Device for administration of medicines

Abstract

A device for the oral inhalation of finely divided solid medicaments, which comprises within a housing a capsule holder fixed to an elongate vibratable member which is fixed to the housing. A capsule in the capsule holder is pierced and inhalation by a patient causes the vibratable member to vibrate, medicament is shaken from the capsule and inhaled into the patient's lungs.

Parent Case Text

This is a continuation, of application Ser. No. 382,214 filed July 24, 1973, and now abandoned.

Description

This invention relates to a device for the application of finely divided solid medicaments by oral inhalation.

The application of medicaments by oral inhalation, inhalation therapy, is of considerable value in treating ailments of the bronchial tract and of the lungs, and the route is also of value in the systemic application of medicaments.

In order to obtain the maximum beneficial effect the medicament should be carried to the area to be treated in the form of fine particles suspended in the inhaled air. In the past this has been achieved for example, by applying the medicament with a nebuliser or by applying the medicament from a solution or suspension in a pressurised pack. Both of these methods are however, rather costly, and in the case of the pressurised pack, the apparatus is not reusable. A disadvantage of the nebuliser is the difficulty of administering an exact predetermined dose of medicament. Devices are known for the insufflation of powdered medicament but many require an additional source of power besides the patients inhalation to blow the powder out of the device. Examples of such additional sources of power include for example a rubber squeeze bulb (see Belgian Pat. No. 764,576) or a source of gas under pressure (see British Pat. No. 1,305,172). In such devices it is difficult to synchronise the patients inhalation with the operation of the additional source of power. Other inhalation devices which are activated solely by the user's inhalation are described in British Pat. Nos. 1,118,341, 1,182,779, 1,122,284, 1,295,081, 1,301,856 U.S. Pat. No. 3,635,219, and Belgian Pat. No. 781,102.

According to the present invention, there is provided a device for the oral inhalation of finely divided solid medicaments which device comprises a hollow housing and a capsule holder fixed to an elongate vibratable member which is fixed towards one end within the housing at a point remote from the capsule holder, said housing having inlet and outlet vents permitting air to flow through the housing the outlet vent being adapted for application to or insertion into the mouth and the interior of the housing being constructed and arranged so that the intake of breath by the user of the device through the outlet vent causes a turbulent airstream to flow within the housing which in turn causes the said member to vibrate. In use the device of this invention is first loaded by placing a capsule containing finely divided medicament into the capsule holder. As the patient inhales through the outlet vent the vibratable member vibrates in the turbulent airstream which is set up within the hollow housing and the capsule holder and the capsule held therein vibrate along with the vibratable member. Providing the capsule is pierced, the finely divided medicament is shaken from the capsule by the vibration into the interior of the housing. It is then caught up in the airstream and is carried through the outlet vent and down into the user's lungs. It will thus be clear that the medicament capsule must either be pierced before insertion into the capsule holder or must be pierced in situ. This latter method is most convenient and thus in a preferred embodiment of this invention the device is provided with means for piercing a medicament capsule in situ in the device.

The capsule may be pierced at any position on its surface and the preferred position of piercing depends on the particular embodiment of the invention, as will be discussed below.

For ease of access to the interior of the housing in order to load the device with a medicament capsule, part of the housing may be detachable e.g. by way of screw threads or a snap-on/snap-off locking mechanism. The hollow housing may conveniently be long and narrow with the vibratable member mounted longitudinally within the housing. With this embodiment a pleasing slim shape may be achieved.

The elongate vibratable member may be in the form of a long narrow flat strip of a suitable material e.g. a metal or plastic reed, such that the primary component of vibration is in a single plane i.e., the vibration corresponds roughly to harmonic motion. Alternatively, the vibratable member may be in the form of a rod or spindle which is able to vibrate in any direction at right angles to its long axis. Preferably the rod is circular in cross-section.

A capsule holder is fixed to one end of the vibratable member. Preferably the capsule holder is located near the air outlet in the housing. The capsule holder may be in the form of a simple cup into which the capsule fits securely. It is then advantageous to position the capsule holder in a constricted neck region within the hollow housing e.g. an approximate Venturi orifice in order to give a minimum pressure area in the vicinity of the capsule when the patient inhales through the air outlet vent. Alternatively the capsule holder may be in the form of a cup which has a passage to allow a flow of air from within the hollow housing to one end of the major axis of the capsule.

