WO2004075874A1

WO2004075874A1 - Method for treatment and prevention of acute and chronic pseudomonas aeruginosa airway infections with inhalable macrolides

Info

Publication number: WO2004075874A1
Application number: PCT/CH2003/000148
Authority: WO
Inventors: Oktay Menekse
Original assignee: Anbics Patents-Licences Ag
Priority date: 2003-02-28
Filing date: 2003-02-28
Publication date: 2004-09-10
Also published as: AU2003205499A1

Abstract

Macrolides, in particular azalides such as azithromycin, are suited for the treatment or prevention of acute or chronic P. aeruginosa infections of the airways by inhalation. The mechanism of action is the inhibition of the quorum sensing of P. aeruginosa, in particular the impediment of the las and rhl quorum sensing systems synthesis and the impediment of the synthesis of the autoinducers N-[3-oxodo1o decanoyl]-L-homoserine lactone and N-butyrylhomoserine lactone. This allows for inhalation treatments of P. aerugi-nosa infections at non-inhibiting concentrations of the macrolide.

Description

Method for treatment and prevention of acute and chronic Pseudomonas aeruginosa airway infections with inhalable macrolides

Field of the invention

The present invention relates to a method for the treatment and prevention of acute or chronic Pseudomonas aeruginosa airway infections through delivery to the lung endobron- chial space, including alveoli, through delivery of an inhalable formulation.

Background of the invention

Pseudomonas aeruginosa, an increasingly prevalent opportunistic human pathogen, is the most common gram negative bacterium found in nosocomial (i.e. hospital-acquired) infections. P. aeruginosa is responsible for 16% of nosocomial pneumonia cases, 12% of hospital -acquired urinary tract infections, 8% of surgical wound infections, and 10% of bloodstream infections. Immunocompromised patients, such as neutropenic cancer and bone marrow transplant patients and particularly susceptible to opportunistic infections. In this^' group of patients, P. aeruginosa is responsible for pneumonia and septicemia with attributable deaths reaching 30%. P. aeruginosa is also one of the most common and lethal pathogens responsible for ventilator -associated pneumonia in intubated patients, with directly attributable death rates reaching 38%. P. aeruginosa bacteremia is also a source of concern in burn patients. P. aeruginosa outbreaks in burn units are associated with high (60%) death rates. In the expanding AIDS population, P. aeruginosa bac- teremia is associated with 50% of deaths. Cystic fibrosis (CE) patients are characteristically susceptible to chronic infection by P. aeruginosa, which is responsible for high rates of illness and death in this population. This high pathogenic potential of P. aeruginosa derives mainly from a range of extracellular virulence factors controlled by two complex regulatory systems, the las and rhl quorum sensing systems ("quorum sensing" is also known as "cell-to-cell- signaling") . Pseudomonas aeruginosa has multiple means to develop resistance to the limited number of antibiotics with anti-pseudomonal activity.

Prior art

The treatment of P. aeruginosa airway infections includes various intravenous antibacterial agents, often used in two or three way combination. Commonly used antibiotics include β-lactams (imipenem and meropenem, piperazillin/tazobactam, 3^rd and 4^th generation cephalosporins, aztreonam) , aminogly- cosides (tobramycin) , and quinolones (ciprofloxacin) , most of them only available in injectable form. In agreement with conventional management of infectious diseases, the current antibiotic treatment of Pseudomonas infections, irrespective of the method of administration, apply basic an- timicrobiological procedures while aiming to eradicate or significantly reduce the bacterial burden by delivering as much drug as possible to the infected body site. Preferably, the concentration of a particular antibiotic drug at the infection site is a multiple of the Minimal Inhibitory Concentration (MIC) that was determined for the infecting bacterial species in order to avoid or limit the survival of less susceptible mutants within the bacterial population. However, this approach is not effective on long-term since the selective pressure antibiotics exert on bacteria finally results in the emergence of resistant clones which continue to be a growing concern from the epidemiologic perspective. The therapeutic limitations of the prior art antibacterial agents predominantly administered via the in- travenous route include the poor penetration into bronchial secretions and decreased susceptibility (high MIC's) of Pseudomonas, necessitating the administration of high doses which in turn increases the risk for serious adverse events such as ototoxicity and nephrotoxicity. Therefore, it re- mains difficult to eradicate the organism completely without regrowth occurring^' after discontinuation of antibiotic therapy.

In the international application PCT/CHOl/00532 (unpub- lished at the filing date of the present application) it is disclosed that orally or intravenously administered mac- rolide antibiotics, in particular azithromycin, are able to interfere at far subinhibitory concentrations with the las and rhl quorum sensing systems of Pseudomonas aeruginosa by inhibiting the synthesis of two autoinducer (signalling) molecules, namely 3-oxo-Cχ₂-HSL (N- [3-oxododecanoyl] -L-ho- moserine lactone) and the Cj-HSL (N-butyrylhomoserine lactone) , required for the intrabacterial communication, and that macrolides are thus effective, when administered by these routes, against nosocomial P. aeruginosa infections.

