Efficacy of once-daily tobramycin monotherapy for acute pulmonary exacerbations of cystic fibrosis: a preliminary study

Is there a multinational consensus of tobramycin prescribing and monitoring for cystic fibrosis? Survey of current therapeutic drug monitoring practices in USA/Canada, UK/Ireland, and Australia/New Zealand

OBJECTIVES

Sophisticated scientific methods have facilitated dose individualisation with substantial advancements in therapeutic drug monitoring (TDM) practice. It is unclear whether these methods have translated to the clinical setting. This study aimed to determine current TDM practice for tobramycin monitoring in cystic fibrosis (CF) centres in the USA and Canada, UK and Ireland, and Australia and New Zealand due to a high prevalence of CF.

METHODS

A web-based survey was developed and circulated via CF specialist groups within the targeted geographical regions. Themes included centre demographics, tobramycin usage, dosing and infusion practices, TDM practices, and blood sampling methods.

RESULTS

In total 77 responses were received from 75 different CF centres over the 3-month evaluation period (October 2019-January 2020). Respondents were from the USA and Canada (60%), Australia and New Zealand (25%), and the UK and Ireland (15%). Tobramycin was used in 97% of sites, with an international variation in practice across all survey aspects including dosing and infusion practice. TDM-based dose adjustment in the UK and Ireland was most commonly based only on trough sample collection for avoidance of toxicity, where use of computer programs for targeting both efficacy and toxicity endpoints were most common in Australia and New Zealand. The underlying pharmacokinetic basis of that program was not known by 33% of sites who utilised a computer program for tobramycin dose individualisation.

CONCLUSION

There remains substantial heterogeneity in tobramycin management worldwide. Despite two decades of research into TDM of tobramycin, there has been a slow uptake of new technologies and evolution of practice. An improved understanding of TDM processes is required for translation of evidence-based research into clinical practice. International guidelines require updating due to the advances in research to support confidence in the changes in clinical practice.

Pooling isolates to address the diversity in antimicrobial susceptibility of Pseudomonas aeruginosa in cystic fibrosis

IMPORTANCE

People with cystic fibrosis (pwCF) often suffer from chronic lung infections with Pseudomonas aeruginosa. While antibiotics are still commonly used to treat P. aeruginosa infections, there is a high discordance between in vitro and in vivo antibiotic efficacy, which contributes to suboptimal antibiotic therapy. In the present study, we found that isolates from the same sputum sample had highly diverse antibiotic resistance profiles [based on the minimal inhibitory concentration (MIC)], which may explain the reported discrepancy between in vitro and in vivo antibiotic efficacy. Through systematic analysis, we report that pooling nine isolates per sputum sample significantly decreased intrasample diversity in MIC and influenced clinical interpretation of antibiotic susceptibility tests compared to single isolate testing. Hence, pooling of isolates may offer a solution to obtain a consistent MIC test result and could lead to optimizing antibiotic therapy in pwCF and other infectious diseases where diversity in antibiotic resistance is observed.

Population Pharmacokinetics and AUC-Guided Dosing of Tobramycin in the Treatment of Infections Caused by Glucose-Nonfermenting Gram-Negative Bacteria

PURPOSE

Tobramycin (TOB) exhibits variable pharmacokinetic properties due to the clinical condition of patients. This study aimed to investigate the AUC-guided dosing of TOB based on population pharmacokinetic analysis in the treatment of infections caused by Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia.

METHODS

This retrospective study was conducted between January 2010 and December 2020 after obtaining approval from our institutional review board. For 53 patients who received therapeutic drug monitoring of TOB, a population pharmacokinetic model was developed with covariates of estimated glomerular filtration rate using serum creatinine (eGFRcre) on clearance (CL) and weight on both CL and V_d in exponential error modeling (CL = 2.84 × [weight/70] × eGFRcre^0.568, interindividual variability [IIV] = 31.1%; V_d = 26.3 × [weight/70], IIV = 20.2%; residual variability = 28.8%).

FINDINGS

The final regression model for predicting 30-day mortality was developed with risk factors of AUC during a 24-hour period after the first dose to MIC ratio (odds ratio [OR] = 0.996; 95% CI, 0.968-1.003) and serum albumin (OR = 0.137; 95% CI, 0.022-0.632). The final regression model for predicting acute kidney injury was developed with the risk factors of C-reactive protein (OR = 1.136; 95% CI, 1.040-1.266) and AUC during a 72-hour period after the first dose (OR = 1.004; 95% CI, 1.000-1.001). A dose of 8 or 15 mg/kg was beneficial for achievement of AUC during a 24-hour period after the first dose/MIC >80 and trough concentration <1 µg/mL in patients with preserved kidney function and TOB CL >4.47 L/h/70 kg in the events of MIC of 1 or 2 µg/mL, respectively. We propose that the first dose of 15, 11, 10, 8, and 7 mg/kg for eGFRcre >90, 60 to 89, 45 to 59, 30 to 44, and 15 to 29 mL/min/1.73 m² be followed by therapeutic drug monitoring at peak and 24 hours after the first dose.

IMPLICATIONS

This study suggests that TOB use encourages the replacement of trough- and peak-targeted dosing with AUC-guided dosing.

Diagnosis and Management of Cystic Fibrosis Exacerbations

With the improving survival of cystic fibrosis (CF) patients and the advent of highly effective cystic fibrosis transmembrane conductance regulator (CFTR) therapy, the clinical spectrum of this complex multisystem disease continues to evolve. One of the most important clinical events for patients with CF in the course of this disease is acute pulmonary exacerbation (PEx). Clinical and microbial epidemiology studies of CF PEx continue to provide important insight into the disease course, prognosis, and complications. This work has now led to several large-scale clinical trials designed to clarify the treatment paradigm for CF PEx. The primary goal of this review is to provide a summary and update of the pathophysiology, clinical and microbial epidemiology, outcome and treatment of CF PEx, biomarkers for exacerbation, and the impact of highly effective modulator therapy on these events moving forward.

Antipseudomonal treatment decisions during CF exacerbation management

BACKGROUND

Cystic fibrosis (CF) pulmonary exacerbation (PEx) treatment guidelines suggest that Pseudomonas aeruginosa (Pa) airway infection be treated with two antipseudomonal agents.

METHODS

We retrospectively studied treatment responses for STOP2 PEx treatment trial (NCT02781610) participants with a history of Pa infection. Mean lung function and symptom changes from intravenous (IV) antimicrobial treatment start to Visit 2 (7 to 10 days later) were compared between those receiving one, two, and three+ antipseudomonal classes before Visit 2 by ANCOVA. Odds of PEx retreatment with IV antimicrobials within 30 days and future IV-treated PEx hazard were modeled by logistic and Cox proportional hazards regression, respectively. Sensitivity analyses limited to the most common one-, two-, and three-class regimens, to only IV/oral antipseudomonal treatments, and with more stringent Pa infection definitions were conducted.

RESULTS

Among 751 participants, 50 (6.7%) were treated with one antipseudomonal class before Visit 2, while 552 (73.5%) and 149 (19.8%) were treated with two and with three+ classes, respectively. Females and participants with a negative Pa culture in the prior month were more likely to be treated with a single class. The most common single, double, and triple class regimens were beta-lactam (BL; n = 42), BL/aminoglycoside (AG; n = 459), and BL/AG/fluoroquinolone (FQ; n = 73). No lung function or symptom response, odds of retreatment, or future PEx hazard differences were observed by number of antipseudomonal classes administered in primary or sensitivity analyses.

CONCLUSIONS

We were unable to identify additional benefit when multiple antipseudomonal classes are used to treat PEx in people with CF and Pa.

Comparison of the predictive value of area under the curve versus maximum serum concentration of intravenous tobramycin in cystic fibrosis patients treated for an acute pulmonary exacerbation

OBJECTIVES

The primary objective of this study was to compare the therapeutic predictive value of area under the curve (AUC₂₄ ) versus maximum concentration (C_max ) in cystic fibrosis (CF) patients receiving intravenous (IV) tobramycin for a Pseudomonas aeruginosa (PsA) acute pulmonary exacerbation (APE). Acute kidney injury (AKI) incidence and the relationship between time undetectable and efficacy were also assessed.

METHODS

A retrospective review was conducted in patients aged at least 1 month with a diagnosis of CF receiving IV tobramycin for treatment of a PsA APE and admitted to the University of Kentucky between August 2015 and August 2019. Patients were excluded if they had no growth of PsA on sputum culture or if two postdose tobramycin levels were not obtained following a dose adjustment of ≥20%.

RESULTS

A total of 44 pediatric and 107 adult patient encounters met inclusion criteria. In patients with therapeutic success (n = 91), 75.8% had an AUC₂₄  ≥80% and 80.3% had a C_max ≥8 times the highest PsA minimal inhibitory concentration. There was a significant correlation between AUC₂₄ and C_max (r[149] = 0.727; p < 0.001). AKI incidence was significantly higher in patients receiving IV tobramycin dosed multiple times daily versus at least every 24 h (χ² [1, 151] = 3.9; p =  0.047).

CONCLUSIONS

The results of this study indicate that both AUC₂₄ and C_max serve as relatively accurate predictors of tobramycin efficacy. Additionally, given the significant increase in incidence of AKI, multidaily dosing of IV tobramycin should be avoided in pediatric and adult patients with CF.

Variation in treatment preferences of pulmonary exacerbations among Australian and New Zealand cystic fibrosis physicians

BACKGROUND

Despite advances in cystic fibrosis (CF) management and survival, the optimal treatment of pulmonary exacerbations remains unclear. Understanding the variability in treatment approaches among physicians might help prioritise clinical uncertainties to address through clinical trials.

METHODS

Physicians from Australia and New Zealand who care for people with CF were invited to participate in a web survey of treatment preferences for CF pulmonary exacerbations. Six typical clinical scenarios were presented; three to paediatric and another three to adult physicians. For each scenario, physicians were asked to choose treatment options and provide reasons for their choices.

