AU5809200A

AU5809200A - Special steel canister for propellant-operated dosing aerosols

Info

Publication number: AU5809200A
Application number: AU58092/00A
Authority: AU
Inventors: Hubert Hoelz; Richard Thomas Lostritto; Juergen Nagel; Julio Cesar Vega
Original assignee: BOEHRINGER INGELHEIM PHARMA; Boehringer Ingelheim Pharma GmbH and Co KG
Current assignee: Boehringer Ingelheim Pharma GmbH and Co KG
Priority date: 1999-05-26
Filing date: 2000-05-24
Publication date: 2000-12-18
Anticipated expiration: 2020-05-24
Also published as: DE50009558D1; IL146713A; EG22571A; MY128067A; NO20015718D0; KR20020015330A; DE19924098A1; EA200101158A1; ZA200109597B; CZ305422B6; HU224648B1; EA003690B1; HK1045973B; CA2373094A1; JP4048027B2; SK17092001A3; BG106108A; NO20015718L; PL352052A1; EE200100620A

Description

1/1089 PCT - 1 - Boehringer Ingelheim Pharma KG 76623pct.205 Stainless steel canister for propellant-driven metering aerosols 5 The present invention relates to corrosion-resistant stainless steel canisters for propellant gas-containing aerosol formulations for use in propellant gas-operated inhalers. 10 Background of the Invention In propellant-driven inhalers, the active substances are stored together with the propellant in cartridge-like canisters. These canisters generally consist of an 15 aluminium container sealed with an aluminium valve cup in which a valve is embedded. A canister of this kind can then be placed in the inhaler in the manner of a cartridge and is either left there permanently or replaced with a new cartridge after use. Since chlorofluorocarbons (CFCs) 20 were proscribed on the grounds of their ozone-destroying properties at the Rio de Janeiro Conference at the beginning of the 90s, the use of fluorohydrocarbons (FHC) is promoted as an alternative for use in propellant-driven inhalers. The most promising example to date are TG 134a 25 (1,1,2,2-tetrafluoroethane) and TG 227 (1,1,1,2,3,3,3 heptafluoropropane). Accordingly, existing systems of delivery for treatments by inhalation have had to be converted to CFC-free propellants and new delivery systems and active substance formulations have had to be 30 developed. Surprisingly, it has been found that aluminium canisters are not always resistant to drug formulations containing fluorohydrocarbons as propellants but have a high risk of 35 corrosion depending on the composition of the formulations. This is particularly true of formulations 1/1089 PCT - 2 - Boehringer Ingelheim Pharma KG which contain electrolytes and/or free ions, particularly free halides. In these cases, the aluminium is attacked, which means that aluminium cannot be used as a casing material for the canisters. Similar instabilities in the 5 aluminium canisters have been observed when fluorohydrocarbons are used as propellants if the formulations contain acid or basic components, e.g. in the form of the active substances, the additives, in the form of stabilisers, surfactants, flavour enhancers, 10 antioxidants, etc. Description of the Invention One of the tasks of the present invention is to provide a canister for propellant-driven inhalers which is 15 corrosion-resistant in the presence of active substance formulations for inhalation therapy containing a fluorohydrocarbon as propellant, which has sufficient compressive and breaking strength to withstand processing and use, which ensures the quality of the formulations 20 stored therein and overcomes the other disadvantages known from the prior art. A further objective of the invention is to provide a canister for propellant-driven inhalers, the container of 25 which consists of a single inherently homogeneous material. Surprisingly, it has been found that canisters consisting of a container and a valve cup with valve wherein at least 30 the container consists of certain stainless steel alloys solve the problem according to the invention. These alloys contain as components chromium (Cr), nickel (Ni), molybdenum (Mo), iron (Fe) and carbon (C). Such alloys may additionally contain copper (Cu), manganese (Mn) and 35 silicon (Si). The container preferably consists of one of the alloys described below.

