Once- versus twice-daily gentamicin dosing in neonates >/=34 Weeks' gestation: cost-effectiveness analyses

Extended Interval Aminoglycoside Treatment for Klebsiella Pneumoniae Endocarditis in an Extremely Low Birth Weight Neonate

Infective endocarditis (IE) in neonates is associated with high mortality and incidence has been increasing over the past two decades. The majority of very low birth weight infants will be treated with at least one nephrotoxic medication during their hospital course. Over one-quarter of very low birth weight neonates exposed to gentamicin may develop acute kidney injury (AKI); this is particularly worrisome as AKI is an independent factor associated with increased neonatal mortality and increased length of stay. AKI during periods of neonatal nephrogenesis, which continues until 34-36 weeks postmenstrual age, may also have serious effects on the long-term nephron development which subsequently puts infants at risk of chronic kidney disease. Extended interval (EI) aminoglycoside (AMG) dosing has been used for decades in adult populations and has proven to reduce AKI while being at least as effective as traditional dosing, although there is limited published research for using an EI AMG in endocarditis in adults or pediatric patients. We describe an extremely low birth weight neonate, born preterm at 24 weeks gestation treated for Klebsiella pneumoniae IE that required AMG therapy who also had concurrent AKI. We utilized EI AMG combination therapy for treatment of Klebsiella pneumoniae endocarditis with good outcome and encourage others to report their experiences to improve our knowledge of EI AMG in this population.

Antibiotic-related adverse events in paediatrics: unique characteristics

Introduction: Antibiotics have saved and are still saving countless human lives from the burden of infectious diseases. However, as with all other drugs, they can cause adverse events. Generally, these are uncommon, mild and spontaneously resolving. However, in some cases, they can cause relevant clinical problems. Compared with adults, children, particularly in the first years of life, have a higher risk of antibiotic-related adverse events for several reasons. Areas covered: In this paper, the conditions that can contribute to the elevated risk of antibiotic-related adverse events in children are discussed. Expert opinion: Antibiotic stewardship can be a solution to limit antibiotic abuse and misuse and consequently the incidence of antibiotic-related adverse events in children. Moreover, most of the antibiotic-associated adverse events can be avoided with more extensive pre-marketing medicine investigations, improved postmarket safety surveillance system, increased transparency throughout the clinical research enterprise, increased training of clinical pharmacologists and paediatric researchers, expanded pool of paediatric patients, and providing additional funding and incentives for paediatric drug development.

Daily gentamicin using ideal body weight demonstrates lower risk of postpartum endometritis and increased chance of successful outcome compared with traditional 8-hour dosing for the treatment of intrapartum chorioamnionitis

Background: Clinical chorioamnionitis complicates approximately 1-4% of pregnancies overall. Although universal agreement does not exist regarding the antibiotic regimen of choice, most studies have evaluated intravenous ampicillin dosed at 2 g every 6 hours plus gentamicin dosed every 8 hours. Only three studies have examined daily gentamicin for the treatment of intrapartum chorioamnionitis and thus is insufficiently investigated. Objective: This study seeks to determine whether daily dosing of gentamicin using ideal body weight for the treatment of intrapartum chorioamnionitis is more or equivalently efficacious when compared to traditional 8-hour dosing regimens. Materials and methods: We conducted a retrospective cohort study and reviewed charts on all women receiving treatment for intrapartum chorioamnionitis, which included intravenous gentamicin daily dosing calculated using 5 mg/kg ideal body weight or receiving traditional every 8 hours dosing of gentamicin at two large academic centers. Our primary outcomes were resolution of infection following delivery without the development of maternal endometritis and/or neonatal sepsis. Baseline characteristics were compared between dosing groups using Welch two-sample t-tests for continuous variables, uncorrected X² test and exact binomial 95% confidence intervals. We calculated the risk ratios of each outcome in the ideal versus traditional dosing groups using modified Poisson regression, both crude and adjusted. Adjusted models were controlled for variables determined to be potential confounders, which included BMI, diabetes mellitus, gestational blood pressure >140/90, group β-Streptococcus status, race, advanced maternal age (>34 y), and parity. Results: The study included 500 patients with 255 patients receiving daily dosing of gentamicin and 245 receiving traditional dosing of gentamicin. Of the patients receiving daily gentamicin compared to traditional dosing, 95.7% (95% CI 94.9-96.6%) achieved the primary outcome versus 92% (95% CI 90.8 - 93.2%), 2.4% (95% CI 1.8-3%) developed endometritis versus 5.6% (4.5-6.7%), 1.6% (95% CI 1.1-2.1%) delivered neonates with sepsis versus 3.3% (CI 2.5-4.1%), and 36.9% required cesarean delivery versus 41.4%. In crude analysis, compared to traditional dosing, IDW daily dosing was associated with a lower risk of postpartum endometritis (RR 0.42, 95% CI 0.16-1.10, p = .032). After adjusting for BMI, diabetes mellitus, gestational blood pressure >140/90, group β-Streptococcus status, race, advanced maternal age (>34 y), and parity, the IDW daily dosing group had a 5% greater chance of successful outcome (RR 1.05, 95% CI 1.00-1.10, p = .046) and a 64% lower risk of endometritis (RR 0.35, 95% CI 0.15-0.83, p = .017). Conclusion: Daily dosing of gentamicin using ideal body weight is associated with a lower risk of postpartum endometritis and high chance of a successful outcome in the treatment of intrapartum chorioamnionitis compared with traditional 8-hour dosing in our ethnically diverse, urban population and thus may be considered a superior option to every 8 hours dosing regimens.

Daily dosing of gentamicin using ideal body weight for the treatment of intrapartum chorioamnionitis: a pilot study

PURPOSE

This study aimed to determine whether daily dosing of gentamicin using ideal body weight in the treatment of chorioamnionitis is effective.

MATERIALS AND METHODS

We conducted a prospective observational study and followed all women receiving treatment for chorioamnionitis which included gentamicin daily dosing calculated using 5 mg/kg ideal body weight. Patients were excluded if pathological analysis of placenta did not confirm chorioamnionitis. Our primary outcome was resolution of infection following delivery without the development of maternal endometritis and/or neonatal sepsis. Ninety-five percent confidence intervals for proportions were calculated using exact binomial tests. These patients were retrospectively compared to patients who received treatment for chorioamnionitis which included traditional gentamicin every 8 h.

RESULTS

The study included 160 patients. Of the patients receiving daily dosing (n = 80) compared to traditional dosing (n = 80), 96% (95% CI 95.7-97.6%) achieved the primary outcome versus 91% (88.9-93.1%), 2.5% (95% CI 1.2-3.8%) developed endometritis versus 6.3% (4.2-8.4%), 1.3% (95% CI 0.4-2.2%) delivered neonates with sepsis versus 2.5% (1.2-3.8%), and 39% required cesarean delivery (95% CI 46.2-53.8) versus 37% (33.2-40.8%).

CONCLUSION

Daily dosing of gentamicin using ideal body weight is effective in successful treatment of chorioamnionitis without development endometritis and/or neonatal sepsis across different ethnicities.

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.

Should gentamicin trough levels be routinely obtained in term neonates?

