Bronchial constriction after nebulized tobramycin preparations and saline in patients with cystic fibrosis

Inhaled anti-pseudomonal antibiotics for long-term therapy in cystic fibrosis

BACKGROUND

Inhaled antibiotics are commonly used to treat persistent airway infection with Pseudomonas aeruginosa that contributes to lung damage in people with cystic fibrosis. Current guidelines recommend inhaled tobramycin for individuals with cystic fibrosis and persistent Pseudomonas aeruginosa infection who are aged six years or older. The aim is to reduce bacterial load in the lungs so as to reduce inflammation and deterioration of lung function. This is an update of a previously published review.

OBJECTIVES

To evaluate the effects of long-term inhaled antibiotic therapy in people with cystic fibrosis on clinical outcomes (lung function, frequency of exacerbations and nutrition), quality of life and adverse events (including drug-sensitivity reactions and survival).

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched ongoing trials registries. Date of last search: 28 June 2022.

SELECTION CRITERIA

We selected trials where people with cystic fibrosis received inhaled anti-pseudomonal antibiotic treatment for at least three months, treatment allocation was randomised or quasi-randomised, and there was a control group (either placebo, no placebo or another inhaled antibiotic).

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, judged the risk of bias, extracted data from these trials and judged the certainty of the evidence using the GRADE system.

MAIN RESULTS

The searches identified 410 citations to 125 trials; 18 trials (3042 participants aged between five and 45 years) met the inclusion criteria. Limited data were available for meta-analyses due to the variability of trial design and reporting of results. A total of 11 trials (1130 participants) compared an inhaled antibiotic to placebo or usual treatment for a duration between three and 33 months. Five trials (1255 participants) compared different antibiotics, two trials (585 participants) compared different regimens of tobramycin and one trial (90 participants) compared intermittent tobramycin with continuous tobramycin alternating with aztreonam. One trial (18 participants) compared an antibiotic to placebo and also to a different antibiotic and so fell into both groups. The most commonly studied antibiotic was tobramycin which was studied in 12 trials. Inhaled antibiotics compared to placebo We found that inhaled antibiotics may improve lung function measured in a variety of ways (4 trials, 814 participants). Compared to placebo, inhaled antibiotics may also reduce the frequency of exacerbations (risk ratio (RR) 0.66, 95% confidence interval (CI) 0.47 to 0.93; 3 trials, 946 participants; low-certainty evidence). Inhaled antibiotics may lead to fewer days off school or work (quality of life measure) (mean difference (MD) -5.30 days, 95% CI -8.59 to -2.01; 1 trial, 245 participants; low-certainty evidence). There were insufficient data for us to be able to report an effect on nutritional outcomes and there was no effect on survival. There was no effect on antibiotic resistance seen in the two trials that were included in meta-analyses. We are uncertain of the effect of the intervention on adverse events (very low-certainty evidence), but tinnitus and voice alteration were the only events occurring more often in the inhaled antibiotics group. The overall certainty of evidence was deemed to be low for most outcomes due to risk of bias within the trials and imprecision due to low event rates. Different antibiotics or regimens compared Of the eight trials comparing different inhaled antibiotics or different antibiotic regimens, there was only one trial for each unique comparison. We found no differences between groups for any outcomes except for the following. Aztreonam lysine for inhalation probably improved forced expiratory volume at one second (FEV1) % predicted compared to tobramycin (MD -3.40%, 95% CI -6.63 to -0.17; 1 trial, 273 participants; moderate-certainty evidence). However, the method of defining the endpoint was different to the remaining trials and the participants were exposed to tobramycin for a long period making interpretation of the results problematic. We found no differences in any measure of lung function in the remaining comparisons. Trials measured pulmonary exacerbations in different ways and showed no differences between groups except for aztreonam lysine probably leading to fewer people needing treatment with additional antibiotics than with tobramycin (RR 0.66, 95% CI 0.51 to 0.86; 1 trial, 273 participants; moderate-certainty evidence); and there were fewer hospitalisations due to respiratory exacerbations with levofloxacin compared to tobramycin (RR 0.62, 95% CI 0.40 to 0.98; 1 trial, 282 participants; high-certainty evidence). Important treatment-related adverse events were not very common across comparisons, but were reported less often in the tobramycin group compared to both aztreonam lysine and colistimethate. We found the certainty of evidence for these comparisons to be directly related to the risk of bias within the individual trials and varied from low to high.

AUTHORS' CONCLUSIONS

Long-term treatment with inhaled anti-pseudomonal antibiotics probably improves lung function and reduces exacerbation rates, but pooled estimates of the level of benefit were very limited. The best evidence available is for inhaled tobramycin. More evidence from trials measuring similar outcomes in the same way is needed to determine a better measure of benefit. Longer-term trials are needed to look at the effect of inhaled antibiotics on quality of life, survival and nutritional outcomes.

Inhaled antibiotics for pulmonary exacerbations in cystic fibrosis

BACKGROUND

Cystic fibrosis is a genetic disorder in which abnormal mucus in the lungs is associated with susceptibility to persistent infection. Pulmonary exacerbations are when symptoms of infection become more severe. Antibiotics are an essential part of treatment for exacerbations and inhaled antibiotics may be used alone or in conjunction with oral antibiotics for milder exacerbations or with intravenous antibiotics for more severe infections. Inhaled antibiotics do not cause the same adverse effects as intravenous antibiotics and may prove an alternative in people with poor access to their veins. This is an update of a previously published review.

OBJECTIVES

To determine if treatment of pulmonary exacerbations with inhaled antibiotics in people with cystic fibrosis improves their quality of life, reduces time off school or work, and improves their long-term lung function.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Group's Cystic Fibrosis Trials Register. Date of the last search: 7 March 2022. We also searched ClinicalTrials.gov, the Australia and New Zealand Clinical Trials Registry and WHO ICTRP for relevant trials. Date of last search: 3 May 2022.