Advances have been made on the other hand in the management of chronic and localised P. aeruginosa airway infections by delivering anti-pseudomonal non-macrolide drugs in an aero- solised form or dry powder form to overcome the drawbacks of intravenous administration. A number of various inhal- able non-macrolide antibiotics formulations have been described and proposed for use mainly in patients with cystic fibrosis or bronchiectasis suffering from Pseudomonas or other Gram-negative bacterial infection (US-B-6, 083, 922; US-B-6,387,886; O-A-2002/051356) . The principal advantage of this delivery route is the possibility to achieve concentrations in sputum of up to thousand times higher than the minimal inhibitory concentrations of target organisms while avoiding systemic side effects. This principle has in fact been shown to be safe and clinically beneficial. Since extremely high concentrations can be achieved in a dose-dependent fashion, even organisms with high MIC s and consid- ered resistant to these antibacterial agents can be treated.

The administration of non-macrolide antibacterial agents by inhalation constitutes a therapeutic advance, it is, how- ever, still based on the basic principle of antibiotic treatment, meaning that a drug concentration in excess of the organism' s MIC needs to be generated at the infection site for effective treatment, being in the range of several hundred mg and necessitating a concentration of the drug in an as small as possible volume of liquid in order to shorten the administration time. The currently approved in- halative formulation Tobi® (tobramycin, Chiron Corporation) for instance requires a twice-a-day administration while the time for one application is 15 minutes. But even the extremely high administered concentrations do not seem to fully prevent the emergence of strains showing a steady increase in their MIC during treatment (Tobi® drug information as approved by FDA) . Furthermore, it is believed that a chronic treatment with inhalable antibiotics may induce cross-resistance to otherwise useful antibiotics and further limit therapeutic options in patients who will eventually be admitted to hospitals due to an exacerbation of their condition and in need for parenteral antibiotic treatment. From the above it is evident that the need exists to provide a therapeutic or preventive process against acute or chronic Pseudomonas aeruginosa airway infections which avoids in particularly the buildup of resistance.

Summary of the invention

The object set is achieved by a therapeutic or prophylactic process comprising administering a macrolide antibiotic by inhalation in an amount which is effective in impeding quorum sensing in Pseudomonas aeruginosa .

The inventors of the present application have found that administration of macrolides, azalides and in particular azithromycin by inhalation interferes with the quorum-sensing mechanism in P. aeruginosa , and that these agents, when administered by inhalation, are active against acute or chronic Pseudomonas aeruginosa airway infections at concen- trations much lower than the minimum inhibiting concentrations (MIC's) of the P. aeruginosa strain in question. The administration according to the invention of macrolides, in particular azithromycin, is not attempting to harm the vital functions of P. aeruginosa as it is the case with other antibiotics suggested for this purpose. With the use of macrolides it is intended to only impede the quorum sensing mechanism of P. aeruginosa and to decrease its pathogenic and malicious potential in the described patient population.

It was particularly found that macrolides administered by inhalation interferes with two autoinducers molecules required in the quorum sensing of P. aeruginosa, namely 3- 0X0-C₁₂-HSL and C₄-HSL (HSL = homoserine lactone) . Another object of the invention is a therapeutic or prophylactic process comprising administration by inhalation of an amount of macrolide antibiotic which is effective to achieve sputum concentrations in the range of 1 to 100 μg/ml, more preferably in the range of 10 μg/ml; and the use of a macrolide antibiotic for the preparation of such inhalation formulations.

Another object of the invention is a therapeutic or prophylactic process comprising aerosolizing a solution having a concentration of 0.5 to 100 mg/ml, and administration of the aerosol so produced; and the use of macrolide antibiotics for the preparation of such aerosolizable formulations.

A further object of the invention is an inhalation formulation comprising a macrolide antibiotic in an amount which is effective in impeding quorum sensing in Pseudomonas aeruginosa .

In a particularly preferred embodiment of all objects of the present invention the macrolide antibiotic is an azalide, in particularly azithromycin.

Detailed description of the invention

The term "subject" shall mean in the context of the present application any animal, including the mammals and man.

The term "impeding" means in the context of the present application that quorum sensing, in particular the las and/or rhl quorum sensing systems, resp. the synthesis of the corresponding autoinducer molecules 3-oxo-Cι₂-HSL and C4-HSL, is inhibited to an extent which is detectable by a suited assay.

The term "macrolide antibiotic" shall encompass, where chemically possible, also any pharmaceutically acceptable acid addition salt of the macrolide antibiotic.

