Citation for published version (APA): Westerman, E. M. (2009). Studies on antibiotic aerosols for inhalation in cystic fibrosis s.n.

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1 University of Groningen Studies on antibiotic aerosols for inhalation in cystic fibrosis Westerman, Elisabeth Mechteld IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2009 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Westerman, E. M. (2009). Studies on antibiotic aerosols for inhalation in cystic fibrosis s.n. Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date:

2 1 General introduction

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4 General introduction 11 Cystic fibrosis: introduction Cystic fibrosis (CF) is one of the most common life-shortening, chronic hereditary diseases among the Caucasian population. Median survival used to lie in childhood or adolescency decades ago, but has improved considerably to advanced adulthood nowadays. From the 1940 s onward, the treatment of CF patients has gradually progressed from attempts to cure CF-related symptoms to organized, multidisciplinary care including early intervention and prevention of CF related complications. The correction of malabsorption due to exocrine pancreatic insufficiency with (enteric coated) pancreatic enzyme supplements has been one of the major break-throughs, as has been the prevention or correction of nutritional failure with calorie-dense oral supplements or enteral feedings. Relief of airway obstruction, either by physiotherapy and/or inhaled drug treatment, and suppression of inflammation with oral drugs are two other treatment pillars. Early and intensive therapy of airway infections with either oral or aerosolized antibiotic drug treatment is considered to be another major reason for the ongoing rise in life expectancy. Although drug treatment with aerosolized antibiotics has several therapeutic benefits over oral treatment, administration of these drugs with currently available nebuliser equipment takes up a significant amount of time on a daily basis, which negatively influences the quality of life and adherence to therapy. It is agreed upon that improvements are needed with respect to both knowledge on optimal aerosolized treatment of pulmonary infections and simplifying the administration of the drug aerosol. This is the motive for the work described in this thesis. CF related complications are caused by a disturbed chloride transport in the body. Chloride channels are missing or malfunctioning which results in failure of the cell to transport chloride into the extracellular space. As a result, chloride and sodium ions accumulate within cells, inhibiting water transport across cell membranes and causing dehydration of the mucus that normally coats these surfaces, thereby affecting the respiratory and digestive systems. As a result of increased viscosity of the mucus in the respiratory tract, the clearance of microorganisms is reduced and chronic bacterial infections resulting in inflammation of lung tissue and fibrosis of the airways are a fact (Tiddens 2002). Staphylococcus aureus (51.5%) and Pseudomonas aeruginosa (55.0%) infections play the greatest role in morbidity and mortality (Cystic Fibrosis Foundation 2006). Local application of aerosolized antibiotics in the lung to combat these microorganisms has been proven successful. The primairy objectives are to prevent the development of or to stabilise a chronic infection with Pseudomonas aeruginosa. Applying aerosolized tobramycin or colistimethate sodium early in recently acquired Pseudomonas aeruginosa infections has shown to be effective either as monotherapy or in combination with ciprofloxacin or intravenously administered tobramycin or colistimethate sodium (Döring and Hoiby 2004). Once a chronic infection has been established, daily use of aerosolized antibiotics to stabilise local inflammation and improve pulmonary function (FEV 1 ) is common practice. This strategy has been shown to result in improvement of lung function, or to slow down deterioration of lung function and in a reduction in hospital admissions (Kerem et al., 2005).