SELECTION CRITERIA

Randomised controlled trials in people with cystic fibrosis with a pulmonary exacerbation in whom treatment with inhaled antibiotics was compared to placebo, standard treatment or another inhaled antibiotic for between one and four weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected eligible trials, assessed the risk of bias in each trial and extracted data. They assessed the certainty of the evidence using the GRADE criteria. Authors of the included trials were contacted for more information.

MAIN RESULTS

Five trials with 183 participants are included in the review. Two trials (77 participants) compared inhaled antibiotics alone to intravenous antibiotics alone and three trials (106 participants) compared a combination of inhaled and intravenous antibiotics to intravenous antibiotics alone. Trials were heterogenous in design and two were only available in abstract form. Risk of bias was difficult to assess in most trials but, for four out of five trials, we judged there to be a high risk from lack of blinding and an unclear risk with regards to randomisation. Results were not fully reported and only limited data were available for analysis. One trial was a cross-over design and we only included data from the first intervention arm. Inhaled antibiotics alone versus intravenous antibiotics alone Only one trial (18 participants) reported a perceived improvement in lifestyle (quality of life) in both groups (very low-certainty evidence). Neither trial reported on time off work or school. Both trials measured lung function, but there was no difference reported between treatment groups (very low-certainty evidence). With regards to our secondary outcomes, one trial (18 participants) reported no difference in the need for additional antibiotics and the second trial (59 participants) reported on the time to next exacerbation. In neither case was a difference between treatments identified (both very low-certainty evidence). The single trial (18 participants) measuring adverse events and sputum microbiology did not observe any in either treatment group for either outcome (very low-certainty  evidence). Inhaled antibiotics plus intravenous antibiotics versus intravenous antibiotics alone Inhaled antibiotics plus intravenous antibiotics may make little or no difference to quality of life compared to intravenous antibiotics alone. None of the trials reported time off work or school. All three trials measured lung function, but found no difference between groups in forced expiratory volume in one second (two trials; 44 participants; very low-certainty evidence) or vital capacity (one trial; 62 participants). None of the trials reported on the need for additional antibiotics. Inhaled plus intravenous antibiotics may make little difference to the time to next exacerbation; however, one trial (28 participants) reported on hospital admissions and found no difference between groups. There is likely no difference between groups in adverse events (very low-certainty evidence) and one trial (62 participants) reported no difference in the emergence of antibiotic-resistant organisms (very low-certainty evidence).

AUTHORS' CONCLUSIONS

We identified only low- or very low-certainty evidence to judge the effectiveness of inhaled antibiotics for the treatment of pulmonary exacerbations in people with cystic fibrosis. The included trials were not sufficiently powered to achieve their goals. Hence, we are unable to demonstrate whether one treatment was superior to the other or not. Further research is needed to establish whether inhaled tobramycin may be used as an alternative to intravenous tobramycin for some pulmonary exacerbations.

Optimizing Spray-Dried Porous Particles for High Dose Delivery with a Portable Dry Powder Inhaler

This manuscript critically reviews the design and delivery of spray-dried particles for the achievement of high total lung doses (TLD) with a portable dry powder inhaler. We introduce a new metric termed the product density, which is simply the TLD of a drug divided by the volume of the receptacle it is contained within. The product density is given by the product of three terms: the packing density (the mass of powder divided by the volume of the receptacle), the drug loading (the mass of drug divided by the mass of powder), and the aerosol performance (the TLD divided by the mass of drug). This manuscript discusses strategies for maximizing each of these terms. Spray drying at low drying rates with small amounts of a shell-forming excipient (low Peclet number) leads to the formation of higher density particles with high packing densities. This enables ultrahigh TLD (>100 mg of drug) to be achieved from a single receptacle. The emptying of powder from capsules is directly proportional to the mass of powder in the receptacle, requiring an inhaled volume of about 1 L for fill masses between 40 and 50 mg and up to 3.2 L for a fill mass of 150 mg.

Off-label use of intravenous antimicrobials for inhalation in patients with cystic fibrosis

Management of infections in patients with cystic fibrosis (CF) presents challenges for healthcare providers, including the eradication of initial acquisition, treatment of acute exacerbations, and chronic infection with suppressive therapy. Inhaled antimicrobial therapy for infections in patients with CF has been used in these capacities, often in an effort to achieve optimal concentrations in sputum for antimicrobial efficacy while mitigating potential toxicities associated with systemic therapy. Unfortunately, there are few commercially available products formulated for inhalation, resulting in the off-label use of other formulations, such as intravenous products, administered via nebulization. This review aims to examine the evidence supporting the efficacy of these off-label formulations for management of acute and chronic infections associated with CF, as well as adverse effects associated with their use.

Inhaled antibiotics for pulmonary exacerbations in cystic fibrosis

BACKGROUND

Cystic fibrosis is a genetic disorder in which abnormal mucus in the lungs is associated with susceptibility to persistent infection. Pulmonary exacerbations are when symptoms of infection become more severe. Antibiotics are an essential part of treatment for exacerbations and inhaled antibiotics may be used alone or in conjunction with oral antibiotics for milder exacerbations or with intravenous antibiotics for more severe infections. Inhaled antibiotics do not cause the same adverse effects as intravenous antibiotics and may prove an alternative in people with poor access to their veins. This is an update of a previously published review.

OBJECTIVES

To determine if treatment of pulmonary exacerbations with inhaled antibiotics in people with cystic fibrosis improves their quality of life, reduces time off school or work and improves their long-term survival.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Group's Cystic Fibrosis Trials Register. Date of the last search: 03 October 2018.We searched ClinicalTrials.gov, the Australia and New Zealand Clinical Trials Registry and WHO ICTRP for relevant trials. Date of last search: 09 October 2018.

SELECTION CRITERIA

Randomised controlled trials in people with cystic fibrosis with a pulmonary exacerbation in whom treatment with inhaled antibiotics was compared to placebo, standard treatment or another inhaled antibiotic for between one and four weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected eligible trials, assessed the risk of bias in each trial and extracted data. They assessed the quality of the evidence using the GRADE criteria. Authors of the included trials were contacted for more information.

