Dispensing apparatus for delivering powdered product

A dispensing device for dispensing a powdered product includes a housing having a first end and a second end defining a first outlet; a plunger slidably received in the first end of the housing, the housing and plunger together defining an interior of the dispensing device which is open to atmosphere; a chamber located within the plunger for housing a powdered product; a sheathing member slidably mounted on an end of the plunger proximate the second end of the housing, and having an inlet and a second outlet closed by a frangible membrane. Additionally, the plunger includes a perforating element for puncturing the frangible membrane when the plunger is moved towards the second end of the housing.

CROSS REFERENCE TO RELATED APPLICATIONS

The present patent application claims priority under 35 U.S.C. to patent application GB 0201409.0 filed Jan. 22, 2002, which is incorporated herein by reference.

BACKGROUND OF INVENTION

The present invention relates to a disposable dispensing apparatus for delivering a powdered product nasally or orally. More specifically, but not exclusively, there is provided a single use dry powder medicament inhaler which can be used by persons who have not had medical training.

Such dispensing devices are well known in the art and are of particular use for the dispensing of drugs which can easily be absorbed through the nasal or pulmonary passages, especially for drugs which only need to be dispensed occasionally.

A dispensing device is known from U.S. Pat. No. 5,683,361 (incorporated herein by reference) which dispenses a single dosage of a powdery drug which is stored in a cylindrical storage chamber within the sealed main body of the device until dispensation of the drug is required. The chamber is located in an axially displaceable piston, which is mounted in the main body of the device between an end wall of the main body and a plunger for releasing the drug. The chamber is sealed with breakable membranes at either end of the cylinder which are, upon activation of the dispensing device, punctured by one or more perforating elements. An outlet duct is provided at the end of the main body remote from the plunger for dispensation of the drug to the user. The perforating element is provided at the end of the outlet duct nearest to the piston to puncture at least the outermost membrane of the drug chamber.

Both embodiments of the device described in U.S. Pat. No. 5,683,361 involve pressurization of the air inside the device prior to dispensation of the powdered medicament. When the plunger is pressed by the user into the main body of the device a pocket of air, which is trapped inside the main body of the device between the piston and the plunger, is compressed and the pressure inside the device increases. This increase in pressure causes the piston to move towards the outlet duct of the dispensing device, thereby causing the outermost membrane to be punctured by the perforating element. The remaining intact membrane is then punctured in one of two possible ways: by the penetrating element provided at the inner end of the outlet duct as the plunger, and therefore also the piston, is pushed further into the main body of the device, or by a second perforating element which is optionally provided at the inner end of the plunger.

A disadvantage with the devices described in U.S. Pat. No. 5,683,361 is that they do not always dispense the whole drug dose to the patient. As the outermost membrane is punctured, pieces of the perforated membrane are pushed into the chamber in the opposite direction to movement of the plunger and the desired drug flow path. This results in some of the powdered drug particles being trapped between pieces of the perforated membrane and the wall of the chamber as the drug is forced out of the dispensing device via the outlet duct. Furthermore, as the patient inhales, the pieces of the perforated membrane are drawn in the direction of the outlet duct and thereby interfere with the dispensing of the drug as the powder can no longer flow freely out of the drug chamber. In this way, the dose dispensed by the device is often incomplete, which can mean that the drug is not wholly effective.

Another single-use dispensing device is described in patent application GB 0025027.4 (incorporated herein by reference) which device comprises a bellows unit for pressurizing the interior of the device and for propelling the powdered drug out of the dispensing apparatus.

A single-use dispensing device needs to be simple and cheap to manufacture. The known devices described above require a sealed main body to enable the device to be pressurized.

SUMMARY OF INVENTION

According to the present invention there is provided a dispensing device for dispensing a powdered product comprising a housing, having a first end and a second end defining a first outlet, a plunger slidably received in the first end of the housing, the housing and plunger together defining an interior of the dispensing device which is open to atmosphere, a chamber located within said plunger for housing a powdered product, a sheathing member slidably mounted on an end of the plunger proximate the second end of the housing, and having an inlet and a second outlet closed by a frangible membrane, and the plunger comprising a perforating element for puncturing the frangible membrane when the plunger is moved towards the second end of the housing.

DETAILED DESCRIPTION

A preferred embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings.

As shown inFIGS. 1 and 2, the apparatus of the present invention comprises a housing1, a plunger3and a sheath19. The housing1comprises a generally tubular body2of varying diameter having an open second end forming a first outlet31in a tip4and an open first end in which the plunger3is slidably received. The housing1is provided with an external shoulder5for use as a finger rest. Alternatively, the housing1may be provided with a protruding lip to act as a finger rest.