5 Monotherapy in exacerbation treatment with an aerosolized anti-pseudomonal drug has so far not been proven effective (Sexauer and Fiel 2003). There is scarce experience with inhaled antibiotics during exacerbations. Cystic fibrosis: history Cystic fibrosis has been described as a separate entity for the first time by Dorothy Anderson, a pathologist from New York, in 1938 (Littlewood 2002). At that time, the focus was on malfunction of the pancreas and therefore the disease was called cystic fibrosis of the pancreas. At a later stage it was recognized that the disease is a more generalised secretory defect, influencing the lung as well as the pancreas. Only in the late 1980 s, the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes a membrane-bound camp-regulated chloride channel, and the mutations causing the chloride transport defect, have been identified causing this defect. The ΔF508 is the most common mutation, indicating a missing phenylalanine molecule in position 508 of the 1480 amino acid protein (Koch and Hoiby 1993). Chapter 1 12 Prospects for CF patients in the early days were bad: most patients died in infancy, predominantly from lung disease. Fortunately, in the same period the first antibiotics were discovered. The main pathogen in CF identified at that time was Staphylococcus aureus and penicillin, active against Staphylococcus aureus, became available for injection in The first use of an aerosolized antibiotic in CF dates back from 1946 (Di Sant Agnese and Andersen 1946). Apparently, patients responded well to a dose of penicillin aerosol units 7 times a day alone or in combination with intramuscular penicillin (Littlewood 2002). Whether every CF patient had access to this therapy in those days could not be found in literature, but aerosol antibiotics have been used extensively in later years (Hodson et al., 1981, Kuhn 2001). Certainly the penicillin aerosol had its application in pulmonary diseases like lung abscess (Wolcott and Murphy 1957) and pneumococcal pneumonia (Kuhn 2001). A dry powder inhaler with penicillin for inhalation became available in the late 1940 s. However, no recording has been found on CF patients inhaling this dry powder. Already in the fifties Pseudomonas aeruginosa was cultured but Staphylococcus aureus was still considered to be the main pathogen. In the early 1970s the first successes on early aggressive (intravenous) antibiotic treatment were documented (Mearns 1972). It was shown that the mortality rate for children under 5 years of age could be reduced from 14% to 6.5% by early and vigorous anti-staphylococcal treatment. In the late seventies it was found that Pseudomonas aeruginosa infection and its severity were closely associated with the prognosis (Hoiby et al., 1977) and opinion changed from CF being a lethal disease to CF being a condition that could be controlled. Antibiotics active against Pseudomonas aeruginosa became available: colistimethate sodium (1959), carbenicillin (1967), gentamicin (1968), tobramycin (1971). Newer antibiotics became available in later years:

6 General introduction 13 piperacillin (1982), ceftazidime (1983), aztreonam (1986), ciprofloxacin (1986) and meropenem (1995). Intermittent, three monthly courses of two weeks of intravenous antibiotics were introduced in Denmark with impressive results (Szaff et al., 1983), but these results could not be confirmed in a subsequent study two decades later (Elborn et al., 2000). Despite good results, some patients started to relapse between two intravenous courses and aerosolized antibiotics got renewed interest. The main objective for this approach was the knowledge that penetration of intravenously administered aminoglycosides into lung parenchymal tissue and bronchial secretions is low (Pennington 1981). Inhalation, on the other hand, results in higher sputum concentrations, direct drug deposition in the lung, a low risk of systemic toxicity and enables long term treatment outside the hospital (Steinkamp 1991). Pulmonary administration of these antibiotics showed to be effective: long-term twice-daily aerosolized gentamicin (80 mg) and carbenicillin (1 gram) were effective in patients with a relapsing chronic Pseudomonas aeruginosa infection (Hodson et al., 1981), as were tobramycin (80 mg) and ticarcillin (1 gram) twice daily (Wall et al., 1983). Gradually the use of aerosolized antibiotics increased, despite a continuing discussion on the possible increase in antibiotic resistance (Ashby et al., 1993). Anti-staphylococcal aerosol treatment has been applied, but it was subsequently shown to have no additional effect over agents administered orally (Nolan et al., 1982; MacLusky et al., 1986). Furthermore, aerosolized penicillins were avoided because of concerns regarding development of hypersensitivity, odour, effect on teeth and greater difficulty in nebulisation (Kerem et al., 2005). Nowadays, colistimethate sodium and tobramycin are used in anti-pseudomonal aerosol therapy for prevention or stabilisation of chronic infections. Patients with a chronic Pseudomonas aeruginosa infection benefited from long-term nebulised antibiotics (Jensen et al., 1987), and early treatment with aerosolized colistimethate sodium or tobramycin to eradicate Pseudomonas aeruginosa appeared effective too (Littlewood et al., 1985, Valerius et al., 1991, Frederiksen et al., 1997, Ratjen 2001). Although aerosolized colistimethate sodium has been used for chronic Pseudomonas aeruginosa infection for decades, proper prospective placebo controlled trials are missing. A prospective unblinded study on aerosolized colistimethate sodium and tobramycin showed superiority of tobramycin in improvement of lung function, but the decrease of Pseudomonas aeruginosa in sputum was similar (Hodson et al., 2002, Adeboyeku et al., 2006). Some critical remarks should be made however: the subjects had all been using colistimethate sodium prior to the study so were naïve to tobramycin for inhalation and a relatively low dose of 80 mg of colistimethate sodium was compared to a regular 300 mg dose of tobramycin. Efficacy of tobramycin solution for inhalation (TSI) has been studied in a clinical trial with 520 patients, being the first placebo controlled trial of this size with an anti-pseudomonal antibiotic for inhalation (Ramsey et al., 1999). Treatment with tobramycin resulted in an improvement in lung function, a decrease of Pseudomonas aeruginosa density in sputum and a lower risk on hospitalisation.