RESULTS

Forty-nine CF physicians (31 paediatric and 18 adult medicine) participated; more than half reported 10+ years of experience. There was considerable variation in primary antibiotic selection; none was preferred by more than half of respondents in any scenario. For secondary antibiotic therapy, respondents consistently preferred intravenous tobramycin and a third antibiotic was rarely prescribed, except in one scenario describing an adult patient. Hypertonic saline nebulisation and twice daily chest physiotherapy was preferred in most scenarios while dornase alfa use was more variable. Most CF physicians (>80%) preferred to change therapy if there was no early response. Professional opinion was the most common reason for antibiotic choice.

CONCLUSIONS

Variation exists among CF physicians in their preferred choice of primary antibiotic and use of dornase alfa. These preferences are driven by professional opinion, possibly reflecting a lack of evidence to base policy recommendations. Evidence from high-quality clinical trials is needed to inform physician decision making.

Single versus combination intravenous anti-pseudomonal antibiotic therapy for people with cystic fibrosis

BACKGROUND

The choice of antibiotic, and the use of single or combined therapy are controversial areas in the treatment of respiratory infection due to Pseudomonas aeruginosa in cystic fibrosis (CF). Advantages of combination therapy include wider range of modes of action, possible synergy and reduction of resistant organisms; advantages of monotherapy include lower cost, ease of administration and reduction of drug-related toxicity. Current evidence does not provide a clear answer and the use of intravenous antibiotic therapy in CF requires further evaluation. This is an update of a previously published review.

OBJECTIVES

To assess the effectiveness of single compared to combination intravenous anti-pseudomonal antibiotic therapy for treating people with CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Most recent search of the Group's Trials Register: 07 October 2020. We also searched online trials registries on 16 November 2020.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing a single intravenous anti-pseudomonal antibiotic with a combination of that antibiotic plus a second anti-pseudomonal antibiotic in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. We assessed the certainty of the data using GRADE.

MAIN RESULTS

We identified 59 trials, of which we included eight trials (356 participants) comparing a single anti-pseudomonal agent to a combination of the same antibiotic and one other. There was a wide variation in the individual antibiotics used in each trial. In total, the trials included seven comparisons of a beta-lactam antibiotic (penicillin-related or third generation cephalosporin) with a beta-lactam-aminoglycoside combination and three comparisons of an aminoglycoside with a beta-lactam-aminoglycoside combination.  There was considerable heterogeneity amongst these trials, leading to difficulties in performing the review and interpreting the results. These results should be interpreted cautiously. Six of the included trials were published between 1977 and 1988; these were single-centre trials with flaws in the randomisation process and small sample size. Overall, the methodological quality was poor and the certainty of the evidence ranged from low to moderate. The review did not find any differences between monotherapy and combination therapy in either the short term or in the long term for the outcomes of different lung function measures, bacteriological outcome measures, need for additional treatment, adverse effects, quality of life or symptom scores.

AUTHORS' CONCLUSIONS

The results of this review are inconclusive. The review raises important methodological issues. There is a need for an RCT which needs to be well-designed in terms of adequate randomisation allocation, blinding, power and long-term follow-up. Results need to be standardised to a consistent method of reporting, in order to validate the pooling of results from multiple trials.

Outcomes and endpoints reported in studies of pulmonary exacerbations in people with cystic fibrosis: A systematic review

BACKGROUND

There is no consensus about which outcomes should be evaluated in studies of pulmonary exacerbations in people with cystic fibrosis (CF). Outcomes used for evaluation should be meaningful; that is, they should capture how people feel, function or survive and be acknowledged as important to people with CF, or should be reliable surrogates of those outcomes. We aimed to summarise the outcomes and corresponding endpoints which have been reported in studies of pulmonary exacerbations, and to identify those which are most likely to be meaningful.

METHODS

A PROSPERO registered systematic review (CRD42020151785) was conducted in Medline, Embase and Cochrane from inception until July 2020. Registered trials were also included.

RESULTS

144 studies met the inclusion criteria. A wide range of outcomes and corresponding endpoints were reported. Death, QoL and many patient-reported outcomes are likely to be meaningful as they directly capture how people feel, function or survive. Forced expiratory volume in 1-second [FEV₁] is a validated surrogate of risk of death and reduced QoL. The extent of structural lung disease has also been correlated with lung function, pulmonary exacerbations and risk of death. Since no evidence of a correlation between airway microbiology or biomarkers with clinically meaningful outcomes was found, the value of these as surrogates was unclear.

CONCLUSIONS

Death, QoL, patient-reported outcomes, FEV₁, and structural lung changes were identified as outcomes that are most likely to be meaningful. Development of a core outcome set in collaboration with stakeholders including people with CF is recommended.

Pharmacokinetic/pharmacodynamic analysis of weight- and height-scaled tobramycin dosage regimens for patients with cystic fibrosis

OBJECTIVES

To determine the outcomes of weight- and height-based tobramycin dosing regimens for patients with cystic fibrosis (CF).

METHODS

A simulated dataset of 5000 patients based on 331 patients with CF was created using NONMEM. Pharmacokinetic (PK) parameters were derived for each patient from a published model using Monte Carlo simulation. The abilities of 10 and 12 mg/kg/day and 3 and 4 mg/cm/day to achieve standard and extended Cmax (20-30 and 20-40 mg/L) and AUC0-24 (80-120 and 80-150 mg·h/L) targets were evaluated. PK/pharmacodynamic (PK/PD) indices were a Cmax/MIC ratio ≥10 and an AUC0-24/MIC ratio ≥110. For these indices and a range of MICs, cumulative fractions of response (CFRs) for Pseudomonas aeruginosa were also determined.

RESULTS

More patients achieved standard Cmax and AUC0-24 targets with 3 mg/cm/day (64% and 62%, respectively) than with 10 mg/kg/day (43% and 48%, respectively). AUC0-24 estimates >120 mg·h/L were more common with weight-based dosing. With higher doses, 72% achieved high target peaks with 4 mg/cm/day and 65% with 12 mg/kg/day. For the Cmax/MIC index, the maximal MIC for the target microorganism was 2 mg/L with lower doses, 2.5 mg/L with higher doses and 0.5 mg/L for AUC0-24/MIC-based regimens. The CFR for all regimens was >90% for Cmax targets and 66% to 79% for AUC0-24 targets.

CONCLUSIONS

A tobramycin dose of 3 mg/cm/day rather than 10 mg/kg/day achieved similar PK/PD outcomes but dose and AUC0-24 ranges were narrower and the incidence of high AUC0-24 values was lower. Height-based doses should therefore be considered for patients with CF.

Once-daily versus multiple-daily dosing with intravenous aminoglycosides for cystic fibrosis

BACKGROUND

People with cystic fibrosis, who are chronically colonised with the organism Pseudomonas aeruginosa, often require multiple courses of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations. The properties of aminoglycosides suggest that they could be given in higher doses less often. This is an update of a previously published review.

OBJECTIVES

To assess the effectiveness and safety of once-daily versus multiple-daily dosing of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations in cystic fibrosis.

SEARCH METHODS

We searched the Cystic Fibrosis Specialist Register held at the Cochrane Cystic Fibrosis and Genetic Disorders Group's editorial base, comprising references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings.Date of the most recent search: 31 January 2019.We also searched online trial registries. Date of latest search: 25 February 2019.

SELECTION CRITERIA

All randomised controlled trials, whether published or unpublished, in which once-daily dosing of aminoglycosides has been compared with multiple-daily dosing in terms of efficacy or toxicity or both, in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The two authors independently selected the studies to be included in the review and assessed the risk of bias of each study; authors also assessed the quality of the evidence using the GRADE criteria. Data were independently extracted by each author. Authors of the included studies were contacted for further information. As yet unpublished data were obtained for one of the included studies.

MAIN RESULTS

We identified 15 studies for possible inclusion in the review. Five studies reporting results from a total of 354 participants (aged 5 to 50 years) were included in this review. All studies compared once-daily dosing with thrice-daily dosing. One cross-over trial had 26 participants who received the first-arm treatment but only 15 received the second arm. One study had a low risk of bias for all criteria assessed; the remaining included studies had a high risk of bias from blinding, but for other criteria were judged to have either an unclear or a low risk of bias.There was little or no difference between treatment groups in: forced expiratory volume in one second, mean difference (MD) 0.33 (95% confidence interval (CI) -2.81 to 3.48, moderate-quality evidence); forced vital capacity, MD 0.29 (95% CI -6.58 to 7.16, low-quality evidence); % weight for height, MD -0.82 (95% CI -3.77 to 2.13, low-quality evidence); body mass index, MD 0.00 (95% CI -0.42 to 0.42, low-quality evidence); or in the incidence of ototoxicity, relative risk 0.56 (95% CI 0.04 to 7.96, moderate-quality evidence). Once-daily treatment in children probably improved the percentage change in creatinine, MD -8.20 (95% CI -15.32 to -1.08, moderate-quality evidence), but showed no difference in adults, MD 3.25 (95% CI -1.82 to 8.33, moderate-quality evidence). The included trials did not report antibiotic resistance patterns or quality of life.

AUTHORS' CONCLUSIONS

Once- and three-times daily aminoglycoside antibiotics appear to be equally effective in the treatment of pulmonary exacerbations of cystic fibrosis. There is evidence of less nephrotoxicity in children.

Antimicrobial susceptibility testing (AST) and associated clinical outcomes in individuals with cystic fibrosis: A systematic review

BACKGROUND

Antimicrobial susceptibility testing (AST) is a cornerstone of infection management. Cystic fibrosis (CF) treatment guidelines recommend AST to select antimicrobial treatments for CF airway infection but its utility in this setting has never been objectively demonstrated.

METHODS

We conducted a systematic review of primary published articles designed to address two PICO (patient, intervention, comparator, outcome) questions: 1) "For individuals with CF, is clinical response to antimicrobial treatment of bacterial airways infection predictable from AST results available at treatment initiation?" and 2) "For individuals with CF, is clinical response to antimicrobial treatment of bacterial airways infection affected by the method used to guide antimicrobial selection?" Relationships between AST results and clinical response (changes in pulmonary function, weight, signs and symptoms of respiratory tract infection, and time to next event) were assessed for each article and results were compared across articles when possible.

