Inhaled antibiotic therapy: What drug? What dose? What regimen? What formulation?

Nanomaterials for Delivering Antibiotics in the Therapy of Pneumonia

Bacterial pneumonia is one of the leading causes of death worldwide and exerts a significant burden on health-care resources. Antibiotics have long been used as first-line drugs for the treatment of bacterial pneumonia. However, antibiotic therapy and traditional antibiotic delivery are associated with important challenges, including drug resistance, low bioavailability, and adverse side effects; the existence of physiological barriers further hampers treatment. Fortunately, these limitations may be overcome by the application of nanotechnology, which can facilitate drug delivery while improving drug stability and bioavailability. This review summarizes the challenges facing the treatment of bacterial pneumonia and also highlights the types of nanoparticles that can be used for antibiotic delivery. This review places a special focus on the state-of-the-art in nanomaterial-based approaches to the delivery of antibiotics for the treatment of pneumonia.

Sputum microbiota in adults with CF associates with response to inhaled tobramycin

BACKGROUND

Inhaled tobramycin powder/solution (TIP/S) use has resulted in improved clinical outcomes in patients with cystic fibrosis (CF) with chronic Pseudomonas aeruginosa. However, TIP/S effect on the CF sputum microbiome has not been explored. We hypothesised that TIP/S has additional 'off-target' effects beyond merely P. aeruginosa and that baseline microbiome prior to initiation of therapy is associated with subsequent patient response.

METHODS

We drew sputum samples from a prospectively collected biobank. Patients were included if they had one sputum sample in the 18 months before and after TIP/S. Bacterial 16S rRNA gene profiling was used to characterise the sputum microbiome.

RESULTS

Forty-one patients met our inclusion criteria and 151 sputum samples were assessed. At baseline, median age was 30.4 years (IQR 24.2-35.2) and forced expiratory volume in 1 (FEV₁) second was 57% predicted (IQR 44-74). Nineteen patients were defined a priori as responders having no net decrease in FEV₁ in the year following TIP/S. No significant changes were observed in key microbiome metrics of alpha (within-sample) or beta (between-sample) diversity for samples collected before and after TIP/S. However, significant beta-diversity (Bray-Curtis) differences were noted at baseline between patients based on response status. Notably, responders were observed to have a higher abundance of Staphylococcus in pretherapy baseline samples.

CONCLUSIONS

Our longitudinal study demonstrates that the sputum microbiome of patients with CF is relatively stable following inhaled tobramycin over many months. Intriguingly, our findings suggest that baseline microbiome may associate with patient response to TIP/S-suggesting the sputum microbiome could be used to personalise therapy.

Scope and limitations on aerosol drug delivery for the treatment of infectious respiratory diseases

The rise of antimicrobial resistance has created an urgent need for the development of new methods for antibiotics delivery to patients with pulmonary infections in order to mainly increase the effectiveness of the drugs administration, to minimize the risk of emergence of resistant strains, and to prevent patients reinfection. Since bacterial resistance is often related to antibiotic concentration, their pulmonary administration could eradicate strains resistant to the same drug at the concentration achieved through the systemic circulation. Pulmonary administration offers several advantages; it directly targets the site of the infection which allows the inhaled dose of the drug to be reduced compared to that administered orally or parenterally while keeping the same local effect. The review article is made with an objective to compile information about various existing modern technologies developed to provide greater patient compliance and reduce the undesirable side effect of the drugs. In conclusion, aerosol antibiotic delivery appears as one of the best technologies for the treatment of pulmonary infectious diseases and able to limit the systemic adverse effects related to the high drug dose and to make life easier for the patients.