The term "mass median aerodynamic diameter" (MMAD) has for the purpose of the present invention the meaning usual in the art, i.e. 50 % by weight of the powder or aerosol particles are smaller that the MMAD, and 50% by weight are larger than the MMAD. The MMAD of powder or aerosol particles may be determined by a cascade impactor with an appropriate number of stages (see e.g. "Aerosol Measurement: Principles, Techniques and Applications", edited by Klaus Willeke and Paul A. Baron, Van Nostrand Reinhold, New York, 1993) . An example of such an impactor is the "Thermo Andersen Eight Stage Non-Viable Cascade Impactor", cited in US Pharmacopoeia Chapter 601 as a measuring device for aero- sols in metered-dose and dry powder inhalers. It is preferred according to the invention that the MMAD lies in the range of about 2 to about 4 microns, more preferred in the range of about 2 to about 3 microns.

That the aerodynamic diameter of the individual particles be "predominantly" within the range of 1 to 5 microns means in the context of the present application that at least 70 % by weight, but preferably more than 80 % by weight of all generated aerosol or powder particles that are to be in- haled have an aerodynamic diameter of between 1 to 5 microns. This is one way of expressing the distribution of the particle diameters around the MMAD. Particles to be inhaled with such a range of aerodynamic diameters will also be called hereinafter as particles of "inhalable size". The "aerodynamic diameter" itself is defined as the diameter of a unit-density sphere having the same terminal settling velocity as the particle in question, and is use- ful in predicting where in the respiratory tract such particles will deposit. The distribution of the aerodynamic diameters of the particles is also measurable with the above cascade impactor.

The amount of macrolide which is "effective" for the treatment or prevention of the P. aeruginosa-originated disease, by impeding quorum sensing, in particularly las and/or rhl quorum sensing and, more particularly, by impeding the synthesis of the autoinducers 3-oxo-Cι₂-HSL and C₄-HSL in P. aeruginosa , will vary on the type of macrolide and on the P. aeruginosa strain in question and may be determined by clinical studies on laboratory animals or on human volunteers .

The primary hint that a "effective amount" in treatment was used is the overcome of the airway infection itself, when the macrolide is administered in an inhalable formulation (see below) to a subject suffering from such infection, or, in the case of the preventive administration, that the in- fection does not occur under conditions where without administration the subject would have been infected with significant statistical probability.

A further hint that an "effective amount" in treatment was achieved in vivo is the regress or absence of the symptoms associated with the P. aeruginosa infection, such as chronic inflammatory response or tissue damage, and which would follow the release of extracellular virulence factors by P. aeruginosa . It is recalled that the eventual effect of the impediment of quorum sensing by macrolides is that the population of P. aeruginosa keeps behaving as isolated cells (i.e. the bacteria do not mutually perceive their presence anymore) and that this misleading prevents the population from producing extracellular virulence factors such as elastase and rhamnolipid.

Further experimental hints that this^' "effective amount" in treatment was achieved may be derived from assayed samples of the subject's sputum, lung tissue samples, or smears, It is known that the said autoinducer molecules, essential for quorum sensing, are released by the bacteria into their environment. A comparison of samples from subjects infected with a P. aeruginosa strain, and not treated with macrolide, with samples from subjects infected with the same strain, but treated with macrolide, may reveal, at a given administered threshold amount of the macrolide, a statistically significant difference in autoinducer concentration between the samples from the two groups (statistically significant in consideration of the differences between the individual subjects of the groups and the variabilities in cell counts and behaviour of the bacterial strain) . This threshold amount may then be considered as the "effective amount". The samples may be assayed by any technique known in the art for this purpose. An example of an assay for the autoinducer 3-oxo-C₁₂-HSL may be the one described in Pearson, J.P., Pesci, E.C., Iglewski, B.H., J. Bacteriol. 1997, 179, 5756-5767; and for C₄-HSL the Chromobacterium violaceum assay (McClean,K.H. , Winson, M.K., Fish, L., Taylor, A., Chhabra, S.R. Camara, M., Daykin M., Lamb, J.H., Swift, S., Bycroft, B.W., Stewart, G.S.A.B., Williams, P., Microbiology 1997, 143, 3703-3711; Shaw, P.D., Ping, G., Daly, S.L., Cha, C, Cronan, J.E. Jr., Rinehart, K.L., Fa- rand, S.K., Proc. Natl. Acad. Sci. USA, 1997, 94, 6036- 6041) or the assay described in Seed, P.C., Passador, L., Iglewski, B.H., J. Bacteriol. 1995, 177, 654-659. One exam- pie of an analysed sample is the sputum of patients suffering from cystic fibrosis (Geisenberger, 0., Givskov, Riedel, K., Hoiby, N., Tummler, B., Eberl. L., FEMS Micro- biol. Lett. 184, 273-278; Singh, P.K., Schaefer, A.L., Parsek, M.R., Moninger, T.O., Welsh, M.J., Greenberg, E.P., Nature 2000, 407, 762-764) .