MAIN RESULTS

Four trials with 167 participants are included in the review. Two trials (77 participants) compared inhaled antibiotics alone to intravenous antibiotics alone and two trials (90 participants) compared a combination of inhaled and intravenous antibiotics to intravenous antibiotics alone. Trials were heterogenous in design and two were only available in abstract form. Risk of bias was difficult to assess in most trials, but for all trials we judged there to be a high risk from lack of blinding and an unclear risk with regards to randomisation. Results were not fully reported and only limited data were available for analysis.Inhaled antibiotics alone versus intravenous antibiotics aloneOnly one trial (n = 18) reported a perceived improvement in lifestyle (quality of life) in both groups (very low-quality of evidence). Neither trial reported on time off work or school. Both trials measured lung function, but there was no difference reported between treatment groups (very low-quality evidence). With regards to our secondary outcomes, one trial (n = 18) reported no difference in the need for additional antibiotics and the second trial (n = 59) reported on the time to next exacerbation. In neither case was a difference between treatments identified (both very low-quality evidence). The single trial (n = 18) measuring adverse events and sputum microbiology did not observe any in either treatment group for either outcome (very low-quality evidence).Inhaled antibiotics plus intravenous antibiotics versus intravenous antibiotics aloneNeither trial reported on quality of life or time off work or school. Both trials measured lung function, but found no difference between groups in forced expiratory volume in one second (one trial, n = 28, very low-quality evidence) or vital capacity (one trial, n = 62). Neither trial reported on the need for additional antibiotics or the time to the next exacerbation; however, one trial (n = 28) reported on hospital admissions and found no difference between groups. Both trials reported no difference between groups in adverse events (very low-quality evidence) and one trial (n = 62) reported no difference in the emergence of antibiotic-resistant organisms (very low-quality evidence).

AUTHORS' CONCLUSIONS

There is little useful high-level evidence to judge the effectiveness of inhaled antibiotics for the treatment of pulmonary exacerbations in people with cystic fibrosis. The included trials were not sufficiently powered to achieve their goals. Hence, we are unable to demonstrate whether one treatment was superior to the other or not. Further research is needed to establish whether inhaled tobramycin may be used as an alternative to intravenous tobramycin for some pulmonary exacerbations.

Inhaled anti-pseudomonal antibiotics for long-term therapy in cystic fibrosis

BACKGROUND

Inhaled antibiotics are commonly used to treat persistent airway infection with Pseudomonas aeruginosa that contributes to lung damage in people with cystic fibrosis. Current guidelines recommend inhaled tobramycin for individuals with cystic fibrosis and persistent Pseudomonas aeruginosa infection who are aged six years or older. The aim is to reduce bacterial load in the lungs so as to reduce inflammation and deterioration of lung function. This is an update of a previously published review.

OBJECTIVES

To evaluate the effects long-term inhaled antibiotic therapy in people with cystic fibrosis on clinical outcomes (lung function, frequency of exacerbations and nutrition), quality of life and adverse events (including drug sensitivity reactions and survival).

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched ongoing trials registries.Date of last search: 13 February 2018.

SELECTION CRITERIA

We selected trials if inhaled anti-pseudomonal antibiotic treatment was used for at least three months in people with cystic fibrosis, treatment allocation was randomised or quasi-randomised, and there was a control group (either placebo, no placebo or another inhaled antibiotic).

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, judged the risk of bias, extracted data from these trials and judged the quality of the evidence using the GRADE system.

MAIN RESULTS

The searches identified 333 citations to 98 trials; 18 trials (3042 participants aged between five and 56 years) met the inclusion criteria. Limited data were available for meta-analyses due to the variability of trial design and reporting of results. A total of 11 trials (1130 participants) compared an inhaled antibiotic to placebo or usual treatment for a duration between three and 33 months. Five trials (1255 participants) compared different antibiotics, two trials (585 participants) compared different regimens of tobramycin and one trial (90 participants) compared intermittent tobramycin with continuous tobramycin alternating with aztreonam. One of the trials (18 participants) compared to placebo and a different antibiotic and so fell into both groups. The most commonly studied antibiotic was tobramycin which was studied in 12 trials.We found limited evidence that inhaled antibiotics improved lung function (four of the 11 placebo-controlled trials, n = 814). Compared to placebo, inhaled antibiotics also reduced the frequency of exacerbations (three trials, n = 946), risk ratio 0.66 (95% confidence interval (CI) 0.47 to 0.93). There were insufficient data for us to be able to report an effect on nutritional outcomes or survival and there were insufficient data for us to ascertain the effect on quality of life. There was no significant effect on antibiotic resistance seen in the two trials that were included in meta-analyses. Tinnitus and voice alteration were the only adverse events significantly more common in the inhaled antibiotics group. The overall quality of evidence was deemed to be low for most outcomes due to risk of bias within the trials and imprecision due to low event rates.Of the eight trials that compared different inhaled antibiotics or different antibiotic regimens, there was only one trial in each comparison. Forced expiratory volume at one second (FEV1) % predicted was only found to be significantly improved with aztreonam lysine for inhalation compared to tobramycin (n = 273), mean difference -3.40% (95% CI -6.63 to -0.17). However, the method of defining the endpoint was different to the remaining trials and the participants were exposed to tobramycin for a long period making interpretation of the results problematic. No significant differences were found in the remaining comparisons with regard to lung function. Pulmonary exacerbations were measured in different ways, but one trial (n = 273) found that the number of people treated with antibiotics was lower in those receiving aztreonam than tobramycin, risk ratio 0.66 (95% CI 0.51 to 0.86). We found the quality of evidence for these comparisons to be directly related to the risk of bias within the individual trials and varied from low to high.

