FI85947B - Device intended for measuring an inhalable medicinal dose in powder form - Google Patents

Description

1 85947

Apparatus for measuring the dose of powdered medicinal product to be inhaled - Anordning avsedd för mätning av en inhalerbar läkemedelsdos i pulverform

The invention relates to a part of a powder inhaler for inhaling a medicament powder, which comprises a medicament powder and a mechanism for measuring its dose and transferring it out of the container.

A propellant-pressurized anhosaic aerosol or powder inhaler is generally used to administer the inhaled drug. Dose aerosol dose measurement is accurate based on determining the volume of liquid in the dose valve, and external moisture cannot affect the event. With powder hay tiles, the measurement is inaccurate for several reasons. Dose measurement is known to be based on two principles. The powder may be pre-measured in small dose containers, e.g. capsules, from which it is delivered to the patient's inhaled air during administration. A larger amount of drug powder may also be contained in a container in the inhaler, from which an amount of powder measured by a special mechanism is transferred to the patient's inhaled air. Such multi-dose inhalers are more comfortable for the patient due to their ease of use.

· ...: The inhalable doses of the powder inhaler may vary between tenths of a milligram and tens of milligrams. The lower the doses, the more difficult it is to measure the dose accurately enough and the more external disturbances can reduce the measurement accuracy. The main distraction is external humidity. If the medicine powder gets wet, for example during storage, it may clump, which reduces the measurement accuracy. The penetration of moisture into the drug depends on the tightness of the drug container, the water vapor permeability of the structural material, and the moisture absorption of the drug powder itself. It is known that the disadvantages of moisture have been reduced by the desiccant attached to the medicine container.

Moisture also affects the accuracy of the dose of medicine coming out of the inhaler in another way. If the inner surfaces of the inhaler that are in contact with the outgoing drug powder become wet, the amount of drug coming out will be reduced to a fraction of normal. Humidification can occur by exhaling through the inhaler or by bringing the device from cold to warm. This disadvantage of moisture could be prevented by equipping the inhaler with a one-way valve to prevent exhalation and other airflows through the device.

Based on the above, the medicine container and dose measurement mechanism of a multidose powder inhaler should meet the following conditions: - measure both large and small doses with sufficient accuracy - be as compact as possible - allow the use of a one-way valve in the inhaler due to its design.

In addition, it would be beneficial for the overall cost of medication if the medication container were to be replaced.

The structure of the multi-dose powder inhaler and the dose measurement mechanism of the medicament are thus very important not only for the accuracy of the dose measurement and the shelf life of the medicament, but also for the advantageous design of the entire inhaler. The drug reservoir and dose measurement mechanism of any known multi-dose powder inhaler do not meet all of the above conditions.

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Finnish Patent Publication No. 69963 discloses a multi-dose powder dispenser with a medicine container and a dose measuring device. The medicine container is conical at the bottom and has an axis rotating about its longitudinal axis at the bottom. The shaft has one or more dosing holes into which the powder flows as the shaft is rotated. The tank can be provided with a desiccant and a vibrator 11, which enhances the flow of powder as the shaft rotates. When the shaft has been rotated half a turn, the dosing cavity is rotated into the inhalation channel below the container, where the powder falls.

The medicated powder is well protected against moisture, but is required to have exceptionally good flow properties to evenly fill the dose cavity. Based on the structure shown, the patient may receive an overdose of the drug if multiple loading movements are performed prior to inhalation. The medication container is not replaceable and the exhalation check valve is not included.

U.S. Patent No. 4,046,146 discloses a multi-dose inhaler in which the dose is measured by rotating a perforated cylindrical drug container at the bottom. The cylinder rotates *. about its central axis on a fixed, round base plate with a hole for the dose to fall into the inhalation channel.

*: · *: When the medicine container is rotated for 1 hour, the holes in the bottom of the medicine container are filled with medicine powder and come under the plate inside the container at the hole in the round base plate from where the powder drops by gravity for inhalation.

The medicated powder is poorly protected against moisture due to the wide, non-tight sliding surface, and the risk of overdoses exists by performing multiple charging movements before inhalation. The measurement of small doses is obviously inaccurate, because gravity alone is not enough to completely inhale the dose into the inhalation channel • • • · i «· 4 85947. The design does not allow efficient use of the one-way valve1. However, the medicine container is replaceable.