1/1089 PCT - 3 - Boehringer Ingelheim Pharma KG The invention further relates to the use of a container or canister of this kind consisting of a container and a valve cup with valve in propellant-operated metering aerosols (inhalers) and a process for producing them. 5 The invention is hereinafter explained more fully with reference to Figures 1 and 2. Fig. 1 shows the canister consisting of container (2), 10 valve cup (8) and the valve (9) in cross-section. Fig. 2 shows another embodiment of the valve cup (8) and the valve (9) in cross-section. Figure 1 shows the canister (1) according to the invention 15 in cross-section. The canister (1) consists of a container (2) for holding the pharmaceutical formulation and a valve cup (8) with valve (9). The shape and dimensions of the canister correspond to those of the aluminium canisters known from the prior art. 20 The container (2) according to the invention is made of an alloy containing 40.0 - 53.0% iron, 23.0 - 28.0% nickel, 25 19.0 - 23.0% chromium, 4.0 - 5.0% molybdenum, 0.0 - 2.0% manganese, 1.0 - 2.0% copper, 0.0 - 1.0% silicon, 30 0.0 - 0.045% phosphorus, 0.0 - 0.035% sulphur and 0.0 - 0.020% carbon. This alloy is an alloy according to material number 1.4539 of the Iron and Steel List of the Society of German 35 Metallurgists.

1/1089 PCT - 4 - Boehringer Ingelheim Pharma KG A preferred alloy of this kind has the following composition: 19.0 - 21.0% chromium, 24.0 - 26.0% nickel, 5 4.0 - 5.0% molybdenum, 1.0 - 2.0% copper, up to 2.0% manganese, up to 0.5% silicon and up to 0.02% carbon, the remainder being substantially 10 iron. In an almost identical alternative alloy the molybdenum content is restricted to 4.5 - 5.0%. 15 In an alternative embodiment the container (2) according to the invention consists of an alloy according to material number 1.4404 of the Iron and Steel List of the Society of German Metallurgists. The composition of the alloy is: 20 60.0 - 72.0% iron, 9.0 - 13.0% nickel, 17.0 - 21.0% chromium, 2.0 - 3.0% molybdenum, 0.0 - 1.5% manganese, 25 0.0 - 1.5% silicon, 0.0 - 0.04% phosphorus, 0.0 - 0.04% sulphur and 0.0 - 0.03% carbon. 30 Another embodiment of the container consists of an alloy having the following composition: 16.5 - 18.5% chromium, 11.0 - 14.0% nickel, 2.0 - 2.5% molybdenum, 35 maximum 0.03% carbon, the remainder being iron.

1/1089 PCT - 5 - Boehringer Ingelheim Pharma KG The alloys mentioned above are such that they are corrosion-resistant to various liquefied fluorohydro carbons such as TG 134a (1,1,1,3-tetrafluorohydrocarbon) and TG 227 (1,1,1,2,3,3,3-heptafluoropropane). These 5 include propellant gas formulations having active substances suitable for inhalation therapy, surfactants, cosolvents, stabilisers, complexing agents, flavour correctors, antioxidants, salts, acids, bases or electrolytes, such as hydroxide ions, cyanide ions and/or 10 halide anions such as fluoride, chloride, bromide or iodide. The container (2) is formed from a casing made of one of the alloys described above. The container (2) has four 15 different zones: the flat or concave, inwardly domed base (3), a cylindrical portion (4) which merges into the tapering neck (5) in its upper third and finally ends in the bead (6) which encircles the opening (7) of the container. 20 The wall thickness of the container (2) is between 0.1 and 0.5 mm in a preferred embodiment, preferably between 0.15 and 0.35 mm, most preferably about 0.19 to 3.0 mm. 25 In a preferred embodiment the container (2) will withstand a bursting pressure of more than 30,000 hPa, preferably more than 100,000 hPa, most preferably more than 200,000 hPa. The weight of the container (2) is 5-15 g in a preferred embodiment, 7-10 g in another and 7.9 - 8.7 g 30 in yet another. In an equally preferred embodiment the container (2) has a volume of 5 to 50 ml. Other containers have a volume of 10 to 20 ml whilst still others have volumes of about 15 - 18 ml.

