GB2470403A - Valve assembly with valve stem for use with an aerosol canister - Google Patents

Abstract

A valve assembly 10 consists of a valve stem 11, a valve body 12 one or more seals and a ferrule 15, the valve stem 11 being co-axially slidable within the valve body 12, wherein an inner diameter of the ferrule 15 is from 13 mm to 16.3 mm. The valve 10 may further include a metering chamber defined within the valve body 12, such that it forms a metering valve. The valve assembly 10 may be attached to an aerosol dispensing canister 100 by crimping the ferule 15 to the canister 100. The canister 100 may be put to pharmaceutical dispensing, e.g. as an inhaler. The canister 100 and valve assembly 10 may be provided with a mechanical or electronic dose counter, and a breath actuable trigger.

Description

IMPROVEMENTS IN VALVE ASSEMBLIES FOR

DISPENSING CONTAINERS

The invention relates to improvements in valve assemblies for dispensing containers.

Dispensing containers are used for dispensing a wide variety of products from mobile to viscose liquid products, powdered products and the like and typically employ a liquid propellant such as a hydro-carbon or fluoro-carbon having sufficiently high vapour pressure at normal working temperatures to propel the product from a container through a valve. These are commonly used for dispensing pharmaceutical medicaments.

Typically a dispensing container will comprise a canister and a valve assembly. The valve assembly comprises a ferrule. The canister defines a volume for storing a product which typically comprises one or more active ingredients and a volatile propellant. The canister is sealed by means of the valve assembly to form the dispensing container.

The valve assembly may comprise, for example, a continuous flow valve or a metering valve.

The dispensing container is typically combined with an actuator housing to form a dispenser apparatus. The actuator housing holds the dispensing container and defines an outlet such as a nasal duct or mouthpiece for the metered dose of discharged product.

An example of a valve assembly comprising a metering valve is shown in GB2375098 in which a metering valve of the capillary-retention type is illustrated. By capillary-retention' is meant that the metering chamber of the valve is designed to remain charged with product between actuations by surface tension between the liquefied product and the valve components. An alternative type of valve is illustrated in GB2417479 in which the metering chamber of the valve does not remain charged with product between actuations. Rather, the valve is designed to allow rapid filling of the metering chamber when the apparatus is inverted immediately prior to actuation.

Dispensing containers have hitherto been used to contain a large number of doses of product. Typically, up to 200 doses may be stored in a single container.

An industry standard dispensing container comprising a canister and a valve assembly is illustrated in Figure 1.

Figure 2 shows, to a larger scale, part of the canister together with the ferrule of the valve assembly.

The canister comprises a body, a neck and a head. The head of the canister comprises an upper rim and a cylindrical, or at least largely cylindrical, portion. The outer diameter of the largely cylindrical portion is labelled OD in Figure 2. In the case of an industry standard canister the outer diameter of the cylindrical portion of the canister is 20 mm.

A valve assembly of an industry standard dispensing container comprises a valve stem, a valve body, one or more seals and a ferrule. Prior to assembly of the valve with the canister, the internal diameter of the ferrule (shown as ID in Figure 2) is designed to be fractionally larger than the outer diameter of the cylindrical portion of the canister (shown as OD in Figure 2) . Thus, the internal diameter of the industry standard ferrule is approximately 20.15 mm. Consequently, the ferrule (Internal Diameter 20.15 mm) can be placed over the cylindrical portion of the canister (Outer Diameter 20 mm) and crimped into place to seal the canister.

According to the present invention there is provided a valve assembly comprising a valve stem, a valve body, one or more seals and a ferrule, the valve stem being co-axially slidable within the valve body, wherein an inner diameter of the ferrule is from 13 mm to 16.3 mm.

