Gentamicin dosage intervals in neonates: longer dosage interval--less toxicity

Gentamicin Dosing in Neonates with Normal Renal Function: Trough and Peak Levels

BACKGROUND AND OBJECTIVE: Gentamicin is commonly used in neonates, and it requires drug concentration monitoring. The objective of this study was to determine the extent of high trough (≥ 2 mg/l) and therapeutic peak serum gentamicin concentrations (5-12 mg/l) using our current gentamicin regimen and to adjust the dosing regimen accordingly and reassess.

METHODS

This was a prospective cohort study of neonates, with normal renal function, who were prescribed gentamicin. Group 1: March 2014-July 2017-gentamicin intravenous (IV) 2.5 mg/kg given every 36 h if < 30 weeks gestational age (GA) and every 24 h if ≥ 30 weeks GA; Group 2: August 2019-February 2020-gentamicin IV 3.5 mg/kg given every 36 h if < 30 weeks GA and every 24 h if ≥ 30 weeks GA. We assessed the number of neonates with aberrant trough and peak serum gentamicin concentrations.

RESULTS

Forty-eight neonates < 30 weeks GA and 34 ≥ 30 weeks GA were given 2.5 mg/kg gentamicin. Eleven (23%) neonates < 30 weeks GA and four (13%) ≥ 30 weeks GA had subtherapeutic peak concentrations (< 5 mg/l); none had supratherapeutic (> 12 mg/l) or toxic trough concentrations (≥ 2 mg/l). Forty-four neonates < 30 weeks GA and 54 ≥ 30 weeks GA were given 3.5 mg/kg gentamicin. Eighty-four (86%) had non-toxic trough concentrations (< 2 mg/l). One (1%) < 30 weeks GA neonate had subtherapeutic (< 5 mg/l) and one (1%) neonate ≥ 30 weeks GA had supratherapeutic (> 12 mg/l) peak concentrations.

CONCLUSIONS

Gentamicin regimen of 2.5 mg/kg given every 36 h for neonates < 30 weeks GA and every 24 h for neonates ≥ 30 weeks GA was suboptimal at achieving therapeutic gentamicin peak. Increasing the dosage to 3.5 mg/kg achieved therapeutic peak concentrations in 98% and non-toxic trough concentrations in 86% of all neonates (prior to dose interval adjustment).

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.

Identification of Risk Factors for Elevated Neonatal Gentamicin Trough Concentrations

OBJECTIVES: The objective of this study was to identify neonatal and maternal characteristics that may be associated with elevated neonatal gentamicin trough concentrations despite application of a previously published gentamicin dosage strategy.

METHODS: Retrospective cohort study of all neonates admitted to University of Vermont Medical Center (562-bed academic teaching hospital, Burlington, VT) receiving gentamicin between June 1, 2009, and August 31, 2013. A total of 205 neonates were included, with 41 cases and 164 controls.

RESULTS: Postmenstrual age (PMA, gestational age plus chronological age) and small-for–gestational age (SGA) status were independently associated with elevated neonatal gentamicin trough concentrations. No maternal risk factor evaluated remained significantly associated in the multivariate analysis.

CONCLUSIONS: The probability of an elevated gentamicin trough concentration increases with lower PMA and is further accentuated in neonates with SGA status. In contrast, the presence of maternal risk factors did not increase the likelihood of elevated gentamicin trough concentrations. Neonates with lower PMA and SGA status may require an individualized dosage and monitoring strategy.

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.

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.

Individualising netilmicin dosing in neonates

PURPOSE

The aim of this study was develop an optimal dosing regimen for netilmicin in neonates.

METHODS

This was a population pharmacokinetic study in 97 neonates aged from 2 to 28 days after the due date who were being treated with netilmicin for suspected sepsis. The model was used to simulate dosing regimens.

RESULTS

The principle factors influencing netilmicin clearance (CL) were postmenstrual age (PMA) and current body weight (CWT), and the principal determinant of volume of distribution (V) was CWT. The final covariate model was CL = 0.192 x (CWT/2)(1.35) x (PMA/40)(1.03), V = 1.5 x (CWT/2)(0.3). The optimal dosing was 5 mg/kg ever 36 h, 5 mg/kg every 24 h, 6 mg/kg every 24 h and 7 mg/kg every 24 h for neonates < or =27, 28-30, 31-33 and > or =34 weeks PMA, respectively.

CONCLUSION

Individualisation of netilmicin dosing in neonates requires adjustment of dose by body weight, and dosing interval by both PMA and CWT.

"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.

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.

Antibiotic prophylaxis with cefazolin and gentamicin in cardiac surgery for children less than ten kilograms

OBJECTIVE

Antibiotic prophylaxis is recommended in pediatric cardiac surgery, but no data concerning the current antibiotic regimen were available.

DESIGN

Prospective study from April to June 2000.

SETTING

University hospital operating room and postoperative intensive care unit.

PARTICIPANTS

Nineteen consecutive infants less than 10 kg with normal renal function undergoing cardiac surgery with cardiopulmonary bypass longer than 30 minutes.

INTERVENTIONS

Intravenous administration of cefazolin, 40 mg/kg, and gentamicin, 5 mg/kg, at induction of anesthesia; followed by cefazolin, 35 mg/kg every 8 hours, and gentamicin, 2 mg/kg every 12 hours, over 48 hours.