The device of this invention also has at least one outlet vent and one or more inlet vents. Preferably the device has only one outlet vent, and one or more inlet vents. In the case where there is one inlet vent, this may be in the end or in the sides of the device. Further inlet vents may be provided in the end or the sides of the device for example there may be one main inlet in the end and one or more subsidiary inlets e.g. the sides of the device.

When the vibratable member is in the form of a reed, it is preferably that the cross-sectional area of the outlet vent is of the same general magnitude as the total cross-sectional area of the inlet vents.

The interior of the housing of the device is constructed and arranged so that the intake of breath by the user of the device through the outlet vent causes a turbulent airstream to flow within the housing which in turn causes the said member to vibrate. Such construction depends on the method desired to achieve dispersion of the medicament in the air stream. When the vibratable member is in the form of a reed turbulent airflow within the housing may be ensured by the provision of baffles within the housing and/or on the vibratable member itself. A second possible method of producing the required turbulence, preferred when the vibratable member is in the form or a rod, is to provide a number of inlet vents in the side of the device in the region of the capsule holder. Preferably these inlets are angled or are positioned adjacent internal angled barriers, so that incoming air is directed to a circular path.

Dispersion of the medicament from the capsule may be further facilitated and turbulence increased by providing the capsule holder with a protuberance, for example in the form of a disc which is able to strike the inner walls of the housing when the vibratable member vibrates.

Suitably the device also incorporates a means for piercing the medicament capsule. In the embodiments wherein the capsule holder is in the form of a simple cup preferably the capsule is pierced on opposite sides of its major axis. When the capsule holder is in the form having an air passage it is preferable to pierce the capsule along its major axis so that the two ends each have one centrally placed hole through them.

It is usually preferable to position a guard grid in the outlet vent in order to prevent the entire capsule from being inhaled by the patient should some mishap dislodge the capsule from the capsule holder. In the case of patients who find it difficult to inhale strongly the airflow through the housing may be supplemented by an additional source of power such as a rubber squeeze bulb which is squeezed as the the patient inhales. With such an embodiment the bulb must be fitted to an air inlet in the housing leaving another air outlet free to allow the user of the device to inhale.

The invention will now be illustrated in some of its specific embodiments with reference to the accompanying drawings wherein:

FIG. 1 is a cross section of an oral inhalation device in accordance with this invention;

FIG. 2 is a cross section of a second device in accordance with this invention;

FIG. 3 is a cross section through the line A--A of FIG. 2;

FIG. 4 is a cross section of a third device in accordance with this invention;

FIG. 5 is a cross section of a fourth device in accordance with this invention;

FIG. 6 is a cross section of a further device in accordance with this invention;

FIG. 7 is a cross section through the line B--B of FIG. 6;

FIG. 8 is a cross section through the line C--C of FIG. 6;

FIG. 9 is a cross-section of a further device in accordance with this invention;

FIG. 10 is a cross-section through line D--D of FIG. 9;

FIG. 11 is a cross-section through line E--E of FIG. 9;

FIGS. 12 and 13 are cross-sections of two further, preferred devices in accordance with this invention.

Referring first to FIG. 1 a hollow housing 1 contains capsule holder 2 which is shown as holding a capsule 3 containing finely divided medicament. The capsule holder 2 is mounted on the end of a vibratable member in the form of a reed 4 which is fixed at the end remote from the capsule holder to a projection 5 extending from the housing. Air inlet vents 6 and air outlet vents 7 permit the passage of air through the housing. The outlet vents 7 are adapted to be inserted into the mouth by suitably shaping the housing in the vicinity of the outlet vents. Baffles 8 project from the wall of the housing in a direction normal to the logitudinal axis of the housing and a co-operating baffle 9 is mounted on the vibratable member. The dimensions and location of co-operating baffle 9 are chosen to leave a small gap 11 between baffles 8 and co-operating baffle 9. Constrictions 10 form a neck region about the capsule and capsule holder.