RESULTS

Twenty-five articles describing the results of 20 separate studies, most of which described Pseudomonas aeruginosa treatment, were identified. Thirteen studies described pulmonary exacerbation (PEx) treatment and seven described 'maintenance' of chronic bacterial airways infection. In only three of 16 studies addressing PICO question #1 was there a suggestion that baseline bacterial isolate antimicrobial susceptibility was associated with clinical response to treatment. None of the four studies addressing PICO question #2 suggested that antimicrobial selection methods influenced clinical outcomes.

CONCLUSIONS

There is little evidence that AST predicts the clinical outcome of CF antimicrobial treatment, suggesting a need for careful consideration of current AST use by the CF community.

Safety of intravenous tobramycin in combination with a variety of anti-pseudomonal antibiotics in children with cystic fibrosis

OBJECTIVES

Previous studies have examined renal safety of once daily intravenous tobramycin in individuals with cystic fibrosis. This has been mainly in combination with ceftazidime in an adolescent or adult population. In this report, we describe our institutional experience of once daily intravenous tobramycin in combination with a variety of second anti-pseudomonal antibiotics in children with cystic fibrosis.

METHODS

We present a retrospective review including children with cystic fibrosis, who were admitted for a pulmonary exacerbation from January 2009 to December 2011, and treated using intravenous tobramycin. A literature review of once daily intravenous aminoglycoside dosing in cystic fibrosis was performed to compare our results to existing literature.

RESULTS

A total of 35 subjects were divided into once daily dosing (n = 20) versus multiple daily dosing (n = 15) groups. Mean age was 11.3 years (± 5.7) for the once daily dosing group and 13.1 years (± 4.4) for the multiple daily dosing group (p = 0.34). All subjects had normal baseline serum creatinine at admission (once daily dosing 0.49 ± 0.14 mg/dL vs multiple daily dosing 0.62 ± 0.23 mg/dL, p = 0.07). All subjects received intravenous tobramycin, and most received piperacillin-tazobactam as their second anti-pseudomonal antibiotic (once daily dosing 45% and multiple daily dosing 40%). There was no significant change in serum creatinine in either group during antibiotic treatment (once daily dosing 0.08 ± 0.12 mg/dL vs. multiple daily dosing 0.06 ± 0.10 mg/dL, p = 0.43). All subjects had significant improvement in lung function following intravenous antibiotic therapy.

CONCLUSION

We show that both once daily dosing and multiple daily dosing of intravenous tobramycin in combination with a variety of second anti-pseudomonal antibiotics were safe in terms of nephrotoxicity in children with cystic fibrosis. These findings are important given existing literature mainly examines once daily tobramycin in combination with ceftazidime, a cephalosporin, and the majority of our patients were on tobramycin with piperacillin-tazobactam, an extended spectrum penicillin plus beta-lactam. This contributes new information not previously examined in a pediatric cystic fibrosis population.

Once-daily versus multiple-daily dosing with intravenous aminoglycosides for cystic fibrosis

BACKGROUND

People with cystic fibrosis, who are chronically colonised with the organism Pseudomonas aeruginosa, often require multiple courses of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations. The properties of aminoglycosides suggest that they could be given in higher doses less often. This is an update of a previously published review.

OBJECTIVES

To assess the effectiveness and safety of once-daily versus multiple-daily dosing of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations in cystic fibrosis.

SEARCH METHODS

We searched the Cystic Fibrosis Specialist Register held at the Cochrane Cystic Fibrosis and Genetic Disorders Group's editorial base, comprising references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings.Date of the most recent search: 24 June 2016.

SELECTION CRITERIA

All randomised controlled trials, whether published or unpublished, in which once-daily dosing of aminoglycosides has been compared with multiple-daily dosing in terms of efficacy or toxicity or both, in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The two authors independently selected the studies to be included in the review and assessed the risk of bias of each study; authors also assessed the quality of the evidence using the GRADE criteria. Data were independently extracted by each author. Authors of the included studies were contacted for further information. As yet unpublished data were obtained for one of the included studies.

MAIN RESULTS

Fifteen studies were identified for possible inclusion in the review. Four studies reporting results from a total of 328 participants (aged 5 to 50 years) were included in this review. All studies compared once-daily dosing with thrice-daily dosing. One study had a low risk of bias for all criteria assessed; the remaining three included studies had a high risk of bias from blinding, but for other criteria were judged to have either an unclear or a low risk of bias.There was no significant difference between treatment groups in: forced expiratory volume in one second, mean difference 0.33 (95% confidence interval -2.81 to 3.48, moderate quality evidence); forced vital capacity, mean difference 0.29 (95% confidence interval -6.58 to 7.16, low quality evidence); % weight for height, mean difference -0.82 (95% confidence interval -3.77 to 2.13, low quality evidence); body mass index, mean difference 0.00 (95% confidence interval -0.42 to 0.42, low quality evidence); or in the incidence of ototoxicity, relative risk 0.56 (95% confidence interval 0.04 to 7.96, moderate quality evidence). The percentage change in creatinine significantly favoured once-daily treatment in children, mean difference -8.20 (95% confidence interval -15.32 to -1.08, moderate quality evidence), but showed no difference in adults, mean difference 3.25 (95% confidence interval -1.82 to 8.33, moderate quality evidence). The included trials did not report antibiotic resistance patterns or quality of life.

AUTHORS' CONCLUSIONS

Once- and three-times daily aminoglycoside antibiotics appear to be equally effective in the treatment of pulmonary exacerbations of cystic fibrosis. There is evidence of less nephrotoxicity in children.

Single versus combination intravenous anti-pseudomonal antibiotic therapy for people with cystic fibrosis

BACKGROUND

Choice of antibiotic, and the use of single or combined therapy are controversial areas in the treatment of respiratory infection due to Pseudomonas aeruginosa in cystic fibrosis (CF). Advantages of combination therapy include wider range of modes of action, possible synergy and reduction of resistant organisms; advantages of monotherapy include lower cost, ease of administration and reduction of drug-related toxicity. Current evidence does not provide a clear answer and the use of intravenous antibiotic therapy in cystic fibrosis requires further evaluation. This is an update of a previously published review.

OBJECTIVES

To assess the effectiveness of single compared to combination intravenous anti-pseudomonal antibiotic therapy for treating people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search of the Group's Trials Register: 14 October 2016.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing a single intravenous anti-pseudomonal antibiotic with a combination of that antibiotic plus a second anti-pseudomonal antibiotic in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

We identified 45 trials, of which eight trials (356 participants) comparing a single anti-pseudomonal agent to a combination of the same antibiotic and one other, were included.There was a wide variation in the individual antibiotics used in each trial. In total, the trials included seven comparisons of a beta-lactam antibiotic (penicillin-related or third generation cephalosporin) with a beta-lactam-aminoglycoside combination and three comparisons of an aminoglycoside with a beta-lactam-aminoglycoside combination. These two groups of trials were analysed as separate subgroups.There was considerable heterogeneity amongst these trials, leading to difficulties in performing the review and interpreting the results. The meta-analysis did not demonstrate any significant differences between monotherapy and combination therapy, in terms of lung function; symptom scores; adverse effects; and bacteriological outcome measures.These results should be interpreted cautiously. Six of the included trials were published between 1977 and 1988; these were single-centre trials with flaws in the randomisation process and small sample size. Overall, the methodological quality was poor.

AUTHORS' CONCLUSIONS

The results of this review are inconclusive. The review raises important methodological issues. There is a need for an RCT which needs to be well-designed in terms of adequate randomisation allocation, blinding, power and long-term follow up. Results need to be standardised to a consistent method of reporting, in order to validate the pooling of results from multiple trials.

Duration of intravenous antibiotic therapy in people with cystic fibrosis

BACKGROUND

Respiratory disease is the major cause of mortality and morbidity in cystic fibrosis. Life expectancy of people with cystic fibrosis has increased dramatically in the last 40 years. One of the major reasons for this increase is the mounting use of antibiotics to treat chest exacerbations caused by bacterial infections. The optimal duration of intravenous antibiotic therapy is not clearly defined. Individuals usually receive intravenous antibiotics for 14 days, but treatment may range from 10 to 21 days. A shorter duration of antibiotic treatment risks inadequate clearance of infection which could lead to further lung damage. Prolonged courses of intravenous antibiotics are expensive and inconvenient and the incidence of allergic reactions to antibiotics also increases with prolonged courses. The use of aminoglycosides requires frequent monitoring to avoid some of their side effects. However, some organisms which infect people with cystic fibrosis are known to be multi-resistant to antibiotics, and may require a longer course of treatment. This is an update of previously published reviews.

OBJECTIVES

To assess the optimal duration of intravenous antibiotic therapy for treating chest exacerbations in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals, abstract books and conference proceedings.Most recent search of the Group's Cystic Fibrosis Trials Register: 05 May 2016.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different durations of intravenous antibiotic courses for acute respiratory exacerbations in people with CF, either with the same drugs at the same dosage, the same drugs at a different dosage or frequency or different antibiotics altogether, including studies with additional therapeutic agents.

DATA COLLECTION AND ANALYSIS

No eligible trials were identified.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

There are no clear guidelines on the optimum duration of intravenous antibiotic treatment. Duration of treatment is currently based on unit policies and response to treatment. Shorter duration of treatment should improve quality of life and compliance; result in a reduced incidence of drug reactions; and be less costly. However, this may not be sufficient to clear a chest infection and may result in an early recurrence of an exacerbation. This systematic review identifies the need for a multicentre, randomised controlled trial comparing different durations of intravenous antibiotic treatment as it has important clinical and financial implications.

Tobramycin and Beta-Lactam Antibiotic Use in Cystic Fibrosis Exacerbations: A Pharmacist Approach

OBJECTIVES

Survey suggests that recommended doses and dosage regimens for antipseudomonal antibiotics for the treatment of acute pulmonary exacerbations in cystic fibrosis (CF) patients are not used, and one way to address these disparities is the involvement of pharmacists who are dedicated to CF. This is the first survey specifically designed for pharmacists at Cystic Fibrosis Foundation (CFF)-accredited centers to identify how tobramycin and antipseudomonal beta-lactams are being used. The purpose of this survey is to quantify this information and to promote future study to allow for implementation of tobramycin and beta-lactam dosage and monitoring standardization.