The tip4comprises an outer wall16which defines an outlet duct17through which medicament may be dispensed. An innermost end of the outlet duct17is provided with an enlarged duct27which has a larger cross-sectional diameter than the outlet duct17. The innermost end of the enlarged duct27is provided with a shoulder26.

The tip4is frusto-conically shaped so as to form a nozzle which is inserted, in use, into a patient's nostril. However, the tip4may also be shaped into a substantially cylindrical shape or similar, suitable for insertion, in use, into a patient's mouth.

The plunger3comprises a substantially cylindrical body8and a probe6. The body8is closed at one end to form an end face12. The opposite end is left open. The probe6is coupled or joined to an inner surface of the end face12and projects there from. The probe6is coupled to the end face12by means of a retaining lip7, although in an alternative embodiment the probe6and plunger3may be moulded as one piece, therefore avoiding the need for a retaining lip7. With the plunger3received in the housing1, the probe3projects towards the first outlet31of the tip4. Together, the plunger3and housing1define an interior32of the apparatus.

The probe6is substantially cylindrical in shape and is provided with an inwardly directed shoulder28. Alternatively, the inwardly directed shoulder28could be replaced by a flange. An end33of the probe6remote from the end face12is provided with a piercing tip14. The piercing tip14is provided with a sharpened cutting edge15.

A portion of the probe6, at the end33of the probe6, is provided with a hollow bore forming a storage chamber24. The storage chamber extends upwardly to the piercing tip14. A radially directed aperture23is provided through the thickness of the wall of the probe6communicating with a lower end of the storage chamber24.

The storage chamber24is substantially cylindrical in shape and is large enough to contain a single dose of powdered medicament which is to be dispensed. The powdered medicament is located in an end of the storage chamber24remote from the tip4. Likewise, the aperture23is located at the end of the storage chamber24remote from the tip4.

An external surface of the body8of the plunger3is provided with at least one axially oriented channel9. Each channel9receives a lug10which is located on an inner surface11of the housing1. The lug10and channel9arrangement prevents the plunger3from being withdrawn fully from the housing1. The channel9also allows for air from atmosphere to pass between the plunger3and the housing1, since the interference fit is not air tight.

The end face12of the plunger3is provided with an indentation13which is suitable for use as a thumb rest.

A sheath19, which is substantially cylindrical in shape, is slidably received over the end33of the probe6remote from the end face12. The sheath19comprises an open end20for receiving the probe6and an opposite closed end21, which is closed by a frangible membrane18. An aperture22is provided in the sheath19. The aperture22is in the form of a radially directed inlet which passes through the wall thickness of the sheath19. An outwardly directed shoulder25is provided on the sheath19in the vicinity of the closed end21.

Typically, the thickness of the frangible membrane18is between 0.03 and 0.20 mm. Furthermore, as shown inFIGS. 3aand3b, the membrane18is provided with one or more pre-formed lines of weakness29to aid the rupturing of the membrane by the piercing tip14.FIG. 3adepicts a star pattern of weaknesses andFIG. 3bdepicts a half-moon pattern of weaknesses. Alternatively, the frangible membrane18may comprise a plurality of castellations30which are of a reduced thickness compared to the rest of the frangible membrane18as shown inFIG. 3c.

In a storage position, as shown inFIG. 1, the sheath19is mounted on the probe6with the piercing tip14in close proximity but not quite abutting against the frangible membrane18. In this position, the radial apertures22and23are out of alignment and there is consequently no open flow path between the interior32of the housing1and the storage chamber24. Thus, the apertures22and23, which together form an inlet valve are in a closed position. However, there is an open flow path from the interior32of the housing1to the outlet duct17, via the duct27.

In use, a user holds the apparatus typically by means of two or more fingers positioned on the external shoulder5and a thumb positioned on the end face12. The tip4is then inserted into the nose (or mouth if the apparatus is for pulmonary use). Inhalation at this stage is possible freely but is ineffective since air is drawn from the interior32of the housing1through the enlarged duct27and out via the outlet duct17. Pressure in the interior32is equalized by air flow into the interior32between the plunger3and the housing1.

The user depresses the end face12of the plunger3relative to the housing1so as to move the probe6and sheath19axially in the direction of the tip4. Initially, the probe6and the sheath19are free to move unhindered into the enlarged duct27.

Further movement of the probe6and sheath19brings the outwardly directed shoulder25of the sheath19into contact with the internal shoulder26of the enlarged duct27. At this point, further movement of the sheath19towards the tip4is prevented. The abutment of the outwardly directed shoulder25of the sheath19against the internal shoulder26also closes the flow path from the interior32of the housing1to the outlet duct17. Continued movement of the probe6towards the tip4causes the probe6to slide relative to the sheath19and the piercing tip14of the probe6to pierce and break the frangible membrane18.

