Vancomycin pharmacokinetics and dose recommendations for preterm infants

Using population pharmacokinetics to optimize initial vancomycin dosing guidelines for neonates to treat sepsis caused by coagulase-negative staphylococcus

INTRODUCTION

Vancomycin dosing tailored for newborns is challenging due to the significant influence of maturation and organ function on pharmacokinetics. Population pharmacokinetic (popPK) models can be used to improve target attainment in neonates.

OBJECTIVES

The primary objective was to derive and evaluate a popPK model of intravenous vancomycin for neonates. Second, the predictive performance of this popPK model was compared with published popPK models.

METHODS

This is a retrospective cohort study of neonates admitted to the neonatal intensive care unit receiving intravenous vancomycin. A popPK model was derived with 70% of the dataset using a nonlinear mixed effects modeling method. The predictive performance of the current popPK model was validated and compared with 22 published popPK models using the remaining 30% of the dataset. Monte Carlo simulations (MCS) were performed to derive optimal dosing regimens to treat neonatal sepsis caused by coagulase-negative staphylococci (CoNS).

RESULTS

Among 655 vancomycin courses from 448 neonates, 78% of vancomycin trough concentrations were outside target range (10-15 mg/L) for central nervous system infections and 43% were outside target range (5-12 mg/L) for other infections using the institution's vancomycin dosing. A one-compartment model best described the observed data with a mean clearance of 0.11 ± 0.03 L/kg/h and volume of distribution (V) of 1.02 ± 0.08 L/kg. Body weight (WT), postmenstrual age (PMA), and serum creatinine (SCr) were significant covariates associated with clearance (p < 0.001) and body WT was a significant covariate associated with V (p = 0.009). Our study's popPK model has similar or better accuracy and precision than other published models. MCS-derived vancomycin doses from the validated model achieved >90% target attainment for a steady state through target range of 10-15 mg/L in the majority of PMA and SCr categories (78%) to treat CoNS sepsis.

CONCLUSION

A vancomycin dosing guideline derived from a validated popPK model in neonates with CoNS sepsis is recommended to improve target attainment.

Reappraisal of therapeutic vancomycin trough concentrations with empirical dosing in neonatal infections

BACKGROUND

Vancomycin is commonly used for neonatal sepsis. However, consensus on an empirical neonatal vancomycin regimen remains uncertain. We aimed to reappraise the therapeutic optimum concerning vancomycin trough concentrations with empirical dosing and to evaluate the relationship between trough concentrations and predicted 24-h area under the curve (AUC₂₄).

METHODS

This was a 3-year retrospective study. Neonates who were admitted to the neonatal intensive care unit with available vancomycin trough concentrations were enrolled. Trough levels were obtained before the fourth dose. Achievement of goal trough after implementing the vancomycin dosing regimen was based on the Practical Neonatology Medical Manual, published by the National Taiwan University College of Medicine.

RESULTS

A total of 46 neonates were included for analysis. Coagulase-negative staphylococci were the most commonly identified pathogens of sepsis. Among these patients, 22 achieved goal trough levels of 10-20 mcg/mL. Trough levels of 5-10 or >20 mcg/mL occurred in 13 and 11 patients, respectively. A moderately positive correlation between trough and predicted AUC₂₄ was found in all patients (Spearman's rho = 0.676, p < 0.001). In patients with body weight 1200-2000 g and postnatal age >7 days, the serum creatinine of those with trough levels >20 mcg/mL was significantly higher than those with goal trough levels (0.61 vs. 0.45 mg/dL, p = 0.01). Among those with trough levels >20 mcg/mL, 5 patients received ibuprofen for patent ductus arteriosus closing prior to vancomycin treatment (45%, 5/11), compared to only 3 patients with trough levels <20 mcg/mL (9%, 3/35) (p = 0.013).

CONCLUSION

Only half of the neonates receiving empirical vancomycin regimen achieved goal trough levels of 10-20 mcg/mL. Higher serum creatinine or ibuprofen treatment may increase the risk of overly high trough levels. The vancomycin regimen needs further validation and modification to provide adequate dosing for optimal use in neonates.

Pharmacokinetics and pharmacodynamics of peptide antibiotics

Antimicrobial resistance is a major global health challenge. As few new efficacious antibiotics will become available in the near future, peptide antibiotics continue to be major therapeutic options for treating infections caused by multidrug-resistant pathogens. Rational use of antibiotics requires optimisation of the pharmacokinetics and pharmacodynamics for the treatment of different types of infections. Toxicodynamics must also be considered to improve the safety of antibiotic use and, where appropriate, to guide therapeutic drug monitoring. This review focuses on the pharmacokinetics/pharmacodynamics/toxicodynamics of peptide antibiotics against multidrug-resistant Gram-negative and Gram-positive pathogens. Optimising antibiotic exposure at the infection site is essential for improving their efficacy and minimising emergence of resistance.

Optimizing Vancomycin Dosing and Monitoring in Neonates and Infants Using Population Pharmacokinetic Modeling

We determined optimal vancomycin starting dose regimens in infants ≤180 days of age to achieve the highest probability of target attainment with an area under the concentration-time curve for 24 h (AUC₂₄) of ≥400 using population pharmacokinetic (PK) modeling. Secondarily, determination of the relationship between serum creatinine (SCR) and vancomycin clearance in neonates was done. A retrospective population PK study was designed and included pediatric patients ≤180 days old who had received vancomycin and had a serum vancomycin concentration sampled. A population PK model was developed using Pumas (v1.0.5). Simulation was performed with various dosing regimens to evaluate the probability of AUC₂₄ target attainment and probability of trough of ≤20 mg/liter, and comparison to published models was performed. Individual clearance estimates, obtained from the final model, were plotted against SCR and faceted by age quartiles to assess the relationship between SCR and vancomycin clearance. A total of 934 patients were included in the study (58.6% male; median age, 43.6 days [range of 0 to 184]; median number of concentration samples, 1 [range of 1 to 29]). A one-compartment model was developed with body weight (WT), SCR, and postmenstrual age (PMA) identified as significant covariates on clearance. Plotting vancomycin clearance versus SCR demonstrated no clear relationship between the two at <10 days postnatal age (PNA). Dosing regimens to attain AUC₂₄ and trough targets were stratified according to SCR for ≥10 days PNA and PMA for <10 days PNA. A vancomycin population PK model was developed for pediatric patients <180 days of age incorporating WT, SCR, and PMA. The relationship between vancomycin clearance and serum creatinine is not clear at <10 days PNA.