7 Although inhaled antibiotics appeared to be relatively safe, in some patients airway narrowing was observed during or shortly after nebulisation. Additives, present in intravenous medications, were designated as one of the possible causes. Although the mechanisms of drug-induced airway narrowing in CF have not been elucidated, preservative-free preparations for inhalation are nowadays preferred by many clinicians. Nevertheless, airway narrowing after colistimethate sodium or tobramycin may occur in susceptible patients (Ramsey et al., 1999, Hodson et al., 2002). Chapter 1 14 Cystic fibrosis: facts The incidence of cystic fibrosis in the Netherlands is 1:4750 and currently 1275 patients have been identified. There are approximately CF patients in the 27 countries in the European Union, corresponding with a prevalence of per patients (Farrell 2008). The Dutch ratio, per patients, is similar to this. This means that cystic fibrosis meets the requirements for an orphan disease (prevalence < 5 per 10000; A total of patients worldwide have been estimated (Hodson et al., 2007, Cystic Fibrosis Worldwide 2005), of which approximately patients live in the USA (Cystic Fibrosis Foundation, 2006). There is a high likelihood of underreporting and underdiagnosing, especially in developing countries. USA data show that about 30% of patients in the patient registry program were age 18 or older in 1990 and this percentage has grown to almost 45% in The predicted median survival has risen to 36.9 years in 2006 and is expected to increase in future years because of improved therapeutic interventions (Cystic Fibrosis Foundation, 2006). Over 90% of CF patient premature deaths can be attributed to loss of pulmonary function due to infection and inflammation caused by microorganisms (Koch and Hoiby 1993, Geller et al., 2002, Döring et al., 2000). The presence of Pseudomonas aeruginosa is a significant predictor of mortality. A relationship between chronic respiratory tract infection with Pseudomonas aeruginosa, decline in lung function and mortality has been found (Henry et al., 1992). The relative risk of death, adjusted for age and gender, for a CF patient doubles with each 10% loss of FEV 1predicted (Kerem et al., 1992). Effective prevention of pulmonary infection or treatment of inflammation caused by Pseudomonas aeruginosa is therefore of utmost importance. Cystic fibrosis: recent developments in aerosolized drug therapy In recent years, aerosols of other antibiotics (aztreonam, levofloxacin, ciprofloxacin and amikacin) have been studied and are either in a preclinical or clinical phase of development. Next to these developments, explorations on inhaler devices have attracted attention during the past two decades. Although aerosolized antibiotics have been used since 1946 and various inhalers have been available for a long time (Anderson 2005), only in the mid 1980s research on nebulisers and compressors for use in CF drug aerosolisation was initiated (Newman et al.,

8 General introduction a, Newman et al., 1986b). Conventional jet nebulisers were the first nebulisers used, but soon these devices became known for their inefficiency. An improved pulmonary drug delivery became possible with the introduction of breath-enhanced, breath-actuated and breathcontrolled devices (Devadason et al., 1997, Asmus et al., 2002, Leung et al., 2004, Kohler et al., 2005). Ultrasonic nebulisers, which generally have a higher output rate and produce a larger average particle size than jet nebulisers, were used as well (Rau 2002). However, neither jet nor ultrasonic nebulisers are ideal for administration of aerosols in CF treatment. These devices are large, need electricity to operate, are able to deliver only approximately 9-18% of the nominal drug dose to the lung and require relatively long treatment times (> 10 min.), depending on the nebuliser used (Le Brun et al., 1999, Touw et al., 1997). Newer wet nebulisers have been designed to improve drug delivery efficiency and to decrease treatment times. Adaptive aerosol delivery has been introduced (Leung et al., 2004, Marsden et al., 2002). This technique adapts the delivery of aerosol to the patient s breathing pattern, thereby aiming at optimising the delivered dose. Vibrating mesh technology is a new technology for aerosol generation. Recently, data became available from clinical studies with aztreonam and a vibrating mesh device (Gibson et al., 2006, Retsch-Bogart et al., 2008). Although these new developments are promising, currently insufficient scientific data are available on clinical application in CF patients to fully estimate their value in CF treatment. The concept of dry powder inhalation for antibiotics in CF has been explored in recent years as well. Several initiatives have been taken in the last two decades (Goldman et al., 1990, Crowther Labiris et al., 1999, Le Brun et al., 2002, Newhouse et al., 2003) and the most recent clinical results became available lately (Westerman, this thesis, Geller et al., 2007, Pilcer et al., 2008). The use of a dry powder inhalation system is thought to result in improved lung deposition, in a higher patient acceptance of and adherence to long term therapy and an improvement of the quality of life of patients. Furthermore, the reduced treatment time may offer an opportunity for the introduction of other, new drugs to a patient s individual treatment. Aim and outline of this thesis The focus of this thesis is on investigations in the field of inhaled antibiotics in cystic fibrosis. This introductory chapter has illustrated that CF treatment has evolved impressively during the past decades. Inhalation of antibiotic aerosols has been established as chronic treatment for Pseudomonas aeruginosa positive patients. Those involved in treating CF patients are aware that there is still much to improve in inhalation treatment. That is why in recent years attention is growing to optimise aerosol therapy in CF patients, resulting in a gradual increase in knowledge. The aim of this thesis is to explore and expand knowledge on inhalation of aerosols in CF patients. Chapter 2 describes the current knowledge regarding the inhalation of drugs by CF patients: mechanisms of action, important indications, effects on lung function, exacerbation

