifold through which air can be drawn when the inhaler 101 is in use, and a dose counter for counting the number of doses dispensed by the inhaler 101 or remaining in the inhaler 101.

The inhaler housing comprises a pair of outer housing components, namely an upper component 103 and a lower component 105, which snap-fit together to define a major portion of the outer surface of the inhaler 101. The upper and lower housing components 103, 105 also define an internal cavity. The inhaler 101 is additionally provided with a pivotally mounted cover 107, the cover 107 being arranged to rotate about the housing between an open position and a closed position.

The medicament dispensing mechanism of the inhaler 101 is mostly housed within a housing and comprises peeling means for peeling the cover sheet 7 from the base sheet 5 of the blister pack 1 to open the blisters 3, and indexing means for indexing the longitudinal position of the blister pack 1.

More specifically, the medicament dispensing mechanism comprises a pivotally mounted trigger 109 with a finger engagement projection, a blister pack indexing wheel 111, a base sheet winding wheel 113, a cover sheet winding wheel 115 and a guide surface 117 for guiding the cover sheet side of the blister pack 1. The guide surface 117 comprises a peeling edge 119 for separating the cover sheet 7 of the blister pack 1 from the base sheet 5.

The dose counter of the inhaler 101 comprises a display aperture 121 formed in the lower outer housing part 105 and a display element in the form of a display ring 147, the display element being provided with dose counting indicia and being arranged such that when the display ring 147 is rotated about the axis of the disc-like outer shape of the inhaler 101, a series of indicia can be sequentially seen through the display aperture. The dose counting indicia comprise arabic numerals counting down in steps of 1 from the numeral "60" to the numeral "0" to represent the number of doses remaining in the inhaler 101.

The inner edge of the display ring 147 is provided with teeth for rotatably driving the display ring 147, the teeth being driven by a gear train coupled to the medicament dispensing mechanism. The gear train is arranged such that the indicia visible through the display aperture 121 is progressive each time the medicament dispensing mechanism is actuated.

The display aperture 121 formed in the upper outer housing part 103 is provided with a convex lens 123 spaced from and arranged to magnify the dose counting indicia of the display ring. The convex lens 123 is formed of a transparent plastic material.

By providing a convex lens 123, the dose counting indicia of the dose counter may be more easily viewed by the patient and/or the need for multiple display rings may be avoided (as a large number of small indicia may be provided on a single ring).

With particular reference to fig. 6 to 10, the manifold of the inhaler 101 comprises an air inlet 125 for receiving outside air; a pair of medicament apertures 127a, 127b for communicating with an open blister pocket 3 of the blister pack to allow medicament to be carried by air drawn through the manifold; and an air outlet 129 for delivering the medicament to the patient. The air inlet 125 defines the only point where outside air enters the inhaler 101.

The manifold is formed as part of the upper outer housing part 103. In other words, the manifold and upper housing body component 103 are formed as a one-piece component, particularly a one-piece molded plastic component formed of High Density Polyethylene (HDPE).

When the inhaler 101 is in use (that is to say with the lid 107 in the open position), the integral component defines part of the outer surface of the inhaler 101 surrounding the air inlet 125. In other words, the unitary component not only defines the manifold, but also the outer surface of the inhaler in which the air inlet 125 of the manifold is formed. Also, air is drawn into the manifold only through the air inlet (separate from the air circulating through the drug ports 127a, 127 b).

By such an arrangement, the risk of sucking air from inside the suction housing into the manifold can be reduced. Such air may be contaminated by medicament left over from a previous actuation of the medicament dispensing mechanism.

The air inlet 125 of the manifold has an elongated arcuate cross-section with a length that shortens in the direction of the suction airstream. The medicament apertures 127a, 127b are arranged in series along an airflow direction which is parallel to the axis of the external shape of the inhaler 101 and the width direction of the blister pack 1. A protrusion 131 in the wall of the manifold facing the medicament apertures 127a, 127b is arranged to restrict air flow in the manifold between the medicament apertures 127a, 127 b. In this way, air drawn through the manifold is directed from the air inlet 125 through the first medicament aperture 127a into the open blister pocket 3 and entrained medicament is directed from the open blister pocket 3 through the second medicament aperture 127b into the manifold.