AUTHORS' CONCLUSIONS

Inhaled anti-pseudomonal antibiotic treatment probably improves lung function and reduces exacerbation rate, but pooled estimates of the level of benefit were very limited. The best evidence is for inhaled tobramycin. More evidence from trials measuring similar outcomes in the same way is needed to determine a better measure of benefit. Longer-term trials are needed to look at the effect of inhaled antibiotics on quality of life, survival and nutritional outcomes.

Long-acting inhaled bronchodilators for cystic fibrosis

BACKGROUND

Cystic fibrosis is a life-limiting inherited condition which affects one in 2500 newborns in the UK and 70,000 children and adults worldwide. The condition is multifaceted and affects many systems in the body. The respiratory system is particularly affected due to a build up of thickened secretions and a predisposition to infection. Inhaled bronchodilators are prescribed for 80% of people with cystic fibrosis in order to widen the airways and alleviate symptoms. Both short- and long-acting inhaled bronchodilators are used to improve respiratory symptoms. Short-acting inhaled bronchodilators take effect in minutes and typically last for four to eight hours (muscarinic antagonists). Long-acting inhaled bronchodilators also take effect within minutes but typically last for around 12 hours and sometimes longer. This review is one of two which are replacing a previously published review of both long- and short-acting inhaled bronchodilators.

OBJECTIVES

This review aims to evaluate long-acting inhaled bronchodilators in children and adults with cystic fibrosis in terms of clinical outcomes and safety. If possible, we aimed to assess the optimal drug and dosage regimen.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books.Date of last search: 10 October 2017.We also carried out a separate search of Embase and the reference lists of included trials. We searched clinical trials registries for any ongoing trials and made contact with pharmaceutical companies for any further trials.Date of Embase search: 11 October 2017.

SELECTION CRITERIA

Randomised or quasi-randomised parallel trials comparing long-acting inhaled bronchodilators (beta-2 agonists and muscarinic antagonists) with placebo, no treatment or a different long-acting inhaled bronchodilator in adults and children with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Both authors independently assessed trials for inclusion (based on title, abstract and full text). The authors independently assessed the included trials for quality and risk of bias and extracted data. Discrepancies were resolved by a third party.

MAIN RESULTS

The searches identified 195 unique references, of which 155 were excluded on title and abstract. We assessed the full texts of the remaining references, excluded 16 trials (28 references) and included four trials (12 references) in the review with 1082 participants.One trial (n = 16) measuring the effect of beta-2 agonists reported an improvement in forced expiratory volume at one second (FEV₁) after treatment (at one month), but the trial was small with an unclear risk of bias so we judged the evidence to be very low quality. The trial did not report on participant-reported outcomes, quality of life or adverse events.Three trials (n = 1066) looked at the effects of the muscarinic antagonist tiotropium at doses of 2.5 µg and 5.0 µg in both the short term (up to 28 days) and the longer term (up to three months). Only one of the trials reported the change in FEV₁ (L) after 28 days treatment and showed no significant difference between groups; with 2.5 µg tiotropium, mean difference (MD) -0.02 (95% confidence interval (CI) -0.13 to 0.09), or 5.0 µg tiotropium, MD 0.00 (95% CI -0.10 to 0.10) (moderate-quality evidence). All three trials of muscarinic antagonists provided data on adverse events which were found to differ little from placebo at doses of 2.5 µg, risk ratio (RR) 1.01 (95% CI 0.92 to 1.11) or 5.0 µg, RR 0.98 (95% CI 0.90 to 1.06). Very little participant-reported outcome data or quality of life data were available for analysis. Two of the trials were at low risk of bias overall whilst the remaining trial was at an unclear risk overall.

AUTHORS' CONCLUSIONS

Neither long-acting beta-2 agonists nor long-acting muscarinic antagonist bronchodilators demonstrate improvement in our primary outcome of FEV₁. No difference was observed between intervention and placebo in terms of quality of life or adverse events. The quality of evidence for the use of beta-2 agonists was very low. The use of a long-acting inhaled bronchodilator may help to reduce the burden of treatment for people with cystic fibrosis as it is taken less often than a short-acting inhaled bronchodilator, but future trials would benefit from looking at the effects on our primary outcomes (spirometric changes from baseline, quality of life and adverse effects) in the longer term.

WITHDRAWN: Inhaled bronchodilators for cystic fibrosis

This review has been withdrawn because it has been split into the following reviews: 'Long‐acting inhaled bronchodilators for cystic fibrosis' and 'Short‐acting inhaled bronchodilators for cystic fibrosis'.

The editorial group responsible for this previously published document have withdrawn it from publication.

The Influence of Nebulized Drugs on Nasal Ciliary Activity

INTRODUCTION

Nebulized drugs are used in the treatment of cystic fibrosis (CF) lung disease, asthma, and COPD, and increasingly also in other chronic lung diseases. Their use in CF is reasonably evidence based, but this is not so for use in other orphan diseases. Potential side effects often have not been studied. Therefore, we evaluated the influence of nebulized drugs on ciliary activity in an in vitro model.

METHODS

We constructed an in vitro nebulization model to examine the effect of drugs on ciliary activity. The model was validated by testing solutions with known neutral, positive, or negative effect on ciliary beat frequency (CBF). Next, the influence on CBF of other inhaled drugs was tested.

RESULTS

Nebulization of NaCl 0.9% had no influence on CBF, and was used as paired neutral control in further experiments. Salbutamol (Ventolin(®)) had a ciliostimulatory effect (CBF +18%, CBF at t0-t10-t60 7.1-8.5-8.6 Hz, p = 0.002), while hypertonic saline (CBF - 11%, CBF at t0-t10-t60 6.5-5.1-5.9 Hz, p = 0.018) and dry air (CBF -10%, CBF at t0-t10-t60 6.8-5.8-6.1 Hz, p = 0.008) had a cilioinhibitory effect. Nebulization of tobramycin inhaled solution (TOBI(®)) (p = 0.662), colistimethate (Colistineb(®)) (p = 0.369), rhDNAse (Pulmozyme(®)) (p = 0.069), ceftazidim (Glazidim(®)) (p = 0.875), and aztreonam (Cayston(®)) (p = 0.435) did not affect CBF. Obracin(®), a tobramycin containing solution manufactured for intravenous use, had a negative effect on CBF (CBF - 21%, CBF at t0-t10-t60 6.9-5.2-4.5 Hz, p = 0.004).