Population pharmacokinetics and dose optimization of vancomycin in neonates

The pharmacokinetics of vancomycin vary among neonates, and we aimed to conduct population pharmacokinetic analysis to determine the optimal dosage of vancomycin in Korean neonates. From a retrospective chart review, neonates treated with vancomycin from 2008 to 2017 in a neonatal intensive care unit (NICU) were included. Vancomycin concentrations were collected based on therapeutic drug monitoring, and other patient characteristics were gathered through electronic medical records. We applied nonlinear mixed-effect modeling to build the population pharmacokinetic model. One- and two-compartment models with first-order elimination were evaluated as potential structural pharmacokinetic models. Allometric and isometric scaling was applied to standardize pharmacokinetic parameters for clearance and volume of distribution, respectively, using fixed powers (0.75 and 1, respectively, for clearance and volume). The predictive performance of the final model was developed, and dosing strategies were explored using Monte Carlo simulations with AUC_0–24 targets 400–600. The patient cohort included 207 neonates, and 900 vancomycin concentrations were analyzed. Only 37.4% of the analyzed concentrations were within trough concentrations 5–15 µg/mL. A one-compartment model with first-order elimination best described the vancomycin pharmacokinetics in neonates. Postmenstrual age (PMA) and creatinine clearance (CLcr) affected the clearance of vancomycin, and model evaluation confirmed the robustness of the final model. Population pharmacokinetic modeling and dose optimization of vancomycin in Korean neonates showed that vancomycin clearance was related to PMA and CLcr, as well as body weight. A higher dosage regimen than the typical recommendation is suggested.

Assessment of Vancomycin Pharmacokinetics and Dose Regimen Optimisation in Preterm Neonates

BACKGROUND

The pharmacokinetics of vancomycin, a drug used for the treatment of methicillin-resistant Staphylococcus aureus (MRSA), varies between paediatric and adult patients.

OBJECTIVE

The objective of this study was to assess the pharmacokinetics of vancomycin in preterm neonates and determine the optimum dose regimen.

METHODS

This was a randomised double-blind study of preterm neonates admitted to neonatal intensive care units. They all received vancomycin 15 mg/kg every 12 h. Blood was sampled just before administration of the third, sixth and ninth vancomycin dose. Pharmacokinetic parameters were estimated using a Bayesian approach implemented in Monolix 2018R2 software. Covariates assessed included postmenstrual age, current weight, creatinine clearance, albumin, gestational age, body surface area and current age. We used Monte Carlo simulations for dose regimen optimisation targeting area under the concentration-time curve up to 24 h (AUC_0-24h) of ≥ 400 mg × h/L.

RESULTS

In total, 19 preterm neonates were enrolled in the study with a median age of 14 (3-58) days. A one-compartment model with linear elimination best described the pharmacokinetics of vancomycin. Volume of distribution and clearance was 0.88 L and 0.1 L/h, respectively, for a typical neonate weighing 1.48 kg. Simulation of the current dose regimen showed that 27.5% of the neonates would achieve the target AUC_0-24h of ≥ 400 mg × h/L, and 70.7% of the neonates would achieve it with 12 mg/kg every 8 h.

CONCLUSION

The majority of the neonates were under dosed. Vancomycin 12 mg/kg should be administered every 8 h over 1 h infusion to improve the likelihood of achieving the AUC_0-24h target of ≥ 400 mg × h/L. This target is considered optimal for MRSA infections, where the vancomycin minimum inhibitory concentration is ≤ 1 µg/mL.

Towards Rational Dosing Algorithms for Vancomycin in Neonates and Infants Based on Population Pharmacokinetic Modeling

Because of the recent awareness that vancomycin doses should aim to meet a target area under the concentration-time curve (AUC) instead of trough concentrations, more aggressive dosing regimens are warranted also in the pediatric population. In this study, both neonatal and pediatric pharmacokinetic models for vancomycin were externally evaluated and subsequently used to derive model-based dosing algorithms for neonates, infants, and children. For the external validation, predictions from previously published pharmacokinetic models were compared to new data. Simulations were performed in order to evaluate current dosing regimens and to propose a model-based dosing algorithm. The AUC/MIC over 24 h (AUC24/MIC) was evaluated for all investigated dosing schedules (target of >400), without any concentration exceeding 40 mg/liter. Both the neonatal and pediatric models of vancomycin performed well in the external data sets, resulting in concentrations that were predicted correctly and without bias. For neonates, a dosing algorithm based on body weight at birth and postnatal age is proposed, with daily doses divided over three to four doses. For infants aged <1 year, doses between 32 and 60 mg/kg/day over four doses are proposed, while above 1 year of age, 60 mg/kg/day seems appropriate. As the time to reach steady-state concentrations varies from 155 h in preterm infants to 36 h in children aged >1 year, an initial loading dose is proposed. Based on the externally validated neonatal and pediatric vancomycin models, novel dosing algorithms are proposed for neonates and children aged <1 year. For children aged 1 year and older, the currently advised maintenance dose of 60 mg/kg/day seems appropriate.

How to use vancomycin optimally in neonates: remaining questions

In neonates, vancomycin, a narrow-spectrum antibiotic, is the first choice of treatment of late-onset sepsis predominantly caused by Gram-positive bacteria (coagulase-negative staphylococci and enterococci). Although it has been used for >50 years, prescribing the right dose and dosing regimen remains a challenge in neonatal intensive care units for many reasons including high pharmacokinetic variability, increase in the minimal inhibition concentration against staphylococci, lack of consensus on dosing regimen and way of administration (continuous or intermittent), duration of treatment, use of therapeutic drug monitoring, limited data on short- and long-term toxicity, risk of mutant selection and errors of administration linked to concentrated formulations. This article highlights and discusses future research directions, with specific attention given to dosing optimization of vancomycin, including the advantages of modeling and simulation approaches.