OBJECTIVE

Gentamicin is a common antibiotic used to treat sepsis in neonates. We hypothesize that obtaining routine gentamicin trough levels may not be necessary in low-risk, term infants.

STUDY DESIGN

We performed a retrospective cohort study of term infants (n=346) treated with gentamicin in a single level III neonatal intensive care unit (NICU). The results of gentamicin trough levels and the correlation with risk factors and potential side effects were recorded. In addition, we conducted a survey of 75 academic NICUs across the United States regarding their gentamicin monitoring practice.

RESULTS

Routine trough levels did not predict potential gentamicin toxicity in neonates with low risk factors. Regression analysis demonstrated a positive correlation between gentamicin trough levels and serum creatinine. The survey of the NICUs in the United States demonstrated significant inconsistency in gentamicin monitoring practice.

CONCLUSION

Obtaining gentamicin trough levels guided by risk factors is more appropriate than obtaining routine trough levels in low-risk term neonates.

Extended-interval gentamicin administration in neonates: a simplified approach

OBJECTIVE

Gentamicin dosing is highly variable and remains complicated in the neonatal population. Traditional dosing in our unit resulted in an excessive number of elevated trough serum gentamicin levels. We hypothesized that one uniform gentamicin dose for neonates of all gestational ages will reduce the incidence of elevated trough levels from 50 to 10%.

STUDY DESIGN

Our prospective, randomized, controlled trial enrolled eligible neonates into two groups, according to gestational age (⩽34 6/7 (group I) and >35 0/7 weeks (group II)). Patients in the study arm received a dose of gentamicin 5 mg kg(-1) intravenous (i.v.) every 36 h, whereas patients in the control arm received traditional dosage. Patients were monitored for resolution of infection, serum gentamicin levels and adverse effects. We confirmed our findings in a follow-up study. Fisher's exact and Mann-Whitney tests were used for statistical analysis.

RESULTS

We enrolled 96 neonates, 50 in group I (n=25 per arm) and 46 in group II (n=23 per arm). Elevated trough levels were reduced by 66% in group I (P=0.61) and 100% in group II (P=0.0015). In the study arm of both groups, 48/49 neonates had Cmin serum gentamicin concentration (SGC) <2 mg l(-1) and the majority had a trough SGC <1 mg l(-1) (P<0.0001). The study dose resulted in maximum gentamicin levels in the goal range and a 50% reduction in dosage modifications. There were no treatment failures or adverse effects. Our follow-up study phase confirmed these results.

CONCLUSION

A standardized gentamicin dosage of 5 mg kg(-1) i.v. every 36 h to neonates of all gestational ages was safe and resulted in SGCs in goal therapeutic ranges. The implications of this simplified gentamicin dosage are to reduce health-care costs by less frequent dosing of gentamicin and reducing medication errors in physician prescribing from complicated dosing schemes.

[Dosing regimens of antibiotics in neonates: Variations in clinical practice and what should be done?]

There is wide variation in neonatal dosages of antibiotics in clinical practice, both nationally and internationally. This reflects the lack of evaluation of drugs in this therapeutic class, although widely prescribed. Given this situation, optimization of antibiotic prescription is required to ensure efficacy and safety of neonatal treatment and reduce microbial resistance. Rational prescription should be based on the knowledge of developmental pharmacokinetics and pharmacodynamics. Rigorous studies, conducted in collaboration between neonatologists and pharmacologists, are essential to develop and validate evidence-based neonatal dosage regimens.

Bacteremia in Early Infancy: Etiology and Management

We reviewed the literature regarding bacteremia in early infancy (age ≤ 90 days). Bacteremia remains a major cause of morbidity and mortality in young infants. However, recent epidemiologic data suggest that the incidence of bacteremia is decreasing and the pathogens responsible for invasive disease are changing. These changes will impact the evaluation and management of young infants. We review the current epidemiology of community-acquired bacteremia in early infancy with particular emphasis on the causative agents, diagnostic evaluation, and empiric and definitive antimicrobial treatment.

Gentamicin extended interval regimen and ototoxicity in neonates

OBJECTIVES

To assess the extended interval regimen gentamicin associated ototoxicity in neonatal intensive care unit using hearing tests.

METHODS

Two hundred and twenty neonates admitted to neonatal intensive care were assessed; 110 neonates who had received gentamicin and 110 neonates who had not received gentamicin served as control group. Gentamicin group were further subdivided according to the duration of treatment into 50 neonates who had received gentamicin for 5 days or less and 60 neonates who had received gentamicin for more than 5 days. TEOAEs were used for hearing screening. Auditory brain response was performed 3 months later for failed cases to confirm the hearing impairment.

RESULTS

Three neonates failed TEOAEs screening in each group but hearing impairment was confirmed in one neonate only (0.9%) in each group (gentamicin and control groups). Neonates who received gentamicin for more than 5 days showed comparable results as regard TEOAEs or ABR results with those who received gentamicin for 5 days or less, and control group.

CONCLUSIONS

Extended interval dosing of gentamicin therapy in neonates does not increase the incidence of hearing loss. This suggests that hearing loss in neonatal intensive care unit may be attributed to factors other than gentamicin treatment.

Extended-interval gentamicin dosing in achieving therapeutic concentrations in malaysian neonates

OBJECTIVE

To evaluate the usefulness of extended-interval gentamicin dosing practiced in neonatal intensive care unit (NICU) and special care nursery (SCN) of a Malaysian hospital.

METHODS

Cross-sectional observational study with pharmacokinetic analysis of all patients aged ≤28 days who received gentamicin treatment in NICU/SCN. Subjects received dosing according to a regimen modified from an Australian-based pediatric guideline. During a study period of 3 months, subjects were evaluated for gestational age, body weight, serum creatinine concentration, gentamicin dose/interval, serum peak and trough concentrations, and pharmacokinetic parameters. Descriptive percentages were used to determine the overall dosing accuracy, while analysis of variance (ANOVA) was conducted to compare the accuracy rates among different gestational ages. Pharmacokinetic profile among different gestational age and body weight groups were compared by using ANOVA.

RESULTS

Of the 113 subjects included, 82.3% (n = 93) achieved therapeutic concentrations at the first drug-monitoring assessment. There was no significant difference found between the percentage of term neonates who achieved therapeutic concentrations and the premature group (87.1% vs. 74.4%), p = 0.085. A total of 112 subjects (99.1%) achieved desired therapeutic trough concentration of <2 mg/L. Mean gentamicin peak concentration was 8.52 mg/L (95% confidence interval [Cl], 8.13-8.90 mg/L) and trough concentration was 0.54 mg/L (95% CI, 0.48-0.60 mg/L). Mean volume of distribution, half-life, and elimination rate were 0.65 L/kg (95% CI, 0.62-0.68 L/kg), 6.96 hours (95% CI, 6.52-7.40 hours), and 0.11 hour(-1) (95% CI, 0.10-0.11 hour(-1)), respectively.

CONCLUSION

The larger percentage of subjects attaining therapeutic range with extended-interval gentamicin dosing suggests that this regimen is appropriate and can be safely used among Malaysian neonates.