The integral parts defining the manifold and the upper outer housing part 103 further define a mouthpiece 133, said mouthpiece 133 being arranged to receive the entrained medicament from the air outlet 129 of the manifold. The mouthpiece 133 is arranged substantially perpendicular to the manifold such that the axis of the mouthpiece 33 is aligned with the second medicament aperture 127 b. The tapered wall of the mouthpiece 133 is provided with airflow diversion apertures 135a, 135b which communicate with the manifold and provide alternative paths for air drawn through the manifold, as shown by the arrows in figure 10. The air flow diverting apertures 135a, 135b are arranged to cause air to be drawn into the mouthpiece 133 therefrom in a direction substantially parallel to the axis of the mouthpiece 133 to prevent excessive diffusion of the entrained medicament.

Each medication aperture 127a, 127b is provided with a divider. The divider serves to prevent agglomeration of the drug by breaking up the drug particles.

The mouthpiece 133 is provided with a mouthpiece insert 145 formed from a soft plastics material which provides a comfortable surface against which the patient can seal his lips during use of the inhaler 101.

Referring again to fig. 4, 5 and 11, it will be seen that the inhaler 101 also includes an inner housing member 137. The inner housing member 137 is arranged in the outer housing member 103, 105 and is in the form of a tray-like molded plastic member having a flat base surface from which transverse walls extend in a direction perpendicular to the base surface (corresponding to the width direction of the blister pack 1). An aperture is provided in the base surface of the inner housing part 137 to enable the elements of the medicament dispensing mechanism to function properly. The transverse wall serves to separate the used portion from the unused portion of the blister pack 1. Thus, the first transverse wall 139 separates the used portion of the cover sheet 7 from the unused portion of the blister pack 1 and the second transverse wall 141 separates the used portion of the base sheet 5 from the unused portion of the blister pack 1.

The transverse walls of the inner housing member 137 actually define separate compartments for accommodating different parts of the blister pack 1, thereby minimizing the risk of residual medicament on used parts of the base and cover sheets 5, 7 contaminating unused parts of the blister pack 1, which may lead to overdosing.

The inner housing member 137 and the upper outer housing member 103 together define an enclosure 143 which substantially encloses the unused portion of the blister pack 1 to protect it from contamination by residual medicament contained in the inhaler housing.

The inner housing member 137 described above also defines the guide surface 117 of the medicament dispensing mechanism, i.e. the inner housing member 137 and the guide surface 117 are provided as a unitary component.

The blister pack 1 is arranged in the inhaler 101 such that the unused portion is loosely wrapped in a package 143 defined by the housing components. The used portion of the cover sheet 7 is wound around the cover sheet winding wheel 115. The used portion of the base sheet 5 is loosely wound around the base sheet winding wheel 113.

The portion of the blister pack 1 where the cover sheet 7 is spaced from the base sheet 5 is arranged so that the recesses of the base sheet 5 (which are projections as viewed from the other side of the base sheet 5) are received in circumferentially spaced recesses on the surface of the indexing wheel 111. The recesses of the base sheet 5 are held in the recesses of the index wheel 111 by the guide surfaces 117 acting on the cover sheet side of the blister pack 1. The used portion of the base sheet 5 extends in a direction towards the base sheet winding wheel 113 to the front of the medicament apertures 127a, 127b of the manifold and the used portion of the cover sheet 7 passes between the peeling edge 119 of the guide surface 117 and the outer side surface of the manifold in a direction towards the cover sheet winding wheel 115.

During assembly of the inhaler 101, the used portion of the cover sheet 7 passes through the gap between the peeling edge 119 and the side of the manifold and then engages with the cover sheet winding wheel 115.

According to the present invention, by providing an inhaler 101 as follows: wherein the guide surface 117 and manifold are defined by separate components (i.e. inner housing component 137 and upper outer housing component 103, respectively), the width of the gap between the stripping edge 119 and manifold in the assembled inhaler can be minimized. In particular, the used part of the cover sheet 7 may be passed through the gap before assembly of the parts 137, 103, when said gap is relatively wide, and then the parts 137, 103 may be assembled with the blister pack 1 into the inhaler 101 with the gap having a reduced width, for example only slightly wider than the thickness of the cover sheet 7. By minimizing the width of the gap, the risk of medicament being lost from an open blister pocket 3 when the blister pocket 3 is moved from the peeling edge 119 into alignment with the medicament apertures 127a, 127b of the manifold during use of the inhaler can be minimized. In this way, underdosing (and possible subsequent overdosing) can be avoided.