In use the patient inserts the portion of the housing in the vicinity of outlet vent 7 into his mouth having first loaded the device with a capsule 3. The capsule may either be pierced before loading or pierced in situ by a mechanism not shown in FIG. 1. In order to load the device the housing is separable at points X by screw threads (not shown). The patient then inhales through outlet vents 7 thereby drawing air through the inlet vents 6 and thence through the housing 1. As the airstream negotiates baffles 8 and 9 via the gap 11, an aerodynamically unstable situation arises at the gap 11. The vibratable member begins to vibrate in the plane of the drawing and the medicament is shaken from the pierced capsule into the interior of the housing. It is then caught up in the airstream and drawn down into the patient's lungs as he inhales. The constricted neck formed by the constrictions 10 ensures a minimum pressure area in the vicinity of the capsule thereby assisting in the dispersal of the medicament.

FIGS. 2 and 3 represent a device similar to that of FIG. 1. Again a hollow housing 101 contains a capsule holder 102 fitted with a capsule 103 of finely divided medicament. A harmonically vibratable member in the form of a reed 104 is fixed to projection 105 from the housing at the end remote from the capsule holder 102. The housing again may be separated at point Y and the capsule may either be pierced before loading or pierced in situ. The housing has inlet vents 106 and outlet vents 107. The vibratable member carries baffles 109 positioned adjacent the inlet vents 106, with a small gap between baffles 109 and the wall 108 of the inlet vents 106.

In operation as the patient inhales through inlet vents 107 air flows into the device through inlet vent 106. As the airstream negotiates the gap between baffle 109 and walls 108, again an unstable aerodynamic situation is set up and the vibratable member vibrates in the plane of the drawing.

FIG. 4 represents another device in accordance with this invention. Again a housing 201 contains a capsule holder 202 fitted with a capsule 203, the capsule holder mounted on a vibratable member in the form of a reed 204 fixed to projection 205. The housing has inlet vents 206 in its side and outlet vents 207. The walls 208 of the inlet vents define slots 213. The vibratable member has mounted thereon baffles 209 which have leading edges 212 positioned near to and parallel to longitudinal slots 213.

As air is sucked through inlet vents 206 and thence through slots 213, the airstream plays on leading edges 212 of baffles 209 and causes the entire vibratable member to vibrate.

FIG. 5 represents another device in accordance with this invention. Again a housing 301 contains a capsule holder 302 fitted with a capsule 303, the capsule mounted on a vibratable member in the form of a reed 304 fixed within the end of the housing 305. The housing has one inlet vent 306 in its side and outlet vents 307. The reed 304 is able to move away from inlet vent 306 and expose an annular gap 314. The region of the housing near to the outlet 307 is provided with a plug 315 which is drilled with a hole 316. The cross-sectional area of the hole 316 is approximately equal to the area of the annular gap 314 exposed at the maximum excursion position. For example using a device with a reed about 12 mm wide covering a circular inlet vent 306 of diameter 8 mm it is possible to produce an ampitude of movement of some 0.5 mm at the mid-point of the inlet vent 306. The area of the annular gap exposed at the maximum excursion position is thus fractionally over 12 mm.sup.2. An area of 12 mm.sup.2 corresponds also to a circular hole of about 4 mm diameter. Thus a hole 316, of diameter 4 mm is provided in the plug 315.

In operation a pulse of air passes through the inlet vent 306 lifting the reed 304 slightly and travels on towards the outlet vent 307. As the air reaches the plug 315 its movement is restricted and consequently the rate of air intake is reduced and the reed 304 closes. The contained air passes through the outlet vents 307 so that the internal pressure is reduced, and the reed is once again opened by the external air pressure. A continuation of this sequence causes the reed to move up and down, and the rate at which this happens will tend to set at a natural resonant frequency of the reed.