Advantageously, the frangible membrane18is ruptured from below with the piercing tip14moving relative to the membrane18in the direction of tip4. As a result the flap of the membrane18which is left after rupture is positioned above the membrane periphery such that as powdered medicament particles pass the membrane18the flap tends to be moved away from the hole formed in the membrane so as not to block the flow path.

Subsequent inward movement of the probe6causes the storage chamber24to be moved into the outlet duct17. During this stage of actuation, air within the housing1can escape between the plunger3and the housing1. Further relative axial movement of the sheath19and probe6causes the apertures22and23to come into alignment, opening the inlet valve of the storage chamber24. The apparatus is now in the dispensing position, as shown in FIG.2.

In the dispensing position the inlet valve is open and the frangible membrane18is ruptured. Thus a continuous flow path is established between the interior32of the housing1, and the outlet duct17via the storage chamber24. As a result, upon inhalation air is displaced from the interior32of the housing1, through the inlet valve formed by the apertures22and23and into the storage chamber24where it entrains the powdered product. The air and entrained product is then displaced through the piercing tip14, and outlet duct17where it exits the apparatus and is inhaled.

Movement of the probe6is finally limited by abutment of the inwardly directed shoulder28, against the open end20of the sheath19.

In an alternative embodiment of the invention, shown inFIG. 5, a second porous membrane34is provided in the storage chamber24, between the aperture23and the piercing tip14, on which a single dose of powdered medicament35is located. During use of this alternative embodiment, the tip4is placed into the nose or mouth and the end face12is depressed relative to the housing1so that the apparatus is in a dispensing position. During subsequent inhalation by the user, air is displaced from the interior32of the housing1through the apertures22,23into the storage chamber24. Due to the porosity of the second membrane34, the air travels through the membrane34, thus entraining the powdered medicament35such that air and powdered medicament35exit the apparatus via the first outlet31and are inhaled. The second membrane34may be made of a porous paper, sintered plastic or similar material, provided that the pore size of the material is large enough to allow air through but small enough not to allow the powdered medicament35through.

The dispensing device is described above as being placed in the nose, or mouth as the case may be, before the device is actuated. However, the dispensing device may also be actuated prior to insertion of the tip4into the nose or mouth, as long as the device is maintained in an upright position to avoid spillage of the powdered medicament prior to insertion of the device in the nose or mouth.

The dispensing apparatus may be provided in a sterile package such as a foil packet in order to prevent moisture from affecting the apparatus, and also for reasons of hygiene. The apparatus will not function adequately if the powdered drug becomes damp. Alternatively, a cover may be provided to encase and close tip4before use.

FIG. 4shows a variant of the aperture23wherein the aperture is directed so as to have a component in the axial direction as well as the radial direction. In this way the air entering the storage chamber24is directed towards the closed lower end of the chamber24so as to more efficiently entrain the powdered product. Alternatively, the inlet aperture23may be angled so as to have components in the radial, axial and circumferential directions such that air entering the storage chamber24is directed towards the lower end of the chamber24with a spiraling motion. In any of these arrangements the inlet aperture23may be positioned so as to be covered or uncovered by the powdered product in the storage condition. More than one aperture23may be provided.

Alternatively, the inlet aperture23may be positioned in the lower end of the storage chamber24such that air entering the chamber enters underneath the powdered product and is directed axially along the chamber24towards the piercing tip14. In a yet further alternative, the powdered product may be suspended on a mesh within the storage chamber24such that air entering the storage chamber24enters below the mesh and entrains the powdered product as it passes through the mesh.

Optionally, the storage chamber24may be provided with rifling grooves or similar along its length to impart a spiraling motion to the air and entrained product as it passes along the chamber towards the piercing tip14.

In the above description, item19is described as a “sheath”. This item may be in the form of a cap, case or similar.

The housing1, plunger3, probe6and sheath19are manufactured from polyethylene, polypropylene, polyester, any engineering plastic or a similar material. Similarly, the frangible membrane18is manufactured from polyethylene or polypropylene or a similar material. Alternatively, the probe6may be manufactured from a metal such as stainless steel.

The variants described above may be combined with the described embodiments in any combination as will be obvious to the skilled person.

Advantageously, the materials of the dispensing apparatus lend themselves to easy and ready recycling. In the preferred embodiment, the absence of any metallic or ceramic components reduces the cost of processing the recycled material.

Advantageously, the components of the dispensing apparatus are moulded. This leads to low levels of material waste. The current design allows for a low number of individual parts which reduce the assembly time and cost. In a preferred embodiment of the invention, the whole apparatus may be formed from only three components, the first component being the housing1including the tip4, the second component being the plunger8and probe6and the third component being the sheath19including the frangible membrane18.