Optimizing Aerosolization Using Computational Fluid Dynamics in a Pediatric Air-Jet Dry Powder Inhaler

The objective of this study was to optimize the performance of a high-efficiency pediatric inhaler, referred to as the pediatric air-jet DPI, using computational fluid dynamics (CFD) simulations with supporting experimental analysis of aerosol formation. The pediatric air-jet DPI forms an internal flow pathway consisting of an inlet jet of high-speed air, capsule chamber containing a powder formulation, and outlet orifice. Instead of simulating full breakup of the powder bed to an aerosol in this complex flow system, which is computationally expensive, flow-field-based dispersion parameters were sought that correlated with experimentally determined aerosolization metrics. For the pediatric air-jet DPI configuration that was considered, mass median aerodynamic diameter (MMAD) directly correlated with input turbulent kinetic energy normalized by actuation pressure and flow kinetic energy. Emitted dose (ED) correlated best with input flow rate multiplied by the ratio of capillary diameters. Based on these dispersion parameters, an automated CFD process was used over multiple iterations of over 100 designs to identify optimal inlet and outlet capillary diameters, which affected system performance in complex and unexpected ways. Experimental verification of the optimized designs indicated an MMAD < 1.6 μm and an ED > 90% of loaded dose. While extrathoracic depositional loss will be determined in future studies, at an operating flow rate of 15 L/min, it is expected that pediatric mouth-throat or even nose-throat aerosol deposition fractions will be below 10% and potentially less than 5% representing a significant improvement in the delivery efficiency of dry powder pharmaceutical aerosols to children.

The effects of cycled inhaled aztreonam on the cystic fibrosis (CF) lung microbiome

BACKGROUND

To improve clinical outcomes, cystic fibrosis (CF) patients with chronic Pseudomonas aeruginosa infections are prescribed inhaled anti-pseudomonal antibiotics. Although, a diverse microbial community exists within CF airways, little is known about how the CF microbiota influences patient outcomes. We hypothesized that organisms within the CF microbiota are affected by inhaled-antibiotics and baseline microbiome may be used to predict therapeutic response.

METHODS

Adults with chronic P. aeruginosa infection from four clinics were observed during a single 28-day on/off inhaled-aztreonam cycle. Patients performed serial sputum collection, CF-respiratory infection symptom scores (CRISS), and spirometry. Patients achieving a decrease of ≥2 CRISS by day 28 were categorized as subjective responders (SR). The airway microbiome was defined by Illumina MiSeq analysis of the 16S rRNA gene.

RESULTS

Thirty-seven patients (median 37.4 years and FEV₁ 44% predicted) were enrolled. No significant cohort-wide changes in the microbiome were observed between on/off AZLI cycles in either alpha- or beta-diversity metrics. However, at an individual level shifts were apparent. Twenty-one patients (57%) were SR and fourteen patients did not subjectively respond. While alpha-diversity metrics did not associate with response, patients who did not subjectively respond had a higher abundance of Staphylococcus and Streptococcus, and lower abundance of Haemophilus.

CONCLUSIONS

The CF microbiome is relatively resilient to AZLI perturbations. However, associated changes were observed at the individual patient level. The relative abundance of key "off-target" organisms associated with subjective improvements suggesting that the microbiome may be used as a tool to predict patient response - potentially improving outcomes.

Patient-specific modelling of regional tobramycin concentration levels in airways of patients with cystic fibrosis: can we dose once daily?

Background

Inhaled tobramycin is important in the treatment of Pseudomonas aeruginosa (Pa) infections in cystic fibrosis (CF). However, despite its use it fails to attenuate the clinical progression of CF lung disease. The bactericidal efficacy of tobramycin is known to be concentration-dependent and hence changing the dosing regimen from a twice-daily (q12h) inhalation to a once-daily (q24h) inhaled double dose could improve treatment outcomes.

Objectives

To predict local concentrations of nebulized tobramycin in the airways of patients with CF, delivered with the small airway-targeting Akita® system or standard PARI-LC® Plus system, with different inspiratory flow profiles.

Methods

Computational fluid dynamic (CFD) methods were applied to patient-specific airway models reconstructed from chest CT scans. The following q12h and q24h dosing regimens were evaluated: Akita® (150 and 300 mg) and PARI-LC® Plus (300 and 600 mg). Site-specific concentrations were calculated.

Results

Twelve CT scans from patients aged 12-17 years (median = 15.7) were selected. Small airway concentrations were 762-2999 mg/L for the q12h dosing regimen and 1523-5997 mg/L for the q24h dosing regimen, well above the MIC for WT Pa strains. Importantly, the q24h regimen appeared to be more suitable than the q12h regimen against more resistant Pa strains and the inhibitory effects of sputum on tobramycin activity.