Vancomycin pharmacokinetic models: informing the clinical management of drug-resistant bacterial infections

This review aims to critically evaluate the pharmacokinetic literature describing the use of vancomycin in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. Guidelines recommend that trough concentrations be used to guide vancomycin dosing for the treatment of MRSA infections; however, numerous in vitro, animal model and clinical studies have demonstrated that the therapeutic effectiveness of vancomycin is best described by the area under the concentration versus time curve (AUC) divided by the minimum inhibitory concentration (MIC) of the infecting organism (AUC/MIC). Among patients with lower respiratory tract infections, an AUC/MIC ≥400 was associated with a superior clinical and bacteriological response. Similarly, patients with MRSA bacteremia who achieved an Etest AUC/MIC ≥320 within 48 h were 50% less likely to experience treatment failure. For other patient populations and different clinical syndromes (e.g., children, the elderly, patients with osteomyelitis, etc.), pharmacokinetic/pharmacodynamic studies and prospective clinical trials are needed to establish appropriate therapeutic targets.

Determination of vancomycin pharmacokinetics in neonates to develop practical initial dosing recommendations

Variability in neonatal vancomycin pharmacokinetics and the lack of consensus for optimal trough concentrations in neonatal intensive care units pose challenges to dosing vancomycin in neonates. Our objective was to determine vancomycin pharmacokinetics in neonates and evaluate dosing regimens to identify whether practical initial recommendations that targeted trough concentrations most commonly used in neonatal intensive care units could be determined. Fifty neonates who received vancomycin with at least one set of steady-state levels were evaluated retrospectively. Mean pharmacokinetic values were determined using first-order pharmacokinetic equations, and Monte Carlo simulation was used to evaluate initial dosing recommendations for target trough concentrations of 15 to 20 mg/liter, 5 to 20 mg/liter, and ≤20 mg/liter. Monte Carlo simulation revealed that dosing by mg/kg of body weight was optimal where intermittent dosing of 9 to 12 mg/kg intravenously (i.v.) every 8 h (q8h) had the highest probability of attaining a target trough concentration of 15 to 20 mg/liter. However, continuous infusion with a loading dose of 10 mg/kg followed by 25 to 30 mg/kg per day infused over 24 h had the best overall probability of target attainment. Initial intermittent dosing of 9 to 15 mg/kg i.v. q12h was optimal for target trough concentrations of 5 to 20 mg/liter and ≤20 mg/liter. In conclusion, we determined that the practical initial vancomycin dose of 10 mg/kg vancomycin i.v. q12h was optimal for vancomycin trough concentrations of either 5 to 20 mg/liter or ≤20 mg/liter and that the same initial dose q8h was optimal for target trough concentrations of 15 to 20 mg/liter. However, due to large interpatient vancomycin pharmacokinetic variability in neonates, monitoring of serum concentrations is recommended when trough concentrations between 15 and 20 mg/liter or 5 and 20 mg/liter are desired.

Clinical pharmacokinetics of vancomycin in the neonate: a review

Neonatal sepsis is common and is a major cause of morbidity and mortality. Vancomycin is the preferred treatment of several neonatal staphylococcal infections. The aim of this study was to review published data on vancomycin pharmacokinetics in neonates and to provide a critical analysis of the literature. A bibliographic search was performed using PubMed and Embase, and articles with a publication date of August 2011 or earlier were included in the analysis. Vancomycin pharmacokinetic estimates, which are different in neonates compared with adults, also exhibit extensive inter-neonatal variability. In neonates, several vancomycin dosing schedules have been proposed, mainly based on age (i.e., postmenstrual and postnatal), body weight or serum creatinine level. Other covariates [e.g., extracorporeal membrane oxygenation (ECMO), indomethacin or ibuprofen, and growth restriction] of vancomycin pharmacokinetics have been reported in neonates. Finally, vancomycin penetrates cerebrospinal fluid (range = 7-42%). Renal function drives vancomycin pharmacokinetics. Because either age or weight is the most relevant covariate of renal maturation, these covariates should be considered first in neonatal vancomycin dosing guidelines and further adjusted by renal dysfunction indicators (e.g., ECMO and ibuprofen/indomethacin). In addition to the prospective validation of available dosing guidelines, future studies should focus on the relevance of therapeutic drug monitoring and on the value of continuous vancomycin administration in neonates.

Vancomycin pharmacokinetic-pharmacodynamic parameters to optimize dosage administration in critically ill children

OBJECTIVE

Critically ill children may present changes in pharmacokinetic parameters and may not reach effective concentrations of vancomycin with current dosages. The objective of this study is to calculate vancomycin pharmacokinetic parameters in critically ill children and to estimate area under the curve at 24 hrs/minimal inhibitory concentration reached for Staphylococcus aureus.

DESIGN, SETTING, AND PATIENTS

Children treated with vancomycin, hospitalized in the Intensive Care Unit of the Pediatric Hospital-Centro Hospitalario Pereira Rossell, were included. Samples to determine vancomycin serum concentration were obtained on first and third days of treatment, 1 hr after the end of the third daily dose administration (maximum drug concentration) and 15 mins before the fourth (minimum drug concentration). Half-life elimination, volume of distribution, clearance, and area under the curve at 24 hrs were estimated. Vancomycin concentration values of 20-40 μg/mL (maximum drug concentration) and 5-10 μg/mL (minimum drug concentration) were considered therapeutic.

MEASUREMENTS AND MAIN RESULTS

Twenty-two children were included. On day 1, seven of 18 children for maximum drug concentration and 16 of 22 for minimum drug concentration reached concentrations in therapeutic range; on day 3, seven of 16 children for maximum drug concentration and 11 of 17 for minimum drug concentration did. Mean values of maximum drug concentration and minimum drug concentration were higher in children with negative water balance. Mean value of half-life elimination increased from day 1 to day 3. Considering a value of minimal inhibitory concentration for S. aureus of 1 μg/mL, nine of 18 children reached a relationship area under the curve at 24 hrs/minimal inhibitory concentration >400 on day 1 and seven of 15 on day 3. Considering a minimal inhibitory concentration of 2 μg/mL, one child reached it on day 1 and one on day 3.

CONCLUSIONS

Critically ill children show changes in pharmacokinetic parameters. Serum concentration monitorization is necessary for dosage individualization. Most children do not reach an area under the curve at 24 hrs/minimal inhibitory concentration >400 with current dosage.