1/1089 PCT - 6 - Boehringer Ingelheim Pharma KG In the sealed state the container (2) is tightly sealed by means of the valve cup (8) after being filled with the pharmaceutical formulation and the propellant. 5 In one embodiment the valve cup (8) also consists of corrosion-resistant material. Preferably this is one of the alloys described above for the containers and/or a plastics material of suitable pharmaceutical quality. 10 In another embodiment the valve cup (8) consists of aluminium. In this case the seal (10) and/or the valve (9) are constructed so that the valve cup (8) itself cannot come into contact with the liquid inside the container. 15 A preferred embodiment of the valve cup (8) is as described in GB 2324121, to which reference is hereby made in its entirety. 20 In the closed state of the canister, the valve cup (8) is crimped around the container (2) at its bead (6). In preferred embodiments a seal or gasket (10) seals the valve cup (8) relative to the bead (6). The seal may be annular or disc shaped. It is preferably disc shaped. It 25 may consist of materials known from the prior art which are suitable for use with pharmaceutical formulations with fluorohydrocarbons as the propellants. Examples of suitable materials include thermoplasts, elastomers, materials such as neoprene, isobutylene, isoprene, butyl 30 rubber, buna rubber, nitrile rubber, copolymers of ethylene and propylene, terpolymers of ethylene, propylene and a diene, e.g. butadiene, or fluorinated polymers. The preferred materials are ethylene/propylene/diene terpolymers (EPDM). 35 1/1089 PCT - 7 - Boehringer Ingelheim Pharma KG On the side of the valve cup (8) facing the inside of the container, a valve (9) is constructed so that the valve stem (12) passes through the valve cup (8) to the other side. The valve (9) sits in the central opening of the 5 gasket (10) to form a seal. The gasket (10) and valve (9) together seal the valve cup (8) from the inside of the container, so that it cannot come into contact with the liquid in the container (2). 10 The valve (9) is constructed so that every element which is capable of coming into contact with the liquid inside the container (2) consists of a material which is corrosion-resistant with respect to this liquid. Such elements include for example the spring or springs (11), 15 the valve stem (12), which projects from the inside to the outside through the opening (17) in the valve cup (8), the metering chamber (13) and the valve body (14). The spring (11) consists of steel, preferably a stainless steel. The other elements of the valve (9) may consist, for example, 20 of steel, the alloy described above and/or a plastic. The elements (12), (13) and (14) preferably consist of a plastic, particularly a polyester, most preferably polybutylene terephthalate. 25 As shown in Figure (1), one or more other gaskets or seals, e.g. the gaskets (15) and/or (16), may be provided to prevent liquid or gas from escaping outwards from the inside of the container. The gasket or gaskets may be arranged so that the liquid inside the container comes 30 into contact only with the container jacket and the valve, apart from the actual gasket or gaskets. The gasket (15) seals off the valve stem, which is optionally vertically movable, at the point where it 35 penetrates the valve cup (8). The gasket (16) seals the valve stem (12) inside the valve relative to the valve 1/1089 PCT - 8 - Boehringer Ingelheim Pharma KG body (14) and/or the metering chamber (13). In this way, the gaskets (15) and (16) prevent any liquid or gas from escaping from the interior of the container along the outer casing of the valve stem and out of the canister or 5 from coming into contact with the valve cup by this route. The gaskets (15) and (16) may be made of the same material as the gasket (10), preferably an ethylene/propylene/diene terpolymer. 10 In one embodiment in which the valve cup (8) is not made of aluminium but of one of the corrosion-resistant materials described above, it is not necessary for the gasket (10) together with the valve (9) to isolate the valve cup completely from the inside of the container. 15 Therefore, it is not necessary in this case for the gasket (10) and valve (9) to be in sealing contact with one another. There may be a gap between the gasket (10) and the valve (9). In such a case the gasket (10) sits directly on the underside of the valve cup (8), for 20 example, and seals the edge of the valve cup (8) relative to the bead (6) on the container. The gasket (15) then seals the opening (17) in the valve cup (8) from the interior of the container. 