Clinical issues surrounding once-daily aminoglycoside dosing in children

Development of Gentamicin Resistance During Treatment of Escherichia coli Ventilator-Associated Pneumonia in a Neonate

A neonate born at 25 + 1/7 weeks developed ventilator-associated pneumonia at 29 + 3/7 weeks post-menstrual age with Escherichia coli that was originally sensitive to gentamicin. After 3 days of treatment with gentamicin, the minimum inhibitory concentration (MIC) changed from less than 1 mg/L to more than 16 mg/L. It appears that suboptimal gentamicin dosing led to the development of gentamicin resistance. As the patient was not improving clinically, the antibiotics were changed once the gentamicin resistance was identified. To minimize resistance and treatment failure, clinicians should consider the patient-specific pharmacokinetic parameters, achieved peak level, and the amount of time the gentamicin level will remain below the MIC of the organism being treated.

What do I need to know about aminoglycoside antibiotics?

The aminoglycosides are broad-spectrum, bactericidal antibiotics that are commonly prescribed for children, primarily for infections caused by Gram-negative pathogens. The aminoglycosides include gentamicin, amikacin, tobramycin, neomycin, and streptomycin. Gentamicin is the most commonly used antibiotic in UK neonatal units. Aminoglycosides are polar drugs, with poor gastrointestinal absorption, so intravenous or intramuscular administration is needed. They are excreted renally. Aminoglycosides are concentration-dependent antibiotics, meaning that the ratio of the peak concentration to the minimum inhibitory concentration of the pathogen is the pharmacokinetic-pharmacodynamic index best linked to their antimicrobial activity and clinical efficacy. However, due to their narrow therapeutic index, the patient's renal function should be monitored to avoid toxicity, and therapeutic drug monitoring is often required. Here we provide a review of aminoglycosides, with a particular focus on gentamicin, considering their pharmacokinetics and pharmacodynamics, and also practical issues associated with prescribing these drugs in a paediatric clinical setting.

One dose per day compared to multiple doses per day of gentamicin for treatment of suspected or proven sepsis in neonates

BACKGROUND

Animal studies and trials in older children and adults suggest that a 'one dose per day' regimen of gentamicin is superior to a 'multiple doses per day' regimen.

OBJECTIVES

To compare the efficacy and safety of one dose per day compared to multiple doses per day of gentamicin in suspected or proven sepsis in neonates.

SEARCH METHODS

Eligible studies were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 3) in the Cochrane Library (searched 8 April 2016), MEDLINE (1966 to 8 April 2016), Embase (1980 to 8 April 2016), and CINAHL (December 1982 to 8 April 2016).

SELECTION CRITERIA

All randomised or quasi-randomised controlled trials comparing one dose per day ('once a day') compared to multiple doses per day ('multiple doses a day') of gentamicin to newborn infants.

DATA COLLECTION AND ANALYSIS

Data collection and analysis was performed according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Eleven RCTs were included (N = 574) and 28 excluded. All except one study enrolled infants of more than 32 weeks' gestation. Limited information suggested that infants in both 'once a day' as well as 'multiple doses a day' regimens showed adequate clearance of sepsis (typical RR 1.00, 95% CI 0.84 to 1.19; typical RD 0.00, 95% CI -0.19 to 0.19; 3 trials; N = 37). 'Once a day' gentamicin regimen was associated with fewer failures to attain peak level of at least 5 µg/ml (typical RR 0.22, 95% CI 0.11 to 0.47; typical RD -0.13, 95% CI -0.19 to -0.08; number needed to treat for an additional beneficial outcome (NNTB) = 8; 9 trials; N = 422); and fewer failures to achieve trough levels of 2 µg/ml or less (typical RR 0.38, 95% CI 0.27 to 0.55; typical RD -0.22, 95% CI -0.29 to -0.15; NNTB = 4; 11 trials; N = 503). 'Once a day' gentamicin achieved higher peak levels (MD 2.58, 95% CI 2.26 to 2.89; 10 trials; N = 440) and lower trough levels (MD -0.57, 95% CI -0.69 to -0.44; 10 trials; N = 440) than 'multiple doses a day' regimen. There was no significant difference in ototoxicity between two groups (typical RR 1.69, 95% CI 0.18 to 16.25; typical RD 0.01, 95% CI -0.04 to 0.05; 5 trials; N = 214). Nephrotoxicity was not noted with either of the treatment regimens. Overall, the quality of evidence was considered to be moderate on GRADE analysis, given the small sample size and unclear/high risk of bias in some of the domains in a few of the included studies.