Pharmacokinetics of gentamicin in newborns with moderate-to-severe hypoxic-ischemic encephalopathy undergoing therapeutic hypothermia

OBJECTIVE

To investigate gentamicin pharmacokinetics in neonates with moderate-to-severe hypoxic-ischemic encephalopathy (HIE) who underwent therapeutic hypothermia (TH).

METHODS

Data were collected retrospectively from infants admitted between January 2007 and February 2011. Gentamicin was given at 2.5 mg/kg/dose q12h intravenously. Infants not eligible for TH underwent therapeutic normothermia (TN). After reviewing the data which showed >85 % of infants undergoing TH had gentamicin trough concentration >2 µg/ml at steady state, the gentamicin level monitoring protocol was modified since March 2011.

RESULTS

In the initial retrospective study, 15 TN infants were compared with 19 TH infants. There was significant difference in median gentamicin half-life (7.01 vs. 9.57 h). A higher proportion of infants in the TH group required dosage adjustment (8/15 vs. 17/19). After March 2011, gentamicin level taken 12-h post 1st dose was measured routinely and 18/22 infants had trough gentamicin levels >2 µg/ml. Their dosing intervals were extended to Q18h or beyond.

CONCLUSIONS

Infants with moderate-to-severe HIE who undergo TH may exhibit changes in the pharmacokinetic properties of gentamicin compared to infants who undergo TN. By measuring gentamicin level at 12-h after the first dose of 2.5 mg/kg/dose, appropriate dosing interval can be determined and the duration of exposure to toxic gentamicin level can be reduced.

Clinical pharmacist impact on care, length of stay, and cost in pediatric cystic fibrosis (CF) patients

BACKGROUND

Cystic fibrosis (CF) patients are often treated with aminoglycoside (AG) antibiotics during infective pulmonary exacerbations. Achieving pharmacokinetic and pharmacodynamic (PK/PD) targets to improve outcomes and counteract resistance is paramount.

PURPOSE

The primary objective was to compare the number of pediatric CF patients achieving AG PK/PD targets when a clinical pharmacist (CP) managed therapeutic drug monitoring (TDM) compared with usual care (UC).

METHODS

A retrospective cohort study was conducted on the records of 40 CF patients that received AGs and ≥2 serum samples between 1/2007 and 5/2009. Chi-square and Student's t-test were used to analyze nominal and continuous variables, respectively.

RESULTS

Twenty-nine patients with 52 courses of AGs were included the CP group, and 22 patients with 42 courses were included the UC group. Ninety-eight percent of patients in the CP group reached AG PK/PD targets compared with 71% in the UC group, P < 0.001. Patients in the CP group reached the AG PK/PD target in a mean of 1.9 ± 0.8 days compared with 4.8 ± 3.4 days in the UC group, P < 0.0001. The average LOS in the CP group was 9 ± 5 days compared with 12 ± 7.5 days in the UC group, P = 0.033. The mean number of levels per patient was 2.7 in the CP group compared with 5.2 (range of 2-20) in the UC group, P < 0.001. Resource utilization associated with drug levels, dosing adjustments and LOS were $26,549, $14,069, and $1,680,000 in the CP group as compared with $40,683, $27,812, and $1,940,000, respectively, in the UC group.

CONCLUSION

CP managed TDM resulted in a significantly higher percentage of pediatric CF patients achieving AG PK/PD targets 3 days sooner with an average LOS that was 3 days shorter. CP managed TDM resulted in significantly fewer dosage adjustments, drug levels, and cost associated with serum sampling, drug wastage, and LOS.

High-dose gentamicin in newborn infants: is it safe?

Dosing regimens often recommend lower gentamicin doses in neonates (3-5 mg/kg) than in older children (7 mg/kg or more) despite the higher volume of distribution in neonates. We studied an extended-interval high-dose (6 mg/kg) gentamicin regimen in a single tertiary neonatal unit from 2004-2012. During the first week of life, dosing interval was 24 h for term infants, 36 h for preterm infants with gestational age (GA) 29-36 weeks and 48 h for preterm infants with GA <29 weeks. After the first week of life, dosing interval was 24 h if corrected age (GA + postnatal age) ≥29 weeks and 36 h if corrected age <29 weeks. Outcome measures were trough plasma concentration (TPC), ototoxicity and prescription errors. In 546 treatment episodes, TPC was measured prior to the third gentamicin dose. There were 37 episodes (6.7 %) of prescription errors, mainly a too long dosing interval. We included 509 treatment episodes (440 infants) in the final analysis. Mean (standard deviation) gentamicin TPC during the first week of life was 1.1 (0.5) mg/L and after the first week of life 0.8 (0.6) mg/L. In 31 (6 %) episodes, TPC was ≥2.0 mg/L, predominantly among term infants with renal impairment. Thirty-eight patients failed the neonatal hearing screening, but only four of these 38 had permanent hearing loss. All four had a TPC <2.0 mg/L. Conclusions: This extended-interval high-dose gentamicin regimen was associated with low numbers of elevated TPCs, low numbers of prescription errors and no evidence for ototoxicity.

Antibiotics and Antifungals in Neonatal Intensive Care Units: A Review

The incidence of infections is higher in the neonatal period than at any time of life. The basic treatment of infants with infection has not changed substantially over the last years. Antibiotics (with or without supportive care) are one of the most valuable resources in managing sick newborn babies. Early-onset (ascending or transplacental) or late-onset (hospital acquired) infections present different chronology, epidemiology, physiology and outcome. Some classes of antibiotics are frequently used in the neonatal period: penicillins, cephalosporins, aminoglycosides, glycopeptides, monobactams, carbapenems. Other classes of antibiotics (chloramphenicol, cotrimoxazole, macrolides, clindamycin, rifampicin and metronidazole) are rarely used. Due to emergence of resistant bacterial strains in Neonatal Intensive Care Units (NICU), other classes of antibiotics such as quinolones and linezolid will probably increase their therapeutic role in the future. Although new formulations have been developed for treatment of fungal infections in infants, amphotericin B remains first-line treatment for systemic Candida infection. Prophylactic antibiotic therapy is almost always undesirable. Challenges from pathogens and antibiotic resistance in the NICU may warrant modification of traditional antibiotic regimens. Knowledge of local flora and practical application of different antibiotic characteristics are key to an effective and safe utilization of antibiotics and antifungals in critical newborns admitted to the NICU, and especially in very low birth weight infants.

Validation of a dosage individualization table for extended-interval gentamicin in neonates

BACKGROUND

Extended-interval aminoglycoside dosing is increasingly used in neonates; however, guidance on how to monitor concentrations and adjust dosages accordingly is limited.

OBJECTIVE

To prospectively validate the use of a 22-hour gentamicin concentration dosing table for the individualization of extended-interval dosing in the neonatal population by examining the peak and trough concentrations achieved through its use.

METHODS

A prospective observational study was carried out on gentamicin concentrations achieved using a 22-hour post-first-dose gentamicin concentration dosing table for determining dosing intervals in neonates. Neonates (N = 104) in the first week of life, gestational age 23 weeks to full term, in level II and III neonatal intensive care units were included. Neonates were given gentamicin 5 mg/kg intravenously; a table using 22-hour post-first-dose gentamicin concentrations was then used to individualize dosing intervals. Pre- and post-serum gentamicin concentrations on the dosing interval indicated were measured with the second or third doses and used to calculate the peak and trough concentrations achieved.