Conclusions

CFD modelling showed that high concentrations of inhaled tobramycin are indeed delivered to the airways, with the Akita® system being twice as efficient as the PARI-LC® system. Ultimately, the q24h dosing regimen appears more effective against subpopulations with high MICs (i.e. more resistant strains).

Triclosan Is an Aminoglycoside Adjuvant for Eradication of Pseudomonas aeruginosa Biofilms

One of the most important clinical obstacles in cystic fibrosis (CF) treatment is antibiotic treatment failure due to biofilms produced by Pseudomonas aeruginosa The ability of this pathogen to survive eradication by tobramycin and pathoadapt into a hyperbiofilm state leading to chronic infections is key to its success. Retrospective studies have demonstrated that preventing this pathoadaptation by improving eradication is essential to extend the lives of CF patients. To identify adjuvants that enhance tobramycin eradication of P. aeruginosa, we performed a high-throughput screen of 6,080 compounds from four drug-repurposing libraries. We identified that the Food and Drug Administration (FDA)-approved compound triclosan, in combination with tobramycin, resulted in a 100-fold reduction of viable cells within biofilms at 6 h, but neither compound alone had significant antimicrobial activity against biofilms. This synergistic treatment significantly accelerated the killing of biofilms compared to that with tobramycin treatment alone, and the combination was effective against 6/7 CF clinical isolates compared to tobramycin treatment alone, including a tobramycin-resistant strain. Further, triclosan and tobramycin killed persister cells, causing a 100-fold reduction by 8 h and complete eradication by 24 h. Triclosan also enhances tobramycin killing of multiple Burkholderia cenocepacia and Staphylococcus aureus clinical isolates grown as biofilms. Additionally, triclosan showed synergy with other aminoglycosides, such as gentamicin or streptomycin. Triclosan is a well-tolerated aminoglycoside adjuvant shown to be safe for human use that could improve the treatment of biofilm-based infections.

The effects of inhaled aztreonam on the cystic fibrosis lung microbiome

BACKGROUND

Aztreonam lysine for inhalation (AZLI) is an inhaled antibiotic used to treat chronic Pseudomonas aeruginosa infection in CF. AZLI improves lung function and quality of life, and reduces exacerbations-improvements attributed to its antipseudomonal activity. Given the extremely high aztreonam concentrations achieved in the lower airways by nebulization, we speculate this may extend its spectrum of activity to other organisms. As such, we sought to determine if AZLI affects the CF lung microbiome and whether community constituents can be used to predict treatment responsiveness.

METHODS

Patients were included if they had chronic P. aeruginosa infection and repeated sputum samples collected before and after AZLI. Sputum DNA was extracted, and the V3-hypervariable region of the 16S ribosomal RNA (rRNA) gene amplified and sequenced.

RESULTS

Twenty-four patients naïve to AZLI contributed 162 samples. The cohort had a median age of 37.1 years, and a  median FEV₁ of 44% predicted. Fourteen patients were a priori defined as responders for achieving ≥3% FEV₁ improvement following initiation. No significant changes in alpha diversity were noted following AZLI. Furthermore, beta diversity demonstrated clustering with respect to patients, but had no association with AZLI use. However, we did observe a decline in the relative abundance of several individual operational taxonomic units (OTUs) following AZLI initiation suggesting that specific sub-populations of organisms may be impacted. Patients with higher abundance of Staphylococcus and anaerobic organisms including Prevotella and Fusobacterium were less likely to respond to therapy.

CONCLUSIONS

Results from our study suggest potential alternate/additional mechanisms by which AZLI functions. Moreover, our study suggests that the CF microbiota may be used as a biomarker to predict patient responsiveness to therapy suggesting the microbiome may be harnessed for the personalization of therapies.