AUTHORS' CONCLUSIONS

There is insufficient evidence from the currently available RCTs to conclude whether a 'once a day' or a 'multiple doses a day' regimen of gentamicin is superior in treating proven neonatal sepsis. However, data suggest that pharmacokinetic properties of a 'once a day' gentamicin regimen are superior to a 'multiple doses a day' regimen in that it achieves higher peak levels while avoiding toxic trough levels. There was no change in nephrotoxicity or auditory toxicity. Based on the assessment of pharmacokinetics, a 'once a day regimen' may be superior in treating sepsis in neonates of more than 32 weeks' gestation.

Pharmacological response sensitization in nerve cell networks exposed to the antibiotic gentamicin

Gentamicin is an aminoglycoside antibiotic that is used in clinical, organismic, and agricultural applications to combat gram-negative, aerobic bacteria. The clinical use of gentamicin is widely linked to various toxicities, but there is a void in our knowledge about the neuromodulatory or neurotoxicity effects of gentamicin. This investigation explored the electrophysiologic effects of gentamicin on GABAergic pharmacological profiles in spontaneously active neuronal networks in vitro derived from auditory cortices of E16 mouse embryos and grown on microelectrode arrays. Using the GABA_A agonist muscimol as the test substance, responses from networks to dose titrations of muscimol were compared in the presence and absence of 100µM gentamicin (the recommended concentration for cell culture conditions). Spike-rate based EC₅₀ values were generated using sigmoidal fit concentration response curves (CRCs). Exposure to 100µM gentamicin exhibited a muscimol EC₅₀±S.E.M. of 80±6nM (n=10). The EC₅₀ value obtained in the absence of gentamicin was 124±11nM (n=10). The 35% increase in potency suggests network sensitization to muscimol in the presence of gentamicin. Action potential (AP) waveform analyses of neurons exposed to gentamicin demonstrated a concentration-dependent decrease in AP amplitudes (extracellular recordings), possibly reflecting gentamicin effects on voltage-gated ion channels. These in vitro results reveal alteration of pharmacological responses by antibiotics that could have significant influence on the behavior and performance of animals.

Optimized antimicrobial dosing strategies: a survey of pediatric hospitals

BACKGROUND

Extended-interval aminoglycoside (EIAG) and extended- and continuous-infusion β-lactam (EIBL and CIBL) dosing strategies are increasingly used in adults, but pediatric literature is limited.

OBJECTIVE

The objective of this study was to describe the use of EIAG, EIBL, and CIBL dosing in pediatric hospitals in the USA.

STUDY DESIGN, SETTING, AND PARTICIPANTS

A national survey of children's hospitals was conducted. A single practitioner from each target hospital was identified through the Children's Hospital Association. Practice-based survey questions identified whether hospitals utilize EIAG, EIBL, and CIBL dosing.

MAIN OUTCOME MEASURE

The main outcome measure was the percentage utilization of the dosing strategies, with secondary outcomes being the reasons for not using these dosing strategies.

RESULTS

Seventy-seven of 215 identified practitioners (36 %) participated in the survey. EIAG, EIBL, and CIBL dosing were utilized in 63 %, 24 %, and 13 % of responding hospitals, respectively. The most common reasons for not using EIAG were concern regarding lack of efficacy data (56 %) and concern regarding the duration of the drug-free period (41 %). Respondents who did not utilize EIBL cited concern due to lack of pediatric EIBL efficacy data (54 %), the need for more intravenous access (54 %), intravenous medication compatibility issues (39 %), and the time during which the patient is attached to an intravenous infusion (31 %).

CONCLUSION

This survey of children's hospitals indicates that EIAG is used in over 50 % of hospitals, but there is some lag in adoption of EIBL and CIBL dosing, both of which are used in fewer than 25 % of hospitals. Additional studies may provide much-needed evidence to increase the utilization of these strategies.