RESULTS

Use of the 22-hour post-first-dose gentamicin concentration dosing table resulted in dosing intervals that provided appropriate peak (mean 10.55 mg/L) and trough (mean 0.75 mg/L) concentrations (with second or third doses) in all neonates. All patients had trough concentrations less than 2 mg/L, and 73% had a trough concentration less than 1 mg/L. No peak concentrations were less than 5 mg/L, 82% of patients had a peak concentration from 5 to 12 mg/L, and the remaining 18% had concentrations from 12.1 to 16 mg/L. Peak and trough concentrations were similar across all gestational ages.

CONCLUSIONS

Use of a 22-hour post-first-dose gentamicin concentration dosing table to individualize extended-interval gentamicin dosages in neonates resulted in appropriate peak and trough concentrations in all neonates studied. Use of this table will result in appropriate extended-interval aminoglycoside dosages in neonates early in treatment, using a single serum concentration.

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.

The efficacy and toxicity of two dosing-regimens of amikacin in neonates with sepsis

WHAT IS KNOWN AND OBJECTIVE

Neonatal sepsis is one of the most common reasons for admission to neonatal units in developing countries. Aminoglycosides widely used in its treatment are usually administered two or three times a day. Less frequent doing may be more convenient and as effective. We aim to compare the efficacy and safety (nephrotoxicity) of once daily vs. twice daily dosing of amikacin in neonates with suspected or proven sepsis and report on the drug's pharmacokinetics in these subjects.

METHODS

Thirty neonates of gestational age ≥ 36 weeks and body weight ≥ 2500 g with suspected or proven sepsis were randomized to receive amikacin either at a dose of 15 mg/kg once per day; group I (n = 15), or a dose of 7.5 mg/kg twice per day, group II (n = 15). All neonates received classical treatment of sepsis including antibiotics, hemodynamic support, inotropic support based on blood pressure levels and size of the heart in chest X-ray, if needed. Amikacin was infused over 1 h. Peak and trough serum samples for amikacin were measured for all infants at steady state. Nephrotoxicity was assessed by serum creatinine and urinary N-acetyl β-D-glucosaminidase before and 7 days after therapy. Clinical efficacy was compared using both observation of clinical status and normalization of laboratory tests.

RESULTS

All the patients in group I had achieved a trough level < 10 μg/mL and two patients had trough concentration > 10 μg/mL in group II. No significant difference between group I and group II in either baseline or day 7 serum creatinine was demonstrated (P >0.05). No significant difference was found between the two groups in clinical efficacy or renal toxicity. The calculated pharmacokinetic parameters were in group I and II, respectively: clearance = 63.8 ± 15.9 mL/kg/h and 73.5 ± 18.1 mL/kg/h; volume of distribution = 0.54 ± 0.09 L/kg and 0.61 ± 0.13 L/kg, half-life =6.1 ± 1.0 h and 5.95 ± 1.1 h.

WHAT IS NEW AND CONCLUSION

As expected, amikacin given once every 24 h to septic neonates of ≥ 36 weeks of gestation achieved higher peak levels and lower trough concentrations than the twice daily regimen. Treatment with once daily regimen did not lead to more nephrotoxicity than with a twice-daily regimen, and showed comparable efficacy.

Pharmacokinetic outcomes of a simplified, weight-based, extended-interval gentamicin dosing protocol in critically ill neonates

STUDY OBJECTIVE

To determine the pharmacokinetic outcomes of a simplified, weight-based, extended-interval gentamicin dosing protocol for critically ill neonates.

DESIGN

Retrospective medical record review with pharmacokinetic analysis.

SETTING

Two neonatal intensive care units in a pediatric tertiary care system.

PATIENTS

Sequential sample of 644 critically ill neonates less than 7 days old without evidence of renal dysfunction who received gentamicin, dosed by using a simplified, weight-based, extended-interval dosing protocol, on the first day of life for suspected sepsis between February 2003 and January 2008, and who had subsequent gentamicin plasma concentrations measured during their first week of life.

MEASUREMENTS AND MAIN RESULTS

Data were collected on birth weight, gestational age at birth, serum creatinine concentration during the first 10 days of life, medical conditions, and concomitant drugs. Gentamicin dosing and its pharmacokinetic parameters were noted for each patient. A mean dose of 3.96 mg/kg/dose of gentamicin was administered intravenously every 48 hours in neonates weighing less than 1250 g at birth and every 24 hours in those weighing 1250 g or more. If the neonate received concurrent indomethacin, however, gentamicin was given every 48 hours. Protocol success was defined as a peak gentamicin plasma concentration of 7-10 mg/L and a trough concentration less than 2 mg/L. Mean gentamicin peak and trough concentrations were 9.38 mg/L (95% confidence interval [CI] 9.24-9.52 mg/L) and 1.00 mg/L (95% CI 0.96-1.04 mg/L), respectively. With use of the protocol, 361 neonates (56.1%) achieved gentamicin peak plasma concentrations in the range defined as successful and 610 neonates (94.7%) achieved successful trough concentrations. The mean gentamicin apparent volume of distribution and half-life were 0.48 L/kg (95% CI 0.47-0.49 L/kg) and 8.31 hours (95% CI 8.09-8.52 hrs), respectively.

CONCLUSION

This simplified, weight-based, extended-interval gentamicin dosing protocol for critically ill neonates was effective in achieving therapeutic peak plasma concentrations of gentamicin in most of the patients and, as a high proportion of patients had acceptable trough concentrations, may minimize the potential for toxicity.

Accuracy of Empiric Gentamicin Dosing Guidelines in Neonates

OBJECTIVE

To evaluate the accuracy of a neonatal gentamicin nomogram to achieve therapeutic gentamicin serum concentrations without further adjustment, allowing for decreased serum drug monitoring

METHODS

Retrospective single center review of all gentamicin pharmacokinetic evaluations in patients ≤ 30 days of life from July 2005 – June 2007. Patients were evaluated for postnatal age, gestational age, weight, serum creatinine, dose/interval, serum drug peaks and troughs, results of discharge hearing test and recent use of indomethacin. Logistic regression was utilized to determine potential factors impacting overall dosing accuracy, potentially allowing for decreased therapeutic drug monitoring. Factors found to be significant were incorporated into new guidelines which were evaluated through pharmacokinetic modeling.

RESULTS

Overall accuracy rate was 84% when empiric dosing guidelines were utilized; 16% of all doses were changed due to supratherapeutic troughs and 1% were changed due to subtherapeutic peaks. Variables found to impact the necessity for dose changes incuded gestational age (p≤0.001), weight (p≤0.001), indomethacin use (p≤0.001), number of indomethacin doses used (p≤0.001 and p=0.009 for 1–3 and 4–6 doses, respectively), and SCr in patients ≥ 7 days old (p=0.028); however, only gestational age remained a significant predictor when all other factors were considered (p=0.008). The current guidelines were changed to account for increased troughs in patients ≤ 28 weeks gestation and examined through pharmacokinetic modeling. Pharmacokinetic modeling of the new guidelines predicted an overall accuracy of 94%.