Tobramycin inhalation powder (TOBI Podhaler) for the treatment of lung infection in patients with cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive inherited disease secondary to a defect in the CF transmembrane conductance regulator gene (CFTR). Mortality in CF is associated with impairment of lung function in which bacterial infection plays a fundamental role. The microorganism Pseudomonas aeruginosa (P. aeruginosa) is a marker of poor prognosis. Tobramycin was the first parenteral antibiotic to be used as inhaled medication in CF. Owing to its beneficial effects; it was subsequently used in designed inhaled formulations. The first formulation was the inhalation solution, which improved lung function, lowered hospitalization rates, and reduced the courses of intravenous antibiotic. However, the high associated costs and time necessary to administer the medication negatively affected quality of life. The recent development of tobramycin inhalation powder has optimized treatment. The dry powder inhaler is a simple device that reduces administration time and improves adherence. As there is no risk of bacterial contamination, disinfection is unnecessary.

Pharmacokinetics and safety of an 8 week continuous treatment with once-daily versus twice-daily inhalation of tobramycin in cystic fibrosis patients

OBJECTIVES

We evaluated the pharmacokinetics, safety and tolerability of two different continuous treatment regimens of tobramycin inhalation solution (TIS) in 29 cystic fibrosis (CF) patients chronically infected with Pseudomonas aeruginosa.

PATIENTS AND METHODS

In this randomized, multicentre, open-label, two-period crossover study, TIS (300 mg/5 mL) was administered via PARI eFlow(®) rapid once daily and twice daily each for 8 weeks. Serum pharmacokinetics of these two regimens was analysed. Tobramycin levels were determined before the morning dose and at 30, 60 and 90 min after the end of nebulization in the middle and at the end of each 8 week cycle. At these timepoints, trough and peak serum tobramycin concentrations (Cmax, mg/L) as well as the area under the curve for 0-90 min of tobramycin (AUC0-90min) were assessed in order to evaluate the risk of systemic toxicity. Safety parameters and forced expiratory volume in 1 s (FEV1) were assessed.

RESULTS

For once-daily treatment, tobramycin levels were 10% higher after 8 weeks compared with 4 weeks (AUC0-90min ratio = 1.096, 90% CI = 0.860-1.396, P = 0.5237). For twice-daily treatment, tobramycin levels after 8 weeks showed a 40% decrease compared with 4 weeks (AUC0-90min ratio = 0.608, 90% CI = 0.461-0.802, P = 0.0055). The AUC0-90min ratio at 8 weeks (once daily versus twice daily) did not differ significantly (AUC0-90min ratio = 0.749, 90% CI = 0.514-1.092, P = 0.2009). The mean FEV1 did not differ markedly compared between treatment periods or with baseline. No audiological or nephrotoxic side effects were noted.

CONCLUSIONS

Continuous treatment with TIS (once daily or twice daily) over 8 weeks appears to be safe and tolerable.

Clinical applications of pulmonary delivery of antibiotics

The treatment of infection typically involves administration of antibiotics by a systemic route, such as intravenous or oral. However, pulmonary infections can also be approached by inhalation of antibiotics as the infection is more directly accessible via the airways, making inhalation delivery essentially topical administration. This approach offers deposition of high antimicrobial concentrations directly at the site of infection but with a potentially reduced systemic exposure. This review covers the evidence for aerosolized antibiotics for the treatment of a number of conditions such as cystic fibrosis (CF), where it has become the standard of care for chronic infection, as well as non-CF bronchiectasis, non-tuberculous mycobacteria, and ventilator-associated infection where such therapy does not have an approved indication but has been used with increasing frequency.

Novel inhaled combined antibiotic formulations in the treatment of Pseudomonas aeruginosa airways infections in cystic fibrosis

In cystic fibrosis, chronic airways infection caused by Pseudomonas aeruginosa can be treated with inhaled antibiotics such as inhaled tobramycin, aztreonam or colistin. However, biofilm formation induced by this bacterium can reduce the effectiveness of such therapies and can contribute to antibiotic resistance. Inhaled antibiotic combination might represent an optimal antibiofilm strategy in this setting. This review discusses the rationale for combining the antibiotics as well as some emerging or existing combinations. Most of the combinations except for fosfomycin/tobramycin are at an early stage of development. The latter combination was found to be effective in Phase II clinical studies and is planned to be tested in Phase III trials. The clinical data on long-term efficacy are currently missing, but the existing evidence as well as the unmet therapeutic need can prompt the further evaluation of such compounds.