25 Figure 2 shows another embodiment of the valve cup (8) with embedded valve (9). This embodiment is largely identical to that in Figure 1. The major difference is that the gasket (10) and the gasket (16) in the embodiment in Figure 2 are combined to form one gasket (18). The 30 gasket (18) encloses the underside of the valve plate (18). It is arranged so that the valve body (14) is embedded in the gasket. The valve stem (12) passes through the gasket via the opening (19) which is located directly below the opening (17) in the valve cup (8). The 35 opening (19) is of such dimensions as to seal the valve stem (12) relative to the valve cup (8). The sealing 1/1089 PCT - 9 - Boehringer Ingelheim Pharma KG material for the gasket (18) is identical to that described for the gasket (10). The container (2) according to the invention is produced 5 analogously to the processes known from the prior art for producing aluminium canisters and the like, in which the container is stamped out of a sheet of the material in question, or the corresponding alloy. In the present invention, the container (2) is stamped out of a sheet of 10 the above-mentioned alloys of chromium (Cr), nickel (Ni), molybdenum (Mo), iron (Fe) and carbon (C) or from an alloy which additionally contains copper (Cu), manganese (Mn) and silicon (Si). 15 The container (2) or canister consisting of container (2) and valve cup (8) with valve (9) according to the invention is particularly suitable for use with propellant gas formulations containing fluorohydrocarbons. Propellant gas formulations which can preferably be used 20 in conjunction with the invention are disclosed in WO 94/13262, to which reference is hereby made. Particularly preferred formulations disclosed therein are acid-stabilised and/or ethanolic propellant gas formulations containing 1,1,2,2-tetrafluoroethane 25 (TG 134a) and/or 1,1,1,2,3,3,3-heptafluoropropane (TG 227) as the propellant gas, particularly those which contain ipatropium bromide, oxitropium bromide, albuterol, tiotropium bromide or fenoterol as active substance. 30 Depending on the active substance, inorganic or organic acids may be used as stabilisers. Examples of inorganic acids include, in addition to halic acids and other mineral acids: sulphuric acid, hydrochloric acid, nitric acid or phosphoric acid, whilst examples of organic acids 35 include ascorbic acid or citric acid. In the case of the salts of the active substances, the preferred acids are 1/1089 PCT - 10 - Boehringer Ingelheim Pharma KG those wherein the anion is identical to that of the salt of the active substance. Citric acid is generally suitable for all active substances and their salts and is also most preferred. 5 The acid content is such that the pH of the formulation is between 1.0 and 7.0, preferably between 2.0 and 5.0 and most preferably about 3.5. In the case of inorganic acids the preferred acid content is in the range from about 10 0.00002 to 0.01 N. In the case of ascorbic acid the preferred content is roughly in the range from 0.0045 to 5.0 mg/ml and in the case of citric acid it is within the range from 0.0039 to 27.7 mg/ml. 15 The formulations may additionally contain ethanol as cosolvent. The preferred amount is 1.0 to 50.0% by weight of the formulation. The following are some preferred formulations by way of 20 example which can be stored in a canister or a container of the type described above: Example 1 Ipatropium bromide monohydrate 0.001 - 2.5% by weight 25 Absolute ethanol 0.001 - 50% by weight TG 134a 50.0 - 99.0% by weight Inorganic acid 0.01 - 0.00002 normal Water 0.0 - 5.0% by weight 30 Example 2 Ipatropium bromide monohydrate 0.001 - 2.5% by weight Absolute ethanol 0.001 - 50% by weight TG 134a 50.0 - 99.0% by weight Ascorbic acid 0.00015 - 5.0 mg/ml 35 Purified water 0.0 - 5.0% by weight 1/1089 PCT - 11 - Boehringer Ingelheim Pharma KG Example ; Ipatropium bromide monohydrate 0.0187% by weight Absolute ethanol 15.0000% by weight TG 134a 84.47730% by weight 5 Citric acid 0.0040% by weight Purified water 0.5000% by weight Total 100.0000% by weight Example 4 10 Ipatropium bromide monohydrate 0.0374% by weight Absolute ethanol 15.0000% by weight TG 134a 84.4586% by weight Citric acid 0.0040% by weight Purified water 0.5000% by weight 15 Total 100.0000% by weight Example Ipatropium bromide monohydrate 0.0748% by weight Absolute ethanol 15.0000% by weight 20 TG 134a 84.4212% by weight Citric acid 0.0040% by weight Purified water 0.5000% by weight Total 100.0000% by weight 25 Example 6 Fenoterol hydrobromide 0.192% by weight Absolute ethanol 30.000% by weight TG 134a 67.806% by weight Citric acid 0.002% by weight 30 Purified water 2.000% by weight Total 100.0000% by weight A method of filling the canisters with the corresponding formulation might be, for example, the dual stage pressure 35 fill method, the single stage cold fill method or the single stage pressure fill method.