FIGS. 6 to 8 represent a further device in accordance with this invention. A hollow housing 401 contains a capsule holder 402 fitted with a capsule 403 of finely divided medicament. A vibratable member in the form of a rod 404 is fixed to the end of the housing. The housing again may be separated at a point Z. The housing has inlet vents 406 and an outlet vent 407. The inlet vents 406 are in the form of holes drilled roughly tangentially in the housing in the region of the capsule-holder 402, as shown in FIG. 7. The housing has one further inlet vent 406a near the end of the housing to which the rod 404 is attached. The capsule holder 402 has an internal passage 417 and a circular disc 418, which is of larger diameter than the capsule holder 402. A sharpened piercing member 421 is slidably mounted coaxially within the housing by means of a spider arrangement 420.

The extension of the outlet vent 407 projects slightly into the main housing thereby forming an annular trough 422.

In operation the device is first separated at points Z loaded with a capsule 403 and the two halves of the housing are reassembled. The capsule is then pierced at both ends of its major axis by moving the piercing element 421 through the capsule and out again. The patient then inhales through the outlet vent 407 thereby drawing air through the tangential holes 406, inducing a vortex in the region of the capsule holder 403. Providing the flow rate is sufficient the capsule holder 403 is thereby made to rotate in an orbital movement such that the disc 418 strikes the inside of the housing in a succession of light blows. The orbital movement coupled with the tapping effect fluidises the powder inside the capsule so that aggregates are dispersed. At the same time air is drawn in through the inlet vent 406a, passes through the device towards the outlet vent end 407. As the airstream reaches the capsule holder 402, some passes into the passage 417 and thence through the pierced capsule 403. The rapid vibration of the capsule 403 ensures that the powdered medicament issues freely from the hole at the end nearest the outlet vent 407. The remaining portion of the airstream from vent 406a reaches the disc 418 and causes further turbulence in the vicinity of the capsule. As the powder issues from the capsule it is caught up in the airstream and is carried towards the outlet vent 407. As the stream of circulating particles passes through the housing, centrifugal force holds particles above a given size against the walls of the housing and they circulate within the trough 422, while entrainment in the air flow carries finer particles down the outlet vent 407 and into the patient's lungs.

During their rotation in the trough 422, the large particles are subject to attrition by rubbing themselves against the walls of the housing so that progressively more material is released at a low particle size and escape through the outlet vent 407.

An important benefit to be derived from this particular design is ease of construction and assembly. The moving part does not have to be in a critical relation with the static part and as a result of this it is possible to form the assembly from injection mouldings produced in low-cost moulds. Small variations in the shape and size of the moulded parts do not matter particularly and the device works without the necessity for close alignment.

An important characteristic of the preferred device as described with reference to FIGS. 6 to 8 is that vibration does not take place below a certain critical level of air flow; consequently active release of the powdered medicament is always associated with a certain minimum amount of lung ventilation and this ensures effective transfer of the powder to the lungs. In general this critical level will be at or about 30-35 1/min of air flow, but the rate is pre-determined by the number and disposition of the holes through which air passes into the device on suction.

It is possible by covering one such hole with the finger to ensure that powder is released on a reduced rate of air-flow rather than or the normal one. This feature could be of use, for example in the administration of medicaments by adults to small children with relatively low lung capacity.

FIGS. 9 - 11 represent a preferred embodiment of the device of this invention. A hollow housing 501 contains a capsule holder 502 to carry a capsule (not shown) of finely divided medicament. A vibratable member in the form of a plastic rod 504 is fixed at one end to the capsule holder 502 and at the other end to a push button 505 slidably mounted within one end of the housing 501.

A return spring 524 is situated between the push button 505 and an annular stop 525.

The housing is separable into two parts by means of a screw thread 523. The housing has inlet vents 506 and an outlet vent 507. The inlet vents 506 are in the form of holes drilled roughly tangentially in the housing in the region of the capsule-holder 502 as shown in FIG. 10. The capsule holder 502 carries a hollow piercing member 517 having a tapered end which is extended through to the back of the capsule holder. The capsule holder 502 also carries a circular disc 518 which is of larger diameter than the capsule-holder 502. A second sharpened piercing member is fixed co-axially within the housing near to the outlet vent 507 by means of a spider arrangement 520. The region of the housing near to the outlet 507 is provided with a plug 515 which is drilled with a hole 516.