CONCLUSION

Inhaled drugs that are used off-label might have an influence on ciliary activity. This must be taken into account when prescribing these drugs for non-CF indications.

Cost Reduction of Inhaled Tobramycin by Use of Preservative-Free Intravenous Tobramycin Given via Inhalation

This study evaluates drug cost outcomes related to automatic therapeutic substitution of branded tobramycin solution for inhalation (TOBI^®) with inhaled generic preservative-free intravenous tobramycin (PFIT). A retrospective single-center evaluation of inhaled tobramycin use from 2008 through 2012 was performed. Number of doses dispensed and acquisition costs were obtained. Hourly wage data was acquired, pharmacy production costs were estimated and total cost-savings calculated. Days of therapy (DOTs) were determined for each year. Quality assurance and safety data was collected. In 2008, TOBI^® drug costs and doses dispensed were $118,665 and 1769, respectively. Following implementation of the interchange in May 2009, TOBI^® utilization ceased. PFIT costs in 2010 through 2012 averaged $34,775 annually and TOBI^® cost-avoidance exceeded $94,000 annually when accounting for pharmacy production costs, which were determined to be at most $5.28 per dose. The maximum estimated pharmacy production cost ranged from $8812 to $11,299 annually. PFIT doses dispensed exceeded 1650 each year and annual DOTs ranged from 815 to 1069. The 40-month savings were calculated to be $374,706. Quality assurance and safety data identified one patient who refused PFIT due to odor complaints and one patient who was inappropriately administered a dose orally. Therapeutic substitution of TOBI^® with PFIT can produce immediate and sustained savings with an acceptable safety profile.

Inhaled antibiotics for pulmonary exacerbations in cystic fibrosis

BACKGROUND

Cystic fibrosis is a genetic disorder in which abnormal mucus in the lungs is associated with susceptibility to persistent infection. Pulmonary exacerbations are when symptoms of infection become more severe. Antibiotics are an essential part of treatment for exacerbations and inhaled antibiotics may be used alone or in conjunction with oral antibiotics for milder exacerbations or with intravenous antibiotics for more severe infections. Inhaled antibiotics do not cause the same adverse effects as intravenous antibiotics and may prove an alternative in people with poor access to their veins.

OBJECTIVES

To determine if treatment of pulmonary exacerbations with inhaled antibiotics in people with cystic fibrosis improves their quality of life, reduces time off school or work and improves their long-term survival.

SEARCH METHODS

We searched ClinicalTrials.gov and the Australia and New Zealand Clinical Trials Registry for relevant trials. Date of last search: 15 March 2012We also searched the Cochrane Cystic Fibrosis Group's Cystic Fibrosis Trials Register. Date of the last search: 01 June 2012.

SELECTION CRITERIA

Randomised controlled trials in people with cystic fibrosis with a pulmonary exacerbation in whom treatment with inhaled antibiotics was compared to placebo, standard treatment or another inhaled antibiotic for between one and four weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected eligible trials, assessed the risk of bias in each trial and extracted data. Authors of the included trials were contacted for more information.

MAIN RESULTS

Six trials with 208 participants were included in the review. Trials were heterogenous in design and interventions (however, all included trials compared inhaled versus intravenous antibiotic regimens). Risk of bias was difficult to assess in most trials. Results were not fully reported and only limited data were available for analysis. Four trials reported some results on forced expiratory volume at one second and found no significant differences between the inhaled antibiotic and the comparison intervention. In two of these trials using 300 mg of inhaled tobramycin, the change in forced expiratory volume at one second was similar to intravenous tobramycin; and in one trial the time until the next exacerbation was not different. No important adverse effects were reported.

AUTHORS' CONCLUSIONS

There is little useful high-level evidence to judge the effectiveness of inhaled antibiotics for the treatment of pulmonary exacerbations in people with cystic fibrosis. The included trials were not sufficiently powered to achieve their goals. Hence, we are unable to demonstrate whether one treatment was superior to the other or not. Further research is needed to establish whether inhaled tobramycin may be used as an alternative to intravenous tobramycin for some pulmonary exacerbations.

Inhaled antibiotics for long-term therapy in cystic fibrosis

BACKGROUND

Inhaled antibiotics are commonly used to treat persistent airway infection that contributes to lung damage in people with cystic fibrosis (CF).

OBJECTIVES

To examine the evidence that inhaled antibiotic treatment in people with CF reduces frequency of exacerbations of infection, and improves lung function, quality of life and survival. To examine adverse effects of inhaled antibiotic treatment.

SEARCH STRATEGY

Trials were identified from the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register.Last search: 31 January 2011.

SELECTION CRITERIA

Trials were selected if inhaled antibiotic treatment was used for at least four weeks in people with CF, treatment allocation was randomised or quasi-randomised, and there was a control group (either placebo, no placebo or another inhaled antibiotic).

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, judged the risk of bias and extracted data from these trials.

MAIN RESULTS

The searches identified 176 citations to 78 trials. Nineteen trials, with 1724 participants, met the inclusion criteria. Adequate meta-analysis was not possible because of the variability of study design and reporting of results. Seventeen trials with 1562 participants compared an inhaled antibiotic with placebo or usual treatment for a duration between 1 and 32 months. Inhaled tobramycin was studied in eight trials. Lung function (measured as forced expired volume in one second) was higher and exacerbations of lung infection (by different measures) were less in the antibiotic-treated group. Resistance to antibiotics increased more in the antibiotic-treated group than in placebo group when results were reported. No auditory or renal impairment was found; analysis showed tinnitus, voice alteration, hemoptysis and cough were more frequent with tobramycin than placebo. One trial, compared tobramycin with colistin in 115 participants, after one month the mean difference in forced expiratory volume at one second was 6.33 (95% confidence interval -0.04 to 12.70) favouring tobramycin.