Human renal function maturation: a quantitative description using weight and postmenstrual age

This study pools published data to describe the increase in glomerular filtration rate (GFR) from very premature neonates to young adults. The data comprises measured GFR (using polyfructose, (51)Cr-EDTA, mannitol or iohexol) from eight studies (n = 923) and involved very premature neonates (22 weeks postmenstrual age) to adulthood (31 years). A nonlinear mixed effects approach (NONMEM) was used to examine the influences of size and maturation on renal function. Size was the primary covariate, and GFR was standardized for a body weight of 70 kg using an allometric power model. Postmenstrual age (PMA) was a better descriptor of maturational changes than postnatal age (PNA). A sigmoid hyperbolic model described the nonlinear relationship between GFR maturation and PMA. Assuming an allometric coefficient of 3/4, the fully mature (adult) GFR is predicted to be 121.2 mL/min per 70 kg [95% confidence interval (CI) 117-125]. Half of the adult value is reached at 47.7 post-menstrual weeks (95%CI 45.1-50.5), with a Hill coefficient of 3.40 (95%CI 3.03-3.80). At 1-year postnatal age, the GFR is predicted to be 90% of the adult GFR. Glomerular filtration rate can be predicted with a consistent relationship from early prematurity to adulthood. We propose that this offers a clinically useful definition of renal function in children and young adults that is independent of the predictable changes associated with age and size.

Vancomycin

This review describes the use of vancomycin in neonates over the last three decades. Given the relation of late-onset neonatal septicaemia to outcome and the increase in coagulase-negative staphylococcal infection as causative organism, vancomycin remains an important antibacterial in the neonatal intensive care unit. The pharmacokinetic behaviour of vancomycin in neonates can be adequately described by a one- or two-compartment model and is mainly determined by postconceptional age and renal function. In neonates, a patent ductus arteriosus as well as treatment with indomethacin or extracorporeal membrane oxygenation (ECMO) leads to an increase in volume of distribution and a decrease in clearance. Microbiological studies in vitro have shown that an increase in vancomycin concentrations above the minimum inhibitory concentration does not result in more effective killing. The microbiological and clinical efficacy of vancomycin in neonates has only been studied explicitly in a restricted number of patients. There are no definitive data relating serum concentrations to effect in this patient group. Vancomycin-related nephrotoxicity and ototoxicity in neonates is rare, and no clear relation to serum concentrations has been demonstrated. Based on the pharmacokinetic profile of vancomycin in neonates, several administration regimens have been constructed. Recent guidelines have suggested that dosage can be independent of gestational age or postconceptional age in neonates without renal failure. In patients with renal failure, therapy can be adequately tailored by using a regimen based on serum creatinine. The usefulness of routine monitoring of peak serum concentrations is doubtful based on the current literature. Recent research demonstrates a shift towards taking only routine trough serum concentrations in order to optimise efficacy. Patients with renal failure and other special subpopulations, such as patients exposed to ECMO or indomethacin, need to be monitored more closely.

Dose regimen for vancomycin not needing serum peak levels?

AIM

To determine the safety, efficacy, and need to measure peak serum vancomycin concentrations in a neonatal population using a standard vancomycin dosage regimen.

METHOD

A total of 101 infants who were admitted to a regional neonatal intensive care unit and received vancomycin (15 mg/kg every 12 or 18 hours depending on postnatal age) were studied retrospectively. Infants who had been started on vancomycin before they were transferred to the unit were excluded. The proportion of infants was measured whose serum vancomycin concentrations were within a conservative therapeutic range of trough 5-10 mg/l, peak 20-40 mg/l, and a less conservative, but still safe, range of trough 5-12 mg/l, peak 15-60 mg/l.

RESULTS

Trough concentrations of 5-10 mg/l were achieved by 46.5% of infants, and 5-12 mg/l by 55.4%. Peak concentrations of 20-40 mg/l were found in 83.2% of infants, and 15-60 mg/l in 99.0%. Highest peak concentration was 47.2 mg/l. Some 89.4% of infants with trough concentrations of 5-10 mg/l had a peak concentration of 20-40 mg/l.

CONCLUSIONS

The vancomycin dosage regimen used in this study produces acceptable therapeutic serum vancomycin concentrations. Peak serum vancomycin concentrations do not need to be measured in neonates using this dosage regimen.

Monitoring the treatment of sepsis with vancomycin in term newborn infants

A prospective study was conducted to determine if standardized vancomycin doses could produce adequate serum concentrations in 25 term newborn infants with sepsis.

PURPOSE

The therapeutic response of neonatal sepsis by Staphylococcus sp. treated with vancomycin was evaluated through serum concentrations of vancomycin, serum bactericidal titers (SBT), and minimum inhibitory concentration (MIC).

METHOD

Vancomycin serum concentrations were determined by the fluorescence polarization immunoassay technique, SBT by the macro-broth dilution method, and MIC by diffusion test in agar.

RESULTS

Thirteen newborn infants (59.1%) had adequate peak vancomycin serum concentrations (20 - 40 mg/mL) and one had peak concentration with potential ototoxicity risk (>40 microg/mL). Only 48% had adequate trough concentrations (5 - 10 mg/mL), and seven (28%) had a potential nephrotoxicity risk (>10 microg/mL). There was no significant agreement regarding normality for peak and trough vancomycin method (McNemar test : p = 0.7905). Peak serum vancomycin concentrations were compared with the clinical evaluation (good or bad clinical evolution) of the infants, with no significant difference found (U=51.5; p=0.1947). There was also no significant difference between the patients' trough concentrations and good or bad clinical evolution (U = 77.0; p=0.1710). All Staphylococcus isolates were sensitive to vancomycin according to the MIC. Half of the patients with adequate trough SBT (1/8), also had adequate trough vancomycin concentrations and satisfactory clinical evolution.

CONCLUSIONS

Recommended vancomycin schedules for term newborn infants with neonatal sepsis should be based on the weight and postconceptual age only to start antimicrobial therapy. There is no ideal pattern of vancomycin dosing; vancomycin dosages must be individualized. SBT interpretation should be made in conjunction with the patient's clinical presentation and vancomycin serum concentrations. Those laboratory and clinical data favor elucidation of the probable cause of patient's bad evolution, which would facilitate drug adjustment and reduce the risk of toxicity or failing to achieve therapeutic doses.