Tobramycin inhalation powder: an efficient and efficacious therapy for the treatment of Pseudomonas aeruginosa infection in cystic fibrosis

Inhaled antipseudomonal therapies are critical components in the management of cystic fibrosis (CF) and have significantly contributed to improved patient outcomes. Dry powder inhaler technologies represent a significant advance in drug delivery, alleviating treatment burden and potentially improving adherence associated with traditional CF nebulized therapies. Tobramycin inhalation powder (TIP) uses PulmoSphere® technology for very efficient drug delivery into the lower airways. In placebo-controlled and comparative studies with traditional tobramycin formulations, TIP is equally efficacious and is associated with increased patient convenience and satisfaction. TIP has been recommended in the 2013 CF Foundation and the 2014 European guidelines as a therapy in CF for the maintenance of lung health. Going forward, TIP may offer a therapeutic advantage over traditional formulations of tobramycin as recent prospective ‘real world’ studies of TIP have demonstrated high patient tolerance and improved adherence compared with traditional formulations.

Tobramycin Inhalation Powder (TIP): An Efficient Treatment Strategy for the Management of Chronic Pseudomonas Aeruginosa Infection in Cystic Fibrosis

Repeated bouts of acute and chronic lung infections are responsible for progressive pulmonary function decline in individuals with cystic fibrosis (CF), ultimately leading to respiratory failure and death. Pseudomonas aeruginosa is the archetypical CF pathogen, causes chronic infection in 70% of individuals, and is associated with an accelerated clinical decline. The management of P. aeruginosa in CF has been revolutionized with the development and widespread use of inhaled antibiotics. Aerosol delivery of antimicrobial compounds in CF enables extremely high concentrations of antibiotics to be reached directly at the site of infection potentially overcoming adaptive resistance and avoiding the potential for cumulative systemic toxicities. Tobramycin inhalation powder (TIP) represents the first dry powder inhaled (DPI) antibiotic available for use in CF. DPIs are notable for a markedly reduced time for administration, ease of portability, and increased compliance. TIP has been developed as a therapeutic alternative to tobramycin inhalation solution (TIS), the standard of care for the past 20 years within CF. Relative to TIS 300 mg nebulized twice daily in on-and-off cycles of 28 days duration, TIP 112 mg twice daily via the T-326 inhaler administered on the same schedule is associated with marked time savings, increased patient satisfaction, and comparable clinical end points. TIP represents an innovative treatment strategy for those individuals with CF and holds the promise of increased patient compliance and thus the potential for improved clinical outcomes.

Inhaled aztreonam lysine for cystic fibrosis pulmonary disease-related outcomes

OBJECTIVE

To evaluate the pharmacology, clinical efficacy, and safety of aztreonam lysine for inhalation (AZLI) for cystic fibrosis (CF)-related signs and symptoms of pulmonary disease.

DATA SOURCES

Literature was searched in MEDLINE through PubMed and cross-referenced with EMBASE (1980-June 2012). The key search terms used were aztreonam lysine, nebulized, inhaled, and cystic fibrosis. Bibliographies of selected articles were used to identify additional references. Ongoing trials were identified through a review of Web site trial registries.

STUDY SELECTION AND DATA EXTRACTION

Articles were limited to those written in English about studies conducted in humans. Studies included in this review examined both adult and pediatric patients with CF.

DATA SYNTHESIS

Aztreonam lysine is an inhaled monocyclic β-lactam antibiotic approved for use in the CF population. Four completed clinical trials with peer-reviewed published data were reviewed to assess the efficacy and safety of single-course AZLI; a fifth trial assessed the safety and efficacy of repeat courses of AZLI. None of these trials compared AZLI in a head-to-head manner with tobramycin for inhalation. In patients with moderate to severe pulmonary disease, AZLI administration improved forced expiratory volume in 1 second measurements, decreased sputum bacterial Pseudomonas aeruginosa density, and improved symptoms. Adverse effects in clinical trials were generally mild and similar to those with placebo.

CONCLUSIONS

AZLI is safe and effective for management of pulmonary-related symptoms in patients with CF who are colonized with P. aeruginosa and have moderate to severe pulmonary disease. Additional trial data comparing AZLI with tobramycin are warranted to further establish the place of AZLI in therapy.

