Observational trial of a 48-hour gentamicin dosing regimen derived from Monte Carlo simulations in infants born at less than 28 weeks' gestation

Simplified Dosing Regimens for Gentamicin in Neonatal Sepsis

Background: The effectiveness of antibiotics for the treatment of severe bacterial infections in newborns in resource-limited settings has been determined by empirical evidence. However, such an approach does not warrant optimal exposure to antibiotic agents, which are known to show different disposition characteristics in this population. Here we evaluate the rationale for a simplified regimen of gentamicin taking into account the effect of body size and organ maturation on pharmacokinetics. The analysis is supported by efficacy data from a series of clinical trials in this population.

Methods: A previously published pharmacokinetic model was used to simulate gentamicin concentration vs. time profiles in a virtual cohort of neonates. Model predictive performance was assessed by supplementary external validation procedures using therapeutic drug monitoring data collected in neonates and young infants with or without sepsis. Subsequently, clinical trial simulations were performed to characterize the exposure to intra-muscular gentamicin after a q.d. regimen. The selection of a simplified regimen was based on peak and trough drug levels during the course of treatment.

Results: In contrast to current World Health Organization guidelines, which recommend gentamicin doses between 5 and 7.5 mg/kg, our analysis shows that gentamicin can be used as a fixed dose regimen according to three weight-bands: 10 mg for patients with body weight <2.5 kg, 16 mg for patients with body weight between 2.5 and 4 kg, and 30 mg for those with body weight >4 kg.

Conclusion: The choice of the dose of an antibiotic must be supported by a strong scientific rationale, taking into account the differences in drug disposition in the target patient population. Our analysis reveals that a simplified regimen is feasible and could be used in resource-limited settings for the treatment of sepsis in neonates and young infants with sepsis aged 0–59 days.

Optimizing gentamicin conventional and extended interval dosing in neonates using Monte Carlo simulation - a retrospective study

BACKGROUND

Although aminoglycosides are routinely used in neonates, controversy exists regarding empiric dosing regimens. The objectives were to determine gentamicin pharmacokinetics in neonates, and develop initial mg/kg dosing recommendations that optimized target peak and trough concentration attainment for conventional and extended-interval dosing (EID) regimens.

METHODS

Patient demographics and steady-state gentamicin concentration data were retrospectively collected for 60 neonates with no renal impairment admitted to a level III neonatal intensive care unit. Mean pharmacokinetics were calculated and multiple linear regression was performed to determine significant covariates of clearance (L/h) and volume of distribution (L). Classification and regression tree (CART) analysis identified breakpoints for significant covariates. Monte Carlo Simulation (MCS) was used to determine optimal dosing recommendations for each CART-identified sub-group.

RESULTS

Gentamicin clearance and volume of distribution were significantly associated with weight at gentamicin initiation. CART-identified breakpoints for weight at gentamicin initiation were: ≤ 850 g, 851-1200 g, and > 1200 g. MCS identified that a conventional dose of gentamicin 3.5 mg/kg given every 48 h or an EID of 8-9 mg/kg administered every 72 h in neonates weighing ≤ 850 g, and every 24 and 48 h, respectively, in neonates weighing 851-1200 g, provided the best probability of attaining conventional (peak: 5-10 mg/L and trough: ≤ 2 mg/L) and EID targets (peak:12-20 mg/L, trough:≤ 0.5 mg/L). Insufficient sample size in the > 1200 g neonatal group precluded further investigation of this weight category.

CONCLUSIONS

This study provides initial gentamicin dosing recommendations that optimize target attainment for conventional and EID regimens in neonates weighing ≤ 1200 g. Prospective validation and empiric dose optimization for neonates > 1200 g is needed.