METHODS

An anonymous national cross-sectional survey of pharmacists that are affliated with CFF-accredited programs was performed using Qualtrics.com.

RESULTS

The survey had a 48.5% response rate. Most pediatric pharmacists (78.6%) report using extended-interval tobramycin dosage. The most common reported starting dosage was 10 mg/kg every 24 hours; most centers aim for a maximum serum concentration (Cmax) between 20 and 40 mg/L (78.6%). A total of 26 adult pharmacists reported using extended-interval dosage (96%), using an initial dosage of 10 mg/kg/day. The most common parameters used to adjust dosage were Cmax and area under the curve (AUC; 31%); the Cmax goal was 20 to 40 mg/L (84.2%). Most respondents (79%) report using beta-lactams in combination with tobramycin. Extended-infusion and continuous-infusion beta-lactams were used more in adults than pediatric patients.

CONCLUSIONS

Most CF pharmacists report using extended-interval tobramycin. With the information from this survey, the establishment of future consensus recommendations by pharmacists for optimal and consistent tobramycin and antipseudomonal beta-lactam dosage and monitoring strategies needs to be considered.

Extended-Interval Aminoglycoside Use in Cystic Fibrosis Exacerbation in Children and Young Adults: A Prospective Quality Improvement Project

This is a prospective quality improvement project for patients with cystic fibrosis who are 5 years of age and older who were admitted for intravenous antibiotic administration as part of treatment of cystic fibrosis exacerbation. The goal of this project was to compare the pharmacokinetics of once-daily versus thrice-daily aminoglycoside use when treating cystic fibrosis exacerbation in different age groups. Of the total of 119 patient encounters, 82.4% were started on once-daily dosing, and the remainder were started on thrice-daily dosing. Patients with pharmacokinetics allowing the continuation of once-daily dosing differed from patients who required a switch to thrice-daily dosing in terms of baseline forced expiratory volume in 1 second, forced expiratory flow from 25% to 75% of vital capacity, age, and body mass index (BMI) but were similar in BMI percentiles. The once-daily dosing group had higher mean 18-hour level, higher mean half-life, higher mean area under the curve, and lower mean elimination constant. This study showed that aminoglycoside clearance is higher in younger children.

Intravenous antibiotics for pulmonary exacerbations in people with cystic fibrosis

BACKGROUND

Cystic fibrosis is a multi-system disease characterised by the production of thick secretions causing recurrent pulmonary infection, often with unusual bacteria. Intravenous antibiotics are commonly used in the treatment of acute deteriorations in symptoms (pulmonary exacerbations); however, recently the assumption that exacerbations are due to increases in bacterial burden has been questioned.

OBJECTIVES

To establish if intravenous antibiotics for the treatment of pulmonary exacerbations in people with cystic fibrosis improve short- and long-term clinical outcomes.

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 the reference lists of relevant articles and reviews and ongoing trials registers.Date of last search of Cochrane trials register: 27 July 2015.

SELECTION CRITERIA

Randomised controlled trials and the first treatment cycle of cross-over studies comparing intravenous antibiotics (given alone or in an antibiotic combination) with placebo, inhaled or oral antibiotics for people with cystic fibrosis experiencing a pulmonary exacerbation.

DATA COLLECTION AND ANALYSIS

The authors assessed studies for eligibility and risk of bias and extracted data.

MAIN RESULTS

We included 40 studies involving 1717 participants. The quality of the included studies was largely poor and, with a few exceptions, these comprised of mainly small, inadequately reported studies.When comparing treatment with a single antibiotic to a combined antibiotic regimen, those participants receiving a combination of antibiotics experienced a greater improvement in lung function when considered as a whole group across a number of different measurements of lung function, but with very low quality evidence. When limited to the four placebo-controlled studies (n = 214), no difference was observed, again with very low quality evidence. With regard to the review's remaining primary outcomes, there was no effect upon time to next exacerbation and no studies in any comparison reported on quality of life. There were no effects on the secondary outcomes weight or adverse effects. When comparing specific antibiotic combinations there were no significant differences between groups on any measure. In the comparisons between intravenous and nebulised antibiotic or oral antibiotic (low quality evidence), there were no significant differences between groups on any measure. No studies in any comparison reported on quality of life.

AUTHORS' CONCLUSIONS

The quality of evidence comparing intravenous antibiotics with placebo is poor. No specific antibiotic combination can be considered to be superior to any other, and neither is there evidence showing that the intravenous route is superior to the inhaled or oral routes. There remains a need to understand host-bacteria interactions and in particular to understand why many people fail to fully respond to treatment.

Single versus combination intravenous antibiotic therapy for people with cystic fibrosis

BACKGROUND

Choice of antibiotic, and the use of single or combined therapy are controversial areas in the treatment of respiratory infection in cystic fibrosis (CF). Advantages of combination therapy include wider range of modes of action, possible synergy and reduction of resistant organisms; advantages of monotherapy include lower cost, ease of administration and reduction of drug-related toxicity. Current evidence does not provide a clear answer and the use of intravenous antibiotic therapy in CF requires further evaluation.

OBJECTIVES

To assess the effectiveness of single compared to combination intravenous antibiotic therapy for treating people with CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search of the Group's Trials Register: 22 August 2013.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing a single intravenous antibiotic with a combination of that antibiotic plus a second antibiotic in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

We identified 43 trials, of which eight trials (356 participants) comparing a single agent to a combination of the same antibiotic and one other, were included.There was a wide variation in the individual antibiotics used in each trial. In total, the trials included seven comparisons of a beta-lactam antibiotic (penicillin-related or third generation cephalosporin) with a beta-lactam-aminoglycoside combination and three comparisons of an aminoglycoside with a beta-lactam-aminoglycoside combination. These two groups of trials were analysed as separate subgroups.There was considerable heterogeneity amongst these trials, leading to difficulties in performing the review and interpreting the results. The meta-analysis did not demonstrate any significant differences between monotherapy and combination therapy, in terms of lung function; symptom scores; adverse effects; and bacteriological outcome measures.These results should be interpreted cautiously. Six of the included trials were published between 1977 and 1988; these were single-centre trials with flaws in the randomisation process and small sample size. Overall, the methodological quality was poor.

AUTHORS' CONCLUSIONS

The results of this review are inconclusive. The review raises important methodological issues. There is a need for an RCT which needs to be well-designed in terms of adequate randomisation allocation, blinding, power and long-term follow up. Results need to be standardised to a consistent method of reporting, in order to validate the pooling of results from multiple trials.

Once-daily versus multiple-daily dosing with intravenous aminoglycosides for cystic fibrosis

BACKGROUND

People with cystic fibrosis, who are chronically colonised with the organism Pseudomonas aeruginosa, often require multiple courses of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations. The properties of aminoglycosides suggest that they could be given in higher doses less often.

OBJECTIVES

To assess the effectiveness and safety of once-daily versus multiple-daily dosing of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations in cystic fibrosis.

SEARCH METHODS

We searched the Cystic Fibrosis Specialist Register held at the Cochrane Cystic Fibrosis and Genetic Disorders Group's editorial base, comprising references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings.Date of the most recent search: 25 November 2013.

SELECTION CRITERIA

All randomised controlled trials, whether published or unpublished, in which once-daily dosing of aminoglycosides has been compared with multiple-daily dosing in terms of efficacy or toxicity or both, in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The two authors independently selected the studies to be included in the review and assessed the risk of bias of each study. Data were independently extracted by each author. Authors of the included studies were contacted for further information. As yet unpublished data were obtained for one of the included studies.

MAIN RESULTS

Fifteen studies were identified for possible inclusion in the review. Four studies reporting results from a total of 328 participants were included in this review. All studies compared once-daily dosing with thrice-daily dosing. One study had a low risk of bias for all criteria assessed; the remaining three included studies had a high risk of bias from blinding, but for other criteria were judged to have either an unclear or a low risk of bias.There was no significant difference between treatment groups in: forced expiratory volume at one second, mean difference 0.33 (95% confidence interval -2.81 to 3.48); forced vital capacity, mean difference 0.29 (95% confidence interval -6.58 to 7.16); % weight for height, mean difference -0.82 (95% confidence interval -3.77 to 2.13); body mass index, mean difference 0.00 (95% confidence interval -0.42 to 0.42); or in the incidence of ototoxicity, relative risk 0.56 (95% confidence interval 0.04 to 7.96). The percentage change in creatinine significantly favoured once-daily treatment in children, mean difference -8.20 (95% confidence interval -15.32 to -1.08), but showed no difference in adults, mean difference 3.25 (95% confidence interval -1.82 to 8.33).

AUTHORS' CONCLUSIONS

Once- and three-times daily aminoglycoside antibiotics appear to be equally effective in the treatment of pulmonary exacerbations of cystic fibrosis. There is evidence of less nephrotoxicity in children.

Is the improvement of CF patients, hospitalized for pulmonary exacerbation, correlated to a decrease in bacterial load?

Background

Cystic Fibrosis (CF) patients are vulnerable to airway colonization with Pseudomonas aeruginosa. In case eradication fails after antibiotic treatment, patients become chronically colonized with P. aeruginosa, with recurrent pulmonary exacerbation, for which patients typically are hospitalized for 2 weeks and receive intravenous antibiotic treatment. Normally, improvement of the patients' health is established.

Aim

Determination of the correspondence between patient improvement and changes of the P. aeruginosa and total bacterial load in the sputum.

Methods

Eighteen CF patients with exacerbation were included for a total of 27 hospitalization episodes. At day 1, 8 and 15, inflammation and lung function parameters were determined, together with the P. aeruginosa load in the sputum using culture, quantitative PCR (qPCR) and propidium monoazide qPCR.

Results

Patients improved during hospitalization (decrease in levels of C-reactive protein, white blood cell counts and erythrocyte sedimentation rate, increase of FEV₁), reaching normal values already after one week. Also the P. aeruginosa load and the total bacterial load decreased during the first week of antibiotic treatment (p<0.05), except for patients with a low lung function (FEV₁≤39.4%), for whom no significant decrease of P. aeruginosa was established. Comparison of culture-based and propidium monoazide qPCR-based quantification of P. aeruginosa showed that at the end of the treatment on average 62% of the P. aeruginosa cells are not cultivable, indicating that many cells are alive but dormant, or dead but still structurally intact.