What is the efficacy and safety of colistin for the treatment of ventilator-associated pneumonia? A systematic review and meta-regression

BACKGROUND

Experience with intravenous and aerosolized forms of colistin for the treatment of ventilator-associated pneumonia (VAP) in patients without cystic fibrosis is limited. We aimed to assess the safety and efficacy of colistin for the treatment of VAP.

METHODS

We searched MEDLINE and Cochrane Database of Systematic Reviews for studies comparing colistin vs other antibiotics for treatment of VAP in patients without cystic fibrosis. QUOROM guidelines were followed, the I(2) method was used for heterogeneity, and a random-effects model for odds ratio (OR) estimates.

RESULTS

Six controlled studies met the inclusion criteria. Clinical response did not differ significantly between colistin and control groups (OR, 1.14; 95% confidence interval [CI], .74-1.77; P = .56; I(2) = 0%). The efficacy of colistin was independent of study design (prospective OR, 0.89 [95% CI, .48-1.66; P = .71; I(2) = 0%]; retrospective OR, 1.45 [95% CI, .79-2.68; P = .23; I(2) = 0%]); randomized trials OR, 0.86 [95% CI, .43-1.74; P = .68; I(2) = 0%]). There was no indication of a significant change in clinical response after controlling for concomitant antibiotic treatment (intercept, 0.121; slope, 0.0315; P = .95). Treatment with colistin vs controls did not affect hospital mortality (OR, 0.92; 95% CI, .50-1.67; P = .78; I(2) = 34.59%) or nephrotoxicity (OR, 1.14; 95% CI, .59-2.20; P = .69; I(2) = 0%). Fourteen single-arm studies have been analyzed, and the results were in concordance with the findings of the controlled studies.

CONCLUSIONS

Our results suggest that colistin may be as safe and as efficacious as standard antibiotics for the treatment of VAP.

Delivery of antibiotics to the respiratory tract: an update

The use of inhaled medications for the treatment of pulmonary diseases has become an increasingly popular drug delivery route over the past few decades. This delivery route allows for a drug to be delivered directly to the site of the disease, with a lower dose than more conventional oral or intravenous delivery methods, with reduced systemic absorption and consequently reduced risk of adverse effects. For asthma this delivery route has become the 'golden standard' of therapy. It is not unexpected therefore, that there has been great interest in the prospect of using inhaled antibiotics for the treatment of both chronic and recurrent respiratory infections. Since the early 1980s, several investigations have demonstrated that antibiotics could be delivered safely by means of inhalation, using nebulisers as their delivery systems. Lately, antibiotics delivery via inhalation have seen a 'revival' in interest and most of these studies have focused on delivering antibiotics to the lungs by means of a dry powder format. This review focuses on recent advances in antibiotic inhalation therapy.

Pulmonary deposition of inhaled tobramycin prior to and after respiratory therapy and use of inhaled albuterol in cystic fibrosis patients colonized with Pseudomonas aeruginosa

OBJECTIVE

To evaluate whether respiratory therapy followed by the use of inhaled albuterol modifies the pulmonary deposition of inhaled tobramycin in patients with cystic fibrosis (CF) and whether pulmonary deposition correlates with disease severity or genotype.

METHODS

A prospective study was carried out including patients with CF older than 6 years of age and colonized with Pseudomonas aeruginosa. Exclusion criteria were pulmonary exacerbation, changes in therapy between the study phases and FEV1 < 25%. All patients were submitted to pulmonary scintigraphy by means of a scintillation camera equipped with a low energy all purpose collimator in order to evaluate drug penetration following the administration of inhaled 99mTc-tobramycin, as well as to pulmonary perfusion with 99mTc-macroaggregated albumin (phase 1). One month later, the same procedure was performed following respiratory therapy and administration of inhaled albuterol (phase 2).