CONCLUSIONS

From the data gathered regarding the accuracy in patients ≥ 35 weeks gestation, we recommend to decrease therapeutic drug monitoring within this cohort. Utilizing the results of regression analysis, the current guidelines have been adjusted to allow for increased clearance in patients ≤ 28 weeks gestation, although they still need to be prospectively evaluated.

Once daily dose gentamicin in neonates - is our dosing correct?

AIM

The aim of this paper is to study the safety and efficacy (measured by therapeutic level) of once daily gentamicin in neonates >or=32 weeks of gestation and <or=7 days of age.

SETTING

Level II neonatal intensive care unit.

SUBJECTS

Neonates >or=32 weeks of gestation and <or=7 days of age treated with gentamicin for presumed sepsis.

METHODS

Gentamicin was administered by intravenous injection at 4 mg/kg/day once daily. Peak and trough gentamicin levels were measured at the third dose.

RESULTS

In neonates with gestational age between 32 and 36 weeks, 14 out of 65 (22%) had trough serum concentration >2 mg/L. Only 39 (60%) had peak and trough levels within the therapeutic range. All babies who had audiometric evaluation (62 out of 65) had normal hearing. Out of the 65 babies, 60 had paired serum creatinine levels estimated and none had evidence of renal dysfunction. Among term neonates, only 2 out of 50 had the trough serum concentration of >2 mg/L. In 38 (76%) of the 50 neonates, the trough serum gentamicin concentration was <2.0 mg/L and the peak level was <10 mg/L. Forty-eight babies had audiometric evaluation which was normal.

CONCLUSION

A dose of 4 mg/kg/day produces serum gentamicin levels outside the therapeutic range in two-fifths of neonates between 32 and 36 +/- 6 weeks. A single dose of 4 mg/kg/day of gentamicin is appropriate for term babies and probably excessive for 32-36 weeks' neonates.

Serum gentamicin concentrations in encephalopathic infants are not affected by therapeutic hypothermia

OBJECTIVE

Mild hypothermia for 72 hours is neuroprotective in newborns with moderate or severe hypoxic-ischemic encephalopathy. A core temperature of 33.5 degrees C might reduce drug clearance leading to potential toxicity. Gentamicin is nephrotoxic and ototoxic at high serum concentrations. No study has investigated the influence of 72 hours of hypothermia on serum gentamicin concentrations (SGCs) in children of any age. We aimed to compare the SGCs in encephalopathic infants who underwent intensive care with therapeutic hypothermia or normothermia.

METHODS

Data were collected retrospectively from 2 NICUs in Bristol, United Kingdom, that offered cooling therapy within clinical trials since 1998. Eligible infants (n = 55) developed grade 2/3 encephalopathy after birth and fulfilled the entry criteria defined in the CoolCap trial. Encephalopathic infants with similar demographic values were either nursed under normothermia or 72 h-hypothermia. Once-daily gentamicin dosage (4-5 mg/kg) was administered, and trough SGC was recorded with corresponding creatinine concentrations. The time and number of omitted drug doses were noted.

RESULTS

Mean trough SGC (pre-second dose) and mean plasma creatinine concentrations for both treatment groups were similar (gentamicin: 2.19 +/- 1.7 [hypothermia] and 2.30 +/- 2.0 [normothermia] mg/L; creatinine: 115.6 +/- 42.8 [hypothermia] and 121.0 +/- 45.1 [normothermia] mumol/L). Forty percent of the trough SGCs in both groups were above the recommended trough concentration of 2.0 mg/L. A significant correlation (r(2) = 0.36) was found between high SGCs and impaired renal function assessed by raised plasma creatinine levels regardless of treatment options.

CONCLUSIONS

Our data confirm that impaired renal function is strongly associated with high SGCs. Reduced body temperatures do not affect the clearance of gentamicin.

Parenteral antibiotics for the treatment of serious neonatal bacterial infections in developing country settings

BACKGROUND

A number of special issues must be considered when selecting simple, safe, inexpensive, and effective antimicrobial regimens for treatment of neonatal sepsis in developing country community settings.

METHODS

We reviewed available data regarding pharmacologic profiles of parenteral antibiotics with specific attention to properties relevant to their use in the treatment of neonatal infections in developing country communities.

RESULTS

For community-based management of neonatal infections, particularly attractive properties include efficacy and safety of extended-interval, intramuscular dosing regimens. The penicillins and cephalosporins have relatively favorable efficacy and safety profiles. Although the aminoglycosides have narrow therapeutic indices, when used appropriately, they are safe and effective. Although inexpensive and effective, the potential for significant life-threatening toxicity among neonates associated with chloramphenicol makes it the least preferred of the parenteral agents for empiric therapy.

CONCLUSIONS

The preferred parenteral regimens for community and first-level facility use are a combination of procaine penicillin G and gentamicin, or ceftriaxone given alone, which are safe and retain efficacy when dosed at extended intervals (> or =24 hours) by intramuscular administration.

[Comparison of two gentamicin dosing schedules in the newborn]

INTRODUCTION

Gentamicin is widely used in full-term neonates as empirical therapy for early-onset suspected or proven sepsis. Several dosing schedules for gentamicin have been recommended for this neonatal population.

OBJECTIVE

To compare gentamicin serum levels, efficacy and toxicity of two dosing schedules in term and preterm newborns.

MATERIAL AND METHODS

The study included 200 newborns who were started on gentamicin therapy. Group A (N=100) was prescribed a multiple-daily dosing regimen and Group B (N=100) on a once-daily dosing regimen. Newborns in Group A received gentamicin at 2.5-3.5 mg/kg/dose q12-18 h depending on postnatal age and serum creatinine levels, and newborns in Group B received 4-5 mg/kg/dose q24-48 h depending on postconceptional and postnatal age. All peak and trough serum drug levels, demographic data, and markers of potential nephrotoxicity and ototoxicity were compared.

RESULTS

Peak serum gentamicin levels were significantly higher (8.2+/-0.22 microg/ml vs. 5.9+/-0.13 microg/ml; p <or= 0.001) and trough levels were significantly lower (0.9+/-0.06 microg/ml vs. 1.7+/-0.08 microg/ml; p <or= 0.001) in Group B than in Group A. There was no significant difference between the groups either in the clinical failure rate or in the nephrotoxicity or ototoxicity outcomes.

CONCLUSIONS

Once-daily dosing regimen of gentamicin in preterm and term newborns is safe and effective, with a reduced risk of serum drug concentrations falling outside the therapeutic range.

Determination of extended-interval gentamicin dosing for neonatal patients in developing countries

BACKGROUND

Infectious diseases account for an estimated 36% of neonatal deaths globally. The purpose of this study was to determine safe, effective, simplified dosing regimens of gentamicin for treatment of neonatal sepsis in developing countries.

METHODS

Neonates with suspected sepsis in the neonatal intensive care unit (NICU) at Christian Medical College and Hospital (CMC), Vellore, India (n = 49), and Dhaka Shishu Hospital (DSH), Bangladesh (n = 59), were administered gentamicin intravenously according to the following regimens: (1) 10 mg every 48 hours for neonates <2000 g; (2) 10 mg every 24 hours for neonates 2000-2249 g; and (3) 13.5 mg every 24 hours for neonates > or =2500 g. Serum gentamicin concentration (SGC) at steady state and pharmacokinetic indices were determined. Renal function was followed while under treatment and hearing was examined 6 weeks to 3 months after discharge.