Advantageously, it has been found that by reducing the inner diameter of the ferrule to measure from 13 mm to 16.3 mm a more compact valve assembly is obtained. A ferrule with these dimensions can be used to seal a canister where the outer diameter of the cylindrical portion of the head of the canister is between 13 mm and 16 mm. In particular, smaller actuator housings can be used with a dispensing container comprising the valve assembly of the present invention, which is beneficial in providing patients with apparatus which are lighter, more portable and less obtrusive to use in public.

It has also been found that the valve assembly of the present invention gives rise to a reduced volume of ullage (waste product that cannot be dispensed because of valve assembly component geometry) compared to 20 mm standard valves. By comparison with a standard 20 mm valve, the present invention provides a reduction in ullage of between 0.5 ml and 0.9 ml. In other words, the present invention leads to less wastage of active ingredient.

According to the present invention there is also provided a metering valve assembly comprising the valve assembly described above and a metering chamber.

Where the valve assembly comprises a metering valve it may further comprise a valve member which defines at least partially the geometry of the metering chamber.

In some embodiments, the valve assembly may further comprise a diptube.

The present invention further provides a dispensing container comprising a valve assembly as described above and a canister, wherein the ferrule is crimped to the canister.

The valve assembly particularly lends itself to use with canisters containing a relatively low number of metered doses. For example, 30, 15 or even 10 metered doses per apparatus.

Advantageously, when the valve assembly of the present invention is used with a canister containing a relatively low number of metered doses, the low volume required to contain the relevant number of metered doses can be achieved largely by reducing the diameter of the canister rather than the length of the canister which hitherto has been the option employed by the skilled person. It is therefore possible to maintain the same (or a similar) aspect ratio of canister compared with the industry standard canister.

Consequently, the canister is easier to handle than one where only the length of the canister has been changed resulting in a stubby profile.

A further advantage of this arrangement is that a diptube can be accommodated and, when the valve assembly comprises a diptube which reaches to a point within the canister where the cylindrical wall meets the end wall, the angle of bend required in the diptube is reduced by comparison with a short canister. By reducing the angle of bend, this reduces the likelihood of restriction in the diptube.

A further aspect of the present invention provides for a dispensing container comprising a canister, a valve assembly and a ferrule, the canister comprising a body and a head with a largely cylindrical portion, wherein the external diameter of the largely cylindrical portion is between 13 mm and 16 mm.

In a further aspect of the present invention there is provided a dispensing apparatus comprising an actuator housing for receiving the valve assembly and canister, wherein the actuator comprises an outlet for discharged product.

The smaller size of the valve assembly allows proportionally a greater volume for other components of the dispensing apparatus, such as counter mechanisms, breath-actuatable triggers, breath co-ordination mechanisms, etc. where the valve assembly is incorporated into an actuator housing of standard size.

A further advantage that the applicant has found is that the volume of seal material, such as elastomeric material, required in the valve assembly is reduced which leads to a beneficial reduction in the quantity of extractables that can be expected to be leached from the seals over the storage and useful lifetime of the dispensing apparatus.

Further, the smaller outer diameter of the valve assembly also reduces the circumferential path length of the outer face of the gasket sealing the valve assembly to the dispensing container. This helps to reduce the likelihood of any significant leakage between the sealing gasket and the inner face of the ferrule.

The valve assembly may, for example, comprise a metering valve of the capillary-retention type or the fast-fill-fast-empty type as described, for example, in GB2375098 and GB2417479.

The dispensing apparatus may include a dose counter mechanism of a mechanical, electronic or mechatronic form.

The dispensing apparatus may further incorporate ancillary features such as breath-actuable triggers and breath co-ordination systems as well known in the art.