In particular in one preferred embodiment the macrolide may be administered in one or two doses per day, to obtain an initial sputum concentration in the range of about 60 to about 100 μg/ml, which then gradually decreases, typically over a period of several hours, to a preferred sputum concentration range of about 2 to about 20 μg/ml, or to a more preferred sputum concentration range of about 5 to about 15 μg/ml .

The treatment and prevention processes of the invention may optionally be performed by also administering (sequentially, simultaneously, separately to the administation of the macrolide antibiotic) a further non-macrolide antibiotic, with the proviso that when the further non-macrolide antibiotic is tobramycin, then a third antibiotic other than tobramycin and other than the macrolide antibiotic is also administered. Alternatively an amino glycoside antibiotic and a third antibiotic which is different from either the macrolide antibiotic and the amino glycoside antibiotic may be administered sequentially, simultaneously, or separately to the macrolide antibiotic. Preferredly, however, the treatment and prevention processes of the invention do not require the co-adminstration of any further non-macrolide antibiotic such as tobramycin or other amino glycosides, or non-macrolide antibiotics.

Examples of P. aeruginosa strains that can be influenced by the therapeutic an prophylactic process according to the invention are all strains possessing a las and/or a rhl quorum sensing system. Examples of such strains are ATCC 33347, PA B16, PA N42, PA103 and in particular the strain PAOl.

Exemplary macrolides that can be used in the therapeutic processes and uses according to the invention are erythro- mycin A and B, erythromycylamine, roxithromycin, the com- pound of formula (VI) of EP-B-0 699 207, clarithromycin and macrolides belonging to the macrolide subgroup of the keto- lides, such as HMR-3647 (telithromycin) , pykromycin, narbo- mycin, A-66321, HMR-3004 (RU-004), HMR-3562, HMR-3787 and CP-654743. A preferred class of macrolides are the azalides, which are expanded in the macrolide ring at the C9 position by one nitrogen atom. Examples of azalides which can be used and administered according to the invention are azithromycin, the compounds (II), (III) and (IV) of EP-B-0 101 186 and the compounds (III), (V) and (VII) of EP-B-0 699 207. Particularly preferred is azithromycin.

Many macrolides, such as those containing a desosamine moiety, possess at least one basic nitrogen atom. Azalides intrinsically contain at least one basic nitrogen atom, the one expanding the macrolide ring, and when furthermore containing a desosamine moiety will contain at least two basic nitrogen atoms. Macrolides containing basic nitrogen atoms may thus be converted, for the purpose of the administra- tion according to the invention, to a pharmaceutically acceptable acid addition salt with inorganic or organic acids. These salts include, but are not limited to the following salts: acetate, citrate, aspartate, digluconate, glycerophosphate, sulfate, hemisulfate, fumarate, hydrochloride, hydrobromide, hydroiodide, lactate, maleate, ox- alate, succinate, hemisuccinate, tartrate and hemitartrate.

Treatment of acute or chronic Pseudomonas aeruginosa airway infections is achieved by an inhalation treatment regimen which provides one to several, preferably one or two, times a day of an inhalable macrolide or of a pharmaceutically acceptable salt thereof, since the most preferred dosage regimen for patient convenience is once or twice a day. However, in patients with severely impaired lung function, the frequency of therapeutic dosing may be increased, if deemed necessary from the medical perspective, up to about twelve times a day each time, providing only such amount of macrolide as necessary to maintain^' therapeutic level in the lung.

Suited formulations for inhalation are particularly solutions of the macrolide, azalide or ketolide in a pharmaceutically acceptable solvent that can be aerosolized by a nebulizer, and dry powders to be administered as such with a dry powder inhalers (DPI) or as a suspension in a pharmaceutically acceptable propellant in a metered dose inhaler (MDI) .

The formulations for inhalation according to the invention may comprise one, two, or more than two different macrolide antibiotics, and, besides the macrolide (s) , optionally a further non-macrolide antibiotic, with the proviso that when this further optional non-macrolide antibiotic is tobramycin, then the formulation must contain a third antibiotic other than tobramycin and other that the macrolide. Alternatively the inhalation formulations may comprise a combination of one or more macrolide antibiotics, an amino glycoside antibiotic, and a third antibiotic which is different from either the macrolide antibiotic (s) and the amino glycoside antibiotic. Preferredly, however, the formulations for inhalation of the invention do not contain any amino glycoside antibiotic, and particularly preferredly they do not comprise any non-macrolide antibiotic.

The inhalation formulations according to the invention may comprise one, two, or more than two macolide antibiotics in a total amount which is effective in preventing quorum sensing in P. aeruginosa, and which preferably is not bactericidal. The effective amount will thus be preferably be such that the minimum inhibiting concentration of the P. aeruginosa strain in question is not attained in the environment of use of the formulation, namely the mucosa of the airways and the sputum. The total macrolide concentration obtained by the effective amount of macrolide in the formulation may preferredly be 40 to 70 % of the minimum inhibiting concentration of the P. aeruginosa strain in question.

