Acute renal failure associated with use of inhaled tobramycin for treatment of chronic airway colonization with Pseudomonas aeruginosa

Therapeutic drug monitoring of inhaled tobramycin in a patient with chronic kidney disease

This case report investigates elevated serum concentrations of inhaled tobramycin in a patient with chronic kidney disease. The patient, a man in his early 80s with complex comorbidities, underwent tobramycin inhalation therapy for chronic respiratory infections caused by Pseudomonas aeruginosa Despite the strategic localised treatment approach, unexpectedly high plasma tobramycin concentrations were observed. After a dosage adjustment guided by a pharmacokinetic-pharmacodynamic model, a final inhalation dose of 300 mg of tobramycin was determined at a 24-hour interval. This case report underscores the need for rigorous monitoring of plasma tobramycin levels in patients with renal impairment undergoing inhaled tobramycin therapy, advocating for enhanced pharmacokinetic models to improve the safety and efficacy of the treatment.

Incidence and associated risk factors for systemic drug levels with inhaled aminoglycoside therapy

OBJECTIVES

To characterize the incidence of and risk factors for a detectable drug level (DDL) in patients that received inhaled aminoglycoside therapy.

METHODS

This retrospective, single-centre study included adult patients who received at least one dose of an inhaled aminoglycoside with a drug level during inpatient hospitalization. Patients were excluded if they received an aminoglycoside intravenously within 7 days or if the drug level was not drawn within 4 h of the next dose. A repeated measures logistic regression model evaluated the association between potential risk factors and a DDL.

RESULTS

Among 286 drug levels, 88 (30.8%) drug levels were detectable. In multivariable analysis, cystic fibrosis (CF) (OR: 3.03; 95% CI: 1.10-8.35), chronic kidney disease (CKD) (OR: 4.25; 95% CI: 1.84-9.83), lung transplant recipient (OR: 3.08; 95% CI: 1.09-8.73), mechanical ventilation (OR: 2.99; 95% CI: 1.25-7.15) and tobramycin (OR: 5.26; 95% CI: 2.35-11.78) were associated with higher odds of a DDL. Among those with a DDL, inhaled aminoglycoside type and drug level concentration were not associated with acute kidney injury (P = 0.161).

CONCLUSIONS

Among 286 drug levels identified among inpatients receiving inhaled aminoglycoside therapy, 88 (30.8%) unique drug levels were detectable. Based on the results of this study, periodic trough concentrations should be considered for patients receiving inhaled aminoglycoside therapy with CF, CKD, lung transplantation, mechanical ventilation or tobramycin.

Unknown Renal Impairment: A Rare Case of Inhaled Tobramycin Induced Acute Kidney Injury in a Cystic Fibrosis Patient

Acute kidney injury is a reversible medical condition commonly caused by nephrotoxic agents. The infrequency that a nebulized medication elicits a renal insult presents a rare diagnostic challenge. Within this case, we report a 57-year-old cystic fibrosis patient with chronic kidney disease (CKD) Stage G3b (baseline 1.5–1.6 mg/dL) who developed an acute kidney injury (AKI) with a serum creatinine elevation to 4.08 mg/dL and associated worsening vestibular dysfunction related to twice-daily nebulized tobramycin inhalation solution (TIS). The patient was found to have a tobramycin serum level of 4.2 μg/mL 2.5 h after TIS dosing, with elevation remaining present at 1.1 μg/mL 24 h after discontinuation of therapy. Laboratory values at one month continued to show elevated creatinine levels at 2.1 mg/dL, suggesting progression of his baseline CKD. This case supports the benefit of obtaining tobramycin serum levels and vestibular/audiology function testing when evaluating patients on chronic nebulized TIS who present with acute or chronic renal dysfunction. From these serum levels, adjustments to daily dosing, regular monitoring of tobramycin serum levels, or discontinuation of treatment should be made to prevent permanent renal damage in patients with CKD. Calculated Naranjo ADR Probability Scale: 9; Definite.