Finnish patent publication 79947 discloses a multi-dose inhaler in which the powder is packed in a perforated film in a medicament container, and the perforated part of the film is transferred to an inhalation channel. In the device according to this patent on the market, the membrane is a thin, round plastic plate which, when making a charging movement, rotates in the inhalation channel. There is a desiccant in the medicine container. Despite the desiccant, moisture can affect the drug powder over time through extensive sliding surfaces. The operation of the device is disturbed by the risk of clogging the holes in the perforated plate and the adhesion of the drug to the moist inner walls of the inhalation channel. The medicine container does not need to be replaced. The mechanism can be used to measure both small and large amounts of drug.

The present invention relates to a multi-dose powder inhaler medicament container and a dose measurement mechanism that accurately measures both large and small doses of medicament while the medicament powder is permanently and tightly protected from external moisture and which by its construction easily allows a one-way valve to prevent inhalation through the inhaler.

The operation of the device is based on filling a cavity in a circular cross-section with a quantity of medicament powder corresponding to a single dose by rotating the medicament container around the shaft and delivering the dose to the inhalation channel by pushing the shaft out of the medicament container. The cavity is filled by gravity-rolling powder and a shaft-mounted sweeping member attached to the medicament container. The sliding surfaces between the shaft and the medicine container are elastically tight.

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The device according to the invention is characterized in that the container has at least one flap-like sweeping member resting on the shaft at the dosing cavity and one end rotatable about the shaft, the other end of the flap dragging the shaft surface filling the dosing cavity with drug, after which the shaft is movable longitudinally the dose compartment 1 with the doses of medicine comes out of the container.

The invention will be described in more detail below with reference to the accompanying drawings, in which Figure 1 shows a schematic view of a device according to the invention, the medicine container cut in the longitudinal axis, Figures 2a, b and c show the device of Figure 1 in the longitudinal direction, and Figures 3a and B show Fig. 4a and b show an inhalation device comprising a device according to the invention, Fig. 5 shows another inhalation device provided with a device according to the invention, and Figures 6-9 show an inhalation device comprising a device according to the invention. 5 variations.

Fig. 1 shows the basic structure of the device with the medicine container cut in the longitudinal direction of the shaft 3 and in Fig. 2 with a cross-section in the axial direction. 5 for measuring the dose The drug powder 6 is freely at the bottom of the drug container 1. A desiccant 7 can be placed inside the container 6 85947, e.g., packed in an annular body.The shaft holes 8 are tight but allow the shaft to be moved in its longitudinal direction. at points 3. There may also be several sweeping members 4. The cross-section of the medicament container 1 is preferably circular, but may also be of other shapes, and the shaft 3 is preferably centrally located in the medicament container, but may also be arranged eccentrically.

The dose measurement event is shown in Figures 2a, b and c. When the medicine container is rotated, the medicine powder initially rotates (Fig. 2a) with the container, but continues to drain and fall down as it rotates, reaching the sweeping member 4 (Fig. 2b). After one turn, the sweeping member 4 has packed the dosing cavity 5 full of powder with a slight tension (Fig. 2c). Pushing the shaft 3 causes the dose to move outside the container, and at the same time the tight shaft hole 8 evens out any excess powder. When a strong gas flow (e.g. provided by inhalation) is directed into the dose cavity 5, it is emptied of the drug powder. The term "cavity" refers to a recess in the shaft whose volume corresponds to a single dose of drug.