The above indicated specific examples of inhalation formulations according to the invention will be discussed here- inafter in detail.

Nebulizer solutions Macrolide antibiotic, azalide antiobiotic or ketolide antibiotic solutions according to the invention may be formulated in a similar way to injectable macrolide solutions.

The use of acid addition salts of macrolides containing basic nitrogen atoms is preferred, because the use of the corresponding unprotonated macrolide would likely result in a solution which is too alkaline for inhalation without causing irritation in the lungs or airways (see below) . A small amount of the corresponding unprotonated macrolide (such as about 0.05 to about 0.5 mol %, based on the total amount of acid addition salt of azalide plus free azalide) may also be present here to account for a slightly buffered solution with a physiologically acceptable pH.

The pH of the solution is an important feature for aero- solizable solutions. When the solution is either acidic or basic, the aerosol generated therefrom can cause broncho- spasm and cough. Although the safe range of pH is relative and some patients may tolerate a mildly acidic aerosol, others, particularly those with cystic fibrosis or other underlying disease will experience bronchospasm. Aerosols with a pH of less than 4.5 typically induce bronchospasm, on the other hand the lung tissue is not capable of buffer- ing pH values above 7.0. Therefore it is preferred for nebulizer solutions according to the invention that they exhibit a pH of 5.5 to 7.0, and more preferred from about 5.5 to about 6.0. Besides making use of the intrinsic buffering capability of nitrogen-containing macrolides (see above) it is also feasible to use some explicit buffering agent tolerated by the lungs and airways such as dihydro- genphosphate/hydrogenphosphate or carbon diox- ide/hydrogencarbonate buffers. The ionic strength of nebulizer solutions, however, needs rather tight control, in order to be tolerable to the lungs and airways. It is thus preferred that nebulizer solutions according to the invention have a total osmolality between 50 and 550 mOsm/kg, preferredly about Such osmolality may be preferredly attained by co-using a diluted aqueous sodium chloride solution such as physiological saline diluted four times.

The primary pharmaceutically aceptable solvent is water, which is preferredly of the quality for injection (WFI) . Besides the water further pharmaceutically acceptable cosolvents miscible with water, which will not interfere with the therapeutic or prophylactic efficiency of the nebulizer solution may optionally be present such as etha- nol, dimethylsulfoxide, glycerol or propylene glycol. These cosolvents may be added in order to enhance the solubility of the macrolide antibiotic and/or to lower the surface tension of the solution, which has the effect of lowering the size of the aerosol particles upon nebulization of the solution.

Nebulizer solutions according to the invention may comprise the macrolide or a pharmaceutically acceptable salt thereof in amount of about 0.5 to about 100 mg/ml, preferredly about 50 to about 100 mg/ml. The choice of the concentration, however, is primarily governed by the goal that the volume to be administered is as small as possible, preferredly about 0.2 to about 2 ml, more preferred about 0.2 to about 1 ml, and yet to obtain the concentration levels in the sputum as indicated hereinbefore. The concentration of the solution and the administered dose should also take into account that nebulizers used to generate the aerosol typically have a low yield of inhaled aerosol, such as only about 5 to 20 %.

Chemical stability of the macrolide in the solutions may sometimes be an issue. In view of enhancing the stability of the solutions it may be advantageous to provide them as two separate components, one containing the dry macrolide antibiotic or a salt thereof, with other optional solid ex- cipients, and a second component containing the appropriate pharmaceutically acceptable solvent. This binary "kit" is then intended to be reconstituted preferably immediately prior to administration. In the case of macrolides of low solubility (such as those that do not contain any basic nitrogen atom) the stability of solutions according to the invention may be enhanced by formulating them in the form of dispersed or emulsified micelles or liposomes by making use of an appropriate pharmaceutically acceptable surfactant such as sorbitan trioleate (SPAN 85), sorbitan monoo- leate and oleic acid.

The particle aerodynamic diameters and MMAD's that are preferred according to the invention for aerosolizable solutions can be achieved with conventional ultrasonic and in particularly jet nebulizers. A large list of examples for jet and ultrasonic nebulizers utilisable for the present invention are given in Table 1 of Contreras, G.C, Hickey, A.J. Advanced Drug Delivery Reviews, 54(2002), p. 1491- 1504.

Dry powder formlations and metered dose inhaler formulations Macrolides or salts thereof intended for use in these formulations in the appropriate particle diameters may be produced by media milling, jet milling, micronizing, spray- drying or precipitation from a solution. These techniques are known per se and commonly used in the art of powdery inhalation formulations. Media milling, jet milling or micronisation of a crystalline macrolide may be preferable if the eventual formulation is intended to exert some "depot" release after inhalation. Spray-dried or precipitated macrolide, giving a material of high amorphous content, may be desirable if a formulation with "loading" (immediate release) characteristics is sought.

