Surgery – Liquid medicament atomizer or sprayer – Pre-pressurized container holding medicament
Reexamination Certificate
2000-05-15
2003-03-18
Lewis, Aaron J. (Department: 3761)
Surgery
Liquid medicament atomizer or sprayer
Pre-pressurized container holding medicament
C128S200140
Reexamination Certificate
active
06532955
ABSTRACT:
BACKGROUND OF THE INVENTION
Drugs for treating respiratory and nasal disorders are frequently administered in aerosol formulations through the mouth or nose. One widely used method for dispensing such aerosol drug formulations involves making a suspension formulation of the drug as a finely divided powder in a liquefied gas known as a propellant. The suspension is stored in a sealed container capable of withstanding the pressure required to maintain the propellant as a liquid. The suspension is dispersed by activation of a dose metering valve affixed to the container.
A metering valve may be designed to consistently release a fixed, predetermined mass of the, drug formulation upon each activation. As the suspension is forced from the container through the dose metering valve by the high vapor pressure of the propellant, the propellant rapidly vaporizes leaving a fast moving cloud of very fine particles of the drug formulation. This cloud of particles is directed into the nose or mouth of the patient by a channelling device such as a cylinder or open-ended cone. Concurrently with the activation of the aerosol dose metering valve, the patient inhales the drug particles into the lungs or nasal cavity. Systems of dispensing drugs in this way are known as “metered dose inhalers” (MDI's). See Peter Byron, Respiratory Drug Delivery, CRC Press, Boca Raton, Fla. (1990) for a general background on this form of therapy.
Patients often rely on medication delivered by MDI's for rapid treatment of respiratory disorders which are debilitating and in some cases, even life threatening. Therefore, it is essential that the prescribed dose of aerosol medication delivered to the patient consistently meet the specifications claimed by the manufacturer and comply with the requirements of the FDA and other regulatory authorities. That is, every dose in the can must be the same within close tolerances.
Some aerosol drugs tend to adhere to the inner surfaces, i.e., walls of the can, valves, and caps, of the MDI. This can lead to the patient getting significantly less than the prescribed amount of drug upon each activation of the MDI. The problem is particularly acute with hydrofluoroalkane (also known as simply “fluorocarbon”) propellant systems, e.g., P134a and P227, under development in recent years to replace chlorofluorocarbons such as P11, P114 and P12.
We have found that coating the interior can surfaces of MDI's with a fluorocarbon polymer significantly reduces or essentially eliminates the problem of adhesion or deposition of albuterol on the can walls and thus ensures consistent delivery of medication in aerosol from the MDI.
SUMMARY OF THE INVENTION
A metered dose inhaler having part or all of its internal surfaces coated with one or more fluorocarbon polymers, optionally in combination with one or more non-fluorocarbon polymers, for dispensing an inhalation drug formulation comprising albuterol, or a physiologically acceptable salt thereof, and a fluorocarbon propellant, optionally in combination with one or more other pharmacologically active agents or one or more excipients.
DETAILED DESCRIPTION OF THE INVENTION
The term “metered dose inhaler” or “MDI” means a unit comprising a can a crimped cap covering the mouth of the can, and a drug metering valve situated in the cap, while the term “MDI” system also includes a suitable channelling device. The terms “MDI can” means the container without the cap and valve. The term “drug metering valve” or “MDI valve” refers to a valve and its associated mechanisms which delivers a predetermined amount of drug formulation from an MDI upon each activation. The channelling device may comprise, for example, an actuating device for the valve and a cylindrical or cone-like passage through which medicament may be delivered from the filled MDI can via the MDI valve to the nose or mouth of a patient, e.g. a mouthpiece actuator. The relation of the parts of a typical MDI is illustrated in U.S. Pat. No. 5,261,538 incorporated herein by reference.
The term “fluorocarbon polymers” means a polymer in which one or more of the hydrogen atoms of the hydrocarbon chain have been replaced by fluorine atoms.