AUTHORS' CONCLUSIONS

Inhaled antibiotic treatment probably improves lung function and reduces exacerbation rate, but a pooled estimate of the level of benefit is not possible. The best evidence is for inhaled tobramycin. More evidence, from trials of longer duration, is needed to determine whether this benefit is maintained and to determine the significance of development of antibiotic-resistant organisms.

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.

Aerosolised antibiotics: a critical appraisal of their use

Aerosolised antimicrobial agents have been used in clinical practice since the 1950s. The main advantage of this route of administration is the targeted drug delivery to the site of infection in the lung. Exploitation of this targeted delivery can yield high concentrations at the site of infection/colonisation while minimising systemic toxicities. It is important to note that the ability of a drug to reach the target area in the lung effectively is dependent on a number of variables, including the nebuliser, patient technique, host anatomy and disease-specific factors. The most convincing data to support the use of aerosolised antimicrobials has been generated with tobramycin solution for inhalation (TOBI, Chiron Corp.) for maintenance treatment in patients with cystic fibrosis. In addition to cystic fibrosis, the use of aerosolised antimicrobials has also been studied for the treatment or prevention of a number of additional disease states including non-cystic fibrosis bronchiectasis, ventilator-associated pneumonia and prophylaxis against pulmonary fungal infections. Key studies evaluating the benefits and shortcomings of aerosolised antimicrobial agents in these areas are reviewed. Although the theory behind aerosolised administration of antibiotics seems to be sound, there are limited data available to support the routine use of this modality. Owing to the gaps still existing in our knowledge base regarding the routine use of aerosolised antibiotics, caution should be exercised when attempting to administer antimicrobials via this route in situations falling outside clearly established indications such as the treatment of patients with cystic fibrosis or Pneumocystis pneumonia.

Inhaled bronchodilators for cystic fibrosis

BACKGROUND

Recurrent wheeze and breathlessness are common in people with cystic fibrosis, and bronchodilators are commonly prescribed. Despite their wide-scale and often long-term use, there is limited objective evidence about their efficacy in cystic fibrosis.

OBJECTIVES

To evaluate the effectiveness of inhaled bronchodilators in children and adults with cystic fibrosis.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic databases searches, and handsearches of relevant journals and abstract books of conference proceedings. Latest search of the Group's Trials Register: August 2005

SELECTION CRITERIA

Randomised or quasi-randomised trials comparing inhaled bronchodilators to placebo or another inhaled bronchodilator in people with CF, diagnosed clinically and by sweat or genetic testing and at all stages and severity of lung disease.

DATA COLLECTION AND ANALYSIS

The authors independently extracted data and assessed trial quality. If data were missing, the primary author was contacted where possible. The data were subgrouped into classes of bronchodilator and for each class into short-term effects (less than one week) and long-term effects (greater or equal to one week).

MAIN RESULTS

The search identified 43 references. Fourteen trials, with a total of 257 participants, were suitable for inclusion. The trials were all cross-over in design; in this case a meta-analysis was not possible. There were varied conclusions from the different trials, reflecting their heterogeneity. Compared to placebo, short-acting beta-2 agonists increased forced expiratory volume at one second (FEV(1)) in the short term in three out of five trials, and in the long-term increased peak expiratory flow rate in individuals who had been shown to have bronchial hyperreactivity or bronchodilator responsiveness or both. Compared to placebo, long-acting beta-2 agonists increased FEV(1) and forced expiratory flow between 25% and 75% of expiratory flow (FEF 25-75%) in the short term in participants known to have bronchodilator responsiveness, but produced inconsistent results in long-term trials. Short acting-anticholinergics had no consistent effect on lung function tests in either the short or the long term. We found no published trials of fenoterol, formoterol or tiotropium and the use of these agents in cystic fibrosis cannot be supported.

AUTHORS' CONCLUSIONS

It was not possible to determine fully the effectiveness of inhaled bronchodilators in cystic fibrosis as a meta-analysis was not possible. However, both short and long-acting beta-2 agonists can be beneficial both in the short and long term in individuals with demonstrable bronchodilator responsiveness or bronchial hyperrresponsiveness.

Traitements inhales bronchodilatateurs et fluidifiants dans la mucoviscidose

Poor clearance of airway secretions contributes to the pulmonary disease in cystic fibrosis (CF). Bronchodilator therapy might benefit in CF, but the efficacy is controversial. Effects of mucolytic agents have not been demonstrated conclusively. Only, efficacy of recombinant human deoxyribonuclease (rhDNase) is established with a rapid onset of benefit.

Nebulised anti-pseudomonal antibiotics for cystic fibrosis

BACKGROUND

Persistent infection by Pseudomonas aeruginosa contributes to lung damage, resulting in illness and death in people with cystic fibrosis (CF). Nebulised antibiotics are commonly used to treat this infection.

OBJECTIVES

To examine the evidence that nebulised anti-pseudomonal antibiotic treatment in people with CF reduces frequency of exacerbations of infection, improves lung function, quality of life and survival. To examine adverse effects of nebulised anti-pseudomonal antibiotic treatment.

SEARCH STRATEGY

Trials were identified from the Cochrane Cystic Fibrosis and Genetic Disorders Group clinical trials register. Companies that marketed nebulised anti-pseudomonal antibiotics were contacted for information on unpublished trials. Most recent search of the Group's trials register: August 2002.

SELECTION CRITERIA

Trials were selected if, nebulised anti-pseudomonal antibiotics treatment was used for four weeks or more in people with CF, allocation to treatment was randomised or quasi-randomised, and there was a placebo or a no placebo control group or another nebulised antibiotic comparison.