Vancomycin pharmacokinetics and Bayesian estimation in pediatric patients

The vancomycin pharmacokinetic profile was characterized in six pediatric patients and the potential of nonlinear mixed effects modeling and Bayesian forecasting for vancomycin monitoring was explored using NONMEM V (1.1). Based on steady state serial vancomycin concentrations, the estimates of mean t1/2, Vd, and Cl derived by the Sawchuk and Zaske method (1) were 3.52 hours, 0.57 L/kg, and 0.12 L/h per kg, respectively. NONMEM analysis demonstrated that a weight-adjusted two-compartment model described individual patients' data better than a comparable one-compartment model. The two-compartment estimates of mean t1/2alpha, t1/2beta, Vss, and Cl were 0.80 hour, 5.63 hours, 0.63 L/kg, and 0.11 L/h per kg, respectively. The relatively long mean t1/2alpha suggests that peak vancomycin concentrations measured earlier than 4 hours postdose do not reflect postdistributional serum concentrations. NONMEM population modeling revealed that a weight-adjusted two-compartment model provided a better fit than a comparable one-compartment model. The resulting population parameters and variances were fixed in NONMEM to obtain Bayesian predictions of individual vancomycin serum concentrations. Bayesian estimation with either a single midinterval or trough sample has the potential to provide accurate and precise predictions of vancomycin concentrations. This should be evaluated using a vancomycin population pharmacokinetic model based on a larger sample of pediatric patients.

Effects of hepatic function on vancomycin pharmacokinetics in patients with cancer

Vancomycin is widely used in the prophylaxis and treatment of infections in neutropenic patients with cancer. The objective of this study was to analyze liver damage effects on vancomycin pharmacokinetics and determine the necessity for liver function evaluation when selecting vancomycin dosing schedules in these patients. A population pharmacokinetic analysis was performed using the global two-stage method. To this purpose serum vancomycin concentrations from 154 cancer patients were measured and individual vancomycin pharmacokinetic parameters were estimated by the Sawchuk and Zaske method. Mean and standard deviation of the vancomycin pharmacokinetic parameters were estimated for various subgroups of patients classified according to the degree of liver damage. Then a multiple linear regression analysis was performed to select the best predictive models for vancomycin clearance (Clvan) and steady state distribution volume (V). Results revealed that Clvan is not influenced by liver failure. Differences in V between patients with and without hepatic failure were initially observed, but these disappeared when patients with ascites were excluded. In conclusion, vancomycin dosing schedule does not need to be modified for patients with liver failure, with the exception of patients with ascites.

Pharmacokinetics and dose requirements of vancomycin in neonates

AIMS

To design and evaluate dosing guidelines for vancomycin based on data collected during routine use of the drug.

METHODS

Following the observation that 66% of neonatal vancomycin trough concentrations were outside the target range, new dose guidelines were developed using a population pharmacokinetic approach. NONMEM (non-linear mixed effects model) was used to analyse dose histories and 347 concentration measurements collected during routine therapeutic drug monitoring in 59 neonates.

RESULTS

Postconceptual ages in the patient group ranged from 26-45 weeks, weights from 0. 57-4.23 kg, and creatinine concentrations from 18-172 micromol/l. The population estimate of vancomycin clearance (l/h/kg) was 3. 56/creatinine concentration (micromol/l) with an interpatient coefficient of variation (CV) of 22% and volume of distribution 0.67 l/kg with a CV of 18%. Residual error was 4.5 mg/l. When the new recommendations on dosing were used prospectively in a separate group of neonates the proportion of acceptable troughs increased from 33% to 72%.

CONCLUSIONS

The pharmacokinetics of vancomycin in neonates and young infants depend on weight and serum creatinine. Preliminary results from the new guidelines indicate an improvement on previous practice, but also an ongoing need to monitor concentrations.

Lack of vancomycin-associated nephrotoxicity in newborn infants: a case-control study

OBJECTIVE

The purpose of this study was to compare the incidence of nephrotoxicity, defined as doubling of baseline serum creatinine concentration, in newborn infants with peak vancomycin serum concentrations </=40 microg/mL at steady state to infants with peak vancomycin serum concentrations >40 microg/mL. A secondary objective was to correlate concomitant disease states and potentially nephrotoxic drug therapy with rises in serum creatinine in vancomycin recipients.

METHODS

Newborn infants with culture-proven Staphylococcus aureus or coagulase-negative staphylococcal septicemia who received vancomycin therapy for >3 days between 1985 and 1995 were identified from an existing database and a review of medical record. All 69 patients included in the study had serial serum creatinine determinations, including a baseline value within 48 hours of starting treatment with vancomycin, and serum vancomycin concentrations determined after at least three doses, with peak and trough concentrations determined 1 hour after a 60-minute infusion and 15 to 30 minutes before a dose, respectively. Infants with congenital renal or cardiac anomalies were excluded. Demographic characteristics, vancomycin dosing regimen, serum vancomycin concentrations and sample times, concomitant drug therapy, and disease states were recorded. Patients were divided into group A (peak vancomycin concentration </=40 microg/mL) and group B (peak vancomycin concentration >40 microg/mL). The change in serum creatinine concentration between the start and end of vancomycin therapy was determined. Nephrotoxicity was identified if serum creatinine doubled at any time from the start to the end of vancomycin therapy. Alternative definitions of nephrotoxicity (any rise in serum creatinine to >0.6 mg/dL or new abnormalities of urine sediment) were used in additional analyses.

RESULTS

A total of 69 evaluable patients (gestational age, 28.9 +/- 3.0 weeks; birth weight, 1219 +/- 516 g) were identified, 61 in group A and 8 in group B. Six patients in group A underwent doubling of serum creatinine concentration during vancomycin therapy, whereas none in group B did so. Serum creatinine doubled to >0.6 mg/dL in only 3 infants (all in group A). Any increase in serum creatinine to >0.6 mg/dL was seen in 10 infants, 9 of whom were in group A. No confounding variable, including previous or concomitant underlying disease states associated with renal dysfunction or treatment with other potentially nephrotoxic agents, were associated with a significant rise in serum creatinine.

CONCLUSION

Vancomycin-associated nephrotoxicity is rare in neonates, even with serum peak concentrations >40 microg/mL.

Population pharmacokinetics of vancomycin in Japanese pediatric patients

The population pharmacokinetic profile of vancomycin (VCM) in Japanese pediatric patients infected with methicillin-resistant Staphylococcus aureus was analyzed using 181 samples of serum concentration data from 49 patients obtained in routine drug monitoring. The one-compartment linear model was adopted, where the VCM clearance (CL) and the distribution volume (Vd) were correlated with covariates such as postnatal age (AGE) and body weight (BWT). The population pharmacokinetic analysis program NONMEM with the first-order conditional estimation method was used. The results showed that the population mean clearance normalized by BWT increases with AGE up to 1 year of age [CL(L/hour per kg) = 0.1 19 + 0.0619 x (AGE - 1)] and decreases with age over 1 year old [CL(L/hour per kg) = 0.119 + 0.00508 x (1 - AGE)]. The population mean of the distribution volume normalized by BWT was independent of AGE (Vd (L/kg) = 0.522). The interindividual variability of CL was 39.6%, and that of Vd was 18.8%. The intraindividual, residual variability was 34.6%. These results were compared with those in other articles, and a guideline for dosage adjustment in VCM therapy is discussed.

