Neonatal vancomycin trough level audit using British National Formulary for Children dosing

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.

An Audit to Evaluate Vancomycin Therapeutic Drug Monitoring in a Neonatal Intensive Care Unit

BACKGROUND

Therapeutic drug monitoring (TDM) is routinely used for optimization of vancomycin therapy, because of exposure-related efficacy and toxicity, in addition to significant variability in pharmacokinetics, which leads to unpredictable drug exposure.

OBJECTIVE

The aim of this study was to evaluate target attainment and TDM of vancomycin in neonates.

METHODS

The authors conducted a retrospective study and collected data from medical records of all neonates who received vancomycin therapy in the neonatal intensive care unit between January 2019 and December 2019. The primary outcome was the proportion of vancomycin courses that reached target trough concentrations of 10-20 mg/L based on appropriate TDM samples collection. Secondary outcomes included proportion of courses with appropriate dose and dose frequency, and proportion of patients who achieved target concentrations after the first dose adjustment.

RESULTS

In total, 69 patients were included, with 129 vancomycin courses. The median initial vancomycin trough concentration was 12 (range: 4-36) mg/L. The target trough concentration was achieved in 75% of courses after the initial dose with appropriate TDM, and 84% of courses after TDM-guided dose adjustments. Patients were dosed appropriately in 121/129 courses and TDM was performed correctly according to protocol in 51/93 courses. A dose adjustment was performed in 18/29 courses, to increase target attainment.

CONCLUSIONS

This study showed that there is a need for an increase in dose to improve target attainment. There is also a need to explore more effective TDM strategies to increase the proportion of neonatal patients attaining vancomycin target trough concentrations.

Target Attainment and Clinical Efficacy for Vancomycin in Neonates: Systematic Review

Vancomycin is commonly used as a treatment for neonatal infections. However, there is a lack of consensus establishing the optimal vancomycin therapeutic regimen and defining the most appropriate PK/PD parameter correlated with the efficacy. A recent guideline recommends AUC-guided therapeutic dosing in treating serious infections in neonates. However, in clinical practice, trough serum concentrations are commonly used as a surrogate PKPD index for AUC24. Despite this, target serum concentrations in a neonatal population remain poorly defined. The objective is to describe the relationship between therapeutic regimens and the achievement of clinical or pharmacokinetic outcomes in the neonatal population. The review was carried out following PRISMA guidelines. A bibliographic search was manually performed for studies published on PubMed and EMBASE. Clinical efficacy and/or target attainment and the safety of vancomycin treatment were evaluated through obtaining serum concentrations. A total of 476 articles were identified, of which 20 met the inclusion criteria. All of them evaluated the target attainment, but only two assessed the clinical efficacy. The enormous variability concerning target serum concentrations is noteworthy, which translates into a difficulty in determining which therapeutic regimen achieves the best results. Moreover, there are few studies that analyze clinical efficacy results obtained after reaching predefined trough serum concentrations, this information being essential for clinical practice.

Development and external evaluation of a population pharmacokinetic model for continuous and intermittent administration of vancomycin in neonates and infants using prospectively collected data

BACKGROUND

Vancomycin is commonly used for nosocomial bacterial pathogens causing late-onset septicaemia in preterm infants. We prospectively collected pharmacokinetic data aiming to describe pharmacokinetics and determine covariates contributing to the variability in neonatal vancomycin pharmacokinetics. Further, we aimed to use the model to compare the ratio of AUC24 at steady-state to the MIC (AUC24,ss/MIC) of several intermittent and continuous dosing regimens.

METHODS

Newborns receiving vancomycin for suspected or confirmed late-onset sepsis were included. Peak and trough concentrations for intermittent vancomycin dosing and steady-state concentrations for continuous vancomycin dosing were measured. NONMEM 7.3 was used for population pharmacokinetic analysis. Monte Carlo simulations were performed to compare dosing schemes.

RESULTS

Data from 54 infants were used for model development and from 34 infants for the model evaluation {corrected gestational age [median (range)] = 29 (23.7-41.9) weeks and 28 (23.4-41.7) weeks, respectively}. The final model was a one-compartment model. Weight and postmenstrual age were included a priori, and then no additional covariate significantly improved the model fit. Final model parameter estimates [mean (SEM)]: CL = 5.7 (0.3) L/h/70 kg and V = 39.3 (3.7) L/70 kg. Visual predictive check of the evaluation dataset confirmed the model can predict external data. Simulations using MIC of 1 mg/L showed that for neonates with gestational age ≤25 weeks and postnatal age ≤2 weeks AUC24,ss/MIC was lower with the intermittent regimen (median 482 versus 663).

CONCLUSIONS

A population pharmacokinetic model for continuous and intermittent vancomycin administration in infants was developed. Continuous administration might be favourable for treating infections caused by resistant microorganisms in very young and immature infants.

Therapeutic drug monitoring in neonates

Therapeutic drug monitoring (TDM) aims to integrate drug measurement results into clinical decision making. The basic rules apply when using TDM in neonates (aminoglycosides, vancomycin, phenobarbital, digoxin), but additional factors should also be taken into account. First, due to both pharmacokinetic variability and non-pharmacokinetic factors, the correlation between dosage and concentration is poor in neonates, but can be overcome with the use of more complex, validated dosing regimens. Second, the time to reach steady state is prolonged, especially when no loading dose is used. Consequently, the timing of TDM sampling is important in this population. Third, the target concentration may be uncertain (vancomycin) or depend on specific factors (phenobarbital during whole body cooling). Finally, because of differences in matrix composition (eg, protein, bilirubin), assay-related inaccuracies may be different in neonates. We anticipate that complex validated dosing regimens, with subsequent TDM sampling and Bayesian forecasting, are the next step in tailoring pharmacotherapy to individual neonates.

Optimizing the Use of Antibacterial Agents in the Neonatal Period

Antibiotics are invaluable in the management of neonatal infections. However, overuse or misuse of antibiotics in neonates has been associated with adverse outcomes, including increased risk for future infection, necrotizing enterocolitis, and mortality. Strategies to optimize the use of antibiotics in the neonatal intensive care unit include practicing effective infection prevention, improving the diagnostic evaluation and empiric therapy for suspected infections, timely adjustment of therapy as additional information becomes available, and treating proven infections with an effective, narrow-spectrum agent for the minimum effective duration. Antibiotic stewardship programs provide support for these strategies but require the participation and input of neonatologists as stakeholders to be most effective.