DATA COLLECTION AND ANALYSIS

For the first version of this review, two reviewers independently selected and judged the quality of, the trials to be included in the review. One reviewer extracted data from these trials and performed all tasks for the updated version of the review.

MAIN RESULTS

Out of 33 trials identified, there were 11, with 873 participants, that met the inclusion criteria. Ten trials with 758 participants compared a nebulised anti-pseudomonal antibiotic with placebo or usual treatment. One of these trials accounted for 68% of the total participants and seven of these trials used a cross-over design. Tobramycin was studied in four trials and follow up ranged from 1 to 32 months. Lung function, measured as forced expired volume in one second (FEV1) was better in the treated group than in control group in nine of these. Resistance to antibiotics increased more in the antibiotic treated group than in placebo group. Tinnitus and voice alteration were more frequent with tobramycin than placebo. One short-term trial of one month, with 115 participants, compared tobramycin and colistin, and showed a trend towards greater improvement in FEV1 in the tobramycin group.

REVIEWER'S CONCLUSIONS

Nebulised anti-pseudomonal antibiotic treatment improves lung function. However, more evidence, from longer duration trials, is needed to determine if this benefit is maintained as well as to determine the significance of development of antibiotic resistant organisms. There is insufficient evidence for recommendations about type of drug and dose regimens.

Pharmaceutical and biotechnological aerosols for cystic fibrosis therapy

This review addresses different aerosol therapies used to treat the underlying cause and symptoms of cystic fibrosis (CF) during the past two decades. A summary of the current methods of aerosol delivery and suggestions that may improve the efficacy of the current treatments are provided.

Evaluation of bronchial constriction in children with cystic fibrosis after inhaling two different preparations of tobramycin

OBJECTIVES

This randomized, double-blind, cross-over study evaluated the risk of bronchoconstriction with two preparations of inhaled tobramycin in children with cystic fibrosis (CF) infected with Pseudomonas aeruginosa with and without airway hyperreactivity.

DESIGN

Of 19 children with CF (age range, 7 to 16 years) with mild-to-moderate pulmonary disease, 10 children were at high risk (HR) for bronchospasm (family history of asthma and previous response to bronchodilators) and 9 children were at low risk (LR) for bronchospasm (no family history of asthma or previous response to bronchodilators). Two solutions of tobramycin were administered: (1) 80 mg in a 2-mL vial diluted with 2 mL of saline solution containing the preservatives phenol and bisulfites (IV preparation); and (2) 300 mg in a preservative-free preparation in a 5-mL solution. Following a bronchodilator-free period of 12 h, the patients inhaled either one or the other preparation in random order on two different occasions, 2 weeks apart.

RESULTS

Prechallenge and postchallenge results for the LR group showed a percentage of fall in FEV(1) (DeltaFEV(1)) of 12 +/- 9% (mean +/- SD) for the IV preparation, compared to 4 +/- 5% for the preservative-free preparation (p = 0.046). An DeltaFEV(1) of > 10% was seen in six of nine patients for the IV preparation and in one of nine patients for preservative-free preparation. For the HR group, the DeltaFEV(1) was 17 +/- 13% for the IV-preparation group, compared to 16 +/- 12% for the preservative-free group (p = 0.4). In this group, equal numbers of patients (8 of 10 patients) had an DeltaFEV(1) > 10% after inhaling each preparation. The largest DeltaFEV(1) was 44% (HR group with the preservative-free preparation that forced the early termination of inhalation).

CONCLUSIONS

Both preparations caused significant bronchoconstriction in the HR group, and the preservative-containing IV preparation caused more bronchospasm in LR group than the preservative-free solution. Heightened airway reactivity in children with CF places them at risk of bronchospasm from inhalation therapy.

Pharmacokinetics and bioavailability of aerosolized tobramycin in cystic fibrosis

STUDY OBJECTIVES

To describe the pharmacokinetics and bioavailability of inhaled tobramycin (TOBI; Chiron Corporation; Seattle, WA), 300-mg dose, delivered by a nebulizer (PARI LC Plus; Pari Respiratory; Richmond, VA) and a compressor (Pulmo-Aide, model 5650D; DeVilbiss Health Care; Somerset, PA) in cystic fibrosis (CF) patients during the pivotal phase III trials.

DESIGN

Data from two identical, 24-week, randomized, double-blind, placebo-controlled, parallel-group studies.

SETTING

US sites randomized 258 patients with CF to receive tobramycin, 300 mg twice daily, in three 28-day on/28-day off treatment cycles.

MEASUREMENT

Tobramycin sputum concentrations were assessed 10 min after the first and last doses were administered in the 20-week study. Serum tobramycin concentrations were assessed before and 1 h after the first and last doses had been administered. The population estimate of the apparent clearance was used to estimate the bioavailability fraction.

RESULTS

The mean peak sputum concentration was 1,237 microg/g. About 95% of patients achieved sputum concentrations > 25 times the minimum inhibitory concentration of the Pseudomonas aeruginosa isolates. One hour after the dose, the mean serum concentration was 0.95 microg/mL. Tobramycin did not accumulate in the sputum or serum over the course of the study. Pharmacokinetic data were best represented by a two-compartment model with biexponential decay and slope estimates comparable to those following parenteral administration. The estimated systemic bioavailability after aerosol administration was 11.7% of the nominal dose.

CONCLUSIONS

The administration of tobramycin, 300 mg bid, in a 28-day off/28-day on regimen produced low serum tobramycin concentrations, reducing the potential for systemic toxicity. High sputum concentrations ensure efficacious antibiotic levels at the site of the infection. Inhaled tobramycin significantly improved the therapeutic ratio over that of parenteral aminoglycosides.

TOBI: reducing the impact of pseudomonal infection

Pseudomonas aeruginosa infection is associated with impaired lung function and reduced life expectancy in cystic fibrosis patients. Tobramycin nebulizer solution (TOBI, Chiron Corporation Ltd, Hounslow) has been specifically formulated for use against P. aeruginosa infection in the lung.