RESULTS

All neonates, except 1 weighing 2000-2249 g at DSH, had a peak SGC >4 microg/mL. Overall, 5 (10%) and 17 (29%) infants had a peak SGC level > or =12 microg/mL from CMC and DSH, respectively, and 10 (20%) and 4 (7%) cases from CMC and DSH, respectively, had a trough SGC level > or =2 microg/mL. However, no infant <2000 g had a trough SGC level > or =2 microg/mL. We found no evidence of gentamicin nephrotoxicity or ototoxicity.

CONCLUSION

Safe, therapeutic gentamicin dosing regimens were identified for treatment of neonatal sepsis in developing country settings. Administration of these doses could be simplified through use of Uniject, a prefilled, single injection device designed to make injections safe and easy to deliver in developing country settings.

"Random" gentamicin concentrations do not predict trough levels in neonates receiving once daily fixed dose regimens

BACKGROUND

Monitoring plasma gentamicin concentrations in neonates 24 hours after a once daily dose (4 mg/kg) often necessitates additional blood sampling. In adults a nomogram has been developed enabling evaluation of gentamicin doses by sampling concentrations with other blood tests, 4-16 hours after administration. We attempted to develop a similar nomogram for neonates.

METHODS

In addition to standard 24 hour sampling to monitor trough concentrations, one additional "random" gentamicin concentration was measured in each of 50 neonates < 4 days of age (median gestation 33 weeks [28-41]), when other blood samples were clinically necessary, 4-20 hours after gentamicin administration. 24 hour concentrations of > 1 mg/L were considered high, and an indication to extend the dosing interval.

RESULTS

Highest correlation (r2 = 0.51) of plasma gentamicin concentration against time (4 to 20 hours) was with logarithmic regression. A line drawn 0.5 mg/L below the true regression line resulted in all babies with 24 hr gentamicin concentrations > 1 mg/L having the additional "random" test result above that line, i.e. 100% sensitivity for 24 hour concentrations > 1 mg/L, though only 58% specificity. Having created the nomogram, 39 further babies (median gestation 34 weeks [28-41]), were studied and results tested against the nomogram. In this validation group, sensitivity of the nomogram for 24 hr concentrations > 1 mg/L was 92%; specificity 14%, positive predictive value 66%, and negative predictive value 50%. Prematurity (< or = 37 weeks) was a more sensitive (94%) and specific (61%) indicator of high 24-hour concentrations. 62 (87%) of 71 preterm babies had high 24-hour concentrations.

CONCLUSION

It was not possible to construct a nomogram to predict gentamicin concentrations at 24 hours in neonates with a variety of gestational ages. Dosage tailored to gestation with monitoring of trough concentrations remains management of choice.

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.

Aminoglycoside extended interval dosing in neonates is safe and effective: a meta-analysis

OBJECTIVES

To review the evidence from controlled clinical trials of neonates given equal daily aminoglycoside doses as extended interval dosing (dosage interval typically 24 hours in term and 36-48 hours in immature neonates) compared with traditional dosing (dosage interval typically 8-12 hours in term and 12-24 hours in immature neonates).

DESIGN

Systematic review and meta-analysis of controlled trials found in electronic databases, trial registers, and references in reviews and selected trials.

SETTINGS

The selected trials were blinded and assessed for methodological quality. Each trial's own predefined criteria for treatment failure, nephrotoxicity, ototoxicity, and therapeutic serum drug concentrations were used.

SUBJECTS

Controlled trials of neonatal aminoglycoside treatment in which equal aminoglycoside daily doses were given at traditional and extended dosage intervals.

MAIN OUTCOME MEASURES

Serum drug concentrations outside the therapeutic range. Treatment failure and toxicity.

RESULTS

Sixteen trials involving 823 neonates met the inclusion criteria for the systematic review. Twelve trials involving 698 neonates were included in the meta-analysis of the pharmacokinetics. Compared with traditional dosing, extended interval dosing was associated with a significantly lower risk of both peak (summary risk ratio 0.50, 95% confidence interval 0.26 to 0.94) and trough (0.36, 0.25 to 0.56) serum drug concentrations outside the therapeutic range. Accurate information on treatment failure was obtained in nine trials involving 555 neonates. One trial reported treatment failure. In this trial two neonates in the traditional dosing group did not respond to treatment within 72 hours. Nephrotoxicity was investigated in 589 neonates in 12 trials and ototoxicity in 210 neonates in four trials, with no significant differences between the two dosing regimens.

CONCLUSIONS

Extended interval dosing of aminoglycosides in neonates is safe and effective, with a reduced risk of serum drug concentrations outside the therapeutic range.

Gentamicin usage in newborns--a simple and practical regime

OBJECTIVE

To audit the gentamicin usage guidelines due to concerns that it resulted in too many sub-therapeutic peak levels, devise a new guideline and re-audit after change in practise.

METHOD

A prospective audit of 50 sets of gentamicin levels on the Old Gentamicin Regime was conducted. Desired levels were a trough <2 microg/ml and peak between 5-10 microg/ml. These were taken just before and one hour after the third dose respectively. Peak levels were found to be in the sub-therapeutic range in the majority on this regime. Therefore the New Gentamicin Regime was put into practise. A re-audit was conducted of the new gentamicin regime and 60 trough levels were taken. Peak levels were taken in only 20 newborns with the intention of not doing peak levels routinely if these were satisfactory and the data were analysed.

RESULTS

Although trough levels were satisfactory in 98% (49/50), peak levels were sub-therapeutic in 92% (46/50) on the old gentamicin regime. Following change in practise to the new gentamicin regime trough levels were satisfactory in 96.6% (58/60). We collected 20 peak levels and these were satisfactory in 80% (16/20).

CONCLUSIONS

The new gentamicin usage guideline achieves peak levels in the therapeutic range in the majority without any added risk of toxic trough levels. Peak levels need not be done routinely in all newborns on the new regime.

The effect of sepsis upon gentamicin pharmacokinetics in neonates

AIM

To investigate the effect of sepsis upon the volume of distribution (Vd) of gentamicin in neonates.

METHODS

A retrospective chart review was conducted of neonates admitted to Dunedin Hospital who had gentamicin concentrations performed between 1st January 2000 and 30th October 2003. Data from 277 neonates, including a total of 576 gentamicin concentrations, were included in the pharmacokinetic analysis. Fifteen (5.4%) of the neonates had confirmed sepsis. Pharmacokinetic analyses were performed with NONMEM using a one compartment first order elimination model. Duration of infusion (D) was included as a parameter in the model. Covariates included sepsis (SEP), chronological age, gestational age (GA), birth weight, current weight, gender, Apgar score at 1 (AP1) and 5 (AP2) minutes, plasma C-reactive protein and serum creatinine.