9 Chapter 1 16 rates, survival, quality of life and adverse effects. This document serves as an European consensus on inhaled medication and inhalation devices in CF. In chapter 2, the basics of inhalation in CF and bacteriological safety and performance of nebulisers over time are especially relevant for the scope of this thesis. The starting point of the scientific work described in this thesis is the information that has been obtained from bench studies with an antibiotic drug and a nebuliser, performed by our group. In chapter 3, the relevance of testing a nebuliser-compressor combination with a specific drug in a clinical setting is once again proven. The focus is on the influence of a more powerful compressor on particle size generation and lung deposition of tobramycin for inhalation in CF patients, compared to an average compressor. A bench study provided the in vitro data, based upon which the two compressors were selected for application in patients. It was studied whether the observed size differences in particle size generation between the two compressors in vitro would result in different lung deposition patterns and adverse effects in vivo. Chapters 4-8 are dedicated to the development of a dry powder inhaler of colistimethate sodium for CF patients. The development of the dry powder drug, including the choice of the antibiotic (chapter 4), and the development of the inhaler (chapter 5) were aspects investigated prior to testing the drug-inhaler combination in vivo. In addition to testing the clinical feasibility of the dry powder inhaler for the first time in volunteers (chapter 6) and patients (chapter 7), initial results have been obtained with dry powder inhalation of colistimethate sodium, including lung deposition (pharmacokinetic approach). The effect on lung deposition after adapting several parameters in the inhalation process is described in chapter 8. Finally, the conclusions, including strengths and limitations of the studies described in this thesis are discussed and perspectives and directions for future research are given.