Constant rate infusion of vancomycin in premature neonates: a new dosage schedule

AIMS

Since vancomycin's bactericidal action has been shown to be time-dependent, a constant rate infusion over 24 h might result in a better bactericidal efficacy. The purpose of this study was to define a new dosage schedule in prematures.

METHODS

Two vancomycin 24 h constant rate infusion schedules were tested in two groups of neonates. Postconceptional age (PCA) was 27 to 41 weeks in group 1 (n=24) and 28 to 51.5 weeks in group 2 (n=29). Group 1 neonates received continuous infusion of 10 to 30 mgkg(-1) day(-1), adjusted for PCA and weight. Group 2 was designed to take into account the significant relationship observed in group 1 between vancomycin clearance standardized on weight and PCA and consisted of a constant loading dose of 7 mg kg(-1) followed by continuous infusion of 10 to 40 mg kg(-1) day(-1) adjusted for PCA and weight.

RESULTS

Mean vancomycin serum concentration at steady state was 11+/-3.1 mg1(-1) in group 1 and 15.4+/-6.2 mg1(-1) in group 2. Fifty-six percent of group 1 values vs 88% of group 2 values were between 10 and 30 mg at steady state (P<0.01). Both regimens were well tolerated.

CONCLUSIONS

A loading dose of vancomycin followed by constant rate infusion of the appropriate dose adjusted for PCA and weight might improve vancomycin concentrations in neonates.

Evaluation of a sparse sampling strategy for determining vancomycin pharmacokinetics in preterm neonates: application of optimal sampling theory

OBJECTIVE

To use optimal sampling theory to determine the fewest vancomycin concentrations required and the appropriate sampling times to calculate vancomycin pharmacokinetic parameters in neonates.

DESIGN

Unblinded evaluation in neonates with presumed sepsis.

SETTING

Level 3 community-based neonatal intensive care unit.

PATIENTS

Eleven neonates with presumed sepsis.

INTERVENTIONS

Twelve courses of intravenous vancomycin 20 mg/kg were administered. Blood samples were collected 3 and 9 hours after initiation of a 1-hour infusion of the first dose.

MEASUREMENTS AND MAIN RESULTS

A two-compartment model was fit to vancomycin concentrations using iterative two-stage analysis. Pharmacokinetic parameter estimates were used for determination of optimal sampling times for two-, three-, and four-sample strategies with subsequent generation of two-, three-, and four-sample concentration data for 100 cases. Relative performance of strategies was compared through calculation and comparison of D efficiency for the determined strategies. Bias (median percent error) and precision (median percent absolute error) of pharmacokinetic parameter estimates for each strategy in the 100 simulated cases were determined.

CONCLUSIONS

For estimation of total clearance and volume in the central and peripheral compartments, all strategies performed similarly with no difference in efficiency or bias and precision of estimates. Our results suggest that for clinical evaluations two appropriately timed samples (0.5 h after a 1-h infusion, trough concentration) are adequate for estimation of vancomycin clearance in neonates.

Pharmacokinetics and administration regimens of vancomycin in neonates, infants and children

The increased use of vancomycin in neonatal and paediatric patients has prompted numerous pharmacokinetic studies and the development of many empirical administration methods. The majority of dosage guidelines use the relationship between pharmacokinetic parameters and patient variables such as chronological age, bodyweight, and/or measures of renal function. Currently, those dosage guidelines which are based upon postconceptional age and bodyweight seem to provide the best options for empirical administration in neonates and infants. In addition, serum creatinine may prove to be a useful guide to the empirical administration of vancomycin in neonates older than 7 to 14 days. Several investigators have reported the individualisation of dosage regimens based on pharmacokinetic-based administration methods. The most common techniques employed have been Sawchuk-Zaske method and Bayesian forecasting. However, only a limited number of studies have evaluated either empirical administration or individualised administration techniques in patient populations outside those of the original reports; this makes choosing between the methods difficult. Pharmacokinetic data and administration recommendations have gradually become available in special paediatric patient populations. The majority of studies have focused on patients requiring cardiopulmonary bypass surgery or with burns, cancer or central nervous system infections. However, a limited amount of information is available regarding vancomycin disposition in children older than 1 year of age with and without end-stage renal failure. The monitoring of serum vancomycin concentrations may be useful in selected neonatal and paediatric patient populations, especially where large interpatient variability occurs and administration guidelines are not clearly established. Similar to the literature on adults, the lack of conclusive evidence concerning the relationship between serum vancomycin concentrations and therapeutic responses leaves this topic open to debate.

Changes in vancomycin pharmacokinetics in critically ill infants

We aimed to assess the pharmacokinetics of vancomycin in critically ill infants, and to evaluate the standard recommended dose of 10 mg/kg 6 hourly. All infants admitted to the Baragwanath Hospital ICU who had arterial lines in situ, and for whom vancomycin 10 mg/kg 6 hourly was prescribed for an infective insult and who had parental consent, were included in the study. Vancomycin was infused over 60 minutes. Serum samples were taken immediately before the dose and at 30, 60, 120 and 300 minutes after the end of the vancomycin infusion, on days 2 and 8 of therapy. Extrapolated peak concentration (Cmax), trough concentration (Cmin), apparent volume of distribution (Vd), elimination half-life (t1/2el) and clearance (CL) were determined for each patient. Day 2 values were compared with those of day 8. Day 2 serum concentrations were assayed on 20 patients and day 8 concentrations in 15. The mean vancomycin Vd on day 2 (0.81 l/kg) was significantly (P = 0.007) larger than that on day 8 (0.44 l/kg). The change in Vd resulted in a significant change in mean Cmax (29.1 vs 35.5 micrograms/ml) (P = 0.02) and mean t1/2el (5.3 vs 3.4h) (P = 0.01) over the treatment period. Critically ill infants displayed a large initial volume of distribution which probably resulted from aggressive fluid resuscitation. This also results in a large variation in other pharmacokinetic parameters, namely Cmax and t1/2el. Although the routine monitoring of vancomycin serum concentrations remain controversial, we feel that in view of these large pharmacokinetic variations, the critically ill infant is a specific group where monitoring of vancomycin serum levels is indicated.