One dose per day compared to multiple doses per day of gentamicin for treatment of suspected or proven sepsis in neonates

BACKGROUND

Animal studies and trials in older children and adults suggest that a one dose per day regimen of gentamicin is superior to a multiple doses per day regimen.

OBJECTIVES

To compare the efficacy and safety of one dose per day compared to multiple doses per day of gentamicin in suspected or proven sepsis in neonates.

SEARCH METHODS

Eligible studies were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, April 2011), MEDLINE (1966 to April 2011), EMBASE 1980 to April 2011, and CINAHL (December 1982 to April 2011). Abstracts of the Society for Pediatric Research were searched from 1980 to 2010 inclusive.

SELECTION CRITERIA

All randomised or quasi randomised controlled trials comparing one dose per day ( 'once a day') compared to multiple doses per day ( 'multiple doses a day') of gentamicin to newborn infants < 28 days of life.

DATA COLLECTION AND ANALYSIS

Data collection and analysis was performed according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Eleven studies were included (N = 574) and nineteen excluded. All infants in both 'once a day' as well as 'multiple doses a day' regimen showed adequate clearance of sepsis [typical RD 0.00 (95% CI - 0.19 to 0.19); 3 trials; N = 36]. For the other primary outcome measures relating to gentamicin pharmacokinetics 'once a day' dosing of gentamicin was superior. 'Once a day' gentamicin regimen was associated with less failures to attain peak level of at least 5 µg/ml [typical RR 0.22 (95% CI 0.11 to 0.47); 9 trials; N = 422] and less failures to achieve trough levels of < 2 µg/ml [typical RR 0.38 (95% CI 0.27 to 0.55); 11 trials N = 503] compared to 'multiple doses a day' regimen.Ototoxicity and nephrotoxicity were not noted with either of the treatment regimens.

AUTHORS' CONCLUSIONS

There is insufficient evidence from the currently available RCTs to conclude whether 'once a day' or 'multiple doses a day' regimen of gentamicin is superior in treating proven neonatal sepsis. However, data suggests that pharmacokinetic properties of 'once a day' gentamicin regimen are superior to 'multiple doses a day' regimen in that it achieves higher peak levels while avoiding toxic trough levels. There is no change in nephrotoxicity or auditory toxicity. Based on this assessment of pharmacokinetics, 'once a day regimen' may be superior in treating neonatal sepsis in neonates greater than 32 weeks gestation.

Compliance with dosing recommendations from common references in prescribing antibiotics for preterm neonates

PURPOSE

Incorrect dosage was the most common type of medication errors in neonate patients. Different dosing recommendations from common reference sources may have contributed to the errors. This study assesses the compliance rate with the common reference sources in antibiotic dosage prescribed for preterm infants in a neonatal intensive care unit (NICU).

METHODS

A retrospective study using chart review was conducted at a tertiary care medical center with university affiliation in Taiwan. Study subjects were preterm neonates admitted to the NICU of the medical center between 2000 and 2002 and prescribed at least one antibiotic during the stay. Recommendations from three commonly used reference sources (Pediatric Dosage Handbook, Neonatal Drug Formulary, and Neofax) were employed to evaluate the dosage compliance of the antibiotic prescriptions.

RESULTS

A total of 433 preterm infants and 3459 prescriptions were included. Depending on the reference source used, the percentages of antibiotic prescriptions where both the dose and the interval were compliant with recommendations ranged from 36.88 to 87.54%.

CONCLUSIONS

A significant proportion of antibiotics prescribed for preterm neonates in this medical center did not comply with the recommended dosage from common reference sources. Future studies should investigate the clinical impacts of the dosing deviation.

Assessment of gentamicin 7 mg/kg once daily for pediatric patients with febrile neutropenia: a pilot project

Context. Use of once daily aminoglycosides continues to increase for the pediatric population, including oncology patients. Concerns have been identified and still need to be resolved including the optimal dose, frequency, and monitoring parameters.