10 General introduction 17 References Adeboyeku D, Scott S, Hodson ME. Open follow-up study of tobramycin nebuliser solution and colistin in patients with cystic fibrosis. J Cyst Fibros 2006; 5: Anderson PJ. History of aerosol therapy: liquid nebulization to MDIs to DPIs. Respir Care 2005; 50: Ashby BL, Ramsey BW, Smith AL. Aerosolized Tobramycin in Patients with Cystic Fibrosis. N Engl J Med 1993; 329: Asmus MJ, Stewart BA, Milavetz G, Teresi ME, Han SH, Wang D et al. Tobramycin as a pharmacologic tracer to compare airway deposition from nebulizers. Pharmacotherapy 2002; 22: Crowther Labiris NR, Holbrook AM, Chrystyn H, MacLeod SM, Newhouse MT. Dry powder versus intravenous and nebulized gentamicin in cystic fibrosis and bronchiectasis. Am J Respir Crit Care Med 1999; 160: Cystic Fibrosis Foundation. Patient Registry 2006 Annual Report, Bethesda, Maryland, USA. Cystic Fibrosis Worldwide. Annual report Devadason SG, Everard ML, Linto JM, Le Souef PN. Comparison of drug delivery from conventional versus Venturi nebulizers. Eur Respir J 1997; 10: Di Sant Agnese PEA, Andersen DH. Celiac Syndrome IV Chemotherapy I infections of the respiratory tract associated with cystic fibrosis of the pancreas; observations with penicillin and drugs of the sulphonamide group, with special reference to penicillin aerosol. Am J Dis Child 1946; 72: Döring G, Conway SP, Heijerman HGM, Hodson ME, Hoiby N, Smyth A et al. Antibiotic therapy against Pseudomonas aeruginosa in cystic fibrosis: a European consensus. Eur Respir J 2000; 16: Döring G, Hoiby N. Early intervention and prevention of lung disease in cystic fibrosis: a European consensus. J Cyst Fibros 2004; 3: Elborn JS, Prescott RJ, Stack BH, Goodchild MC, Bates J, Pantin C et al. Elective versus symptomatic antibiotic treatment in cystic fibrosis patients with chronic Pseudomonas infection of the lungs. Thorax 2000; 55: Farrell PM. The prevalence of cystic fibrosis in the European Union. J Cyst Fibros 2008; 7: Frederiksen B, Koch C, Hoiby N. Antibiotic treatment of initial colonization with Pseudomonas aeruginosa postpones chronic infection and prevents deterioration of pulmonary function in cystic fibrosis. Pediatr Pulmonol 1997; 23: Geller DE, Konstan MW, Smith J, Noonberg SB, Conrad C. Novel tobramycin inhalation powder in cystic fibrosis subjects: Pharmacokinetics and safety. Pediatr Pulmonol 2007; 42: Geller DE, Pitlick WH, Nardella PA, Tracewell WG, Ramsey BW. Pharmacokinetics and bioavailability of aerosolized tobramycin in cystic fibrosis. Chest 2002; 122: Gibson RL, Retsch-Bogart GZ, Oermann C, Milla C, Pilewski J, Daines C et al. Microbiology, safety, and pharmacokinetics of aztreonam lysinate for inhalation in patients with cystic fibrosis. Pediatr Pulmonol 2006; 41: Goldman JM, Bayston SM, O Connor S, Meigh RE. Inhaled micronised gentamicin powder: a new delivery system. Thorax 1990; 45: Henry RL, Mellis CM, Petrovic L. Mucoid Pseudomonas aeruginosa is a marker of poor survival in cystic fibrosis. Pediatr Pulmonol 1992; 12: Hodson ME, Gallagher CG, Govan JR. A randomised clinical trial of nebulised tobramycin or colistin in cystic fibrosis. Eur Respir J 2002; 20: Hodson ME, Geddes D, Bush A. Cystic Fibrosis. London: Hodder Arnold 2007; 3rd edition.: Hodson ME, Penketh ARL, Batten JC. Aerosol carbenicillin and gentamicin treatment of Pseudomonas aeruginosa infection in patients with cystic fibrosis. Lancet 1981; Hoiby N, Flensborg EW, Beck B, Friis B, Jacobsen SV, Jacobsen L. Pseudomonas aeruginosa infection in cystic fibrosis. Diagnostic and prognostic significance of Pseudomonas aeruginosa precipitins determined by means of crossed immunoelectrophoresis. Scand J Respir Dis 1977; 58:65-79.