Claims

1. Canister (1) for propellant operated metering aerosols consisting of a container (2) and a valve cup (8) 5 with valve (9) embedded therein, characterised in that the container consists of an alloy containing 40.0 - 53.0% iron, 23.0 - 28.0% nickel, 19.0 - 23.0% chromium,

4.0 - 5.0% molybdenum, 0.0 - 2.0% manganese, 1.0 - 2.0% copper, 0.0 - 1.0% silicon, 0.0 - 0.045% of phosphorus, 10 0.0 - 0.035% sulphur and 0.0 - 0.020% carbon. 2. Canister according to claim 1, characterised in that the container consists of an alloy having the following composition: chromium 19.0 - 21.0%, nickel 24.0 - 26.0%, 15 molybdenum 4.0 - 5.0%, copper 1.0 - 2.0%, manganese up to 2.0%, silicon up to 0.5% and carbon up to 0.02%, with iron substantially as the remaining ingredient. 3. Canister (1) for propellant-operated metering 20 aerosols consisting of a container (2) and a valve cup (8) with valve (9) embedded therein, characterised in that the container consists of an alloy having the following composition: iron 60.0 - 72.0%, nickel 9.0 - 13.0%, chromium 17.0 - 21.0%, molybdenum 2.0 - 3.0%, manganese 25 0.0 - 1.5%, silicon 0.0 - 1.5%, phosphorus 0.0 - 0.04%, sulphur 0.0 - 0.04% and carbon 0.0 - 0.03%. 4. Canister (1) for propellant-operated metering aerosols consisting of a container (2) and a valve cup (8) 30 with valve (9) embedded therein, characterised in that the container consists of an alloy of 16.5 - 18.5% chromium,