Population pharmacokinetic modelling, Monte Carlo simulation and semi-mechanistic pharmacodynamic modelling as tools to personalize gentamicin therapy

Population pharmacokinetic modelling, Monte Carlo simulation and semi-mechanistic pharmacodynamic modelling are all tools that can be applied to personalize gentamicin therapy. This review summarizes and evaluates literature knowledge on the population pharmacokinetics and pharmacodynamics of gentamicin and identifies areas where further research is required to successfully individualize gentamicin therapy using modelling and simulation techniques. Thirty-five studies have developed a population pharmacokinetic model of gentamicin and 15 studies have made dosing recommendations based on Monte Carlo simulation. Variability in gentamicin clearance was most commonly related to renal function in adults and body weight and age in paediatrics. Nine studies have related aminoglycoside exposure indices to clinical outcomes. Most commonly, efficacy has been linked to a Cmax/MIC ≥7-10 and a AUC24/MIC ≥70-100. No study to date has shown a relationship between predicted achievement of exposure targets and actual clinical success. Five studies have developed a semi-mechanistic pharmacokinetic/pharmacodynamic model to predict bacteria killing and regrowth following gentamicin exposure and one study has developed a deterministic model of aminoglycoside nephrotoxicity. More complex semi-mechanistic models are required that consider the immune response, use of multiple antibiotics, the severity of illness, and both efficacy and toxicity. As our understanding grows, dosing of gentamicin based on sound pharmacokinetic/pharmacodynamic principles should be applied more commonly in clinical practice.

Extended-interval Dosing of Gentamicin in Premature Neonates Born at <32 Weeks' Gestation and >7 Days of age

PURPOSE

Extended-interval dosing (EID) regimens of gentamicin have been validated for treating confirmed or suspected early- and late-onset sepsis in preterm infants in the first week of life. Despite the marked changes in volume of distribution and renal clearance in preterm infants after the first few days of life, few studies have validated EID regimens of gentamicin in this population. The objective of the study was to evaluate an EID regimen of gentamicin in infants born at <32 weeks' gestational age and aged >7 days.

METHODS

This observational study of an EID regimen was conducted in 39 infants. Dosing interval was based on the serum drug concentration at 22 hours after the administration of the first dose of 5 mg/kg. Gentamicin peak (5-12 µg/mL) and trough (<2 µg/mL) levels were compared to those in a historical control group of 39 infants who received traditional-interval dosing (TID) of 2.5 mg/kg of gentamicin with dosing intervals of 8, 12, or 24 hours.

FINDINGS

There were no differences in birthweight, gestational age at birth, postmenstrual age, weight at the start of gentamicin administration, postnatal age, small for gestational age status, antenatal corticosteroid use, or postnatal indomethacin exposure between the 2 groups. In the EID group, dosing intervals were 24 hours in 30 infants, 36 hours in 6 infants, and 48 hours in 3 infants. Compared with the TID group (n = 39), the EID group had a significantly higher peak level (median, 9.0 vs 4.7 µg/mL) and a significantly lower trough level (median, 0.7 vs 1.1 µg/mL) (both, P < 0.001). On regression analysis, the postmenstrual age was correlated significantly with trough levels in the EID group. There was no adverse effect on renal function in either group. On follow-up, 1 infant in the EID group and 2 infants in the TID group had evidence of sensorineural hearing loss.

IMPLICATIONS

In infants born at <32 weeks' gestation and >7 days of age, an EID gentamicin regimen, with a dosing interval based on a single concentration measurement at 22 hours after the administration of the first dose, achieved therapeutic peak and trough levels and performed significantly better than did a TID regimen in reaching target peak and trough levels. Larger-scale trials are needed for assessing the clinical efficacy (treatment failure/success) of these regimens.

Evaluation of evidence for pharmacokinetics-pharmacodynamics-based dose optimization of antimicrobials for treating Gram-negative infections in neonates

BACKGROUND & OBJECTIVES

Neonates present a special subgroup of population in whom optimization of antimicrobial dosing can be particularly challenging. Gram-negative infections are common in neonates, and inpatient treatment along with critical care is needed for the management of these infections. Dosing recommendations are often extrapolated from evidence generated in older patient populations. This systematic review was done to identify the knowledge gaps in the pharmacokinetics-pharmacodynamics (PK-PD)-based optimized dosing schedule for parenteral antimicrobials for Gram-negative neonatal infections.

METHODS

Relevant research questions were identified. An extensive electronic and manual search methodology was used. Potentially eligible articles were screened for eligibility. The relevant data were extracted independently in a pre-specified data extraction form. Pooling of data was planned.