Objective. We completed a study to determine if empiric use of gentamicin 7 mg/kg once daily in pediatric patients admitted with febrile neutropenia provided extrapolated peaks and drug-free intervals consistent with suggested preferred levels.

Design. A review of the patient’s chart was completed following their discharge from the hospital between September 2006 and October 2007.

Setting. A community hospital.

Patients. A consecutive sample of 17 encounters for pediatric patients admitted for febrile neutropenia that received once daily gentamicin.

Main outcome measures. Extrapolated peak levels and drug-free intervals.

Results. There were seven patients with a total of 17 encounters. The mean extrapolated peak level was 16.9 mg/L. The mean drug-free interval was 15.7 h. Both target peak and drug-free interval were obtained for two encounters (12%), which was one patient.

Conclusion. Gentamicin 7 mg/kg/dose once daily does not provide preferred levels for all pediatric febrile neutropenic patients. Further investigation is required to ensure that once daily gentamicin regimens for pediatric oncology patients provide adequate clinical success. J Oncol Pharm Practice (2009) 15: 211—216.

Massive gentamicin overdose in a 14-month-old

A healthy 14-month-old girl received gentamicin 500 mg (56 mg/kg) intravenously as empiric therapy given fever. The overdosage was quickly recognized and the child transferred to a pediatric referral center. Two hours after administration, serum creatinine was 0.3 mg/dl, though serum gentamicin level was 89 mg/L. Hemodialysis was initiated approximately 4 h after gentamicin was given and stopped 4 h later, with a serum gentamicin level of 3.4 mg/L. Gentamicin level 4 h after completion of hemodialysis was 2.3 mg/L. Three months later, the child's serum creatinine was 0.3 mg/dl, urinalysis showed no blood or protein, and audiometry showed normal hearing bilaterally at all frequencies. This child demonstrated the highest gentamicin level recorded in a patient with normal renal function. Her case demonstrates that prompt hemodialysis in this circumstance rapidly clears gentamicin without rebound. If left untreated, long-term adverse sequellae for hearing or renal function were possible; hemodialysis may have altered these outcomes.

Early hospital discharge versus continued hospitalization in febrile pediatric cancer patients with prolonged neutropenia: A randomized, prospective study

BACKGROUND

Hospitalization with single or multi-agent antibiotic therapy has been the standard of care for treatment of febrile neutropenia in cancer patients. We hypothesized that an empiric antibiotic regimen that is effective and that can be administered once-daily will allow for improved hospital utilization by early transition to outpatient care.

PROCEDURE

Febrile pediatric cancer patients with anticipated prolonged neutropenia were randomized between a regimen of once-daily ceftriaxone plus amikacin (C + A) and imipenem monotherapy (control). Afebrile patients on C + A satisfying "Early Discharge Criteria" at 72 hr continued treatment as outpatients. We compared the outcome, adverse events, duration of hospitalization, and cost between both groups.

RESULTS

A prospective randomized controlled clinical trial was conducted on 129 febrile episodes in pediatric cancer patients with prolonged neutropenia. No adverse events were seen in 32 children (84% of study arm) treated on an outpatient basis. We found a statistically significant difference between the duration of hospitalization of the C + A group [median 5 days] and control [median 9 days](P < 0.001), per episode antibiotic cost (P < 0.001) and total episode cost (P < 0.001). There was no statistically significant difference in the response to treatment at 72 hr or after necessary antimicrobial modifications.

CONCLUSIONS

We conclude that pediatric febrile cancer patients initially considered at risk for sepsis due to prolonged neutropenia can be re-evaluated at 72 hr for outpatient therapy. The convenience, low incidence of adverse effects, and cost benefit of the once-daily regimen of C + A may be particularly useful to reduce the overall treatment costs and duration of hospitalization.

One dose per day compared to multiple doses per day of gentamicin for treatment of suspected or proven sepsis in neonates

BACKGROUND

Gentamicin is widely used in the treatment of suspected or proven neonatal sepsis. Animal studies and systematic reviews from trials in older children and adults suggest that a one dose per day regimen is superior to a multiple doses per day regimen. Pharmacokinetic studies and retrospective audits in neonatal population also favour once a day administration of gentamicin. However, there is no consensus regarding the dose interval regimen in the neonatal population.