The inner housing member 137 and the pair of outer housing members 103, 105 include a positioning means for accurately positioning the inner housing member 137 relative to the pair of outer housing members 103, 105. The positioning means comprises engaging projections and recesses (not shown) formed in the inner housing part 137 and the pair of outer housing parts 103, 105, which are arranged to engage with each other to fix the relative positions of the parts.

In use of the inhaler 101 according to the present invention, the patient moves the cap 107 to an open position exposing the mouthpiece insert 145. The patient then presses the finger engaging tab of the trigger 109 to rotate a set of teeth formed on the arcuate surface of the trigger. The teeth of the trigger 29 engage circumferential teeth formed on an indexing ratchet wheel (not shown), the rotation of which causes rotation of the indexing wheel 111. Rotation of the index wheel 111 also causes rotation of the base sheet winding wheel 113, the cover sheet winding wheel 115, the display ring of the dose counter (not shown).

Rotation of the cover sheet winding wheel 115 applies a tension to the used portion of the cover sheet 7 sufficient to peel a portion of the cover sheet 7 from the base sheet 5 of the blister pack, thereby opening a blister 3 containing a dose of dry powder medicament. At the same time, the indexing wheel 111 is rotated through an angle sufficient to longitudinally index the blister pack 1 by a distance equal to the spacing between blisters 3, thereby moving the opened blisters 3 into alignment with the medicament apertures 127a, 127b of the manifold.

Rotation of the display ring of the dose counter causes the dose counting indicia to be advanced, thereby informing the patient that a dose has been dispensed.

The patient may then inhale the dose of dry powder medicament by inhaling via mouthpiece 133 to draw air through air inlet 125 of the manifold (the air passing through medicament orifices 127a, 127b to carry the medicament and being delivered through air outlet 129 and mouthpiece 133).

After use of the inhaler 101, the cover 107 is rotated back to the closed position to reset the medicament dispensing mechanism for the next use.

Specific embodiments of the present invention have been described above in detail. Various changes may be made to the described embodiments without departing from the scope of the invention as defined by the claims.

Claims (48)

1. An inhaler for delivering dry powder medicament to a patient from an open blister pocket of a blister pack, the blister pack being in the form of a flexible elongate strip comprising a base sheet having a plurality of recesses spaced along its length and a cover sheet peelably sealed to the base sheet to define a plurality of blister pockets each containing a measured dose of medicament, the inhaler comprising:

a medicament dispensing mechanism for opening a blister of the blister pack, the medicament dispensing mechanism comprising peeling means for peeling a cover sheet from a base sheet of the blister pack;

a housing for enclosing used and unused portions of the blister pack together with the medicament dispensing mechanism, the housing comprising an inner housing member disposed within at least one outer housing member; and

a manifold through which air can be inhaled when using the inhaler, the manifold comprising: an air inlet for receiving outside air; at least one medicament aperture for communicating with an open blister of the blister pack to enable medicament to be carried by air drawn through the manifold; and an air outlet for delivering the entrained medicament to a patient;

wherein the medicament dispensing mechanism comprises a driven cover sheet winding wheel for winding up and applying tension to a used portion of the cover sheet, and a guide surface for guiding the cover sheet of an unused portion of the blister pack, the ends of the guide surface being disposed adjacent to an outside surface of the manifold and defining a peeling edge,

whereby, in use, the cover sheet is peeled away from the base sheet at the peel edge and the used portion of the cover sheet passes between the peel edge and the outside surface of the manifold and the opened blister pocket is moved into alignment with the at least one medicament aperture of the manifold,

wherein the manifold is defined by the at least one outer housing component and the guide surface comprising the peeling edge is defined by the inner housing component, whereby the manifold and the guide surface are defined by separate components of the inhaler.

2. An inhaler according to claim 1, wherein, in use, the outer side surface of the manifold separates the base sheet from the cover sheet.

3. An inhaler according to claim 1, wherein, in use, the outer side surface of the manifold and the peeling edge are arranged to define a gap sufficient to enable the cover sheet to pass therethrough, the gap being less than or equal to 1 mm.

4. An inhaler according to claim 3, wherein the gap is from 0.1 to 0.8 mm.

5. An inhaler according to claim 1, wherein the at least one outer housing member comprises a pair of outer housing members defining the external shape of the inhaler.

6. An inhaler according to claim 1, wherein the inner housing member and the at least one outer housing member comprise locating means for locating the inner housing member relative to the at least one outer housing member.

7. An inhaler according to claim 6, wherein the locating means comprises engaging protrusions and recesses formed in the inner housing member and the at least one outer housing member, the engaging protrusions and recesses being arranged to engage with one another to fix the location of the inner housing member relative to the at least one outer housing member.