Vestibulotoxicity in a patient without renal failure after inhaled tobramycin

Aminoglycoside antibiotics have a long history of use in the control of gram-negative bacterial infections, but their systemic use has been complicated by known ototoxicity and nephrotoxicity. Because of the utility of these medications in patients with frequent pulmonary infections, there has been a move towards the use of inhaled agents, in particular tobramycin, due to a lower rate of systemic complications. Inhaled tobramycin is generally consider to be safe from otologic complications, with only two previous reports of ototoxicity, both in patients who had underlying chronic renal disease. Here we present the first case of a patient developing isolated vestibular toxicity, without associated hearing loss or evidence of renal insufficiency, in a patient receiving inhaled tobramycin. This is an extremely rare complication of an inhaled aminoglycoside and underscores the importance of careful monitoring despite perceived safety.

Detectable Concentrations of Inhaled Tobramycin in Critically Ill Children Without Cystic Fibrosis: Should Routine Monitoring Be Recommended?

OBJECTIVES

To determine the percentage of detectable tobramycin troughs and acute kidney injury in critically ill children without cystic fibrosis on inhaled therapy.

DESIGN

Historic cohort.

SETTING

Academic hospital.

PATIENTS

Forty children less than 18 years receiving inhaled tobramycin across 6.5 years.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary objective was to determine the percentage of detectable tobramycin troughs greater than or equal to 0.5 µg/mL. Secondary objectives included a comparison of acute kidney injury in children with and without detectable troughs. Twenty-two (55%) had trough concentrations obtained. Ten of these (45.5%) had detectable concentrations, with a median of 0.85 µg/mL (interquartile range, 0.5-2.0). There was no statistical significance between the detectable and nondetectable groups in age, gender, and method of administration. However, patients in the detectable group tended to be younger than nondetectable group and more likely to have a tracheotomy. There was a clinically significant decrease in estimated glomerular filtration rate in the detectable trough group.

CONCLUSIONS

Detectable troughs were noted in almost half of patients with concentrations obtained. A clinically significant decrease in estimated glomerular filtration rate was noted in patients with detectable concentrations. Continued work should be directed to better understand outcomes and monitoring in children requiring inhaled tobramycin.

Off-label use of inhaled tobramycin in Ontario, Canada

Inhaled tobramycin solution is indicated for use in the management of Pseudomonas aeruginosa in patients with cystic fibrosis (CF). Concerns have been raised regarding increasing off-label use of inhaled tobramycin, particularly for the management of COPD. We conducted an 8-year repeated cross-sectional study examining the indication for prescription claims for inhaled tobramycin in Ontario paid for by the Public Drug Benefit Program, which covers all Ontario residents with financial needs or aged 65 and older. Inhaled tobramycin prescription claims increased approximately 3 times greater from 86 prescriptions in the second quarter of 2007 to 261 prescriptions in the first quarter of 2015. Approximately half of all prescriptions (range: 46-65%) per quarter were dispensed to patients with CF. A large proportion of prescriptions (range: 31-36%) were dispensed to individuals who did not have a diagnosis of CF but had a diagnosis of COPD. In 2014, there were 324 unique users of inhaled tobramycin solution in the Ontario Public Drug Program (OPDP). Only half of users (54%; n=163) had a diagnosis of CF. Our study found increasing prescriptions of inhaled tobramycin from 2007 to 2015 in the OPDP with approximately half of these claims being for off-label use, mostly among patients with COPD.

Evidence of inhaled tobramycin in non-cystic fibrosis bronchiectasis

There is currently less experience with inhaled tobramycin in non-cystic fibrosis bronchiectasis than in cystic fibrosis (CF). Intravenous formulation and solution for inhalation (TSI) have been studied in non-CF bronchiectasis patients with chronic P. aeruginosa bronchial infection. An improvement in clinical parameters and a reduction in bacterial density have been shown with both inhaled solutions in these patients. However, further trials are needed to determine the most effective dose and administration protocol in these patients. Based on the current evidence, recommendations cannot be made regarding the use of TSI to treat exacerbations. Although no systemic toxicity has been reported in studies specifically investigating this treatment, patients with known kidney disease or ear disorders should be treated with caution. Adverse respiratory effects are reported to be more common in non-CF patients than in CF patients, who tend to be non-smokers and younger. Research is being conducted into the possibility of combining tobramycin with other antibiotics to increase its antibacterial activity. In this review we will present and discuss the published evidence regarding the use of inhaled tobramycin in non-CF bronchiectasis.