Conclusion

Improvement of the clinical status is accompanied with a decrease of the P. aeruginosa load, whereby both occur mainly during the first week of antibiotic treatment. However, for patients with a low lung function, no decrease of the P. aeruginosa load is observed. Comparison of detection techniques shows that a large amount of noncultivable or dead bacteria are present in the samples.

Optimization of anti-pseudomonal antibiotics for cystic fibrosis pulmonary exacerbations: V. Aminoglycosides

Intravenous (IV) anti-pseudomonal aminoglycosides (i.e., amikacin and tobramycin) have been shown to be tolerable and effective in the treatment of acute pulmonary exacerbations (APEs) in both pediatric and adult patients with cystic fibrosis. The aim of this review is to provide an evidence-based summary of pharmacokinetic/pharmacodynamic, tolerability, and efficacy studies utilizing IV amikacin, gentamicin, and tobramycin in the treatment of APE and to highlight areas where further investigation is needed. The Cystic Fibrosis Foundation Pulmonary Guidelines recommend that once-daily administration of aminoglycosides is preferred over three times per day in the treatment of an APE. The literature supports dosing ranges for amikacin and tobramycin of 30-35 and 7-15 mg/kg/day, respectively, given once daily, with subsequent doses determined by therapeutic drug concentration monitoring. The literature does not support the routine use of gentamicin in the treatment of APE due to a lack of studies showing efficacy and evidence indicating an increased risk of nephrotoxicity. Further studies are needed to determine the optimal dosing strategy of amikacin in the treatment of an APE, and to further identify risk factors and determinants that influence the development of P. aeruginosa resistance with once-daily administration of tobramycin.

Duration of intravenous antibiotic therapy in people with cystic fibrosis

BACKGROUND

Respiratory disease is the major cause of mortality and morbidity in cystic fibrosis (CF). Life expectancy of people with CF has increased dramatically in the last 40 years. One of the major reasons for this increase is the mounting use of antibiotics to treat chest exacerbations caused by bacterial infections. The optimal duration of intravenous antibiotic therapy is not clearly defined. Individuals usually receive intravenous antibiotics for 14 days, but treatment may range from 10 to 21 days. A shorter duration of antibiotic treatment risks inadequate clearance of infection which could lead to further lung damage. Prolonged courses of intravenous antibiotics are expensive and inconvenient and the incidence of allergic reactions to antibiotics also increases with prolonged courses. The use of aminoglycosides requires frequent monitoring to avoid some of their side effects. However, some organisms which infect people with CF are known to be multi-resistant to antibiotics, and may require a longer course of treatment.

OBJECTIVES

To assess the optimal duration of intravenous antibiotic therapy for treating chest exacerbations in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals, abstract books and conference proceedings.Most recent search of the Group's Cystic Fibrosis Trials Register: 15 November 2012.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different durations of intravenous antibiotic courses for acute respiratory exacerbations in people with CF, either with the same drugs at the same dosage, the same drugs at a different dosage or frequency or different antibiotics altogether, including studies with additional therapeutic agents.

DATA COLLECTION AND ANALYSIS

No eligible trials were identified.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

There are no clear guidelines on the optimum duration of intravenous antibiotic treatment. Duration of treatment is currently based on unit policies and response to treatment. Shorter duration of treatment should improve quality of life and compliance; result in a reduced incidence of drug reactions; and be less costly. However, this may not be sufficient to clear a chest infection and may result in an early recurrence of an exacerbation. This systematic review identifies the need for a multicentre, randomised controlled trial comparing different durations of intravenous antibiotic treatment as it has important clinical and financial implications.

Evaluation of serum concentrations achieved with an empiric once-daily tobramycin dosage regimen in children and adults with cystic fibrosis

OBJECTIVES

To assess the ability of an empiric once-daily dosing (ODD) tobramycin regimen to achieve desired serum concentrations in patients with cystic fibrosis (CF); to determine an optimal dosage regimen, using pharmacodynamic parameters; and to evaluate clinical response, adverse effects, and patient/parent satisfaction with ODD.

METHODS

This was a prospective single-center trial in patients with CF who are 5 years of age and older requiring intravenous antibiotics. Tobramycin, 10 mg/kg every 24 hours, was infused over 60 minutes, and two serum concentrations were analyzed using 1-compartment pharmacokinetic modeling. Simulations were performed to identify dosage regimens that maximized desired pharmacodynamic parameters. Other data included demographics, symptoms, spirometry, adverse events, and satisfaction with ODD.

RESULTS

A total of 14 children and 11 adults completed the study. Empiric doses resulted in mean peak tobramycin concentrations of 28.7 ± 5.5 mg/L and undetectable trough concentrations. Only 42% of patients achieved desired peak serum concentrations (20-30 mg/L) with the empiric regimen. A regimen of 12 mg/kg every 24 hours would achieve modified pharmacodynamic goals with an acceptable peak range of 20 to 35 mg/L. Forced expiratory volume in 1 second improved in 15 of 20 (75%) patients with ODD. Two patients experienced reversible vestibular adverse effects attributed to tobramycin. All patients were satisfied or very satisfied with ODD because of convenience and ease of use.

CONCLUSIONS

An empiric tobramycin regimen of 10 mg/kg every 24 hours did not achieve desired serum concentrations for most patients, although all patients demonstrated clinical improvement. Desired tobramycin concentrations with modified pharmacodynamic goals could be achieved by using an empiric dosage of 12 mg/kg every 24 hours. Prospective evaluation of this regimen with individualized patient monitoring is needed to ensure safety and efficacy and to monitor the effects on microbial resistance patterns.

National survey of extended-interval aminoglycoside dosing in pediatric cystic fibrosis pulmonary exacerbations

OBJECTIVES

The Cystic Fibrosis Foundation recently deemed the use of extended-interval dosing (EID) of aminoglycosides acceptable for the treatment of cystic fibrosis (CF) pulmonary exacerbations, but current practices across United States (US) pediatric CF accredited care centers and affiliate programs are unknown. The objectives of this research are to characterize the practice trends, dosing strategies, therapeutic drug monitoring practices, and adverse drug reaction monitoring of EID of aminoglycosides in the treatment of pulmonary exacerbations across US pediatric CF programs.

METHODS

A 38-question online survey was distributed on behalf of the author by the CF Foundation to all US pediatric CF accredited care centers and affiliate programs.

RESULTS

Of the 70 participating CF programs (42.2% survey response rate), 94.3% reported using EID of aminoglycosides (as once-daily or twice-daily dosing), whereas 84.3% reported using once-daily EID in their pediatric CF population. The frequency of EID use increased with patient age. Tobramycin dosed 10 mg/kg per day every 24 hours, infused over the course of 30 minutes, in combination with an antipseudomonal beta-lactam, was the most commonly cited regimen. Monitoring of aminoglycoside serum concentrations was reported by 98.5% of programs, with a tobramycin peak of 25 to 30 mg/L and trough of less than 1 mg/L targeted most frequently. Nephrotoxicity was commonly monitored through serum creatinine measurements, whereas ototoxicity was monitored by audiometry in approximately one-half of programs.

CONCLUSIONS

This study indicates that the use of EID of aminoglycosides across US pediatric CF accredited care centers and affiliate programs is common, particularly among adolescents, with tobramycin being the preferred agent.

Once-daily versus multiple-daily dosing with intravenous aminoglycosides for cystic fibrosis

BACKGROUND

People with cystic fibrosis, who are chronically colonised with the organism Pseudomonas aeruginosa, often require multiple courses of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations. The properties of aminoglycosides suggest that they could be given in higher doses less often.

OBJECTIVES

To assess the effectiveness and safety of once-daily versus multiple-daily dosing of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations in cystic fibrosis.

SEARCH METHODS

We searched the Cystic Fibrosis Specialist Register held at the Cochrane Cystic Fibrosis and Genetic Disorders Group's editorial base, comprising references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings.Date of the most recent search: 29 September 2011.

SELECTION CRITERIA

All randomised controlled trials, whether published or unpublished, in which once-daily dosing of aminoglycosides has been compared with multiple-daily dosing in terms of efficacy or toxicity or both, in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The two authors independently selected the studies to be included in the review and assessed methodological quality of each study. Data were independently extracted by each author. Authors of the included studies were contacted for further information. As yet unpublished data were obtained for one of the included studies.

MAIN RESULTS

Sixteen studies were identified for possible inclusion in the review. Four studies reporting results from a total of 328 participants were included in this review. All studies compared once-daily dosing with thrice-daily dosing. There was no significant difference between treatment groups in: forced expiratory volume at one second, mean difference 0.33 (95% confidence interval -2.81 to 3.48); forced vital capacity, mean difference 0.29 (95% confidence interval -6.58 to 7.16); % weight for height, mean difference -0.82 (95% confidence interval -3.77 to 2.13); body mass index, mean difference 0.00 (95% confidence interval -0.42 to 0.42); or in the incidence of ototoxicity, relative risk 0.56 (95% confidence interval 0.04 to 7.96). The percentage change in creatinine significantly favoured once-daily treatment in children, mean difference -8.20 (95% confidence interval -15.32 to -1.08), but showed no difference in adults, mean difference 3.25 (95% confidence interval -1.82 to 8.33).

AUTHORS' CONCLUSIONS

Once- and three-times daily aminoglycoside antibiotics appear to be equally effective in the treatment of pulmonary exacerbations of cystic fibrosis. There is evidence of less nephrotoxicity in children.

Duration of intravenous antibiotic therapy in people with cystic fibrosis

BACKGROUND

Respiratory disease is the major cause of mortality and morbidity in cystic fibrosis (CF). Life expectancy of people with CF has increased dramatically in the last 40 years. One of the major reasons for this increase is the mounting use of antibiotics to treat chest exacerbations caused by bacterial infections. The optimal duration of intravenous antibiotic therapy is not clearly defined. Individuals usually receive intravenous antibiotics for 14 days, but treatment may range from 10 to 21 days. A shorter duration of antibiotic treatment risks inadequate clearance of infection which could lead to further lung damage. Prolonged courses of intravenous antibiotics are expensive and inconvenient and the incidence of allergic reactions to antibiotics also increases with prolonged courses. The use of aminoglycosides requires frequent monitoring to avoid some of their side effects. However, some organisms which infect people with CF are known to be multi-resistant to antibiotics, and may require a longer course of treatment.