8. An inhaler according to claim 5, wherein the inner housing member defines an inner transverse wall extending in the width direction of the blister pack for separating a used portion of the cover sheet from an unused portion of the blister pack.

9. An inhaler according to claim 8, wherein the medicament dispensing mechanism further comprises a driven base sheet winding wheel for winding up the used portion of the base sheet, and wherein the inner housing member further defines an inner transverse wall extending in the width direction of the blister pack for separating the used portion of the base sheet from the unused portion of the blister pack.

10. An inhaler according to claim 9, wherein the inner transverse walls of the inner housing member define separate compartments for containing used portions of the cover sheet and used portions of the base sheet, the separate compartments being arranged to contain loose medicament.

11. An inhaler according to claim 10, wherein the inner transverse wall of the inner housing member further defines a separate compartment for receiving an unused portion of the blister pack.

12. An inhaler according to any of claims 8 to 11, wherein the inner transverse wall extends in a perpendicular direction from a base surface of the inner housing member, the base surface of the inner housing member being arranged to support a side edge of an unused portion of the blister pack.

13. An inhaler according to claim 12, wherein one of the pair of outer housing members is arranged to support opposite side edges of an unused portion of the blister pack.

14. An inhaler according to claim 13, wherein one of the pair of outer housing members and a surface of the inner housing member are arranged to substantially enclose an unused portion of the blister pack.

15. An inhaler according to any of claims 5 and 8 to 11, wherein the manifold and one of the pair of outer housing members are provided as a one-piece moulded plastics component and in use defines at least a portion of an outer surface of the inhaler in which the air inlet is arranged.

16. An inhaler according to claim 15, wherein the manifold is arranged such that, in use, air is drawn into the manifold solely through the air inlet.

17. An inhaler according to claim 15, wherein the air inlet of the manifold defines the only location for external air to enter the inhaler.

18. An inhaler according to claim 15, wherein the air inlet of the manifold has an elongate cross-sectional shape and the cross-sectional area of the manifold decreases in the direction of airflow.

19. An inhaler according to claim 15, wherein the manifold comprises at least two medicament apertures arranged sequentially in the direction of airflow of the manifold, a first medicament aperture for the flow of air from the manifold into an open blister pocket and a second medicament aperture for the flow of entrained medicament from an open blister pocket into the manifold.

20. An inhaler according to claim 19, wherein the manifold has a geometry adapted to direct air from the air inlet to the open blister pocket through a first medicament aperture and to direct entrained medicament from the open blister pocket to the manifold through a second medicament aperture.

21. An inhaler according to claim 20, wherein the manifold is geometrically shaped to provide an airflow restriction means for restricting airflow between the first and second medicament apertures within the manifold.

22. An inhaler according to claim 21, wherein the airflow restriction means comprises a localised reduction in the cross-sectional area of the manifold.

23. An inhaler according to claim 15, wherein the integrally moulded plastics component further defines a mouthpiece arranged, in use, to receive entrained medicament from the air outlet of the manifold.

24. An inhaler according to claim 23, wherein the cross-sectional area of the mouthpiece increases in the direction of airflow.

25. An inhaler according to claim 24, wherein the tapered wall of the mouthpiece is provided with a plurality of airflow diversion apertures, and the airflow diversion apertures are in fluid communication with the manifold such that: in use, air from the manifold is drawn through the airflow diverting apertures.

26. An inhaler according to claim 25, wherein the airflow diverting apertures are arranged such that: in use, air is drawn through the airflow diverting holes in a direction substantially parallel to the central axis of the mouthpiece for preventing excessive lateral diffusion of the entrained medicament in the mouthpiece.

27. An inhaler according to claim 15, wherein the at least one medicament aperture is provided with at least one obstruction for preventing the entrained medicament from agglomerating.

28. An inhaler according to claim 15, wherein the one-piece moulded plastics component is formed from moulded plastics.

29. An inhaler according to claim 28, wherein the integrally moulded plastics component is formed from a plastics material selected from the group consisting of: polyolefins, polyesters, polyamides, thermosetting polymers, and mixtures or copolymers of the above plastics.