Aminoglycoside-induced nephrotoxicity--a focus on monitoring: a review of literature

The use of aminoglycoside (AG) antibiotics has declined over the past 15 years primarily due to comparable potency of other antimicrobials and the nephrotoxicity potential of AG drugs. However, resurgence in the use of AG antimicrobials is occurring due to multidrug-resistant gram-negative nosocomial infections. Multidrug-resistant Pseudomonas and Acinetobacter isolates as well as extended-spectrum beta-lactamase-producing Enterobacteriaceae continue to force clinicians to consider AG therapy for nosocomial infections in hospitalized patients and enterococcal endocarditis. Additionally, AGs are still indicated in the treatment of pulmonary exacerbations of cystic fibrosis. Along with the use of AG antibiotics is the associated renal insufficiency complication. This review discusses the mechanism for AG-induced nephrotoxicity. Patient- and drug-related risk factors are discussed to help identify patients at increased risk. The issue of serum-level monitoring is discussed relative to the development of nephrotoxicity.

Inhaled antibiotics for lower airway infections

Inhaled antibiotics have been used to treat chronic airway infections since the 1940s. The earliest experience with inhaled antibiotics involved aerosolizing antibiotics designed for parenteral administration. These formulations caused significant bronchial irritation due to added preservatives and nonphysiologic chemical composition. A major therapeutic advance took place in 1997, when tobramycin designed for inhalation was approved by the U.S. Food and Drug Administration (FDA) for use in patients with cystic fibrosis (CF) with chronic Pseudomonas aeruginosa infection. Attracted by the clinical benefits observed in CF and the availability of dry powder antibiotic formulations, there has been a growing interest in the use of inhaled antibiotics in other lower respiratory tract infections, such as non-CF bronchiectasis, ventilator-associated pneumonia, chronic obstructive pulmonary disease, mycobacterial disease, and in the post-lung transplant setting over the past decade. Antibiotics currently marketed for inhalation include nebulized and dry powder forms of tobramycin and colistin and nebulized aztreonam. Although both the U.S. Food and Drug Administration and European Medicines Agency have approved their use in CF, they have not been approved in other disease areas due to lack of supportive clinical trial evidence. Injectable formulations of gentamicin, tobramycin, amikacin, ceftazidime, and amphotericin are currently nebulized "off-label" to manage non-CF bronchiectasis, drug-resistant nontuberculous mycobacterial infections, ventilator-associated pneumonia, and post-transplant airway infections. Future inhaled antibiotic trials must focus on disease areas outside of CF with sample sizes large enough to evaluate clinically important endpoints such as exacerbations. Extrapolating from CF, the impact of eradicating organisms such as P. aeruginosa in non-CF bronchiectasis should also be evaluated.

Reading between the (guide)lines--the KDIGO practice guideline on acute kidney injury in the individual patient

The KDIGO guidelines for acute kidney injury (AKI) are designed to assist health-care providers around the world in managing patients with AKI. Clinical guidelines are intended to help the clinician make an informed decision based on review of the currently available evidence. Due to the generic nature of guidelines, it is sometimes difficult to translate a guideline for a particular individual patient who may have specific clinical circumstances. To illustrate this point, we have discussed the interpretation of the KDIGO guideline in patients who have subtleties in their clinical presentation, which may make treatment decisions less than straightforward.

Diagnosis, evaluation, and management of acute kidney injury: a KDIGO summary (Part 1)

Acute kidney injury (AKI) is a common and serious problem affecting millions and causing death and disability for many. In 2012, Kidney Disease: Improving Global Outcomes completed the first ever, international, multidisciplinary, clinical practice guideline for AKI. The guideline is based on evidence review and appraisal, and covers AKI definition, risk assessment, evaluation, prevention, and treatment. In this review we summarize key aspects of the guideline including definition and staging of AKI, as well as evaluation and nondialytic management. Contrast-induced AKI and management of renal replacement therapy will be addressed in a separate review. Treatment recommendations are based on systematic reviews of relevant trials. Appraisal of the quality of the evidence and the strength of recommendations followed the Grading of Recommendations Assessment, Development and Evaluation approach. Limitations of the evidence are discussed and a detailed rationale for each recommendation is provided.