OBJECTIVES

To assess the optimal duration of intravenous antibiotic therapy for treating chest exacerbations in people with cystic fibrosis.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals, abstract books and conference proceedings.Most recent search of the Group's Cystic Fibrosis Trials Register: 3 December 2010.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different durations of intravenous antibiotic courses for acute respiratory exacerbations in people with CF, either with the same drugs at the same dosage, the same drugs at a different dosage or frequency or different antibiotics altogether, including studies with additional therapeutic agents.

DATA COLLECTION AND ANALYSIS

No eligible trials were identified.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

There are no clear guidelines on the optimum duration of intravenous antibiotic treatment. Duration of treatment is currently based on unit policies and response to treatment. Shorter duration of treatment should improve quality of life and compliance; result in a reduced incidence of drug reactions; and be less costly. However, this may not be sufficient to clear a chest infection and may result in an early recurrence of an exacerbation. This systematic review identifies the need for a multicentre, randomised controlled trial comparing different durations of intravenous antibiotic treatment as it has important clinical and financial implications.

Once-daily versus multiple-daily dosing with intravenous aminoglycosides for cystic fibrosis

BACKGROUND

People with cystic fibrosis, who are chronically colonised with the organism Pseudomonas aeruginosa, often require multiple courses of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations. The properties of aminoglycosides suggest that they could be given in higher doses less often.

OBJECTIVES

To assess the effectiveness and safety of once-daily versus multiple-daily dosing of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations in cystic fibrosis.

SEARCH STRATEGY

We searched the Cystic Fibrosis Specialist Register held at the Cochrane Cystic Fibrosis and Genetic Disorders Group's editorial base, comprising references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings.Date of the most recent search: 19 August 2008.

SELECTION CRITERIA

All randomised controlled trials, whether published or unpublished, in which once-daily dosing of aminoglycosides has been compared with multiple-daily dosing in terms of efficacy or toxicity or both, in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The two authors independently selected the studies to be included in the review and assessed methodological quality of each study. Data were independently extracted by each author. Authors of the included studies were contacted for further information. As yet unpublished data were obtained for one of the included studies.

MAIN RESULTS

Thirteen studies were identified for possible inclusion in the review. Four studies reporting results from a total of 328 participants were included in this review. All studies compared once-daily dosing with thrice-daily dosing. There was no significant difference between treatment groups in: forced expiratory volume at one second, mean difference (MD) 0.33 (95% confidence interval (CI) -2.81 to 3.48); forced vital capacity, MD 0.29 (95% CI -6.58 to 7.16); % weight for height, MD -0.82 (95% CI -3.77 to 2.13); body mass index, MD 0.00 (95% CI -0.42 to 0.42); or in the incidence of ototoxicity, relative risk 0.56 (95% CI 0.04 to 7.96). The percentage change in creatinine significantly favoured once-daily treatment in children, MD -8.20 (95% CI -15.32 to -1.08), but showed no difference in adults, MD 3.25 (95% CI -1.82 to 8.33).

AUTHORS' CONCLUSIONS

Once and three times daily aminoglycoside antibiotics appear to be equally effective in the treatment of pulmonary exacerbations of cystic fibrosis. There is evidence of less nephrotoxicity in children.

Cystic fibrosis pulmonary guidelines: treatment of pulmonary exacerbations

The natural history of cystic fibrosis lung disease is one of chronic progression with intermittent episodes of acute worsening of symptoms frequently called acute pulmonary exacerbations These exacerbations typically warrant medical intervention. It is important that appropriate therapies are recommended on the basis of available evidence of efficacy and safety. The Cystic Fibrosis Foundation therefore established a committee to define the key questions related to pulmonary exacerbations, review the clinical evidence using an evidence-based methodology, and provide recommendations to clinicians. It is hoped that these guidelines will be helpful to clinicians in the treatment of individuals with cystic fibrosis.

Duration of intravenous antibiotic therapy in people with cystic fibrosis

BACKGROUND

Respiratory disease is the major cause of mortality and morbidity in cystic fibrosis (CF). Life expectancy of people with CF has increased dramatically in the last 40 years. One of the major reasons for this increase is the mounting use of antibiotics to treat chest exacerbations caused by bacterial infections. The optimal duration of intravenous antibiotic therapy is not clearly defined. Individuals usually receive intravenous antibiotics for 14 days, but treatment may range from 10 to 21 days. A shorter duration of antibiotic treatment risks inadequate clearance of infection which could lead to further lung damage. Prolonged courses of intravenous antibiotics are expensive and inconvenient and the incidence of allergic reactions to antibiotics also increases with prolonged courses. The use of aminoglycosides requires frequent monitoring to avoid some of their side effects. However, some organisms which infect people with CF are known to be multi-resistant to antibiotics, and may require a longer course of treatment.

OBJECTIVES

To assess the optimal duration of intravenous antibiotic therapy for treating chest exacerbations in people with cystic fibrosis.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals, abstract books and conference proceedings. Most recent search of the Group's Cystic Fibrosis Trials Register: February 2008.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different durations of intravenous antibiotic courses for acute respiratory exacerbations in people with CF, either with the same drugs at the same dosage, the same drugs at a different dosage or frequency or different antibiotics altogether, including studies with additional therapeutic agents.

DATA COLLECTION AND ANALYSIS

No eligible trials were identified.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

There are no clear guidelines on the optimum duration of intravenous antibiotic treatment. Duration of treatment is currently based on unit policies and response to treatment. Shorter duration of treatment should improve quality of life and compliance; result in a reduced incidence of drug reactions; and be less costly. However, this may not be sufficient to clear a chest infection and may result in an early recurrence of an exacerbation. This systematic review identifies the need for a multicentre, randomised controlled trial comparing different durations of intravenous antibiotic treatment as it has important clinical and financial implications.

Once daily dosing of aminoglycosides in pediatric cystic fibrosis patients: a review of the literature

Patients with cystic fibrosis receive many courses of antibiotic therapy throughout their lifetime. Dosing aminoglycosides once daily has become common practice in many of these individuals. Due to ease of home administration, decreased nursing time, and improved quality of life, this regimen is being increasingly explored in the cystic fibrosis population. Because patients with cystic fibrosis have increased aminoglycoside clearance, once daily dosing may result in a prolonged time during the dosing interval when concentrations of the drug may be undetectable. This makes the use of once daily dosing of these antibiotics in patients with cystic fibrosis controversial. Although aminoglycosides exhibit a post antibiotic effect, the duration of this effect is unknown in humans; therefore, the development of resistance to the aminoglycoside is a concern. This manuscript will review the organisms most commonly associated with a pulmonary exacerbation of cystic fibrosis, the properties of the aminoglycoside that make once daily dosing feasible, the concept of once daily dosing in those with cystic fibrosis and the current literature regarding efficacy, monitoring, toxicity and concerns of resistance with once daily dosing in this population.

Therapeutic drug monitoring of once daily tobramycin in cystic fibrosis—caution with trough concentrations

BACKGROUND

: Once daily intravenous aminoglycoside dosing (ODD) is widely used to treat acute Pseudomonas aeruginosa exacerbations in patients with cystic fibrosis. Controversy exists as to what is the most appropriate method of therapeutic drug monitoring (TDM) of such therapy with recommendations including trough plasma concentrations of <1 mg/L or <2 mg/L, area under curve (AUC) and various nomograms. This study aimed to compare the exposures to ODD of tobramycin in adults and children with cystic fibrosis using the AUC and trough TDM approaches.

METHODS

: Using a mono-exponential software program to calculate AUC from 2 plasma concentrations, AUCs were determined in 22 adults with pre-dose tobramycin concentrations <1 mg/L. The exposure of 5 children with reduced tobramycin clearances was simulated at the usual recommended dose of 10 mg/kg/daily but retaining a trough <1 mg/L.

RESULTS

: A tobramycin dose of 10 mg/kg of tobramycin in these patients with normal serum creatinine and a trough concentration <1 mg/L resulted in exposures in excess of those associated with conventional 8-hourly dosing.

CONCLUSIONS

: The TDM approach of a trough <1 mg/L, as used with conventional 8-hourly tobramycin dosing, is not relevant to ODD.

Pharmacokinetic profile of once daily intravenous tobramycin in children with cystic fibrosis

AIM

Once-daily tobramycin in patients with cystic fibrosis (CF) is a more convenient dosing regimen than thrice daily dosing. There are limited data on the pharmacokinetic (PK) profile for once-daily tobramycin in patients with CF. The aim of this study was to define the PK parameters for once-daily tobramycin in children with CF and develop an algorithm for therapeutic drug monitoring dosing.

METHODS

CF patients admitted to hospital were commenced on once-daily intravenous tobramycin (12 mg/kg/day) and ticarcillin/clavulinic acid. Serum tobramycin levels were taken at 30 min, 2-4 h and 12 h post dose. Data points for the PK model included: age, sex, weight, tobramycin dose, time of tobramycin doses and levels, tobramycin levels. WinNonMix was used to obtain the PK parameters.

RESULTS

Forty-four children with 86 admissions who were aged 9 months-20 years were included. A one-compartment intravenous infusion model with first order elimination kinetics produced the best model. Population parameters were: volume of distribution (V(d)) = 0.267 L/kg (95% confidence interval (CL) 0.260-0.272), clearance (CL) 0.103 L/kg/h (95% CI 0.098-0.107) and half-life (t(1/2)) 1.82 (95% CI 1.77-1.88) h. Once the population model was established post hoc analysis was used to calculate individual subject predictions. Plots of individual prediction curves agreed well with observed values.

CONCLUSION

This study has established an algorithm for routine monitoring of once-daily tobramycin in children with CF. Satisfactory serum levels of tobramycin were obtained with a dose of 12 mg/kg/day and a regimen algorithm that uses only one measurement to monitor the plasma concentration is suggested.