30. The inhaler of any of claims 5 and 8-11, further comprising a dose counter, wherein the dose counter comprises:

a display aperture formed in one of the pair of outer housing members;

a display element having a plurality of dose counting indicia, the display element being rotatably mounted within the housing such that a series of dose counting indicia are sequentially visible through the display aperture as the display element is rotated about an axis of the exterior shape of the inhaler; and

drive means for progressively rotating the display element in response to actuation of the medicament dispensing mechanism,

wherein the display aperture formed in the outer housing part is provided with a magnifying lens arranged to magnify the dose counting indicia of the display element.

31. An inhaler according to claim 30, wherein the magnifying lens is a convex lens.

32. An inhaler according to claim 30, wherein the magnifying lens is formed from a transparent plastic.

33. An inhaler according to claim 30, wherein the dose counting indicia of the display element comprises at least 10 dose counting indicia.

34. An inhaler according to claim 30, wherein the dose counting indicia comprise numbers.

35. An inhaler according to claim 30, wherein each dose counting indicium represents the number of doses dispensed by the inhaler or the number of doses remaining in the inhaler.

36. An inhaler according to any of claims 1 to 11, wherein the medicament dispensing mechanism comprises indexing means for longitudinally indexing the blister pack in response to each actuation of the medicament dispensing mechanism, the blister pack being indexed by a distance equal to the spacing between blisters such that each actuation aligns a blister with the at least one medicament aperture of the manifold.

37. An inhaler according to claim 36, wherein the indexing means comprises a driven indexing wheel having a recess adapted to receive the base sheet of the blister pack, the recessed indexing wheel being arranged to rotate a predetermined angle in response to each actuation of the medicament dispensing mechanism.

38. An inhaler according to claim 36, further comprising a trigger for actuating the medicament dispensing mechanism.

39. The inhaler of any one of claims 1-11, further comprising a lid rotatable between an open position in which the inhaler can be used and a closed position in which the inhaler cannot be used.

40. The inhaler of any one of claims 1-11, further comprising the blister pack, wherein each blister contains a measured dose of dry powder medicament.

41. An inhaler according to claim 3, wherein the gap is less than or equal to 0.8 mm.

42. An inhaler according to claim 3, wherein the gap is less than or equal to 0.4 mm.

43. An inhaler according to claim 4, wherein the gap is from 0.2 to 0.6 mm.

44. An inhaler according to claim 4, wherein the gap is from 0.2 to 0.4 mm.

45. An inhaler according to claim 33, wherein the dose counting indicia of the display element comprises at least 30 dose counting indicia.

46. An inhaler according to claim 33, wherein the dose counting indicia of the display element comprises at least 50 dose counting indicia.

47. An inhaler according to claim 34, wherein the dose counting indicia comprise arabic numerals.

48. A method of assembling an inhaler for delivering dry powder medicament to a patient from an open blister pocket of a blister pack, the blister pack being in the form of a flexible elongate strip comprising a base sheet having a plurality of recesses spaced along its length and a cover sheet peelably sealed to the base sheet to define a plurality of blister pockets each containing a measured dose of medicament,

the inhaler includes:

a medicament dispensing mechanism for opening a blister of the blister pack, the medicament dispensing mechanism comprising peeling means for peeling a cover sheet from a base sheet of the blister pack;

a housing for enclosing used and unused portions of the blister pack together with the medicament dispensing mechanism; and

a manifold through which air can be inhaled when using the inhaler, the manifold comprising: an air inlet for receiving outside air; at least one medicament aperture for communicating with an open blister of the blister pack to enable medicament to be carried by air drawn through the manifold; and an air outlet for delivering the entrained medicament to a patient;

wherein the medicament dispensing mechanism comprises a driven cover sheet winding wheel for winding up and applying tension to a used portion of the cover sheet, and a guide surface for guiding the cover sheet of an unused portion of the blister pack, the ends of the guide surface being disposed adjacent to an outside surface of the manifold and defining a peeling edge,

whereby, in use, the cover sheet is peeled away from the base sheet at the peel edge and the used portion of the cover sheet passes between the peel edge and the outside surface of the manifold and the opened blister pocket is moved into alignment with the at least one medicament aperture of the manifold,

wherein the manifold and the guide surface are defined by separate components of the inhaler,

the method comprises the following steps:

passing a portion of the cover sheet between the peeling edge and an outer side surface of the manifold before components of the inhaler defining the peeling edge and the manifold are assembled into the inhaler and when a gap between the peeling edge and the manifold is relatively large; and

assembling the components of the inhaler defining the peeling edge and the manifold into the inhaler together with the portion of the cover sheet passing between the peeling edge and the manifold such that the size of the gap between the peeling edge and the manifold is reduced.