Experiments have shown that a device with a single dose well 5 and a sweep member 4 achieves a measurement accuracy of about ± 101 when measuring doses above 2 mg. In this case, the medicine container 1 may be half-filled with powder, and the measurement accuracy begins to deteriorate when about 2/3 of the powder has been used. In this case, a dose of more than 200 2 mg (depending on the specific weight of the powder) can be measured from an interim drug container 1 with a diameter of 2 cm and a height of 1 cm. Experiments have also shown that the flow properties of some drug formulations are insufficient for accurate device operation. In this case, it is advisable to use a mechanism which, as is known per se, vibrates the τ 85947 drug container during rotation. Drainage and filling of the dosing cavity can also be enhanced by shaping the inner surface of the container and by adjusting the length and width of the sweep, and by the eccentric positioning of the shaft 5. When measuring doses of less than 2 mg, it is advantageous to use the shaft structure according to Figure 3, in which the shaft 3 is hollow at one end slightly beyond the dose cavity 5. Inside the shaft 3 there is a stationary tube 9. When the dosing cavity 5 is filled, the shaft 3 is pushed outside the container 1 while the tube 9 remains in place (Fig. 3b). When part of the gas flow (e.g. provided by inhalation) is directed to pass through the tube 9, the dosing cavity is effectively emptied of the drug.

The medicament container 1 and the end with the scanning member 4 of the device according to the invention can easily be made of plastic and the parts can be connected to each other, e.g. by forcing or by ultrasonic welding. If a suitably elastic material is used as the material, e.g. soft polyethylene or rigid elastomer, separate shaft seals 8 are not required. The preferred material for the shaft and its inner tube is polished stainless steel.

The drug can be filled into the container before the end is connected to the container when its second shaft hole is closed, or through the second shaft hole, respectively, with the end in place.

The device according to the invention is replaceable in the body of a powder inhaler either without a shaft or with it. If the replacement is performed without a shaft, the shaft holes of the medicine container are protected during storage by a plug passing through the medicine container, which at one end has a recess for receiving the shaft end.

Once the empty container has been removed from the shaft, the end of the shaft is placed in this cavity and the container is pushed onto the shaft which pushes the plug out of the container. The tank is installed in its correct position according to the alignment marks on it and on the body of the 8 85947 inhaler.

The device according to the invention measures both very small and large amounts of powder with sufficient accuracy. The medicated powder is very well protected from moisture and its construction easily allows the use of a one-way valve to prevent exhalation through the device. It is easy to manufacture and its interchangeability guarantees reasonable maintenance costs.

The following are examples of connecting a device according to the invention as a complete powder inhaler.

Figure 4a shows a simple device in which the dose is transferred to the inhalation channel 10 by hand pressing the button 11. The shaft is a solid shaft according to Figure 1, which at one end rests on a spring 12 tensioned seat 13. The drug container is tensioned in place by an annular spring-loaded dental device 14 rotating only in the right direction and also vibrates the medicine container as it is rotated, making it easier for the medicine powder to drain. The shaft is chamfered at 15 to maintain its correct position. In the example, a digital dose counter 16 and a contact 17 have been used. The container can be replaced by opening the lock 18, whereby the part containing the container with its shaft disengages along the line 19 (Fig. 4b), and the more expensive part containing the dose counter is durable.

When using the device, the medicament container 1 is manually rotated one turn, e.g. according to the alignment marks, after which the button 11 is pressed in and inhaled from the mouthpiece 20. When the button is released, it returns to its initial position, so that the dose hole is pushed into the medicament container.

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Figure 5 shows a more complex embodiment in which the device according to the invention is used for measuring relatively small amounts of powder in connection with the vortex chamber for comminuting drug particles disclosed in Finnish patent application 892956. The shaft structure shown in Figure 3 is used in the device. The dose is automatically transferred outside the medicine container and the inhaler is well protected against exhalation wetting.

The front lid 2 of the medicine container is arranged as a rear wall of the vortex chamber 21. The other end of the container has two annular teeth, one 22 communicating with the sprocket 24 and the other 23 with a spring 25 attached to the body of the inhaler, the purpose of which is to prevent the container from rotating in the wrong direction and to vibrate the container during rotation. The shaft 26 has a swivel wheel 27, a groove cylinder 28 and a gear 24 and at its end a spike 29 for impulse to the digital metering counter 16. A transfer device 30 is attached to the shaft 3, which at its other end is transmitted almost smoothly under the lower groove of the groove cylinder on the existing rail.