The role of nebulized antibiotics in treating serious respiratory infections

The administration of a nebulized antibiotic in serious respiratory tract infections ensures high antibiotic concentrations at the site of infection, minimising systemic concentrations and their resultant risk of toxicity. Nebulized antibiotics have been used for the treatment of chronic infection with Pseudomonas aeruginosa, particularly in cystic fibrosis, but with variable clinical efficacy. Antibiotic delivery by nebulization is greatly influenced by the product formulation and the nebulizer. Use of intravenous formulations via a nebulizer can lead to exposure to potentially irritant or toxic additives and inappropriate pH or osmolality ranges, whilst the choice of nebulizer can greatly influence the drug deposition in the airway. Tobramycin Nebulizer Solution (TNS) is the first specific formulation for nebulization in cystic fibrosis using a designated nebulizer. The potential extrapolation of nebulized antibiotic therapy to other serious respiratory infections, in particular bronchiectasis and ventilator-associated pneumonia, is explored in this review.

Accounting for radioactivity before and after nebulization of tobramycin to insure accuracy of quantification of lung deposition

The ability to predict drug deposition of inhaled drugs used in cystic fibrosis (CF) is important if there is a need to target specific doses of drug to the lungs of individual patients. The gold standard of measuring pulmonary deposition is the quantification of an aerosolized radiolabel either mixed with the drug solution or tagged directly to the compound of interest. Accuracy of the quantification could be assured if there is agreement between the amount of radioactivity before and after administration. Before administration, the radiolabel is concentrated in the well of the nebulizer, whereas after administration, it is distributed throughout the nebulizer, the expiratory filter and connectors, and the upper airway, stomach, trachea, and lung. Not only is the geometry of the distribution that is presented to the gamma camera different, but there are different attenuation factors for the various body tissues. The primary aim of this study was to evaluate the accuracy of the quantification of deposition. Secondary goals were to compare in vitro nebulizer performance with that measured in vivo during the deposition study. Eighty milligrams of tobramycin and technetium bound to human serum albumin was administered to 10 normal adults using a Pari LC Jet Plus (Pari Respiratory Equipment, Inc., Richmond, VA) breath-enhanced nebulizer. Techniques were developed that allowed for the accounting of 99 +/- 2% of the initial radioactivity. The fraction of the rate of lung deposition to total body deposition was the in vivo respirable fraction (0.62 +/- 0.07), which closely agreed with in vitro measurements of respirable fraction (0.62 +/- 0.04). Drug output measured from the change in weight and concentration in the nebulizer systematically overestimated drug output measured by the deposition study. The results indicate that 11.8 of the initial 80 mg would be deposited in the lungs. This technique could be adapted to accurately quantify the amount of deposition on any inhaled therapeutic agent, but caution must be used when extrapolating performance of a nebulizer on the bench to expected deposition in patients.

Technical report: precautions regarding the use of aerosolized antibiotics. Committee on Infectious Diseases and Committee on Drugs

In 1998, the Food and Drug Administration (FDA) approved the licensure of tobramycin solution for inhalation (TOBI). Although a number of additional antibiotics, including other aminoglycosides, beta-lactams, antibiotics in the polymyxin class, and vancomycin, have been administered as aerosols for many years, none are approved by the FDA for administration by inhalation. TOBI was approved by the FDA for the maintenance therapy of patients 6 years or older with cystic fibrosis (CF) who have between 25% and 75% of predicted forced expiratory volume in 1 second (FEV(1)), are colonized with Pseudomonas aeruginosa, and are able to comply with the prescribed medical regimen. TOBI was not approved for the therapy of acute pulmonary exacerbations in patients with CF nor was it approved for use in patients without CF. Currently, no other antibiotics are approved for administration by inhalation to patients with or without CF. The purpose of this statement is to briefly summarize the data that supported approval for licensure of TOBI and to provide recommendations for its safe use. The pharmacokinetics of inhaled aminoglycosides and problems associated with aerosolized antibiotic treatment, including environmental contamination, selection of resistant microbes, and airway exposure to excipients in intravenous formulations, will be discussed.

Inhaled tobramycin and bronchial hyperactivity in cystic fibrosis

The use of inhaled tobramycin for prophylaxis and treatment of respiratory symptoms in cystic fibrosis (CF) is now widespread. There have been concerns that inhaling the intravenous (I.V.) formulation of tobramycin causes bronchoconstriction. Previous studies using this formulation have either not specified the nebulizing equipment, or studied older, more severely affected patients. This study investigated the incidence of bronchoconstriction with tobramycin inhalation in children with mild to moderate CF. We studied 26 patients between the ages of 7 and 17 years, with mild to moderate CF (20 female). Prior to being placed on prolonged inhaled tobramycin therapy, they underwent a "tobramycin challenge." FEV(1) was measured pre and post challenge. For the test, standard I.V. solution (80 mg/2 mL) diluted with 2 mL of normal saline was nebulized, using the Hudson (Temecula, CA) RCI Updraft II nebulizer. The nebulization lasted 2 min. There was a 3-min "quiet period," following which FEV(1) was measured. A decrease in FEV(1) by at least 10% post-tobramycin inhalation was considered to be a positive test. Results were analyzed using the Pearson Chi-square test. Five of 26 (19%) had a positive reaction to tobramycin. Sixteen of 26 (61.5%) were using salbutamol on a daily basis at the time of testing but not for 48 hr before the challenge, and 16 of 26 (61.5%) had a pre-tobramycin FEV(1) of < or =80%. Neither an FEV(1) of <80% (P = 0.93) nor regular use of salbutamol (P = 0. 34) were associated with a positive tobramycin challenge. This study suggests that, while bronchoconstriction does occur, many patients do not exhibit bronchoconstriction in response to the standard I.V. preparation and, as prior work suggests, this may be reduced further by pretreatment with salbutamol.