RESULTS

The initial model provided a mean estimates of clearance (CL) of 0.0460 l kg(-1) h(-1), volume of distribution (Vd) of 0.483 l kg(-1) and D of 0.748 h. The magnitudes of interpatient variability, expressed as CV%, were 29.2% for CL, 20.8% for Vd and 71.5% for D. The magnitude of residual variability in gentamicin concentrations was 88.0%. The final pharmacokinetic model was: CL = (0.0177 + 0.00147.(GA-20) + 0.000635.AP2) l kg(-1) h(-1), Vd = (0.483 +0.0656. sepsis) l kg(-1), D = 0.672 h. The interpatient variability (CV%) was 22.8% for CL, 22.8% for Vd and 97.7% for D. The magnitude of residual variability in gentamicin concentrations was 83.3%.

CONCLUSIONS

The 14% increase in Vd in septic neonates implies that larger doses may be required to achieve peak therapeutic concentrations in the presence of sepsis. D is an important parameter in neonatal pharmacokinetic models.

High compared with standard gentamicin dosing for chorioamnionitis: a comparison of maternal and fetal serum drug levels

OBJECTIVE

To compare umbilical cord and maternal serum peak gentamicin concentration, gentamicin elimination, and clinical outcomes between women who received once-daily compared with standard, thrice-daily dosing for clinical chorioamnionitis.

METHODS

We randomly assigned 38 laboring women, at least 34 weeks gestation, with clinical chorioamnionitis, into 1 of 2 gentamicin dosing groups: 5.1 mg/kg every 24 hours (once-daily; n = 18), or 120 mg followed by 80 mg every 8 hours (standard; n = 20). We measured maternal serum peak and delivery gentamicin concentrations and cord serum levels at delivery. Polynomial curve fitting was used to summarize gentamicin elimination. We also compared maternal and neonatal outcomes.

RESULTS

Demographic characteristics of the 2 groups were similar. Median maternal peak gentamicin levels were higher with once-daily (18.2 microg/mL) compared with standard dosing (7.1 microg/mL) (P < .001). Maternal serum levels decreased below 2 microg/mL by 10 hours in the once-daily group and by 5 hours in the standard dosing group. Extrapolated peak cord serum levels were 6.9 microg/mL in the once-daily and 2.9 microg/mL in the standard dosing arm. Cord levels decreased below 2 microg/mL by 10 hours in the once-daily and by 5 hours in the standard dosing group. We found no differences in maternal or neonatal outcomes.

CONCLUSION

Peak maternal serum gentamicin levels ranged from 13 to 25 microg/mL after a dose of 5.1 mg/kg. Single-dose gentamicin resulted in fetal serum peak levels that were closer to optimal neonatal values. Gentamicin clearance in the term fetus was similar to published values for the newborn infant. No adverse effects of high-dose therapy were noted.

Dosage regimen of arbekacin for methicillin-resistant Staphylococcus aureus infection in newborns and infants

BACKGROUND

Arbekacin (ABK) is an aminoglycoside antibiotic that has a dose-dependent bactericidal action. Because it inhibits the production of toxic shock syndrome toxin-1 (TSST-1) by methicillin-resistant Staphylococcus aureus (MRSA), it has attracted attention as a therapeutic drug for MRSA infection. In this study, the authors investigated the pharmacokinetics of ABK based on therapeutic drug monitoring (TDM), in order to establish an effective dosage regimen with minimal adverse reactions in MRSA infected newborns and infants.

METHODS

Arbekacin was administered to nine MRSA infected newborns and infants between October 2000 and March 2002. Following the initial ABK administration, blood was collected and the blood concentration of ABK was measured. The blood concentrations of ABK were analyzed by the two-compartment model or by a model-independent method in order to elucidate the pharmacokinetics of ABK. Pharmacokinetic analysis was performed using WinNonlin Professional V3.1.

RESULTS

The mean age at initial ABK administration was 24.0 +/- 26.0 days (postconceptional age: 39.2 +/- 3.9 weeks). The increase in the peak blood concentration of ABK was 2.40 +/- 0.20 microg/mL per mg ABK per kg bodyweight, showing great consistency among cases. The elimination half-life of ABK was 0.22-3.52 h in the alpha phase (T(1/2alpha)) and 2.42-33.44 h in the beta phase (T(1/2beta)), showing great variation among cases. The distribution volume was 0.75 +/- 0.13 L/kg, and systemic clearance was 0.054 +/- 0.012 L/h/kg. ABK alleviated clinical symptoms and inflammations in all cases.

CONCLUSION

Nine newborns and infants with MRSA infection and various underlying diseases were successfully treated with TDM-based administration of ABK with no severe adverse reactions.

Validation of a simplified netilmicin dosage regimen in infants

The aim of this study was to validate a simplified high-dosage, extended-interval netilmicin dosage regimen for infants. A total of 129 infants receiving 163 treatment courses of netilmicin (6 mg kg every 24 or 36 h depending on gestational age (GA), postnatal age and postmenstrual age) was analysed. Serum netilmicin concentrations were monitored before (Cmin), 30 min (C0.5h) after and 7.5 h (C7.5h) after the third dose. In 110 patients during first week of life mean C0.5h was 10.5 mg/l. Mean C0.5h was significantly lower (9.0 mg/l) in 38 infants older than 1 week of age. 14 of 15 patients with Cmin levels > or = 2 mg/l receiving netilmicin every 36 h were < 28 weeks of gestation. In the first week of life significant correlations between GA and elimination half-life (p < 0.001) and between plasma creatinine and elevated Cmin (p < 0.002) were found, but no correlation between C0.5h and GA. In this high-dosage regimen a dosing interval of 48 h for GA < 29 weeks, 36 h for GA 29-36 weeks and 24 h for full term babies seems appropriate, during first week of life, to avoid the majority of elevated trough levels and still obtain maximal therapeutic efficacy.

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.

A randomised, controlled trial of once daily and multi-dose daily gentamicin in young Kenyan infants

AIMS

To test the suitability of a simple once daily (OD) gentamicin regimen for use in young infants where routine therapeutic drug monitoring is not possible.

METHODS

In an open, randomised, controlled trial, infants with suspected severe sepsis admitted to a Kenyan, rural district hospital received a novel, OD gentamicin regimen or routine multi-dose (MD) regimens.

RESULTS

A total of 297 infants (over 40% < or =7 days) were randomised per protocol; 292 contributed at least some data for analysis of pharmacological endpoints. One hour after the first dose, 5% (7/136) and 28% (35/123) of infants in OD and MD arms respectively had plasma gentamicin concentrations <4 microg/ml (a surrogate of treatment inadequacy). Geometric mean gentamicin concentrations at this time were 9.0 microg/ml (95% CI 8.3 to 9.9) and 4.7 microg/ml (95% CI 4.2 to 5.3) respectively. By the fourth day, pre-dose concentrations > or =2 microg/ml (a surrogate of potential treatment toxicity) were found in 6% (5/89) and 24% (21/86) of infants respectively. Mortality was similar in both groups and clinically insignificant, although potential gentamicin induced renal toxicity was observed in <2% infants.

CONCLUSIONS

A "two, four, six, eight" OD gentamicin regime, appropriate for premature infants and those in the first days and weeks of life, seems a suitable, safe prescribing guide in resource poor settings.