RESULTS

We included 24 patients (12 males) aged 5-27 years (mean +/- SD: 12.85 +/- 6.64 years). The Shwachman score (SS) was excellent/good in 8 patients, moderate/fair in 16 and poor in 0. Genotyping revealed that 7 patients were DeltaF508 homozygotes, 13 were DeltaF508 heterozygotes; and 4 presented other mutations. In all patients, lung deposition of tobramycin decreased in phase 2, especially in those with moderate/fair SS (p = 0.017) and in heterozygotes (p = 0.043).

CONCLUSIONS

The use of a respiratory therapy technique and the administration of inhaled albuterol immediately prior to the use of inhaled tobramycin decreased the pulmonary deposition of the latter in CF patients, and this reduction correlates with disease severity and genotype.

A formulation of aerosolized tobramycin (Bramitob) in the treatment of patients with cystic fibrosis and Pseudomonas aeruginosa infection: a double-blind, placebo-controlled, multicenter study

BACKGROUND AND AIM

Chronic infection with Pseudomonas aeruginosa in patients with cystic fibrosis (CF) causes progressive deterioration in lung function. The purpose of this trial was to assess the efficacy and tolerability of a tobramycin highly concentrated solution for inhalation (TSI) [300mg/4mL; Bramitob when added to other antipseudomonal therapies in CF patients with chronic P. aeruginosa infection.

METHODS

In a multinational, double-blind, multicenter study, CF patients with chronic P. aeruginosa infection were randomized to receive nebulized tobramycin or placebo over a 24-week study period in which 4-week treatment periods ('on' cycles) were followed by 4-week periods without treatment ('off' cycles). Forced expiratory volume in 1 second (FEV(1)) percentage of predicted normal was used as the primary efficacy outcome parameter. Forced vital capacity (FVC), forced expiratory flow at 25-75% of FVC (FEF(25)(-)(75%)), P. aeruginosa susceptibility, minimum concentration required to inhibit 90% of strains (MIC(90)), rates of P. aeruginosa-negative culture, P. aeruginosa persistence and superinfection, need for hospitalization and parenteral antipseudomonal antibiotics, loss of school/working days due to the disease, and nutritional status (bodyweight and body mass index) were considered as secondary efficacy outcome parameters. Adverse events reporting, audiometry, and renal function were monitored to evaluate the tolerability and safety of TSI.

RESULTS

A total of 247 patients were randomized in the study. At endpoint time assessment (week 20), FEV(1) was significantly increased in the tobramycin group and the adjusted mean difference between groups (intention-to-treat population) was statistically significant (p < 0.001). At the same time, clinically relevant improvements in FVC and FEF(25-75%) were detected in the TSI group (p = 0.022 and p = 0.001, respectively). The microbiologic outcomes at the end of the last 'on' cycle period were significantly better in the TSI group than the placebo group (p = 0.024), although there was a concomitant trend toward an increase in the MIC of isolated P. aeruginosa strains. The percentage of patients hospitalized as well as the need for parenteral antipseudomonal antibiotics was significantly lower in the TSI group (p = 0.002 and p = 0.009, respectively). Patients treated with TSI had fewer lost school/working days due to the disease (p < 0.001). A favorable effect of tobramycin in terms of an increase in bodyweight and body mass index was also noted, when compared with placebo, at all time points (p < 0.01 and p < 0.001, respectively). No significant changes in serum creatinine and auditory function were detected. The proportion of patients with drug-related adverse events was 15% in both treatment groups.

CONCLUSIONS

Long-term, intermittent administration of this aerosolized tobramycin formulation (300mg/4mL) in CF patients with P. aeruginosa chronic infection significantly improved pulmonary function and microbiologic outcome, decreased hospitalizations, increased nutritional status, and was well tolerated.

[Will we still have antibiotics tomorrow?]

Since the discovery of antibiotics, it has been generally believed that these antimicrobials are capable of curing almost all bacterial infections. More recently, the appearance of increasing resistance to antibiotics and the emergence of multiresistant microorganisms have given rise to growing concern among physicians, and that concern has now started to filter through to society in general. The problem is further aggravated by a situation that not many people are currently aware of, that is, the limited prospects for future development of new antibiotics in the short to medium term. Appropriate use of available antibiotics based on a thorough understanding of their in vivo activity and the emergence of new forms of administration, such as inhalers, may help to alleviate the problem.