Surgery – Liquid medicament atomizer or sprayer – Pre-pressurized container holding medicament
Reexamination Certificate
2000-09-15
2003-11-11
Lo, Weilun (Department: 3761)
Surgery
Liquid medicament atomizer or sprayer
Pre-pressurized container holding medicament
C128S200140
Reexamination Certificate
active
06644306
ABSTRACT:
This application is filed pursuant to 35 U.S.C. §371 as a United States National Phase Application of International Application No. PCT/EP99/01757 filed Mar. 17, 1999, which claims priority from GB9805938.9 filed Mar. 19, 1998.
The invention provides a valve for an aerosol container suitable for use in dispensing a quantity of the contents thereof and which may be used in the treatment of asthma and other ailments. In particular, the invention provides a valve for a metered dose inhaler suitable for use in dispensing metered doses of medicaments.
Containers for aerosol formulations commonly comprise a vial body (can) coupled to a valve. The valve comprises a valve stem through which the formulations are dispensed. Generally the valve includes a rubber valve seal intended to allow reciprocal movement of the valve stem which prevents leakage of propellant from the container. Metered dose inhalers comprise a valve which is designed to deliver a metered amount of an aerosol formulation to the recipient per actuation. Such a metering valve generally comprises a metering chamber which is of a set volume which aims to administer per actuation an accurate, predetermined dose.
Suitable valves for use in the invention are available from manufacturers well known in the aerosol industry, for example, from Valois, France (eg. DF10, DF30, DF60), Bespak plc, United Kingdom (eg. BK300, BK356, BK357) and 3M-Neotechnic Limited, United Kingdom (eg. Spraymiser™). The metering valves are used in association with commercially available canisters such as aluminum canisters, suitable for delivering pharmaceutical aerosol formulations.
Aerosol formulations which are generally used comprise a suspension of a medicament, one or more liquid propellants, optionally with a co-propellant, and optionally an adjuvant such as a solvent or a surfactant, though the invention may be applicable to the dispensing of any aerosol formulation. The aerosol formulation is under pressure in the canister.
It has been found that conventional aerosols, particularly metered dose inhalers, suffer impaired performance due to the deposition of drug particles in the valve component, particularly in the metering chamber. This leads to a high occurrence of inconsistency in the doses of drug being administered which becomes particularly acute over increasing numbers of actuations. The problem of drug deposition in conventional aerosols is particularly exacerbated when excipient-free aerosol formulations are used based on the hydrofluoro alkane (HFA) propellants 134a and 227. It has further been found that drug deposition increases with storage of the aerosol particularly when the aerosol is stored at high temperature and/or high humidity.
The invention provides a valve for an aerosol in which there is significantly reduced drug deposition compared with conventionally available valves when the valve is used in aerosols comprising an aerosol formulation for inhalation. In particular, the invention provides a metering valve having a metering chamber in which there is significantly reduced drug deposition.
Accordingly the invention relates to a valve for an aerosol container for dispensing a suspension or solution of a substance in a liquid propellant contained therein, wherein the valve comprises a valve body defining a chamber, a transfer passage through which a quantity of substance to be dispensed can pass from the container into the chamber, and dispensing means which allows the substance to be dispensed, in which the chamber comprises a fluorinated polymer.
The invention further provides an aerosol container which comprises a valve according to the invention, and an inhalation device, preferably a metered dose inhaler, which comprises the aerosol container.
The invention further provides a method of reducing drug deposition in a metering chamber for use in a metered dose inhaler by the use of a fluorinated polymer according to the invention.
The invention further provides a valve for an aerosol container as described hereinabove in which the surface of the chamber, for example, the metering chamber, in contact with the substance to be dispensed is coated with a fluorinated material including fluorine coatings, plastics materials comprising fluorinated materials etc.
The fluorinated coating is preferably a plasma coating, for example, a CF4 plasma coating. Preferably the fluorinated plasma coating CF4 is applied to the metering chamber of a metering valve which may be made from any conventionally used plastics material such as Acetal, polyester, etc. The plasma coating may consist of a fluorinated polymer laid down on the surface of the valve component, preferably the chamber, by polymerisation or direct modification of the material surface by interchange of hydrogen ions in the material with fluorine ions. The coating process typically takes place in a vacuum at ambient temperature. The components to be coated are placed inside a chamber which is evacuated. The fluorine monomer or fluorine source is introduced into the chamber at a controlled rate. The plasma is ignited within the chamber and maintained for a given time at a chosen power setting. At the end of the treatment the plasma is extinguished, the chamber flushed and the products retrieved. In the polymerisation process, a thin layer of plasma polymer will be bonded to the surface of the chamber, preferably a metering chamber, or any other surface of the valve to be coated.
The fluorinated polymer may be selected from any conventionally used fluorinated polymer/copolymer or mixtures thereof or mixture of the fluorinated polymer in combination with non-fluorinated polymers conventionally used in the manufacture of valves, such as acetal, polyester (PBT) as well as polymer blends with, for example, stainless steel (eg. PBT/stainless steel blend (PDX WO96082)), etc. Examples of suitable fluorinated polymers include polytetrafluoroethylene (PTFE), ethylenetetrafluoroethylene (ETFE), polyvinyldienefluoride (PVDF), perfluoroalkoxyalkane (PFA), polyvinylfluoride (PVF), polychlorotrirluoroethylene (PCTFE), fluorinated ethylenepropylene (FEP) etc. Suitable copolymers include copolymers of tetrafluoroethylene (TFE) with PFA, TFE with hexafluoropropylene (HFP) (available as FEP 6107 and FEP 100 from DYNEON), VDF with HFP (commercially available as Viton A), TFE with perfluoro(propyl vinyl ether) (available as PFA 6515N from DYNEON), a blend of TFE, hexafluoropropylene and vinylidene fluoride (available commercially as THV 200G from DYNEON), etc.
It should be noted, however, that any conventionally available polymer, copolymer or mixture thereof which comprises a fluorinated polymer and which can be used to make the valve for use in an inhaler according to the invention will be suitable. Examples of mixtures of polymers and/or copolymers comprise, for example, up to 80% by weight fluorinated polymer, optionally up to 40% by weight fluorinated polymer, optionally up to 20% by weight fluorinated polymer or optionally up to 5% by weight of fluorinated polymer. Preferably, fluorinated polymers selected from PTFE, PVF and PCTFE are used as mixtures with non-fluorinated polymers. For example a suitable material is HOSTAFORM X329™ (Hoechst) which is a 5% PTFE/Acetal blend, HOSTAFORM C9021TF which is a 20% PTFE/Acetal blend, PTFE/PBT blends (for example, LNP WL4040), PTFE/PBT/silicone blends (for example, LNP WL4540).
The fluorinated polymers and mixtures thereof used in the invention can be moulded in any conventional manner, for example, by injection moulding, plastic moulding etc.
According to a preferred embodiment of the invention, the valve is a metering valve comprising a metering chamber, a transfer passage through which a quantity of substance to be dispensed can pass from the container into the metering chamber, wherein in the first position the dispensing passage is isolated from the metering chamber and the metering chamber is in communication with the container via the transfer passage, and in the second position the dispensing passage is in communication with the metering cham
Riebe Michael Thomas
Schulze Mark Douglas
Erezo Darwin P.
Lo Weilun
Strickland J. Michael
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