In operation, the device is first separated into two parts by unscrewing at the screw thread 523, and the capsule-holder 502 loaded with a capsule by impaling the latter onto the hollow piercing member 517, thereby piercing one end of the capsule. The two halves of the housing are then reassembled. The push button 505 is then depressed by hand against the spring 524, thus moving the capsule onto the second piercing member 521 and piercing its other end. The spring 524 then causes the return of the capsule holder to its original position. The patient inhales through the outlet vent 507 thereby drawing air through the tangential holes 506, inducing a vortex in the region of the capsule holder 502. The capsule holder 502 is thus made to rotate in an orbital movement such that the disc 518 strikes the inside of the housing in a succession of light blows. The orbital motion coupled with the tapping effect again fluidises the powder within the capsule. At the same time some of the air drawn in through the inlet vents 406 passes behind the disc 518 into extended passage 517 and thence through the pierced capsule. As the powder issues from the capsule it is caught up in the vortex of air and carried towards the outlet vent 507. As with the embodiment of FIG. 6, the finer particles in the air stream pass through the hole 516 the outlet vent 507 and into the patients lungs. Coarser particles are held back by the annular plug 515 until they are reduced in size by attrition sufficiently to escape through the central hole 516.

FIGS. 12 and 13 represent embodiments of the device substantially similar to that shown in FIG. 9, but with modifications of the method of piercing the capsule.

In FIG. 12 the end of the vibratable member in the form of a rod 604 is attached to a knob 605, integral with an outer sleeve 626 which fits over the outside of the housing 601. Again a spring 624 returns the knob and sleeve to its original position after if has been depressed during the piercing operation. Alternatively the end of the housing 627 which carries the knob 605 may be provided with a coarse screw thread to co-operate with a similar thread (not shown) on the outer surface 628 of the knob. In such an embodiment, when the sleeve 626 is depressed it also rotates and the capsule in the capsule holder 602 is rotates onto the fixed piercing member 621. This rotating action during the piercing produces an easier and more reliable piercing.

A similar arrangement is shown in FIG. 13. Again the fixed end of the rod 704 is attached to a knob 705 integral with a sleeve 726 which fits over the outside of the housing 701. The outer surface of the knob 705 is provided with a screw thread 728 which screws into a similar thread 727 on the end of the housing. A coiled spring 724 is situated in the annular space between the knob 705 and the sleeve 726, one end being attached to the housing and the other end to the sleeve. To pierce the capsule, the sleeve is screwed in, thereby rotating the capsule contained in the holder 702 onto the fixed piercing member 721 and also imparting torsional tension to the spring 724. When the sleeve is released, the coiled spring exerts torsional torque to the sleeve to unscrew and return the sleeve to its original position, thereby withdrawing the capsule from the piercing member 721.

Claims

We claim:

1. A device for the oral administration of finely divided solid medicaments which device comprises a hollow housing, an elongate semi-flexible vibratable member which is fixed adjacent one end thereof within the housing and free at the other end, a capsule holder attached to said end of the vibratable member at a point remote from its fixed end; said housing having inlet and outlet vents permitting air to flow through the housing, the outlet vent being adapted for application to or insertion into the mouth; and means for causing said member to vibrate comprising directed air flow means reacting with said flexible vibrating member.

2. A device according to claim 1 wherein the air flow means for causing said member to vibrate is provided by the construction and arrangement of said inlet vents such that a turbulent airstream is caused to flow through the housing between the vents by the intake of breath by the user which flow in turn causes said member to vibrate.

3. A device according to claim 1 wherein the air flow means for causing said member to vibrate is provided by the construction and arrangement of air flow control means on the interior of the housing such that a turbulent airstream is caused to flow through the housing between the vents by the intake of breath by the user which flow in turn causes said member to vibrate.

4. A device according to claim 1 which device has only one outlet vent.

5. A device according to claim 1 wherein the elongate vibratable member is in the form of a rod which is able to vibrate in any direction at right angles to its axis.