It may be preferable, in view of lung tolerance, to use macrolides with basic nitrogen atoms in the form of a pharmaceutically acceptable acid addition salt (see above for examples) .

Dry powder formulations for administration according to the invention may be "ordered mixtures", meaning particles of the macrolide antibiotic or macrolide salt with proper MMAD of preferredly in the range of 1 to 5 microns adsorbed onto the surface of particles of a pharmaceutically acceptable inert carrier such as lactose monohydrate, glucose, manni- tol, trehalose or the like. The preparation of such ordered powder mixtures is known in the art of inhalation powders. It may be advantageous to use a lung-compatible carrier material which exerts buffering capacity towards alkalinity and also to some extent against acidity, such as a basic L- amino acid with all its nitrogen atoms protonated. The carrier particles are not intended to be inhaled (they detach from the macrolide upon puffing, and only the macrolide antibiotic particles are to be inhaled) and are thus less critical in size. A typical size for the carrier particles may thus be about 100 microns. The inert carrier of the ordered mixture not only serves to produce a free-flowing and easily dispersible powder, it also serves in accurately dosing the required amount of macrolide, which in case of minute amounts of macrolide to be administered, would be difficult to measure.

Powder formulations may change in time due to contact with residual moisture. This is undesirable, as pickup of moisture may cause the powder particles to aggregate irreversibly and thus to alter its deposition behaviour in the airways. In general careful exclusion of residual moisture in the manufacture process and in the eventual storage con- tainer, such the actual inhaler itself, serves to eliminate this problem. In WO-A-00/28979 it was suggested to improve the moisture resistance of dry powders for inhalation by use of magnesium stearate. In the case of dry powders for suspension in a propellant (see also below) it was sug- gested in US-A-5676931 to improve the overall stability of the powder by using protective colloids such as cholesterol, sodium lauryl sulfate, stearic acid, caprylic acid and taurocholic acid. In the case of the macrolide antibiotic used preferredly according to the invention, azithro- mycin, it is known that the free base is markedly hygroscopic in its anhydrous form. For inhalable powders with azithromycin base it may thus be preferred to use the mono- hydrate of azithromycin, described in US-A-4474768 and WO- A-89/00576, or one of the later discovered non-hygroscopic crystalline solvates or clathrates of azithromycin, such as the dihydrate disclosed in WO-A-89/00576, the clathrate of azithromycin monohydrate with isopropanol disclosed in EP- A-0 984 020, the ethanol solvate of azithromycin monohy- drate of WO-A-2000/32203 or the propyleneglycol clathrate of azithromycin . dihydrate recently described in WO-A- 2002/85898.

Powder formulations according to the invention may be administered by conventional devices such as dry powder inhalers (DPI's) or by metered dose inhalers (MDI's). The MDI ' s dispense the powder formulation by means of a pharmaceutically acceptable propellant, with the macrolide antibiotic being suspended therein. Suited propellants for MDI ' s are those commonly used for such formulations, such as CFC's (chlorofluorocarbons) , lower alkanes such as butane, propane or mixtures thereof, or, preferredly, hydro- fluoroalkanes (HFA's). Particularly preferred examples of the latter are HFA 134a and HFA 227. In some cases it may be advantageous to use a suited pharmaceutically acceptable co-solvent such as ethanol, and a pharmaceutically acceptable surfactant such as sorbitan trioleate (SPAN 85) , sorbitan monooleate and oleic acid.

Dry powder inhalation formulations and metered dose inhaler formulations according to the invention should preferredly also deliver an amount of macrolide antibiotic which is effective in producing a sputum concentration of about 1 to 100 μg/ml, more preferredly a peak sputum concentration of 60 to 100 μg/ml. In order to e.g. obtain a sputum concentration of 100 μg/ml it may be preferred to use a mi- cronized macrolide powder of inhalable size, to be administered as a suspension in a propellant by means of a MDI, whereby the concentration of the suspension would be typically in the order of magnitude of about 2 to about 5 % by weight, and the amount of the suspension to be inhaled in one dose being thus in the range of about 500 to about 200 milligrams, which is easily done in a few puffs, in consideration of a typical puff amount of the MDI of about 30 to about 130 milligrams. In order to obtain the particularly preferred sputum concentration of about 10 μg/ml it may be preferred to use a "ordered mixture" powder, which typically may contain about 0.2 to about 0.5 % by weight of macrolide antibiotic of inhalable size, based on the total weight of the powder. This would amount to a dose of in the order of magnitude of 500 to 200 mg powder per dose, which dose is easily administered in a few puffs by a DPI, in consideration of a typical load per puff of the DPI of about 100 mg.

In accordance with the low target concentration require- ments, the volume and amount of drug to be inhaled is extremely small enabling a quick and unmessy administration by using an inhalation device able to atomize the macrolide into particles of required size.