Once-daily versus multiple-daily dosing with intravenous aminoglycosides for cystic fibrosis

BACKGROUND

People with cystic fibrosis, who are chronically colonised with the organism Pseudomonas aeruginosa, often require multiple courses of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations. The properties of aminoglycosides suggest that they could be given in higher doses less often.

OBJECTIVES

To assess the effectiveness and safety of once-daily versus multiple-daily dosing of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations in cystic fibrosis.

SEARCH STRATEGY

We searched the Cystic Fibrosis Specialist Register held at the Cochrane Cystic Fibrosis and Genetic Disorders Group's editorial base, comprising references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings.Date of the most recent search: August 2005.

SELECTION CRITERIA

All randomised controlled trials, whether published or unpublished, in which once-daily dosing of aminoglycosides has been compared with multiple-daily dosing in terms of efficacy and/or toxicity, in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The two authors independently selected the studies to be included in the review and assessed methodological quality of each study. Data were independently extracted by each author. Authors of the included studies were contacted for further information. As yet unpublished data were obtained for one of the included studies.

MAIN RESULTS

Eleven studies were identified for possible inclusion in the review. Four studies reporting results from a total of 328 participants were included in this review. All studies compared once-daily dosing with thrice-daily dosing. There was no significant difference between treatment groups in: forced expiratory volume at one second, weighted mean difference (WMD) 0.33 (95% confidence interval (CI) -2.81 to 3.48); forced vital capacity, WMD 0.29 (95% CI -6.58 to 7.16); % weight for height, WMD -0.82 (95% CI -3.77 to 2.13); body mass index, WMD 0.00 (95% CI -0.42 to 0.42); or in the incidence of ototoxicity, relative risk 0.56 (95% CI 0.04 to 7.96). The percentage change in creatinine significantly favoured once-daily treatment in children, WMD -8.20 (95% CI -15.32 to -1.08), but showed no difference in adults, WMD 3.25 (95% CI -1.82 to 8.33).

AUTHORS' CONCLUSIONS

Once and three times daily aminoglycoside antibiotics appear to be equally effective in the treatment of pulmonary exacerbations of cystic fibrosis. There is evidence of less nephrotoxicity in children.

Evaluation of Once Daily Tobramycin Versus the Traditional Three Time Daily for the Treatment of Acute Pulmonary Exacerbations in Adult Cystic Fibrosis Patients

Once daily tobramycin is convenient to use and achieves higher tissue levels that should kill Pseudomonas aeruginosa more rapidly. Small trials of OD compared with TDS aminoglycosides in CF patients have shown no dif-ference in efficacy or toxicity. No one has looked in detail at the impact on sputum microbiology. In a prospective, randomized study at Papworth Hospital, UK, we compared OD with TDS tobramycin, each plus a second anti-pseudomonal, for the treatment of acute infective exacer-bation in 15 adult cystic fibrosis patients colonized with Pseudomonas aeruginosa. Using the patients as their own control, the same individuals received the alternate treat-ment regime for the next exacerbation. We aimed to com-pare the clinical and bacteriological efficacy, toxicity>, and the effects on susceptibility of the organism among patients in both treatment groups. Isolates were identified, and the Minimum Inhibitory Concentration (MIC) of the antibi-otic in each patient was performed. Patients were assessed for clinical improvement, toxicity and the total viable count in their sputum on days 0\ 7 and 14. In both treatment groups there was a significant clinical improvement, and toxicity did not occur in either group. There was no differ-ence in clinical outcome, adverse events, or time to the next exacerbation. No difference was seen in the selection of antibiotic resistance. OD tobramycin appeared more ef-fective in reducing the number of bacteria in the group overall at day 7 and in two individuals, at day 14.

The efficacy and safety of meropenem and tobramycin vs ceftazidime and tobramycin in the treatment of acute pulmonary exacerbations in patients with cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is characterized by chronic pulmonary infection with acute pulmonary exacerbations (APEs) requiring IV antibiotic treatment. We report on a blinded comparative trial of IV meropenem (40 mg/kg to 2 g q8h) or ceftazidime (5 mg/kg to 2 g q8h), each of which was administered with IV tobramycin (at a serum peak of > or = 8 microg/mL and a trough of < 2 microg/mL), as treatment for CF patients with APEs.

METHODS

Patients who were > or = 5 years of age who were infected with ceftazidime-susceptible Pseudomonas aeruginosa were stratified by lung function and randomized to treatment with meropenem/tobramycin or ceftazidime/tobramycin. Patients infected with Burkholderia cepacia complex or ceftazidime-resistant P aeruginosa were assigned to receive open-label meropenem/tobramycin. Clinical response was assessed by spirometry to determine the change in percent predicted FEV1 and by a clinical acute change score (ACS).

RESULTS

One hundred two patients were randomized to meropenem/tobramycin (n = 50) or ceftazidime/tobramycin (n = 52). Nineteen patients received open-label meropenem/tobramycin. FEV1 was improved at the end of treatment (EOT) with meropenem/tobramycin (mean [+/- SD] increase, 38.8 +/- 52.3%) and with ceftazidime/tobramycin (mean increase, 29.4 +/- 35.1%; p < 0.0001 vs baseline values). The proportion of patients with > or = 15% relative increase from baseline FEV1 (satisfactory response) at day 7 was 62% for the meropenem/tobramycin group and 44% for the ceftazidime/tobramycin group (p = 0.04). The median time to FEV1 response was 4 days for meropenem/tobramycin therapy vs 6 days for ceftazidime/tobramycin therapy. Similarly, FEV1 improved in the open-label group (mean increase, 12.5 +/- 25.7%; p = 0.05). ACS improved in all three groups at EOT (p < 0.0001 vs baseline values).

CONCLUSIONS

Therapy with both meropenem/tobramycin and ceftazidime/tobramycin improved pulmonary and clinical status and reduced sputum bacterial burden in CF patients with APEs. A larger proportion of patients receiving meropenem/tobramycin therapy demonstrated a satisfactory FEV1 response at day 7. Resistant P aeruginosa emerged infrequently during treatment with both regimens.

Single versus combination intravenous antibiotic therapy for people with cystic fibrosis

BACKGROUND

Choice of antibiotic, and the use of single or combined therapy are controversial areas in the treatment of respiratory infection in cystic fibrosis (CF). Advantages of combination therapy include wider range of modes of action, possible synergy and reduction of resistant organisms; advantages of monotherapy include lower cost, ease of administration and reduction of drug-related toxicity. Current evidence does not provide a clear answer and the use of intravenous antibiotic therapy in CF requires further evaluation.

OBJECTIVES

To assess the effectiveness of single compared to combination intravenous antibiotic therapy for treating people with CF.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Most recent search of the Group's register: January 2004.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing a single intravenous antibiotic with a combination of that antibiotic plus a second antibiotic in people with CF.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

Twenty-seven trials were identified, of which eight trials (with 356 participants) comparing a single agent to a combination of the same antibiotic and one other, were included. There was a wide variation in the individual antibiotics used in each trial. In total, the trials included seven comparisons of a beta-lactam antibiotic (penicillin-related or third generation cephalosporin) with a beta-lactam-aminoglycoside combination and three comparisons of an aminoglycoside with a beta-lactam-aminoglycoside combination. These two groups of trials were analysed as separate subgroups. There was considerable heterogeneity amongst these trials, leading to difficulties in performing the review and interpreting the results. The meta-analysis did not demonstrate any significant differences between monotherapy and combination therapy, in terms of lung function; symptom scores; adverse effects; and bacteriological outcome measures. These results should be interpreted cautiously. Six of the included trials were published between 1977 and 1988; these were single centre trials with flaws in the randomisation process and small sample size. Overall, the methodological quality was poor.

AUTHORS' CONCLUSIONS

The results of this review are inconclusive. The review raises important methodological issues. There is a need for an RCT which needs to be well designed in terms of adequate randomisation allocation, blinding, power and long-term follow up. Results need to be standardised to a consistent method of reporting, in order to validate the pooling of results from multiple trials.

Pseudomonal infection in cystic fibrosis: the battle continues

Pseudomonas aeruginosa lung infection is the major cause of morbidity and mortality in patients with cystic fibrosis. Infection usually begins in childhood and is responsible for respiratory failure and death in most patients with cystic fibrosis. The organism triggers an exuberant chronic inflammatory reaction which damages the airways and leads to progressive loss of lung function. Over the last decade significant advances have been made in the understanding of the pathophysiology of cystic fibrosis airways disease. These should assist the development of new and better therapies to treat this pathogen. This review provides an overview of pseudomonal infection in cystic fibrosis, including mechanisms by which the bacteria may colonize the cystic fibrosis airway, persistence of pseudomonal infection and the biofilm mode of growth. Available treatments and possible novel approaches to therapy will be discussed.

Determination of tobramycin in saliva is not suitable for therapeutic drug monitoring of patients with cystic fibrosis

BACKGROUND

Tobramycin, used in the treatment of infections caused by Gram-negative bacteria, requires therapeutic drug monitoring (TDM) due to its narrow therapeutic index. The collection of blood for these assays may cause pain and trauma to the child and/or be difficult because of limited access to appropriate blood vessels. We undertook an evaluation of the role of saliva concentrations in the TDM of once-daily tobramycin therapy in patients with cystic fibrosis.

METHODS

Fourteen patients (mean age 15 years) with cystic fibrosis were enrolled at Women's and Children's Hospital, Adelaide (WCH). All patients received once-daily dose of intravenous tobramycin for 2-3 weeks and had plasma levels measured once a week. At the same time of blood sampling at 1 and 6 h after initiation of tobramycin infusion, the patients also provided saliva samples. For collection of saliva, the Salivette (Sarstedt Laboratories) system was used which was developed specifically for saliva sampling. Concentrations in blood and saliva were measured by the Beckman Synchron CX system, which is utilized for routine assays of plasma tobramycin.

RESULTS AND CONCLUSION

Tobramycin could not be detected in saliva within the first 6 h after a once-daily dosing. Therefore, plasma cannot be substituted with saliva for the TDM of tobramycin using the clinical routines at WCH.