11.0 - 14.0% nickel, 2.0 - 2.5% molybdenum, a maximum of 0.03% carbon and iron making up the remainder. 1/1089 PCT - 13 - Boehringer Ingelheim Pharma KG 5. Canister according to one of claims 1 to 4, characterised in that the valve cup (8) consists of aluminium and is sealed with a gasket (10) and/or (18) relative to the interior of the container. 5 6. Canister according to one of claims 1 to 5, characterised in that the valve (9) contains one or more stainless steel springs (11), a valve stem (12), the metering chamber (13) and a valve body (14), the valve 10 stem (12), the metering chamber (13) and/or the valve body (14) being made of steel, the alloy according to one of claims 1 to 3 and/or a plastic. 7. Canister according to one of claims 1 to 6, 15 characterised in that the spring(s) (11) consist(s) of a stainless steel and the valve stem (12), the metering chamber (13) and the body of the valve (14) consist of polybutylene terephthalate. 20 8. Canister according to one of claims 1 to 7, characterised in that the valve stem (12) is sealed off from the valve cup (18) by a gasket (15) or (18). 9. Canister according to one of claims 1 to 8, 25 characterised in that the gasket (10) and/or gasket (15) and/or gasket (18) consist or consists of an ethylene/propylene/diene terpolymer. 10. Canister according to one of claims 1 to 9, 30 characterised in that the valve cup (8) consists of the same alloy as the container (2). 11. Canister according to one of claims 1 to 10, characterised in that the container withstands a bursting 35 pressure of more than 30,,000 hPa, preferably more than 100,000 hPa. 1/1089 PCT - 14 - Boehringer Ingelheim Pharma KG

12. Canister according to one of claims 1 to 11, characterised in that the container withstands a bursting pressure of more than 200,000 hPa. 5

13. Canister according to one of claims 1 to 12, characterised in that the container has a wall thickness of 0.1 to 0.5 mm, preferably 0.15 to 0.35 mm. 10 14. Canister according to one of claims 1 to 13, characterised in that the container has a wall thickness of 0.19 to 3.0 mm.

15. Container for a canister (1) for propellant-operated 15 metering aerosols, characterised in that the container consists of an alloy according to one of claims 1 to 4.

16. Container according to claim 15, characterised in that the container withstands a bursting pressure of more 20 than 30,000 hPa, preferably more than 100,000 hPa.

17. Container according to claim 15, characterised in that the container withstands a bursting pressure of more than 200,000 hPa. 25

18. Container according to one of claims 15 to 17, characterised in that the container has a wall thickness of 0.1 to 0.5 mm, preferably 0.15 to 0.35 mm. 30 19. Container according to one of claims 15 to 18, characterised in that the container has a wall thickness of 0.19 to 3.0 mm. 1/1089 PCT - 15 - Boehringer Ingelheim Pharma KG

20. Use of a canister according to claims 1 to 14 or a container according to one of claims 15 to 19 in an inhaler and/or for storing active substance formulations which contain 1,1,2,2-tetrafluoroethane and/or 5 1,1,1,2,3,3,3-heptafluoropropane as propellants.

21. Use of a canister according to claims 1 to 14 or a container according to one of claims 15 to 19 as in claim 20, characterised in that the formulation contains acid 10 for stabilisation, ethanol as a cosolvent and ipatropium bromide, oxitropium bromide, tiotropium bromide, albuterol or fenoterol as active substance.

22. Use of a canister according to claims 1 to 14 or a 15 container according to one of claims 15 to 19 as in claim 20 of 21, characterised in that the formulation contains acid for stabilisation, ethanol and ipatropium bromide, oxitropium bromide or tiotropium bromide as active substance. 20

23. Use of a canister according to claims 1 to 14 or a container according to one of claims 15 to 19 as in claim 20, 21 or 22, characterised in that the formulation contains citric acid. 25

24. Use of a canister according to claims 1 to 14 or a container according to one of claims 15 to 19 as in claim 20, 21 or 22, characterised in that the formulation contains a mineral acid. 30

25. Use of a canister according to claims 1 to 14 or a container according to one of claims 15 to 19 as in claim 20, 21 or 22, characterised in that the formulation contains hydrochloric acid. 35 1/1089 PCT - 16 - Boehringer Ingelheim Pharma KG

26. Process for producing a container (2) or a canister (1) consisting of a container (2) and a valve cup (8) with valve (9) embedded therein for propellant-operated metering aerosols, characterised in that the container (2) 5 is stamped out from a sheet consisting of an alloy according to one of claims 1 to 4.