RESULTS

Of the 340 records screened, 24 studies were included for data extraction and incorporation in the review [carbapenems - imipenem and meropenem (n=7); aminoglycosides - amikacin and gentamicin (n=9); piperacillin-tazobactam (n=2); quinolones (n=2); third- and fourth-generation cephalosporins (n=4) and colistin nil]. For each of the drug categories, the information for all the questions that the review sought to answer was incomplete. There was a wide variability in the covariates assessed, and pooling of results could not be undertaken.

INTERPRETATION & CONCLUSIONS

There is a wide knowledge gap for determining the doses of antimicrobials used for Gram-negative infections in neonates. A different profile of newborns in the developing countries could affect the disposition of antimicrobials for Gram negative infections, necessitating the generation of PK-PD data of antimicrobials in neonates from developing countries. Further, guidelines for treatment of neonatal conditions may incorporate the evidence-based PK-PD-guided dosing regimens.

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.

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.

Applications of the pharmacokinetic/pharmacodynamic (PK/PD) analysis of antimicrobial agents

The alarming increase of resistance against multiple currently available antibiotics is leading to a rapid lose of treatment options against infectious diseases. Since the antibiotic resistance is partially due to a misuse or abuse of the antibiotics, this situation can be reverted when improving their use. One strategy is the optimization of the antimicrobial dosing regimens. In fact, inappropriate drug choice and suboptimal dosing are two major factors that should be considered because they lead to the emergence of drug resistance and consequently, poorer clinical outcomes. Pharmacokinetic/pharmacodynamic (PK/PD) analysis in combination with Monte Carlo simulation allows to optimize dosing regimens of the antibiotic agents in order to conserve their therapeutic value. Therefore, the aim of this review is to explain the basis of the PK/PD analysis and associated techniques, and provide a brief revision of the applications of PK/PD analysis from a therapeutic point-of-view. The establishment and reevaluation of clinical breakpoints is the sticking point in antibiotic therapy as the clinical use of the antibiotics depends on them. Two methodologies are described to establish the PK/PD breakpoints, which are a big part of the clinical breakpoint setting machine. Furthermore, the main subpopulations of patients with altered characteristics that can condition the PK/PD behavior (such as critically ill, elderly, pediatric or obese patients) and therefore, the outcome of the antibiotic therapy, are reviewed. Finally, some recommendations are provided from a PK/PD point of view to enhance the efficacy of prophylaxis protocols used in surgery.

Extended interval dosing of gentamicin in premature neonates ≤ 28-week gestation

AIM

To evaluate an extended interval dosing (EID) regimen of gentamicin in neonates ≤28-week gestation.

METHODS

In 2008, an EID regimen for gentamicin was introduced for all neonates admitted to the NICU in Calgary. The dosing interval was based on a 22 h level after the first dose of 5mg/kg. We conducted an observational study in 33 infants ≤28-week gestation on the EID regimen from the first day of life and compared gentamicin peak and trough levels with a historical control of 34 infants who received gentamicin in a dose of 2.5 mg/kg every 24 h (TID, traditional interval dosing).

RESULTS

In the EID group, based on the 22 h level, dosing interval was 36 h in 20 neonates and 48 h in 13 neonates. All neonates, except one, achieved therapeutic peak and trough levels. Compared to the TID group, the EID group had higher peak levels (median 9.8 μg/mL vs. 4.6 μg/mL, p < 0.001) with no difference in trough levels. With target peak levels of 5-12 μg/mL and trough levels of <2 μg/mL, a higher proportion of neonates in the TID group would need dose adjustment.

CONCLUSION

In neonates ≤ 28-week gestation, an EID regimen from day one of life, using a single level 22 h after the first dose for dosing interval, achieves therapeutic peak and trough levels and more optimum peak levels as compared to a TID regimen.

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.