• · · ': When the transfer wheel 27 is turned one turn, the shaft 3 moves: V: inside the medicine container 1, the inner tube 9 closes the bottom of the dosing cavity 5, ....: the dosing cavity is filled and the shaft 3 moves out to its initial position. From the mouthpiece 1 to the vortex chamber 21. When inhaled through the mouthpiece 20, the butterfly valve 32 acting as a one-way valve opens and air flows through the inlet pipe 33 of the vortex chamber. . account. A small portion of the inhaled air enters through the dose cavity 5 along the tube 9, together with the internal vortex of the chamber "accurately detaching the drug from the dose cavity.

: ***: Exhalation can be exhaled through the device through the dose cavity and tube 9. In practice, however, this is not possible because ίο 85947 when measuring small doses, the hole in the bottom of the dosing cavity is less than 1 mm in diameter, and the patient does not feel able to exhale when the valve valve1 closes the actual air inlet.

If a solid shaft is used, exhalation through the device is completely prevented.

The medicine container is replaced by opening the hinged part of the locking device 18 and turning the swivel wheel 27 one turn. In this case, the medicine container 1 is pushed out by the shaft, so that it can be easily pulled out of the shaft 3. The new container is installed in place, as shown above (page 7).

Figures 6 to 9 show a variation of Figure 5 on an inhaler device equipped with a new dosing system. In this embodiment of the inhalation, the shaft 3 provided with the dose cavity 5 remains stationary, but on the other hand the medicine container 1 and the rotating chamber 21 to be connected to it with its nozzle 20 move. The detachable part containing the medicine container 1 is arranged around a shaft 3 provided with a fixed dosing cavity 1a, which shaft pierces the medicine container. A vortex chamber 1 with a nozzle is removably attached to the open end of the medicine container. The part of the medicament container 1 has a pin projecting in the side wall, which fits into the grooved groove of the device. When the device is rotated, a pin moving in the threaded groove of the medicine container forces the medicine container 1 ____ with its vortex chambers outwards, whereby the medicine container 1 moves and ... rotates with respect to the shaft 3. The groove shape is chosen so as to obtain a complete reciprocating motion in one revolution. Figure 6 shows the device in the closed inhalation position, in which the inhalation cavity 5 of the shaft 3 is located in the vortex chamber 21. Figure 7 shows the device in the middle of the loading movement, where the medicine container 1 is: moved outwards with respect to the shaft 3 so that the dose 5 is now in the medicine container. 1. Fig. 8 shows a cross-section along the line A-A in Fig. 6 and Fig. 9 shows the device opened for changing the container 1 of medicine.

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Claims (9)

Apparatus for measuring an inhalable drug dose in powder form, comprising a medicament container (1) through which extends an at least shaft (5) provided with a dose recess (5), characterized in that the container (1) is provided with at least one heavy-duty ironing member (4) lying on shaft (3) at the dose recess and one end of which can be wound around the shaft (3), the other end sliding along the surface of the shaft filling the recess (5) with the healing recess. means, after which the shaft (3) can be displaced longitudinally in relation to the container (1) such that the dose depression (5) with the drug dose falls outside the container (1). 2. Device according to claim 1, characterized in that one end of the ironing member (4) is fixed to the wall of the container (1), which container is rotatable about the shaft (3). Device according to claim 1 or 2, characterized in that the shaft (3) is at least partially: - · compliant. 4. Device according to claim 3, characterized in. hence, the dose-lined opening (5) in connection with the hollow part of the shaft Γ.1 (3). 5. Device according to claim 3, characterized in that the wall of the shaft (3) is provided with a recess (5) which opens into the hollow space and that the hollow space. has a fixed tube (9) extending into the drug container (1) adjacent the one wall past the depression (5), the shaft (3) being displaceable relative to the container and the fixed tube (9). ) such a distance that the recess (5) falls outside the container (1). i4 85947 Apparatus according to any of the preceding claims, characterized in that the drug container (1) with ironing means (4) and passage seals (8) are interchangeable. Device according to any of the preceding claims, characterized in that the device is provided with a limiter of the direction of rotation of the container, which prevents the rotation of the container (1) in the wrong direction. An inhalation device provided with a device intended for measuring an inhalable drug dose in powder form according to any preceding claim. Device according to claim 8, characterized in that it is provided with a one-way valve (32) to prevent exhalation through the device. ϋ