OBJECTIVES

To compare the efficacy and safety of one dose per day compared to multiple doses per day of gentamicin in suspected or proven sepsis in neonates.

SEARCH STRATEGY

Eligible studies were identified by searching MEDLINE (March 2005), EMBASE 1980 - 2004, Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2005) and CINAHL (December 1982 - March 2005). Abstracts of the Society for Pediatric Research were hand searched from 1980 to 2004 inclusive. No language restrictions were applied.

SELECTION CRITERIA

All randomised or quasi randomised controlled trials comparing one dose per day ( 'once a day') compared to multiple doses per day ( 'multiple doses a day') of gentamicin to newborn infants < 28 days of life.

DATA COLLECTION AND ANALYSIS

Methodological quality of eligible studies was assessed according to allocation concealment, blinding of intervention, blinding of outcome assessment and completeness of follow up. Data were sought regarding effects on clinical efficacy, pharmacokinetic efficacy, ototoxicity and nephrotoxicity of the two regimens. When appropriate, meta-analysis was conducted to provide a pooled estimate of effect. For categorical data, the typical relative risk (RR), typical risk difference (RD) and number needed to treat (NNT) with 95% confidence intervals (CI) were calculated. Continuous data were analysed using weighted mean difference (WMD).

MAIN RESULTS

Twenty four studies were initially identified. Thirteen were excluded and eleven studies (N = 574) included. All studies compared the effectiveness and safety of 'once a day' versus 'multiple doses a day' regimen of gentamicin in newborn infants. Only one study enrolled infants less than 32 weeks gestation. All except one trial used intravenous infusion. One trial used gentamicin as a bolus dose over one minute. Two trials used intramuscular gentamicin in some of their study infants. For the primary outcome of 'clearance of sepsis', all infants in both 'once a day' as well as 'multiple doses a day' regimen showed adequate clearance of sepsis [Typical RD 0.00 (95% CI - 0.19, 0.19); 3 trials; N = 36]. For the other primary outcome measures relating to gentamicin pharmacokinetics, 'once a day dosing' of gentamicin was superior. 'Once a day' gentamicin regimen is associated with less failures to attain peak level of at least 5 microg/ml [Typical RR 0.22 (95% CI 0.11, 0.47); Typical RD -0.13 (95% CI -0.19, -0.08); 9 trials; N = 422]; less failures to achieve trough levels of < 2 microg/ml [Typical RR 0.38 (95% CI 0.27, 0.55); Typical RD -0.22 (95% CI -0.29, -0.15); 11 trials N = 503]; higher peak levels [WMD 2.58 (95% CI 2.26, 2.89); 10 trials; N = 440] and lower trough levels [WMD -0.57 (95% CI -0.69, -0.44); 10 trials; N = 440] compared to 'multiple doses a day' regimen. Ototoxicity and nephrotoxicity were not noted with either of the treatment regimens. Significant heterogeneity was noted for some of the outcomes measured. Hence the results need to be interpreted with caution. Possible reasons for heterogeneity are different gestational ages of study infants and the timing of collection of blood samples in relation to a particular dose and the day of therapy on which the samples were collected.

AUTHORS' CONCLUSIONS

There is insufficient evidence from the currently available RCTs to conclude whether 'once a day' or 'multiple doses a day' regimen of gentamicin is superior in treating proven neonatal sepsis. However data suggests that pharmacokinetic properties of 'once a day' gentamicin regimen are superior to 'multiple doses a day' regimen in that it achieves higher peak levels while avoiding toxic trough levels. There is no change in nephrotoxicity or auditory toxicity. Based on this assessment of pharmacokinetics, 'once a day regimen' may be superior in treating neonatal sepsis in neonates more than 32 weeks gestation.

Tobramycin Pharmacokinetics in Children with Febrile Neutropenia Undergoing Stem Cell Transplantation: Once-Daily versus Thrice-Daily Administration

STUDY OBJECTIVE

To describe the pharmacokinetic disposition of tobramycin in children undergoing stem cell transplantation (SCT) after intravenous administration either every 24 hours or every 8 hours, and to use this information to create initial dosing guidelines for administration every 24 hours in this patient population.