The valve assembly may be for use in a pharmaceutical dispensing device or apparatus, such as, for example, a pulmonary, nasal, or sub-lingual delivery device. A preferred use of the valve assembly is in a pharmaceutical metered dose aerosol inhaler device. The term pharmaceutical as used herein is intended to encompass any pharmaceutical, compound, composition, medicament, agent or product which can be delivered or administered to a human being or animal, for example pharmaceuticals, drugs, biological and medicinal products. Examples include antiallergics, analgesics, bronchodilators, antihistamines, therapeutic proteins and peptides, antitussives, anginal preparations, antibiotics, anti-inflammatory preparations, hormones, or sulfonamides, such as, for example, a vasoconstrictive amine, an enzyme, an alkaloid, or a steroid, including combinations of two or more thereof. In particular, examples include isoprotereno]. [alpha- (isopropylaminomethyl) protocatechuyl alcohol], phenylephrine, phenylpropanolamine, glucagon, adrenochrome, trypsin, epinephrine, ephedrine, narcotine, codeine, atropine, heparin, morphine, dihydrorrtorphinone, ergotamine, scopolamine, methapyrilene, cyanocobalamin, terbutaline, rimiterol, salbutamol, flunisolide, colchicine, pirbuterol, beclomethasone, orciprenaline, fentanyl, and diamorphine, streptomycin, penicillin, procaine penicillin, tetracycline, chiorotetracycline and hydroxytetracycline, adrenocorticotropic hormone and adrenocortical hormones, such as cortisone, hydrocortisone, hydrocortisone acetate and prednisolone, insulin, cromolyn sodium, and mometasone, including combinations of two or more thereof.

The pharmaceutical may be used as either the free base or as one or more salts conventional in the art, such as, for example, acetate, benzenesulphonate, benzoate, bircarbonate, bitartrate, bromide, calcium edetate, camsylate, carbonate, chloride, citrate, dihydrochioride, edetate, edisylate, estolate, esylate, fumarate, fluceptate, gluconate, glutamate, glycollylarsanilate, hexyiresorcinate, hydrobromide, hydrochloride, hydroxynaphthoate, iodide, isethionate, lactate, lactobionate, malate, maleate, mandelate, mesylate, methylbromide, methylnitrate, methylsuiphate, mucate, napsylate, nitrate, pamoate, (embonate), pantothenate, phosphate, diphosphate, polygalacturonate, salicylate, stearate, subacetate, succinate, sulphate, tannate, tartrate, and triethiodide, including combinations of two or more thereof. Cationic salts may also be used, for example the alkali metals, e.g. Na and K, and arnmonium salts and salts of amines known in the art to be pharmaceutically acceptable, for example glycine, ethylene diamine, choline, diethanolamine, triethanolamine, octadecylamine, diethylamine, triethylamine, 1-amino-2-propanol--amino-2- (hydroxymethyl)propafle-1,3di01, and 1-(3,4-dihydroxyphenyl) -2 isopropylaminoethanol.

The pharmaceutical will typically be one which is suitable for inhalation and may be provided in any suitable form for this purpose, for example as a solution or powder suspension in a solvent or carrier liquid, for example ethanol, or isopropyl alcohol. Typical propellants are HFA134a, HFA227 and di-methyl ether.

The pharmaceutical may, for example, be one which is suitable for the treatment of asthma. Examples include salbutamol, beclomethasone, salmeterol, fluticasone, formoterol, terbutaline, sodium chromoglycate, budesonide and flunisolide, and physiologically acceptable salts (for example salbutamol sulphate, sairneterol xinafoate, fluticasone propionate, beclomethasone dipropionate, and terbutaline sulphate), solvates and esters, including combinations of two or more thereof. Individual isomers such as, for example, R-salbutamol, may also be used. As will be appreciated, the pharmaceutical may comprise of one or more active ingredients, an example of which is flutiform, and may optionally be provided together with a suitable carrier, for example a liquid carrier. One or more surfactants may be included if desired.

The seals and gaskets of the valve assembly may be formed from any suitable material having acceptable performance characteristics. Preferred examples include nitrile, EPDM and other thermoplastic elastomers, butyl and neoprene.

Other rigid components of the valve assembly, such as the valve body, valve member and valve stem may be formed, for example, from polyester, nylon, acetal or similar.

Alternative materials for the rigid components of the valve assembly include stainless steel, ceramics and glass.