Thus, “fluorocarbon polymers” include perfluorocarbon, hydrofluorocarbon, chlorofluorocarbon, hydro-chlorofluorocarbon polymers or other halogen substituted derivatives thereof. The “fluorocarbon polymers” may be branched, homo-polymers or co-polymers.
U.S. Pat. No. 3,644,363, incorporated herein by reference, teaches a group of bronchodilating compounds that are particularly useful in the treatment of asthma and other respiratory diseases. The preferred compound taught therein is &agr;
1
-tert-butylaminomethyl-4-hydroxy-m-xylene-&agr;
1
, &agr;
3
-diol also known in the US by its generic name “albuterol” and, in most other countries as “salbutamol”. Albuterol as the free base and as acid addition salts (particularly as the sulfate salt), especially in aerosol form, has been widely accepted by the medical community in the treatment of asthma and is marketed under such trademarks as “Ventolin” and “Proventil”.
The term “drug formulations” means albuterol or a physiologically acceptable salt thereof (particularly the sulfate salt) optionally in combination with one or more other pharmacologically active agents such as antiinflammatory agents, analgesic agents or other respiratory drugs and optionally containing one or more excipients. The term “excipients” as used herein means chemical agents having little or no pharmacological activity (for the quantities used) but which enhance the drug formulation or the performance of the MDI system. For example, excipients include but are not limited to surfactants, preservatives, flavorings, antioxidants, antiaggregating agents, and cosolvents, e.g., ethanol and diethyl ether. Albuterol or salt thereof may be used in the form of its R-isomer.
Suitable surfactants are generally known in the art, for example, those surfactants disclosed in European Patent application No. 0327777. The amount of surfactant employed is desirable in the range of 0.0001% to 50% weight to weight ratio relative to the drug, in particular, 0.05 to 5% weight to weight ratio. A particularly useful surfactant is 1,2-di[7-(F-hexyl) hexanoyl]-glycero-3-phospho-N,N,N-trimethylethanolamine also known as 3,5,9-trioxa-4-phosphadocosan-1-aminium, 17,17,18,18,19,19,20,20,21,21,22,22,22-tridecafluoro-7-[(8,8, 9,9,10,10,11,11,12,12,13,13,13-tridecafluoro-1-oxotridecyl)oxy]-4-hydroxy-N,N,N-trimethyl-10-oxo-, inner salt, 4-oxide.
A polar cosolvent such as C
2-6
aliphatic alcohols and polyols e.g. ethanol, isopropanol and propylene glycol, preferably ethanol, may be included in the drug formulation in the desired amount, either as the only excipient or in addition to other excipients such as surfactants. Suitably, the drug formulation may contain 0.01 to 5% w/w based on the propellant of a polar cosolvent e.g. ethanol, preferably 0.1 to 5% w/w e.g. about 0.1 to 1% w/w.
It will be appreciated by those skilled in the art that the drug formulation for use in the invention may, if desired, contain albuterol or a salt thereof (e.g. the sulphate) in combination with one or more other pharmacologically active agents. Such medicaments may be selected from any suitable drug useful in inhalation therapy. Appropriate medicaments may thus be selected from, for example, analgesics, e.g. codeine, dihydromorphine, ergotamine, fentanyl or morphine; anginal preparations, e.g. diltiazem; antiallergics, e.g. cromoglycate, ketotifen or nedocromil; antiinfectives e.g. cephalosporins, penicillins, streptomycin, sulphonamides, tetracyclines and pentamidine; antihistamines, e.g. methapyrilene; anti-inflammatories, e.g. beclomethasone (e.g. the dipropionate), flunisolide, budesonide, tipredane or triamcinolone acetonide; antitussives, e.g. noscapine; bronchodilators, e.g. salbutamol, salmeterol, ephedrine, adrenaline, fenoterol, formoterol, isoprenaline, metaproterenol, phenylephrine, phenylpropanolamine, pirbuterol, reproterol, rimiterol, terbutaline, isoethari
Ashurst Ian C.
Britto Ignatius Loy
Herman Craig Steven
Li-Bovet Li
Riebe Michael Thomas
Birch, Stewart,. Kolasch & Birch, LLP
Lewis Aaron J.
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