DESIGN

Pharmacokinetic analysis of a randomized controlled trial.

SETTING

The Hospital for Sick Children, Toronto, Ontario, Canada.

PATIENTS

Sixty children (< 18 yrs) with febrile neutropenia undergoing stem cell transplantation.

INTERVENTION

Patients were randomized to receive intravenous tobramycin either every 24 hours (29 patients) or every 8 hours (31 patients). Initially, they received either 2.5 mg/kg/dose every 8 hours or weight-based doses by age group (< 5 yrs, 9 mg/kg/dose; 5 to < 12 yrs, 8 mg/kg/dose; > or = 12 yrs, 7 mg/kg/dose) every 24 hours.

MEASUREMENTS AND MAIN RESULTS

Serum tobramycin concentrations were obtained at 2 and 8 hours after the first dose. Initial guidelines for dosing every 24 hours were derived using the parameters from all patients to achieve a maximum serum concentration (Cmax) of 20-22.5 mg/L and a drug-free interval (time during dosing interval when the tobramycin concentration was < 1 mg/L) of at least 4 hours. After the first tobramycin dose, the elimination rate constant (kel) and volume of distribution (Vd) observed in the every-8-hour group (23 patients) were 0.34 +/- 0.09 hours(-1) and 0.48 +/- 0.21 L/kg, respectively. The kel and Vd in the every-24-hour group (22 patients) were 0.43 +/- 0.12 hr(-1) and 0.43 +/- 0.26 L/kg, respectively. Tobramycin Vd varied with age. Initial doses of tobramycin every 24 hours recommended to achieve the target parameters are 10 mg/kg/dose for patients aged 6 months to less than 9 years, 8 mg/kg/dose for those aged 9 to less than 12 years, and 6 mg/kg/dose for those aged 12 years or older.

CONCLUSION

Children undergoing SCT who receive tobramycin every 24 hours should receive an initial dose based on age. Further validation of the proposed dosing guidelines is required.

Randomized controlled trial of once- versus thrice-daily tobramycin in febrile neutropenic children undergoing stem cell transplantation

BACKGROUND

The benefits of aminoglycoside antibiotics, such as tobramycin, administered as a once-daily dose to manage febrile neutropenia, have been demonstrated in many patient populations. However, toxicity and safety data are lacking for pediatric stem cell transplant recipients, who are at especially high risk for aminoglycoside-related toxicity and infectious morbidity. In particular, the relative nephrotoxicity and efficacy of tobramycin administered as a single daily dose or as three daily doses among this patient population is not known.

METHODS

We conducted a randomized, double-blind controlled study of tobramycin dosing among children 18 years or younger who had fever and neutropenia while undergoing stem cell transplantation. From October 2000 through November 2002, 60 children were randomly assigned to receive intravenous tobramycin, as either a single daily dose (n = 29) or every 8 hours (n = 31), in combination with either piperacillin or ceftazidime (intravenous). Tobramycin doses were adjusted to achieve pharmacokinetic targets. The primary outcome was nephrotoxicity, as represented by the maximal percent increase in serum creatinine concentration throughout the episode of febrile neutropenia relative to the baseline serum creatinine concentration. Efficacy was a secondary outcome and was defined as survival of the episode without modification of the antibacterial regimen. All statistical tests were two-sided.

RESULTS

In a modified intent-to-treat analysis, the mean maximal percent increase in serum creatinine concentration was 32% (N = 26) in the once daily dose group and 51% (N = 28) in the every 8 hours dose group (difference = 19%, 95% confidence interval [CI] = 0% to 38%; P =.054). Among patients evaluable for efficacy, 12 (46%) of 26 patients in the once daily dose group and five (19%) of 27 patients in the every 8 hours dose group survived the episode of febrile neutropenia without requiring antibacterial treatment modification (difference = 27%, 95% CI = 4% to 52%; P =.03). There was one death in each group.

CONCLUSIONS

In febrile neutropenic children undergoing stem cell transplantation, tobramycin may be less nephrotoxic and more efficacious when administered as a once daily dose than when administered every 8 hours.