6. A device according to claim 5 wherein the rod is of circular cross-section.

7. A device according to claim 1 wherein the vibratable member is in the form of a long narrow flat strip, such that its primary component of vibration is in a single plane.

8. A device according to claim 2 wherein the housing is provided with a plurality of inlet vents in the region of the capsule holder.

9. A device according to claim 8 wherein said inlet vents are angled such that incoming air is directed to a circular path.

10. A device according to claim 8 wherein said inlet vents are positioned adjacent internal angled barriers such that incoming air is directed to a circular path.

11. A device according to claim 7 wherein the cross-sectional area of the outlet vent is of the same general magnitude as the total cross-sectional area of the inlet vents.

12. A device according to claim 1 wherein the capsule holder is provided with a protuberance adapted to strike the inner walls of the housing when the vibratable member vibrates.

13. A device according to claim 1 wherein the capsule holder is in the form of a cup adapted to securely carry a capsule.

14. A device according to claim 1 wherein the capsule holder has a passage to allow a flow of air from within the hollow housing to one end of the major axis of the capsule.

15. A device according to claim 1 which device is provided with means for piercing the capsule in situ in the device.

16. A device according to claim 15 which device is provided with means for piercing the capsule at both ends of the major axis thereof.

17. A device according to claim 16 wherein the means of piercing the end of the capsule nearest to the outlet vent is in the form of a sharpened piercing member mounted within the hollow housing coaxial with the capsule holder.

18. A device according to claim 17 wherein the sharpened piercing member is slidably mounted within the housing.

19. A device according to claim 17 wherein the sharpened piercing member is fixed within the housing and the device is provided with means for moving the capsule holder towards the piercing member.

20. A device according to claim 16 wherein the means for piercing the end of the capsule furthest from the outlet vent is in the form of a sharpened hollow piercing member attached to the capsule holder onto which a capsule may be impaled.

21. A device according to claim 1 wherein the housing is separable into two parts.

22. A device according to claim 19 wherein the two parts of the housing are adapted to be reassembled by means of a screw thread.

23. A device for the oral administration of finely divided solid medicaments which device comprises a hollow housing separable into two parts adapted to be reassembled by means of a screw thread; an elongate semi-flexible vibratable rod of circular cross-section which is able to vibrate in any direction at right angles to its long axis and which is fixed towards one end thereof within the housing and free at the other end; a capsule holder attached to said end of the vibratable rod at a point remote from its fixed end, the capsule holder being in the form of a cup adapted to securely carry a capsule, having a passage to allow a flow of air from within the hollow housing to one end of the major axis of the capsule and having a protuberance adapted to strike the inner walls of the housing when the vibratable rod vibrates; said housing having one outlet vent and a plurality of inlet vents permitting air to flow through the housing, the outlet vent being adapted for application to or insertion into the mouth and the inlet vents being in the region of the capsule holder and angled such that incoming air is directed to a circular path, and in turn causes said rod to vibrate; the device being provided with means for piercing the capsule at both ends of the major axis thereof in situ in the device, the means of piercing the end of the capsule nearest the outlet vent being in the form of a sharpened piercing member fixed within the housing coaxial with the capsule holder and means for moving the capsule holder towards the piercing member, the means for piercing the end of the capsule furthest from the outlet vent being in the form of a sharpened hollow piercing member attached to the capsule holder onto which a capsule may be impaled.

24. A device for oral administration of finely divided solid medicaments which device comprises a hollow housing separable into two parts, an elongate semi-flexible vibratable narrow flat strip such that its primary component of vibration is in a single plane, which is fixed towards one end thereof within the housing and free at the other end; a capsule holder attached to said end of the vibratable flat strip at a point remote from its fixed end, the capsule holder being in the form of a cup adapted to securely carry a capsule; said housing having one outlet vent and one inlet vent permitting air to flow through the housing, the outlet vent being adapted for application to or insertion into the mouth, the cross-sectional area of the outlet being of the same general magnitude as the cross-sectional area of the inlet vent, and the interior of the housing having constrictions to provide a turbulent airstream to flow through the housing between the vents by the intake of breath by the user of the device which flow in turn causes the said flat strip to vibrate.