An embodiment of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view of an industry standard dispensing container.

Figure 2 is a cross-sectional view of part of an industry standard dispensing container. The Figure shows only a ferrule and part of a canister prior to the crimping of the ferrule to the canister.

Figure 3 is a cross-sectional view of an embodiment of valve assembly according to one aspect of the present invention.

As shown in Figure 3, a metering valve assembly 10 according to one embodiment of the present invention includes a valve stem 11 which protrudes from and is axially slidable within a valve member 12, the valve member 12 and valve stem 11 defining therebetween an annular metering chamber 13. The valve member 12 is located within a valve body 14.

The valve member 12, sometimes referred to as a chamber body', forms the outer circumferential face of the metering chamber 13. The valve member 12 is provided with a plurality of axial ribs 31 which run the length of the metering chamber 31 and each terminate in a radially-inwardly extending projection 32.

The metering valve assembly 10 comprises a ferrule 15 for holding, on assembly of a dispensing container, the metering valve assembly 10 in position with respect to a canister 100. The ferrule 15 retains the metering valve assembly 10 by means of crimping of the ferrule 15 to the top of the canister 100 in a manner well known in the art.

The ferrule 15 has an aperture 28 through which one end 19 of the valve stem 11 protrudes. Sealing between the valve -10 -body 14 and canister is provided by an annular gasket 16. A dispensing container 1000 comprises the metering valve assembly 10 and the canister 100.

A pair of seals 17, 18 of an elastomeric material extend radially between the valve stem 11 and the valve member 12 and/or valve body 14. An "outer" seal 17 is radially compressed between the valve member 12, valve stem 11 and ferrule 15 so as to provide positive sealing contact to prevent leakage of the contents of the metering chamber 13 between the valve stem 11 through the aperture 28. The compression is achieved by using a seal which provides an interference fit on the valve stem 11 and/or by the crimping of the ferrule 15 onto the canister 30 during assembly to form a dispensing container. An "inner" seal 18 is located between valve member 12 and valve body 14 and the valve stem 11 to seal an "inner" end of the metering chamber 13 from the dispensing container contents.

The end 19 of the valve stem 11 is the discharging end of the valve stem 11 and protrudes from the ferrule 15. The end 19 is a hollow tube, which is closed off by a first flange 20 which is located within the metering chamber 13.

The hollow end 19 of the valve stem 11 includes a discharge port 21 extending radially through the side wall of valve stem 11. The valve stem 11 further has an intermediate section 22, extending between the first flange 20 and a second flange 26. The intermediate section 22 is also hollow between the flanges 20, 26 and defines a central passage. It also has a radial transfer port 23 and a radial inlet port 24 which are interconnected through the central passage. The second flange 26 separates the intermediate section 22 of the valve stem 11 and an inner end 27 of the valve stem 11. Preferably the valve stem 11 is formed from -11 -two separate parts -one part comprising the end 19 and first flange 20 and one part comprising the intermediate section 22, second flange 26 and inner end 27.

A spring 25 extends between the second flange 26 and a shoulder defined by the valve body 14 to bias the valve stem 11 into a non-dispensing position as shown in Figure 3 in which the first flange 20 is held in sealing contact with the outer seal 17. The second flange 26 is located outside the metering chamber 13, but within the valve body 14.

On assembly as part of a dispensing container, the metering chamber 13 is thus sealed from the atmosphere by the outer seal 17, and from the canister 30 to which the valve assembly 10 is attached by the inner seal 18. In the non-dispensing position, radial transfer port 23 and radial inlet port 24, together with the central passage in the intermediate section 22 of the valve member 11 connect the metering chamber 13 with the valve body 14. Inlet ports 55, 56 connect the valve body 14 with the dispensing container so that in this non-dispensing condition, the metering chamber 13 will be charged with product to be dispensed. The valve body 14 is also provided with a vapour vent hole 58.

The valve assembly 10 and canister 100 together form the dispensing container.