Once-daily gentamicin dosing for the preterm and term newborn: proposal for a simple regimen that achieves target levels

OBJECTIVE

Based on recent safety and efficacy data, combined with the known pharmacokinetic parameters of aminoglycosides in the newborn, once-daily gentamicin should be preferable to the many other dosing regimens currently in use. Although there are growing data to support its use in term newborns, experience with preterm infants is more limited. In our Neonatal Intensive Care Unit, we experienced difficulties regarding complicated dosing regimens, actual dosing errors, and the tendency to check trough and peak levels around the third dose for infants receiving only a 48 hour course. Therefore, we conducted a quality improvement initiative in which we developed and tested a clinical practice guideline for the use of once-daily gentamicin for preterm and term infants that we hoped would yield trough and peak levels in our target range.

METHODS

We combined a review of the published English language literature with pharmacokinetic analysis of our own data prior to initiation of this new regimen to design the following dosing regimen: <35 weeks gestation: 3 mg/kg q 24 hours, > or =35 weeks gestation: 4 mg/kg q 24 hours. Our goal serum levels were a trough < or =2 microg/ml and a peak between 6 and 12 microg/ml. We collected and analyzed trough and peak levels from all infants receiving this dosing regimen in the first week of life for at least 72 hours between 3/1/99 and 12/31/00.

RESULTS

In total, 214 babies met our inclusion criteria, 75 of whom were <35 weeks gestation. 100% of babies of all gestational ages had a nontoxic trough level. For infants <35 weeks gestation, 79% had a therapeutic peak level, with a mean value of 6.8 microg/ml. For infants of at least 35 weeks gestation, 93% had a therapeutic peak level, with a mean value of 8.4 microg/ml. 92% of nontherapeutic peaks were too low.

CONCLUSION

This study of once-daily gentamicin represents the largest sample size of pre-term infants published to date. The proposed regimen is simple and yields a high proportion of desirable levels. We recommend it for use in preterm and term newborns.

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.

A gentamicin pharmacokinetic population model and once-daily dosing algorithm for neonates

STUDY OBJECTIVE

To develop a gentamicin pharmacokinetic population model and once-daily dosing algorithm for neonates younger than 10 days.

DESIGN

Prospective, open-label study.

SETTING

Neonatal intensive care unit.

PATIENTS

One hundred thirty-nine neonates prescribed gentamicin.

MEASUREMENTS AND MAIN RESULTS

Gentamicin peak and trough serum concentrations were collected from 139 neonates divided into three groups who were receiving one of the following intravenous 24-hour gentamicin regimens during the first 10 days of life, based on gestational age and birth weight (group 1, < 28 wks, 2.5 mg/kg; group 2, 28-34 wks, 3 mg/kg; and group 3, > 34 wks, 4 mg/kg). A structural model was developed in ADAPT II software using a MAP Bayesian approach. Final population parameter estimates were calculated using iterative two-stage analysis. The median (range) gestational age and birth weight, respectively, were 32 weeks (23-42 wks) and 1.92 kg (0.47-5.00 kg). The final one-compartmental linear model had a median (range) gentamicin total clearance, half-life, and volume of distribution of 0.0709 L/hour (0.0151-0.246 L/hr), 8.59 hours (4.88-16.9 hrs), and 0.262 L (0.0903-0.929 L), respectively. Total clearance increased as gestational age increased (p<0.001). Group 1 (10.2 hrs) had a significantly longer half-life than either group 2 (8.89 hrs, p<0.01) or group 3 (6.98 hrs, p<0.01). Total clearance was associated with gestational age and birth weight: clearance (L/hr) = (0.00504 + [0.00108 x gestational age]) x birth weight (coefficient of determination [r2] = 0.897), and volume of distribution was associated with birth weight (r2 = 0.700). The following dosing algorithm was designed to reach a therapeutic 24-hour area under the curve (87.5 mg/L x hr) in neonates during the first 10 days after birth: 24-hour gentamicin dose (mg) = (0.441 + [0.0945 x gestational age]) x birth weight.

CONCLUSION

This dosing algorithm provides a new approach for determining initial gentamicin dosing regimens in neonates; however, clinical validation is required.

[Once-daily gentamicin dosing versus thrice-daily dosing in infants with acute pyelonephritis]

BACKGROUND

Once-daily dosing (ODD) of gentamicin is advocated as an effective and safe treatment of Gram-negative bacterial infections in adults. There are insufficient data in the literature to justify its use in infants.

OBJECTIVES

To compare the efficacy of ODD of gentamicin with that of classical thrice-daily (t.i.d.) administration in infants with acute pyelonephritis.

METHODS

We performed a quasi-experimental study comparing 33 infants who received ODD of gentamicin with a historical control group of 25 infants treated with gentamicin t.i.d. Leukocytosis, C-reactive protein, creatinine, gentamicin dose, peak and trough values, time required for disappearance of fever, and outcome were analyzed.

RESULTS

The mean doses of gentamicin (mg/kg/day) were higher in the t.i.d. group (6.4 1.14) than in the ODD group (5.06 0.22; p < 0.001). Peak serum gentamicin concentrations (micro g/ml) were significantly higher in the ODD group (9.32 1.4) than in the t.i.d. group (5.09 1.15; p < 0.001). Mean trough gentamicin concentrations (micro g/ml) were lower in the ODD group than in the t.i.d. group (0.23 0.26 vs 0.78 0.45; p 0.001). There were no significant differences in the duration of fever between the groups (30.64 32 hours in the t.i.d. group vs. 28.57 32 hours in the ODD group). Serum creatinine levels were normal during treatment in both groups. In all patients outcome was good and no adverse effects were noted.

CONCLUSIONS

Treatment with ODD of gentamicin in our population of infants with acute pyelonephritis was as effective as traditional administration t.i.d. and possibly was equally safe or safer.

The effect of vecuronium is enhanced by a large rather than a modest dose of gentamicin as compared with no preoperative gentamicin

We compared the effect of two doses of gentamicin versus no gentamicin (NG) given before surgery on the neuromuscular relaxant effect of vecuronium. Seventy patients (intraabdominal procedures) were randomly allocated to receive preoperative large-dose (4 mg/kg) gentamicin (LD), a modest dose (1.2 mg/kg) of gentamicin (MD), or NG. No more than one dose of gentamicin was given before the vecuronium administration. Serum gentamicin levels, the time for 25% recovery of the first twitch in the train-of-four after a bolus of vecuronium, and the time from cessation of the vecuronium infusion to extubation of the trachea were estimated. Serum gentamicin levels were higher (P < 0.001) for LD than MD. The time for 25% recovery of the first twitch after the vecuronium bolus was slightly longer with LD than MD (P = 0.06) and longer in LD than NG (P = 0.001) (42.9 +/- 23.6 min versus 36.2 +/- 17 min and 27.4 +/- 9 min, respectively). The time to extubation was similar with LD and MD and longer for LD than NG (P = 0.008) (34.7 +/- 19.2 min versus 27.4 +/- 19.3 min and 19.4 +/- 10.1 min, respectively). The differences in these times were insignificant between MD and NG. Gentamicin administered as a LD rather than MD enhanced the neuromuscular blockade of vecuronium as compared with NG given before surgery.

IMPLICATIONS

We demonstrated that the neuromuscular relaxant effect of vecuronium is enhanced by a large (4 mg/kg) rather than a modest (1.2 mg/kg) dose of gentamicin as compared with no gentamicin given before surgery.