The present invention is thought to further improve the present methodologies in use for the therapeutic management of acute and chronic Pseudomonas aeruginosa infections in patients with cystic fibrosis, mechanical ventilation, bronchiectasis and AIDS. Thus, the impediment of the quorum sensing circuitry by inhalatory administration of macrolides provides multiple clinically meaningful benefits to patients suffering from acute or chronic P. aeruginosa respiratory infections.

This mode of action of macrolides and, in particular of azithromycin, is novel and is not associated with classical antibiotic features through which they exert a bacterio- static or bactericidal effect on susceptible bacterial pathogens, such as Streptococcus pneumoniae or Haemophilus influenzae_r being frequently isolated from patients with community acquired infections of the airways.

Moreover, the autoinducer 3-oxo-Cι₂-HSL itself appears to act pro-inflammatory while inducing various inflammatory cytokine and chemokines mediated by the induction of the nuclear factor-κB (NF-κB) . Administration of macrolides by inhalation thus exerts a beneficial effect on the inflamma- tory process itself by impeding the synthesis of this autoinducer .

Aerosol therapy of this invention is especially suitable for treatment of patients with cystic fibrόsis, bronchiec- tasis and those patients on the mechanical ventilation.

By the therapeutic or prophylactic process according to the invention the viability of the P. aeruginosa strain in question is preferably not affected by the macrolide, i.e. such treatment is non-inhibitory for P. aeruginosa .

Due to the relatively low amount of macrolide that is effective in impeding quorum sensing the length and amount of administration of macrolide antibiotics by inhalation is greatly reduced. Under optimum conditions it may be reduced to a single puff of an adequately concentrated aerosoliz- able solution or of a powder, whereas conventional treatment with. e.g. aminoglycosides typically requires administration times of 10 to 15 minutes with solutions of sev- eral tens of milligrams of aminogylcoside per ml, in order to attain effective amounts.

The invention will be further illustrated by the following examples. These are merely given by way of illustration and are not meant to limit the scope of the appended claims in any way.

Example 1 : nebulizer solution

Anhydrous azithromycin 1.5 g, ca. 2 mmol, prepared according to was dissolved in 100 ml WFI . This solution was acidified with standard 0.1 N HC1 (ex Merck Titrisol ®) to a doubly protonated state of the azithromycin (the volume of standard HC1 used is indicative of the exact content of azithromycin) . To the resulting solution were added 375 ml physiological saline and the solution was diluted with WFI to 1.5 1. This gave an aerosolizable solution of about 1 mg / ml azithromycin (of known exact content) , in four times diluted physiological saline. The solution was sparged with nitrogen and stored under nitrogen for better stability.

Alternatively, after the acidification, 13.5 solid sodium chloride USP were added, the solution evaporated, and the residue lyophilized, to give an amount of lyophilized powder composition that could be reconstituted with water to 1500 individual doses of 1 ml each, with also a concentration of 1 mg /ml azithromycin in four times diluted physiological saline.

Example 2: MDI formulation

200 g micronized crystalline hydrochloride of erythromycin A (prepared according to example 2 of US-A-2653899) were weighed into a pressure addition vessel. After sealing and evacuating the addition vessel, 9800 g of HFA 134a, containing 1% by weight of a 0.5 % (g/v) solution of oleic acid in ethanol, and adjusted to a pressure of 5 bar (20°C) in another pressure addition vessel, were added with stirring. After homogenizing, the obtained suspension was pressure-filled into aluminium containers sealed with metered- dose valves.

5

Example 3: "Ordered mixture" DPI formulation

995 g lactose monohydrate, milled and sieved with 149 μm (100 mesh) and 88 μm (170 mesh) size sieves to about 100 μm 10_. particle size, were mixed under exclusion of moisture with 5 g micronized azithromycin monohydrochloride (prepared as in example 7 of US-A-4474768) , resulting in an "ordered mixture" formulation suited for DPI administration.

15

Claims

Patent Claims

1. An inhalation formulation comprising a macrolide antibiotic in an amount which is effective in impeding quo- rum sensing in Pseudomonas aeruginosa, said formulation optionally comprising a further non-macrolide antibiotic further to the macrolide antibiotic, with the proviso that when the further non-macrolide antibiotic is tobramycin, then the formulation must contain a third antibiotic other than tobramycin and other that the macrolide antibiotic.

2. An inhalation. formulation in the form of a dry powder formulation or in the form of a metered dose inhaler formulation, .comprising a macrolide antibiotic in an amount which is effective in impeding quorum sensing in Pseudomonas aeruginosa , said formulation optionally comprising an amino glycoside antibiotic.

3. The formulation according to claim 1, not compris- ing any amino glycoside antibiotic.

4. The formulation according to claim 1, not comprising any non-macrolide antibiotic.

5. The formulation according to one of claims 1, 3 or 4 in the form of an aerosolizable solution, said solution comprising as the effective amount a concentration of 0.5 to 100 mg macrolide antibiotic / ml solution, and a pharmaceutically acceptable solvent.