Tobramycin administered by the TOBI(®) Podhaler(®) for persons with cystic fibrosis: a review

From its introduction, the antibiotic tobramycin has been an important tool in the management of persons with cystic fibrosis (CF) and chronic Pseudomonas aeruginosa lung infections. Initially an intravenous rescue treatment for pulmonary exacerbations, tobramycin delivered by inhalation has become a mainstay of chronic suppressive CF infection management. Platforms for tobramycin aerosol delivery have steadily improved, with increased lung deposition complimented by decreased device complexities, loaded tobramycin doses, delivery times, and treatment burdens. Most recently, a unique tobramycin inhalation powder (TIP) formulation with a portable delivery system, the TOBI^® Podhaler^® (Novartis AG, Basel, Switzerland) has been developed and approved in Europe, Canada, and Chile. Four capsules, each containing 28 mg of TIP are successively pierced and inhaled via the T-326 Dry Powder Inhaler Device (Novartis AG, Basel, Switzerland). No external power source is required to deliver an efficacious tobramycin dose in minutes. By comparison, tobramycin inhalation solution (TIS) (TOBI^®; Novartis), is delivered by LC^® Plus (PARI Respiratory Equipment Inc, Midlothian, VA) jet nebulizer powered by an air compressor over 15–20 minutes. Comparative pharmacokinetics, safety, and efficacy studies of TIS and TIP in CF subjects with P. aeruginosa ≥ 6 years old demonstrate that: tobramycin lung deposition with 112 mg TIP is comparable to that attained with 300 mg TIS, TIP is more effective than placebo and not inferior to TIS with respect to pulmonary function benefit, and TIP has significantly faster treatment times and achieves higher patient satisfaction than TIS. TIP is associated with an increased frequency of mild to moderate local adverse events (cough, dysphonia, and dysgeusia) compared with TIS, however, these become less frequent as subjects gain TIP experience. These results suggest that the TOBI Podhaler may better meet the needs of many CF patients and families by reducing treatment time and complexity and improving patient satisfaction compared with TIS.

Management of aminoglycosides in the intensive care unit

Antibacterial resistance is increasing throughout the world, while the development of new agents is slowly progressing. In addition, the increasing prevalence of fluoroquinolone resistance may force many practitioners to choose an aminoglycoside agent in gram-negative regimens. Aminoglycosides are bactericidal agents with potent activity against gram-negative infections and activity against gram-positive infections when added to a cell wall active antimicrobial-based regimen. These agents may be dosed multiple times a day or consolidated as high-dose, extended-interval dosing to maximize pharmacokinetic and pharmacodynamic properties to achieve possible improved efficacy with reduced toxicity. Clinical application includes the treatment of bacteremia, endocarditis, health-care and nosocomial pneumonias, intra-abdominal infections, and others. Nephrotoxicity and ototoxicity are potential risks of aminoglycoside therapy that may be minimized with serum monitoring and short courses of therapy.

Elevated serum tobramycin concentrations after treatment with tobramycin inhalation in a preterm infant

High-dose inhaled tobramycin has been increasingly used for treatment and suppression of Pseudomonas aeruginosa pulmonary infections, especially in patients with cystic fibrosis. The advantage of inhalation over other routes of administration is minimal systemic absorption, which reduces the potential for adverse effects. However, cases of adults who had elevated serum concentrations and experienced systemic adverse effects due to excessive systemic absorption after inhaled tobramycin have been reported. We describe a prematurely born infant with numerous congenital and acquired disorders who required assisted mechanical ventilation and a 60-day stay in the neonatal intensive care unit (NICU). Tracheostomy and mechanical ventilatory support were required throughout the infant's hospital stay. The patient developed several pulmonary infections caused by various bacteria. He was treated with multiple antibiotics, including two different dose preparations of inhaled tobramycin 80 mg and 300 mg, administered through the tracheostomy and the ventilator. The infant was given a total of five preparations of tobramycin 80 mg/dose and three of 300 mg/dose, for a total cumulative dose of 1,300 mg over a 6-day period. His tobramycin concentrations increased, prompting discontinuation of the inhaled tobramycin. The infant died on day 60. To our knowledge, this is the first report of elevated tobramycin concentrations after inhalation in an infant. Although studies have found that tobramycin is safe and effective, certain patient populations are more at risk for toxicity. Tobramycin concentrations should be closely monitored in patients with significant underlying renal disorders, especially those in age-group extremes.