11 Chapter 1 18 Jensen T, Pedersen SS, Garne S, Heilmann C, Hoiby N, Koch C. Colistin inhalation therapy in cystic fibrosis patients with chronic Pseudomonas aeruginosa lung infection. J Antimicrob Chemother 1987; 19: Kerem E, Conway S, Elborn S, Heijerman H. Standards of care for patients with cystic fibrosis: a European consensus. J Cyst Fibros 2005; 4:7-26. Kerem E, Reisman J, Corey M, Canny GJ, Levison H. Prediction of mortality in patients with cystic fibrosis. N Engl J Med 1992; 326: Koch C, Hoiby N. Pathogenesis of cystic fibrosis. Lancet 1993; 341: Kohler E, Sollich V, Schuster-Wonka R, Jorch G. Lung deposition after electronically breath-controlled inhalation and manually triggered conventional inhalation in cystic fibrosis patients. J Aerosol Med 2005; 18: Kuhn RJ. Formulation of aerosolized therapeutics. Chest 2001; 120:94S-98S. Le Brun PP, de Boer AH, Mannes GP, de Fraiture DM, Brimicombe RW, Touw DJ et al. Dry powder inhalation of antibiotics in cystic fibrosis therapy: part 2. Inhalation of a novel colistin dry powder formulation: a feasibility study in healthy volunteers and patients. Eur J Pharm Biopharm 2002; 54: Le Brun PP, Vinks AA, Touw DJ, Hekelaar N, Mannes GP, Brimicombe RW et al. Can tobramycin inhalation be improved with a jet nebulizer? Ther Drug Monit 1999; 21: Leung K, Louca E, Coates AL. Comparison of breath-enhanced to breath-actuated nebulizers for rate, consistency, and efficiency. Chest 2004; 126: Littlewood J. The history of the development of cystic fibrosis care ; Littlewood JM, Miller MG, Ghoneim AT, Ramsden CH. Nebulised colomycin for early pseudomonas colonisation in cystic fibrosis. Lancet 1985; 1:865. MacLusky I, Levison H, Gold R, McLaughlin FJ. Inhaled antibiotics in cystic fibrosis: is there a therapeutic effect? J Pediatr 1986; 108: Marsden RJ, Conway SP, Dodd ME, Edenborough FP, Rigby AS, Taylor CJ et al. Comparison of the HaloLite adaptive aerosol delivery (AAD ) system with a high output nebuliser system in cystic fibrosis patients. Thorax 2002; 57:48-94 (P114). Mearns MB. Treatment and prevention of pulmonary complications of cystic fibrosis in infancy and early childhood. Arch Dis Child 1972; 47:5-11. Newhouse MT, Hirst PH, Duddu SP, Walter YH, Tarara TE, Clark AR et al. Inhalation of a dry powder tobramycin PulmoSphere formulation in healthy volunteers. Chest 2003; 124: Newman SP, Pellow PG, Clarke SW. Choice of nebulisers and compressors for delivery of carbenicillin aerosol. Eur J Respir Dis 1986a; 69: Newman SP, Pellow PG, Clarke SW. Droplet size distributions of nebulised aerosols for inhalation therapy. Clin Phys Physiol Meas 1986b; 7: Nolan G, Moivor P, Levison H, Fleming PC, Corey M, Gold R. Antibiotic prophylaxis in cystic fibrosis: inhaled cephaloridine as an adjunct to oral cloxacillin. J Pediatr 1982; 101: Pennington JE. Penetration of antibiotics into respiratory secretions. Rev Infect Dis 1981; 3: Pilcer G, Goole J, Van Gansbeke B, Blocklet D, Knoop C, Vanderbist F et al. Pharmacoscintigraphic and pharmacokinetic evaluation of tobramycin DPI formulations in cystic fibrosis patients. Eur J Pharm Biopharm 2008; 68: Ramsey BW, Pepe MS, Quan JM, Otto KL, Montgomery AB, Williams-Warren J et al. Intermittent administration of inhaled tobramycin in patients with cystic fibrosis. Cystic Fibrosis Inhaled Tobramycin Study Group. N Engl J Med 1999; 340: Rau JL. Design principles of liquid nebulization devices currently in use. Respir Care 2002; 47: ; discussion Retsch-Bogart GZ, Burns JL, Otto KL, Liou TG, McCoy K, Oermann C et al. A phase 2 study of aztreonam lysine for inhalation to treat patients with cystic fibrosis and Pseudomonas aeruginosa infection. Pediatr Pulmonol 2008; 43:47-58.

12 General introduction 19 Sexauer WP, Fiel SB. Aerosolized antibiotics in cystic fibrosis. Semin Respir Crit Care Med 2003; 24: Steinkamp G. [Antibiotic inhalation in cystic fibrosis. A review of the literature]. Monatsschr Kinderheilkd 1991; 139: Szaff M, Hoiby N, Flensborg EW. Frequent antibiotic therapy improves survival of cystic fibrosis patients with chronic Pseudomonas aeruginosa infection. Acta Paediatr Scand 1983; 72: Tiddens HAWM. Detecting early structural lung damage in cystic fibrosis. Pediatr Pulmonol 2002; 34: Touw DJ, Jacobs FA, Brimicombe RW, Heijerman HG, Bakker W, BreimerBriemer DD. Pharmacokinetics of aerosolized tobramycin in adult patients with cystic fibrosis. Antimicrob Agents Chemother 1997; 41: Valerius NH, Koch C, Hoiby N. Prevention of chronic Pseudomonas aeruginosa colonisation in cystic fibrosis by early treatment. Lancet 1991; 338: Wall MA, Terry AB, Eisenberg J, McNamara M, Cohen R. Inhaled antibiotics in cystic fibrosis. Lancet 1983; 321: Wolcott MW, Murphy JD. The changing picture of lung abscess therapy. Dis Chest 1957; 32: Wolff RK, Niven RW. Generation of aerosolized drugs. J Aerosol Med 1994; 7:89.

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