MEASUREMENTS AND MAIN RESULTS

Levels of serum antibiotics were measured: cefazolin (microbiologic) and gentamicin (fluorescence immunoassay) with 8 intraoperative and 5 postoperative samplings. Intraoperatively, cefazolin levels decreased from 166 +/- 44 (mean +/- standard deviation) down to 54 +/- 16 microg/mL and gentamicin from 20.8 +/- 9.5 down to 5.9 +/- 1.5 microg/mL. The postoperative trough levels were 12 +/- 7, 15 +/- 10, and 19 +/- 22 microg/mL for cefazolin and 1.1 +/- 0.5, 0.8 +/- 0.4, and 0.8 +/- 0.9 microg/mL for gentamicin.

CONCLUSIONS

Antibiotic serum levels are consistent with satisfactory efficacy, but intraoperative gentamicin peak levels appeared too high.

Vancomycin and gentamicin in neonates: hindsight, current controversies, and forethought

The use of both vancomycin and gentamicin in the treatment of suspected or documented neonatal infections, while routine, is a challenge for bedside and advanced practice nurses caring for neonates in intensive care units. A review of the background information surrounding neonatal infections as well as the history, intended use, and the pharmacokinetic and pharmacodynamic properties of vancomycin and gentamicin is presented with the goal of aiding in proper treatment with these two medications. Specific attention is given to doses in special situations, means of drug monitoring, strategies for avoiding antibiotic resistance, alternative medication choices, and areas for future investigation.

Nonparametric population pharmacokinetic analysis of amikacin in neonates, infants, and children

The therapeutic and toxic effects of amikacin are known to depend on its concentration in plasma, but the pharmacokinetics of this drug in neonates, infants, and children and the influences of clinical and biological variables have been only partially assessed. Therapeutic drug monitoring data collected from 155 patients (49 neonates, 77 infants, and 29 children) receiving amikacin were analyzed by a nonparametric population-based approach, the nonparametric maximum-likelihood method. We assessed the effects of gestational and postnatal age, weight, Apgar score, and plasma creatinine and urea concentrations on pharmacokinetic parameters. There is no specific formulation of amikacin for neonates and infants. We therefore used an error model to account for errors due to dilution during preparation of the infusion. The covariates that reduced the variance of clearance from plasma and the volume of distribution by more than 10% were postnatal age (43 and 28%, respectively) and body weight (30.4 and 17.4%, respectively). The expected reduction of clearance was about 10% for the plasma creatinine concentration. The other covariates studied (Apgar scores, plasma urea concentration, gestational age, sex) were found to have little effect. Simulations showed that a smaller percentage of patients had a maximum concentration in plasma/MIC ratio greater than 8 with a regimen of 7.5 mg/kg of body weight twice daily than with a regimen of 15 mg/kg once a day for MICs of 1 to 8 mg/liter.

Gentamicin dosing recommendations

CONCURRENT ADMINISTRATION of an aminoglycoside (e.g., gentamicin) and a β-lactam antibiotic (e.g., ampicillin) is often the cornerstone of empiric therapy for neonatal infection. Once the determination is made to begin gentamicin therapy, how much to give (the dose) and how often to give it (the dosing interval) are the next decision points. Traditional neonatal gentamicin dosing schedules of 2.5 mg/kg/dose at intervals of every 12–24 hours (or longer in very premature neonates) are based on postnatal age and body weight.

Once-daily gentamicin dosing in newborn infants

OBJECTIVE

We developed a simplified gentamicin dosing protocol for all neonates using a loading dose and once-daily dosing that would have an equal or lower incidence of toxicity and an equal or improved effectiveness compared with a regimen with no loading dose that included use of divided daily dosing.

METHODS

All neonatal intensive care unit patients with a postnatal age </=7 days and started on gentamicin therapy at the discretion of the attending neonatologist were evaluated in this comparative cohort study. All peak and trough serum drug levels (SDL), pertinent demographic data, and markers of potential nephrotoxicity, ototoxicity, and cure were tracked prospectively during 132 consecutive, nonrandomized courses of therapy on a new gentamicin protocol. These were compared with data retrieved retrospectively throughout 103 consecutive, nonrandomized courses of therapy in a control group.

RESULTS

Initial measured peak SDL were higher (7.8 +/- 1.1 microgram/mL vs 6.1 +/- 1.0 microgram/mL) and trough SDL were lower (0.9 +/- 0.2 microgram/mL vs 2.7 +/- 0.6 microgram/mL) in the protocol term subset, compared with the control term subset (gestational age, >/=37 weeks; weight, >/=2500 g). One hundred percent of the initial and maintenance peak SDL in term protocol neonates were 5 to 12 micrograms/mL; compared with 84% of the initial and 61% of maintenance peak SDL in the term control group. One hundred percent of the initial and maintenance trough SDL were in the desired range of <2 micrograms/mL in term protocol neonates; compared with 70% of the initial and 94% of maintenance trough SDL in the term control group. No significant differences were found in any SDL in low birth weight neonates (gestational age <37 weeks or weight <2500 g and >1500 g) in the protocol compared with the control group. The very low birth weight (weight <1500 g) protocol neonates had a significantly higher mean initial trough SDL (2.3 +/- 0.7 micrograms/mL vs 1.5 +/- 0.6 micrograms/mL) and a lower incidence of initial trough SDL <2.0 micrograms/mL (30% vs 95%) than very low birth weight neonates in the control group. No differences were seen between groups in incidence of significant rise in serum creatinine or failure of hearing screen.

CONCLUSION

A loading dose followed by once-daily dosing was shown to result in SDL in the safe and therapeutic range in all term neonates in this study. In low birth weight neonates, this regimen resulted in peak and trough SDL throughout therapy that were similar to those observed in the control group. Delaying the initiation of maintenance once-daily dosing until 36 to 48 hours after the loading dose would be expected to result in a higher incidence of initial trough SDL in target range for very low birth weight neonates.