Aerosol formulation containing P134a and particulate medicament

Details Aerosol formulation containing P134a and particulate medicament Aerosol formulation containing P134a and particulate medicament

1999-03-09

2001-03-13

Bawa, Raj (Department: 1619)

Drug, bio-affecting and body treating compositions

Effervescent or pressurized fluid containing

Organic pressurized fluid

C424S046000

Reexamination Certificate

active

06200549

ABSTRACT:

This invention relates to aerosol formulations of use for the administration of medicaments by inhalation.
The use of aerosols to administer medicaments has been known for several decades. Such aerosols generally comprise the medicament, one or more chlorofluorocarbon propellants and either a surfactant or a solvent, such as ethanol. The most commonly used aerosol propellants for medicaments have been propellant 11 (CCl
3
F) and/or propellant 114 (CF
2
ClCF
2
Cl) with propellant 12 (CCl
2
F
2
). However these propellants are now believed to provoke the degradation of stratospheric ozone and there is thus a need to provide aerosol formulations for medicaments which employ so called “ozone-friendly” propellants.
A class of propellants which are believed to have minimal ozone-depleting effects in comparison to conventional chlorofluorocarbons comprise fluorocarbons and hydrogen-containing chlorofluorocarbons, and a number of medicinal aerosol formulations using such propellant systems are disclosed in, for example, EP 0372777, WO91/04011, WO91/11173, WO91/11495 and WO91/14422. These applications are all concerned with the preparation of pressurised aerosols for the administration of medicaments and seek to overcome the problems associated with the use of the new class of propellants, in particular the problems of stability associated with the pharmaceutical formulations prepared. The applications all propose the addition of one or more of adjuvants such as alcohols, alkanes, dimethyl ether, surfactants (including fluorinated and non-fluorinated surfactants, carboxylic acids, polyethoxylates etc) and even conventional chlorofluorocarbon propellants in small amounts intended to minimise potential ozone damage.
Thus, for example EP 0372777 requires the use of 1,1,1,2-tetrafluoroethane in combination with both a cosolvent having greater polarity than 1,1,1,2-tetrafluoroethane (e.g. an alcohol or a lower alkane) and a surfactant in order to achieve a stable formulation of a medicament powder. In particular it is noted in the specification at page 3, line 7 that “it has been found that the use of propellant 134a (1,1,1,2-tetrafluoroethane) and drug as a binary mixture or in combination with a conventional surfactant such as sorbitan trioleate does not provide formulations having suitable properties for use with pressurised inhalers”. Surfactants are generally recognised by those skilled in the art to be essential components of aerosol formulations, required not only to reduce aggregation of the medicament but also to lubricate the valve employed, thereby ensuring consistent reproducibility of valve actuation and accuracy of dose dispensed. Whilst WO91/11173, WO91/11495 and WO91/14422 are concerned with formulations comprising an admixture of drug and surfactant, WO91/04011 discloses medicinal aerosol formulations in which the particulate medicaments are pre-coated with surfactant prior to dispersal in 1,1,1,2-tetrafluoroethane.
SUMMARY OF THE INVENTION
We have now surprisingly found that, in contradistinction to these teachings, it is in fact possible to obtain satisfactory dispersions of medicaments ir: fluorocarbon or hydrogen-containing chlorofluorocarbon propellants such as 1,1,1,2-tetrafluoroethane without recourse to the use of any surfactant or cosolvent in the composition, or the necessity to pre-treat the medicament prior to dispersal in the propellant.
There is thus provided in one aspect of the invention a pharmaceutical aerosol formulation which comprises particulate medicament and a fluorocarbon or hydrogen-containing chlorofluorocarbon propellant, which formulation is substantially free of surfactant and with the proviso that said medicament is other than salmeterol, salbutamol, fluticasone propionate, beclomethasone dipropionate or a physiologically acceptable salt or solvate thereof. By “substantially free of surfactant” is meant formulations which contain no significant amounts of surfactant, for example less than 0.0001% by weight of the medicament.
The particle size of the particulate (e.g. micronised) medicament should be such as to permit inhalation of substantially all of the medicament into the lungs upon administration of the aerosol formulation and will thus be less than 100 microns, desirably less than 20 microns, and preferably in the range 1-10 microns, e.g. 1-5 microns
Medicaments which may be administered in aerosol formulations according to the invention include any drug useful in inhalation therapy which may be presented in a form which is substantially completely insoluble in the selected propellant. 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, anti-infectives, e.g. cephalosporins, penicillins, streptomycin, sulphonamides, tetracyclines and pentamidine, antihistamines, e.g. methapyrilene, anti-inflammatories, e.g. flunisolide budesonide, tipredane or triamcinolone acetonide, antitussives, e.g. noscapine, bronchodilators, e.g. ephedrine, adrenaline, fenoterol, formoterol, isoprenaline, metaproterenol, phenylephrine, phenylpropanolamine, pirbuterol, reproterol, rimiterol, terbutaline, isoetharine, tulobuterol, orciprenaline, or (−)-4-amino-3,5-dichloro-&agr;-[[[6-[2-(2-pyridinyl) ethoxy]hexyl]amino]methyl]benzenemethanol, diuretics, e.g. amiloride, anticholinergics e.g. ipratropium, atropine or oxitropium, hormones, e.g. cortisone, hydrocortisone or prednisolone, xanthines e.g. aminophylline, choline theophyllinate, lysine theophyllinate or theophylline, and therapeutic proteins and peptides, e.g. insulin or glucagon. It will be clear to a person skilled in the art that, where appropriate, the medicaments may be used in the form of saits (e.g. as alkali metal or amine salts or as acid addition salts) or as esters (e.g. lower alkyl esters) or as solvates (e.g. hydrates) to optimise the activity and/or stability of the medicament and/or to minimise the solubility of the medicament in the propellant.
Particularly preferred medicaments for administration using aerosol formulations in accordance with the invention include anti-allergics, bronchodilators and anti-inflammatory steroids of use in the treatment of respiratory disorders such as asthma by inhalation therapy, for example cromoglycate (e.g. the sodium salt), terbutaline (e.g. the sulphate salt), reproterol (e.g. the hydrochloride salt) or (−)4-amino-3,5-dichloro-&agr;-[[[6-[2-(2-pyridinyl)-ethoxy]hexyl]amino]methyl]benzenemethanol.
It will be appreciated by those skilled in the art that the aerosol formulations according to the invention may, if desired, contain a combination of two or more active ingredients. Aerosol compositions containing two active ingredients (in a conventional propellant system) are known, for example, for the treatment of respiratory disorders such as asthma. Accordingly the present invention further provides aerosol formulations in accordance with the invention which contain two or more particulate medicaments. Medicaments may be selected from suitable combinations of the medicaments mentioned hereinbefore. Thus, suitable combinations of bronchodilatory agents include ephedrine and theophylline, fenoterol and ipratropium, and isoetharine and phenylephrine aerosol formulations.
Preferred aerosol formulations in accordance with the invention comprise (a) an effective amount of a particulate bronchodilatory medicament (b) an effective amount of a particulate antiinflammatory, preferably a steroidal antiinflammatory medicament and (c) a fluorocarbon or hydrogen-containing chlorofluorocarbon propellant with the proviso that said medicaments are other than salmeterol, salbutamol, fluticasone propionate, beclomethasone dipropionate or a physiologically acceptable salt or solvate thereof. Alternatively aerosol formulations may contain a bronchodilator such as isoprenaline in combination with an antialler

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