Vancomycin pharmacokinetics in neonates and infants: a retrospective evaluation

OBJECTIVE

To evaluate the frequency with which current loading and maintenance vancomycin dosages achieve target serum concentrations based on pharmacokinetic parameters obtained after the initial dose. Also, to identify the daily vancomycin dosage necessary to achieve target serum concentrations at steady-state and to determine if any relationships exist between vancomycin pharmacokinetic parameters and various patient characteristics.

SETTING

Neonatal intensive care unit (NICU) at Georgia Baptist Medical Center.

PATIENTS/METHODS

Twenty-three infants with suspected or documented gram-positive infection who received intravenous vancomycin between July 1990 and November 1991 were included in this retrospective analysis. Gestational age range from 23 to 41 weeks and postconceptional age (PCA) at the time of the study ranged from 26 to 46 weeks. Vancomycin therapy was initiated with a loading dose of 15 mg/kg, followed by a maintenance dosage of 20-30 mg/kg/d, which was usually given as 10 mg/kg q8-12h. All vancomycin doses were administered using a syringe pump. Peak and trough serum concentrations were obtained following the first dose. Vancomycin pharmacokinetic parameters were determined using a one-compartment model. Infants receiving indomethacin within two weeks prior to study were analyzed separately (group 2, n = 4). All other infants were included in group 1 (n = 19).

RESULTS

For group 1, vancomycin clearance (Cl), volume of distribution (Vd), and half-life were (mean +/- 1 SD) 0.072 +/- 0.032 L/kg/h, 0.52 +/- 0.08 L/kg, and 5.6 +/- 1.6 hours, respectively. For both groups, loading doses provided 1-hour postinfusion peak concentrations of 25-35 mg/L in one of every two infants studied, whereas only three percent of initial maintenance doses were projected to provide desired peak and trough concentrations at steady-state. For group 1, the mean daily dosage necessary to provide target peak (25-35 mg/L) and trough (5-10 mg/L) concentrations at steady-state was larger than that initially prescribed (29.6 +/- 13.1 vs. 22.2 +/- 4.7 mg/kg/d). For group 2, the mean daily dosage required to achieve target peak and trough concentrations at steady-state was smaller than that initially prescribed (14.8 +/- 4.3 vs. 20.0 +/- 0.1 mg/kg/d) and was exactly half of that required for group 1. Excellent correlations were observed between PCA and vancomycin Cl (L/h) (r = 0.92; p < 0.0001), body weight and Vd(L) (r = 0.94; p < 0.0001), body weight and vancomycin Cl (L/h) (r = 0.85; p < 0.0001), PCA and Vd (L) (r = 0.89; p < 0.0001), and body surface area and Vd (L) (r = 0.93; p < 0.0001) for group 1. Moderate correlations were also noted between PCA and Cl relative to body weight (L/kg/h), postnatal age and Cl (L/kg/h), and PCA and vancomycin dosage requirements (mg/kg/d). No linear correlation was observed between any patient characteristic and Vd standardized for body weight.

CONCLUSIONS

Our data demonstrate the need for a more accurate method of estimating initial vancomycin dosage requirements in this NICU population. Although some of the relationships revealed in this study could be used to determine vancomycin dosage for infants in the range of approximately 30-36 weeks PCA, we hesitate to suggest this approach presently because of the potential limitations of our study design. Further prospective study is needed to confirm these observations. In addition, further study is necessary to describe the time course of the interaction between vancomycin and indomethacin in infants with successful and unsuccessful closure of their patent ductus arteriosus.

Effect of obesity on vancomycin pharmacokinetic parameters as determined by using a Bayesian forecasting technique

Few data exist concerning the effect of obesity on the pharmacokinetic parameters of vancomycin. The purpose of this investigation was to assess the effect of obesity on vancomycin pharmacokinetic parameters in 95 nonobese and 135 obese adult patients (age range, 18 to 92 years) receiving vancomycin. All subjects had normal renal function as defined by a creatinine concentration in serum of < or = 1.5 mg/dl (mean estimated creatinine clearance +/- 1 standard deviation, 76 +/- 34; range, 23 to 215 ml/min). Vancomycin concentrations in serum were determined by the fluorescence polarization immunoassay. All data for vancomycin concentration in serum versus time for each course of therapy were fitted by using a two-compartment Bayesian forecasting program. Subjects were stratified into nine groups on the basis of the percent difference between actual body weight (ABW) and lean body weight (LBW) (> -10%, -10 to 0%, > 0 to 10%, > 10 to 20%, > 20 to 30%, > 30 to 40%, > 40 to 50%, > 50 to 60%, > 60%). Analysis of variance with post hoc Scheffe's testing revealed that statistically significant differences occurred in terminal disposition half-life (t1/2 beta) between the extremes of modestly obese (group 4) and morbidly obese (group 9, P < 0.05) patients. Similar analysis with distribution volume (V) identified significant differences in patients at or near their LBW (groups 2 to 4) and patients who were morbidly obese (groups 8 and 9, P < 0.05). Multiple regression models for the pharmacokinetic parameters V, t1/2beta, and vancomycin total body clearance were developed to assess the joint predictive power of LBW, ABW, and percent over LBW, controlling for the effects of age, initial creatinine concentration in serum, initial creatinine clearance, and gender. In the final model for V, both ABW and percent over LBW were independent and significant predictors. For total body clearance, only ABW was significant and predictive. Percent over LBW was a significant and independent predictor of t1/2beta. LBW is not predictive of these pharmacokinetic parameters and should not be used for initial dosing. On the basis of these data, ABW appears to be superior to LBW for calculating initial dose requirements for vancomycin.