According to the present invention, the inner diameter, ID, of the metering valve assembly is from 13 mm to 16.3 mm.

The inner diameter is measured as the widest internal diameter of the ferrule 15 as shown in Figure 3.

These dimensions relate to the inner diameter of the ferrule prior to crimping onto a canister. When crimped the diameter may reduce by up to 0.2 miii.

Compared to standard valve assemblies having an inner diameter of 20 mm, the annular gasket 16, ferrule 15 and -12 -valve body 14 are altered to reduce their respective sizes.

However, advantageously, the valve stem 11, valve member 12, outer and inner seals 17, 18 and spring 25 from a standard mm metering valve such as that described in GB2375098 can be utilised without modification in a valve assembly according to the present invention having an outer diameter of 16 mm. For smaller valve assemblies having an outer diameter of 13 mm modified valve members 12 and inner and outer seals 18, 17 are necessary.

In use, the dispensing container is inverted such that the valve stem ii is lowermost, as shown in Figure 3, such that the liquified propellant in the dispensing container collects at the end of the dispensing container adjacent the metering valve assembly 10 so as to cover inlet ports 55, 56. Depression of the valve stem 11 relative to the valve member 12 causes the stem to move inwardly. Alignment of the valve stem 11 and the valve member 12 is maintained by the axial ribs 31 guiding movement of the flange 20 and the projections 31 guiding movement of the intermediate section 22. The radial inlet port 24 is closed off as it passes through the inner seal 18 thereby isolating the metering chamber 13 from the contents of the valve body 14 and pressurised dispensing container. Upon further movement of the valve stem 11 in the same direction to a dispensing position, the discharge port 21 passes through the outer seal 17 into communication with the metering chamber 13. In this dispensing position, the product in the metering chamber 13 is free to be discharged to the atmosphere via the discharge port 21 and the cavity in the hollow end 19 of the valve stem 11.

-13 -When the valve stem 11 is released, the biasing of the spring 25 causes the valve stem 11 to return to its original position. Vapour vent hole 58 accommodates escape of any gas trapped within valve body 14. As a result, product in the pressurised dispensing container passes through inlet ports 55, 56 into valve body 14 and in turn from valve body 14 into the metering chamber 13 via the radial transfer port 23 and inlet port 24 to re-charge the chamber 13 in readiness for further dispensing operations.

While the specific embodiment described above in detail relates to the use of a metering valve in the valve assembly, the skilled person will appreciate that the invention is equally applicable to other kinds of valves such as, for example, continuous flow valves.

Claims (10)

1. -14 - CLAIMS: - 1. A valve assembly comprising a valve stem, a valve body, one or more seals and a ferrule, the valve stem being co-axially slidable within the valve body, wherein an inner diameter of the ferrule is from 13 mm to 16.3 mm.
2. 2. The valve assembly of claim 1 further comprising a metering chamber.
3. 3. The valve assembly as claimed in claim 2 further comprising a valve member which defines at least partially the geometry of the metering chamber.
4. 4. The valve assembly of any preceding claim and further comprising a diptube.
5. 5. A dispensing container comprising a valve assembly of any preceding claim and a canister, wherein the ferrule is crimped to the canister.
6. 6. A dispensing container comprising a canister, a valve assembly and a ferrule, the canister comprising a body and a head with a largely cylindrical portion, wherein the external diameter of the largely cylindrical portion is between 13 mm and 16 mm.
7. 7. A dispensing apparatus comprising the dispensing container of claim 5 or claim 6 and an actuator housing for -15 -receiving the dispensing container, wherein the actuator comprises an outlet for discharged product.
8. 8. The dispensing apparatus according to claim 7 and further comprising a dose counter mechanism of a mechanical, electronic or mechatronic form.
9. 9. The dispensing apparatus according to claim 7 or 8 and further comprising a breath-actuable trigger.
10. 10. A valve assembly substantially as hereinbefore described with reference to or as shown in Figure 3.