Extended-interval aminoglycoside administration for children: a meta-analysis

BACKGROUND

There has been a long-standing debate regarding whether aminoglycosides should be administered on a multiple daily dosing (MDD) or once-daily dosing (ODD) schedule. Several unique characteristics of the aminoglycosides make ODD an attractive and possibly superior alternative to MDD. These include concentration-dependent bactericidal activity; postantibiotic effect, which allows continued efficacy even when serum concentrations fall below expected minimum inhibitory concentrations; decreased risk of adaptive resistance; and diminished accumulation in renal tubules and inner ear.

OBJECTIVE

To assess the relative efficacy and toxicity of ODD, compared with MDD, of aminoglycosides among pediatric patients.

STUDY SELECTION

Randomized, controlled trials among children, evaluating the relative efficacy and toxicity of ODD versus MDD of aminoglycosides, with similar total daily doses in the compared arms, were selected.

DATA SOURCES

PubMed (1966-2003) and Embase (1982-2003) databases, the Cochrane Controlled Trials Registry (2003), and references of eligible studies and pediatric review articles were searched.

DATA EXTRACTION

Study population characteristics and outcome data were extracted independently in duplicate, and consensus was reached on all items. The following outcome data were considered: (1) clinical or microbiologic failure, as defined in each study; (2) clinical failure; (3) microbiologic failure; (4) primary nephrotoxicity, ie, any rise in serum creatinine or decrease in creatinine clearance with thresholds as defined in each study; (5) secondary nephrotoxicity, ie, urinary excretion of proteins or phospholipids; and (6) ototoxicity based on pure tone audiometry, brainstem auditory evoked responses, or otoacoustic emissions for neonates and infants, vestibular testing, clinical impression, or any other method. All of the efficacy and toxicity outcomes were evaluated at the end of therapy.

RESULTS

Identification of eligible studies and study characteristics: 24 eligible studies published between 1991 and 2003 were identified. Aminoglycosides were used in different clinical settings (neonatal intensive care unit: 6 studies; cystic fibrosis: 3 studies; cancer: 5 studies; urinary tract infections: 4 studies; diverse infectious indications: 5 studies; pediatric intensive care unit: 1 study). Aminoglycosides used included amikacin (9 studies), gentamicin (11 studies), tobramycin (2 studies), netilmicin (2 studies), and tobramycin or netilmicin (1 study).

EFFICACY

There was no significant difference between ODD and MDD in the clinical failure rate, microbiologic failure rate, and combined clinical or microbiologic failure rates, but trends favored ODD consistently. There was no between-study heterogeneity for any outcome. Efficacy analysis of all trials indicating either clinical or microbiologic failures demonstrated pooled failure rates of 4.6% (23 of 501 cases) in the ODD arms and 6.9% (34 of 494 cases) in the MDD arms. The fixed-effects risk ratio was 0.71 (95% confidence interval [CI]: 0.45-1.11). A statistically significant benefit was seen with ODD over MDD in trials using amikacin, whereas no statistical significance was seen in trials using other antibiotics. The pooled clinical failure rates were 6.7% (22 of 330 cases) in the ODD arms and 10.4% (34 of 327 cases) in the MDD arms. The fixed-effects risk ratio was 0.67 (95% CI: 0.42-1.07). The pooled microbiologic failure rates were 1.8% (5 of 283 cases) with ODD and 4.0% (11 of 275 cases) with MDD. The fixed-effects risk ratio was 0.51 (95% CI: 0.22-1.18). NEPHROTOXICITY: There was no significant difference between ODD and MDD in the primary nephrotoxicity outcomes. Secondary nephrotoxicity outcomes were significantly better with ODD. The pooled primary nephrotoxicity rates were 1.6% (15 of 955 cases) in the ODD arms and 1.6% (15 of 923 cases) in the MDD arms. The fixed-effects risk ratio was 0.97 (95% CI: 0.55-1.69). The pooled secondary nephrotoxicity rates were 4.4% (3 of 69 cases) in the ODD arms and 15.9% (11 of 69 cases) in the MDD arms, suggesting a statistically significant superiority of ODD. The fixed-effects risk ratio was 0.33 (95% CI: 0.12-0.89). Results were consistent across types of clinical settings and aminoglycosides. OTOTOXICITY: There was no significant difference between ODD and MDD in the primary ototoxicity outcomes. The pooled ototoxicity rates for studies that provided auditory testing results were 2.3% (10 of 436 cases) in the ODD arms and 2.0% (8 of 406 cases) in the MDD arms. The fixed-effects risk ratio was 1.06 (95% CI: 0.51-2.19). In studies that provided clinical vestibular function testing results, no toxicity was documented among 209 patients given ODD and 206 patients given MDD. Studies noting only the clinical impression of hearing impairment also failed to identify any toxicity (ODD: 114 cases; MDD: 114 cases). SUBGROUP AND BIAS ANALYSES: We detected no statistically significant differences between ODD and MDD in any of the examined subgroups (neonatal intensive care unit, cystic fibrosis, cancer, or urinary tract infection), with respect to combined clinical or microbiologic failure outcomes, primary nephrotoxicity outcomes, or ototoxicity (based on auditory testing), when sufficient data were available. Moreover, there was no significant relationship between the effect size (risk ratio) and the trial size for any of the outcomes. DATA INTERPRETATION: Clinical failures were uncommon in the pediatric trials, regardless of the regimen used. If anything, fewer clinical failures tended to occur with ODD. Moreover, we observed a trend toward decreased bacteriologic failures. One meta-analysis of adult data suggested that ODD might reduce nephrotoxicity, whereas other meta-analyses showed nonsignificant trends or no difference in nephrotoxicity outcomes. In our meta-analysis, we were not able to show any reduction in the risk of primary nephrotoxicity outcomes with ODD. However, the event rate was much lower among children, compared with adults, and the secondary nephrotoxicity outcomes favored ODD. Finally, although the 2 regimens seemed equivalent with respect to ototoxicity, reporting on ototoxicity outcomes was incomplete. Reassuringly, even in the trials that performed auditory testing, the rates of ototoxicity in the MDD arms were very low. These results were consistent with meta-analyses of adult data, which showed no difference in ototoxicity rates between ODD and MDD.

CONCLUSIONS

Although single trials have been small, the available randomized evidence supports the general adoption of ODD of aminoglycosides in pediatric clinical practice. This approach minimizes cost, simplifies administration, and provides similar or even potentially improved efficacy and safety, compared with MDD of these drugs.

Pathophysiology and management of pulmonary infections in cystic fibrosis

This comprehensive State of the Art review summarizes the current published knowledge base regarding the pathophysiology and microbiology of pulmonary disease in cystic fibrosis (CF). The molecular basis of CF lung disease including the impact of defective cystic fibrosis transmembrane regulator (CFTR) protein function on airway physiology, mucociliary clearance, and establishment of Pseudomonas aeruginosa infection is described. An extensive review of the microbiology of CF lung disease with particular reference to infection with P. aeruginosa is provided. Other pathogens commonly associated with CF lung disease including Staphylococcal aureus, Burkholderia cepacia, Stenotrophomonas maltophilia, Achromobacter xylosoxidans and atypical mycobacteria are also described. Clinical presentation and assessment of CF lung disease including diagnostic microbiology and other measures of pulmonary health are reviewed. Current recommendations for management of CF lung disease are provided. An extensive review of antipseudomonal therapies in the settings of treatment for early P. aeruginosa infection, maintenance for patients with chronic P. aeruginosa infection, and treatment of exacerbation in pulmonary symptoms, as well as antibiotic therapies for other CF respiratory pathogens, are included. In addition, the article discusses infection control policies, therapies to optimize airway clearance and reduce inflammation, and potential future therapies.

Pharmacodynamics and dosing of aminoglycosides

Aminoglycosides are concentration-dependent killing agents whose pharmacodynamic predictors of efficacy are the area-under-the-curve to minimum inhibitory concentration ratio and the peak to minimum inhibitory concentration ratio. Prospective studies have shown that these agents can be given once-daily or less frequently in most clinical settings, with equal efficacy and possible reduced toxicity. Dosages for different clinical settings have been studied and methods are available to monitor once-daily dosing.

The pulmonary physician in critical care. Illustrative case 1: cystic fibrosis

The case history of a patient with CF admitted to an ICU is presented and the appropriateness of intensive care management for patients with CF is discussed. Issues relevant to the ICU care of patients with CF are highlighted.

Once daily versus multiple daily dosing with intravenous aminoglycosides for cystic fibrosis

BACKGROUND

Patients with cystic fibrosis, who are chronically colonised with the organism Pseudomonas aeruginosa, often require repeated courses of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations. The properties of aminoglycosides suggest that they could be given in higher concentrations less often.

OBJECTIVES

To assess the effectiveness and safety of once-daily versus multiple-daily dosing of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations in cystic fibrosis.

SEARCH STRATEGY

We searched the Cystic Fibrosis specialist trials register held at the Cochrane Cystic Fibrosis and Genetic Disorders Group's editorial base, which comprises references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings. Date of the most recent search: February 2000.

SELECTION CRITERIA

All randomised controlled trials, whether published or unpublished, in which once-daily dosing of aminoglycosides has been compared with multiple-daily dosing in terms of efficacy and/or toxicity, in patients with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Both reviewers independently extracted data and assessed trial quality. Authors of one study were contacted to obtain missing information.

MAIN RESULTS

Two trials reporting results from a total of 70 patients were included in this review. Both trials compared once-daily dosing with thrice-daily dosing reporting data on Forced Expiratory Volume at one second (FEV1), Forced Vital Capacity (FVC), nutritional status and side effects. There was no significant difference in efficacy or in the incidence of ototoxicity and nephrotoxicity between treatment groups.

REVIEWER'S CONCLUSIONS

Despite a lack of difference between the two groups we feel that these results should be viewed with caution as the numbers of patients involved was small and lacks the power to detect a difference between the groups. This systematic review has highlighted the need for a well designed, adequately-powered, multicentre, randomised controlled trial assessing the efficacy of once-daily versus multiple-daily dosing of intravenous aminoglycosides for pulmonary exacerbations in cystic fibrosis.