An updated comparison of drug dosing methods. Part IV: Vancomycin

The resurgence of the use of and interest in vancomycin, in conjunction with the high degree of interpatient variability in its pharmacokinetic profile, has prompted the development of many and varied dosing methods. Several dosing nomograms have been proposed and evaluated, methods which are useful for initial dosing but do not allow for individualisation of dosage. Given these constraints, several investigators have attempted to apply conventional least-squares regression techniques and, more recently, Bayesian methodologies using either 1- or 2-compartment pharmacokinetic models. Comparative information evaluating algorithmic methods demonstrates that those of Moellering and Lake offer the least biased and most precise predictions of vancomycin dosage. Patient individualisation using conventional least-squares methodology offers some improvement over nomogram-based methods, both in predictive performance and in dosage adjustment once serum concentration data are available. Overall, the latest data indicate that regimens which incorporate Bayesian principles tend to give better results than nomogram-based or conventional least-squares dosing methods for this drug. Despite the advances in methods for dosing vancomycin, several questions remain to be answered. A lack of convincing evidence of a correlation between serum concentrations and therapeutic outcome has prompted debate over the need for serum concentration monitoring and, if it is needed, over which patient population would most benefit. Secondly, little comparative information is currently available as to the dosing of vancomycin in paediatric and neonatal patient populations. Several nomograms for initial dosing have been proposed, but only 2 have been subject to subsequent testing. Finally, information regarding cost-effectiveness and the quality of patient outcome is lacking from the current literature.

Clinical pharmacokinetics of antibacterial drugs in neonates

Neonatal patients are surviving longer due to the rapid advances in medical knowledge and technology. Our understanding of the developmental physiology of both preterm and full term neonates has also increased. It is now apparent that differences in body composition and organ function significantly affect the pharmacokinetics of antibacterial drugs in neonates, and dosage modifications are required to optimise antimicrobial therapy. The penicillins and cephalosporins are frequently used in neonates. Although ampicillin has replaced benzylpenicillin (penicillin G) for empirical treatment of neonatal sepsis, many of the other penicillins may be used in neonates for the management of various infections. Increased volume of distribution (Vd) and decreased total body clearance (CL) affect the disposition of penicillins and cephalosporins. Decreased renal clearance (CLR) due to decreased glomerular filtration and tubular secretion is responsible for the decreased CL for most of the beta-lactams. Aminoglycoside Vd is affected by the increased total body water content and extracellular fluid volume of neonates. The increased Vd, in part, accounts for the extended elimination half-life (t1/2) observed in neonates. Aminoglycoside CL is dependent on renal glomerular filtration which is markedly decreased in neonates, especially those preterm. These drugs appear to be less nephrotoxic and ototoxic in neonates than in older patients, and the role of serum concentration monitoring should be limited to specific neonatal patients. Other antibiotics such as vancomycin, teicoplanin, chloramphenicol, rifampicin, erythromycin, clindamycin, metronidazole and cotrimoxazole (trimethoprim plus sulfamethoxazole) may be used in certain clinical situations. The emergence of staphylococcal resistance to penicillins has increased the need for vancomycin. With the exceptions of vancomycin and chloramphenicol, the efficacy and safety of these other agents in neonates have not been established. The need for serum vancomycin concentration monitoring may be limited, as with aminoglycosides, while safety concerns warrant the routine monitoring of serum chloramphenicol concentrations in neonates. Dosing guidelines are provided, based on the pharmacokinetics of the drugs and previously published recommendations. These dosing guidelines are intended for initial therapy, and close therapeutic monitoring is recommended for maintenance dose requirements to optimise patient outcome. There has been an enormous increase in our knowledge of neonatal physiology and drug disposition. Fortunately, many of the antibacterial drugs used in neonates (e.g. penicillins and cephalosporins) are relatively safe. It will be important to evaluate all newly developed antibiotics in neonates to assure their maximum efficacy and safety.

Dosage guidelines for the use of vancomycin based on its pharmacokinetics in infants

The purpose of this study was to characterize the pharmacokinetics of vancomycin and to develop optimal dosage guidelines in infants. Thirteen infants between the ages of 13 to 183 days were enrolled. All had been born prematurely, and average gestational age, postconceptional age, and actual body weight were 29.8 weeks, 38.2 weeks, and 2.1 kg respectively. Multiple blood samples were obtained from each patient after 72 h of therapy. Serum inhibitory and bactericidal titres were determined for peak and trough samples. There were good correlations between total body clearance of vancomycin and both postconceptional age (r = 0.86) and actual body weight (r = 0.87). This information was used to develop vancomycin dosage guidelines in premature infants. The regression line for vancomycin daily dosage requirements vs postconceptional age may be useful for determining initial dosage recommendations. There were also good correlations between vancomycin serum concentrations and serum inhibitory and cidal titres. Peak and trough concentrations in the therapeutic range (peak, 25-35 micrograms/ml; trough, 5-10 micrograms/ml) corresponded to titres of greater than or equal to 1:8 and 1:2 to 1:8 respectively. Based on these data we suggest the following dosage guidelines for vancomycin: 10 mg/kg 12 hourly for 30-34 weeks postconceptional age and less than 1.2 kg actual body weight; 10 mg/kg 8 hourly for 30-42 weeks postconceptional age and greater than 1.2 kg actual body weight; 10 mg/kg 6 hourly for greater than 42 weeks postconceptional age and greater than 2.0 kg actual body weight. Thus, doses which are lower than currently recommended are needed for infants born prematurely.(ABSTRACT TRUNCATED AT 250 WORDS)

Ethics of drug studies in infants: how many samples are required for accurate estimation of pharmacokinetic parameters in neonates?

Our study aimed to determine the least number of samples that are required to obtain accurate pharmacokinetic parameters in neonates. Patients treated with either netilmicin or ceftazidime had between five and eight samples drawn for drug concentration measurement after the first or the last dose of the drug. Pharmacokinetic parameters were calculated using all the available points as a reference and then recalculated with 2, 3, or 4 points. Systemic clearance and volume of distribution were significantly different from the reference value when 2 points were used for netilmicin after the first dose and ceftazidime after the last dose. Had parameters obtained from 2 points been used, mean dosage would have been underestimated by 15% for ceftazidime and 11% for netilmicin, and some patients would have received only 65% of the dose calculated from all available points. When 3 points were used, dosage would have been underestimated by a mean of only 1% for ceftazidime and 5% for netilmicin when compared with the dosage estimated from the reference parameters. We conclude that 3 concentration time points may be all that are required for estimation of pharmacokinetic parameters sufficiently accurate for practical purposes in neonates.

Intravenous drug therapy in premature infants: practical aspects

Most decisions regarding the methods used for intravenous drug delivery are made by nurses. For this reason, neonatal nurses must recognize the unique problems associated with drug delivery to the low birth weight infant. A review of the associated problems is presented along with suggested solutions to aid the nurse in choosing a therapeutic method for intravenous drug administration.