6. The formulation according to one of claims 1 to 4 in the form of a dry powder formulation, comprising the ef- fective amount of macrolide antibiotic in the form of an ordered mixture of particulate macrolide antibiotic of inhalable particle size with a particulate inert pharmaceutically acceptable carrier.

7. The formulation according to one of claims 1 to 4 in the form of a metered dose inhaler formulation, comprising the effective amount of macrolide antibiotic in the form of a suspension of particulate macrolide antibiotic of inhalable size in a pharmaceutically acceptable propellant, the propellant optionally comprising a pharmaceutically acceptable surfactant and/or optionally comprising a pharmaceutically acceptable cosolvent.

8. The formulation of claim 7, wherein the propellant is HFA 134a or HFA 227.

9. A method of treatment or prophylaxis of acute or chronic Pseudomonas aeruginosa airway infections in a sub- ject in need of such treatment or prophylaxis, comprising administering a macrolide antibiotic by inhalation to said subject in an amount which is effective in impeding quorum sensing in Pseudomonas aeruginosa .

10. The method according to claim 9, wherein the amount is effective in impeding las quorum sensing.

11. The method according to claim 10, wherein the amount is effective in impeding the synthesis of the las quorum sensing autoinducer molecule N-[3-oxododecanoyl] -L- homoserine lactone.

12. The method according to claim 9, wherein the amount is effective in impeding rhl quorum sensing.

13. The method according to claim 12, wherein the amount is effective in impeding the synthesis of the rhl quorum sensing autoinducer molecule N-butyrylhomoserine lactone.

14. The method according to claim 9, whereby the amount is effective in impeding las and rhl quorum sensing.

15. The method according to claim 14, wherein the amount is effective in impeding the synthesis of the las quorum sensing autoinducer molecule N- [3-oxododecanoyl] -L- homoserine lactone and in impeding the synthesis of the rhl quorum sensing autoinducer molecule N-butyrylhomoserine lactone.

16. The method according to one of claims 9 to 15, wherein the macrolide is administered as an aerosol or as a powder of inhalable particle size.

17. The method of claim 16, wherein an inhalation formulation in the form of an aerosolizable solution, con- taining as the effective amount of macrolide antibiotic a concentration of 0.5 to 100 mg macrolide antibiotic / ml solution and a pharmaceutically acceptable solvent, is aerosolized, and the aerosol so produced is administered by inhalation.

18. The method according to one of claims 9 to 17, wherein the effective amount administered is such that a sputum concentration of the macrolide in the range of 1 to 100 μg/ml is achieved.

19. The method according to one of claims 9 to 18, wherein the macrolide antibiotic is an azalide, in particular azithromycin; or a ketolide.

20. Use of a macrolide antibiotic for the preparation of an inhalation formulation for the treatment or the pro- phylaxis of acute or chronic Pseudomonas aeruginosa airway infections .

21. The use according to claim 20, whereby the inhalation formulation contains the macrolide antibiotic in an' amount which is effective in impeding quorum sensing in Pseudomonas aeruginosa .

22. The use according to claim 21, characterized in that the amount is effective in impeding las quorum sensing in Pseudomonas aeruginosa .

23. The use according to claim 22, characterized in that the amount is effective in impeding the synthesis of the las quorum sensing autoinducer N- [3-oxododecanoyl] -L- homoserine lactone in Pseudomonas aeruginosa .

24. The use according to claim 20, characterized in that the amount is effective in impeding rhl quorum sensing in Pseudomonas aeruginosa .

25. The use according to claim 24, characterized in that the amount is effective in impeding the synthesis of the rhl quorum sensing autoinducer molecule N-butyrylhomoserine lactone in Pseudomonas aeruginosa .

26. The use according to claim 20, characterized in that the amount is effective in impeding las and rhl quorum sensing.

27. The use according to claim 26, characterized in that the amount is effective in impeding the synthesis of the las quorum sensing autoinducer molecule N- [3-oxododecanoyl] -L-homoserine lactone and in impeding the synthesis of the rhl quorum sensing autoinducer molecule N-butyrylhomoserine lactone.

28. The use according to one of claims 20 to 27, characterized in that the formulation is in the form of an aerosolizable solution, of a dry powder formulation, or of a metered dose inhaler formulation.

29. The use according to claim 28, characterized in that the formulation is in the form of an aerosolizable so- lution which comprises the macrolide antibiotic in a concentration of 0.5 to 100 mg/ml solution, and a pharmaceutically acceptable solvent.

30. The use according to one of claims 20 to 28, characterized in that the formulation contains per dose an amount of macrolide which is effective in producing a sputum concentration of 1 to 100 μg/ml.

31. The use according to one of claims 20 to 30, characterized in that the macrolide antibiotic is an azalide, in particular azithromycin; or a ketolide.