Pharmacokinetic-pharmacodynamic model for gentamicin and its adaptive resistance with predictions of dosing schedules in newborn infants

Gentamicin is commonly used in the management of neonatal infections. Development of adaptive resistance is typical for aminoglycosides and reduces the antibacterial effect. There is, however, a lack of understanding of how this phenomenon influences the effect of different dosing schedules. The aim was to develop a pharmacokinetic-pharmacodynamic (PKPD) model that describes the time course of the bactericidal activity of gentamicin and its adaptive resistance and to investigate different dosing schedules in preterm and term newborn infants based on the developed model. In vitro time-kill curve experiments were conducted on a strain of Escherichia coli (MIC of 2 mg/liter). The gentamicin exposure was either constant (0.125 to 16 mg/liter) or dynamic (simulated concentration-time profiles in a kinetic system with peak concentrations of 2.0, 3.9, 7.8, and 16 mg/liter given as single doses or as repeated doses every 6, 12, or 24 h). Semimechanistic PKPD models were fitted to the bacterial counts in the NONMEM (nonlinear mixed effects modeling) program. A model with compartments for growing and resting bacteria, with a function allowing the maximal bacterial killing of gentamicin to reduce with exposure, characterized both the fast bactericidal effect and the adaptive resistance. Despite a lower peak concentration, preterm neonates were predicted to have a higher bacterial killing effect than term neonates for the same per-kg dose because of gentamicin's longer half-life. The model supported an extended dosing interval of gentamicin in preterm neonates, and for all neonates, dosing intervals of 36 to 48 h were as effective as a 24-h dosing interval for the same total dose.

Pharmacokinetic/pharmacodynamic (PK/PD) indices of antibiotics predicted by a semimechanistic PKPD model: a step toward model-based dose optimization

A pharmacokinetic-pharmacodynamic (PKPD) model that characterizes the full time course of in vitro time-kill curve experiments of antibacterial drugs was here evaluated in its capacity to predict the previously determined PK/PD indices. Six drugs (benzylpenicillin, cefuroxime, erythromycin, gentamicin, moxifloxacin, and vancomycin), representing a broad selection of mechanisms of action and PK and PD characteristics, were investigated. For each drug, a dose fractionation study was simulated, using a wide range of total daily doses given as intermittent doses (dosing intervals of 4, 8, 12, or 24 h) or as a constant drug exposure. The time course of the drug concentration (PK model) as well as the bacterial response to drug exposure (in vitro PKPD model) was predicted. Nonlinear least-squares regression analyses determined the PK/PD index (the maximal unbound drug concentration [fC(max)]/MIC, the area under the unbound drug concentration-time curve [fAUC]/MIC, or the percentage of a 24-h time period that the unbound drug concentration exceeds the MIC [fT(>MIC)]) that was most predictive of the effect. The in silico predictions based on the in vitro PKPD model identified the previously determined PK/PD indices, with fT(>MIC) being the best predictor of the effect for β-lactams and fAUC/MIC being the best predictor for the four remaining evaluated drugs. The selection and magnitude of the PK/PD index were, however, shown to be sensitive to differences in PK in subpopulations, uncertainty in MICs, and investigated dosing intervals. In comparison with the use of the PK/PD indices, a model-based approach, where the full time course of effect can be predicted, has a lower sensitivity to study design and allows for PK differences in subpopulations to be considered directly. This study supports the use of PKPD models built from in vitro time-kill curves in the development of optimal dosing regimens for antibacterial drugs.

Fewer infants than older patients in paediatric randomised controlled trials

To determine whether the youngest age groups are less likely to be included in paediatric randomised controlled trials (PRCTs) than older children, we conducted a PubMed search using the keyword "randomised controlled trial" and the limit "all child: 0-18 years". We retrieved 417 articles published in 2006 in 34 leading journals classified as general medical journals, paediatric medical journals, or specialist medical journals. We arbitrarily selected 144 articles, at random. For each study, we evaluated population age characteristics (central tendency, range, and dispersion), study design, sample size and topic. Of the 144 studies, only 82 were first reports of paediatric randomised controlled trials (PRCTs). Among the other studies, many were done in adults. Of the 82 PRCTs, only 11% included newborns and 26% infants; 59% included children and 39% adolescents. Using the same search strategy to retrieve PRCTs in the same journals in the last 4 months of 2009 retrieved 66 PRCTs, of which 17% included newborns, 24% infants, 61% children and 55% adolescents. The three health conditions most often reported were respiratory diseases, infectious diseases, and mental and behavioural disorders. In 34 leading journals, PRCTs were significantly less likely to include newborns and infants than older paediatric patients. Given the huge impact of PRCTs on paediatric health, additional efforts are needed to promote studies in newborns and infants, as well as studies of the impact of recent European and American regulations designed to encourage paediatric drug trials.

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.

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.