Tobramycin Pharmacokinetics in Children with Febrile Neutropenia Undergoing Stem Cell Transplantation: Once-Daily versus Thrice-Daily Administration

Optimizing Antibiotic Drug Therapy in Pediatrics: Current State and Future Needs

The selection of the right antibiotic and right dose necessitates clinicians understand the contribution of pharmacokinetic variability stemming from age-related physiologic maturation and the pharmacodynamics to optimize drug exposure for clinical response. The complexity of selecting the right dose arises from the multiplicity of pediatric age groups, from premature neonates to adolescents. Body size and age (which relate to organ function) must be incorporated to optimize antibiotic dosing in this vulnerable population. In the effort to optimize and individualize drug dosing regimens, clinical pharmacometrics that incorporate population-based pharmacokinetic modeling, Bayesian estimation, and Monte Carlo simulations are utilized as a quantitative approach to understanding and predicting the pharmacology and clinical and microbiologic efficacy of antibiotics. In addition, opportunistic study designs and alternative blood sampling strategies can serve as practical approaches to ensure successful conduct of pediatric studies. This review article examines relevant literature on optimization of antibiotic pharmacotherapy in pediatric populations published within the last decade. Specific pediatric antibiotic data, including beta-lactam antibiotics, aminoglycosides, and vancomycin, are critically evaluated.

Optimal Trough Concentration of Teicoplanin in Febrile Neutropenic Patients with Hematological Malignancy

BACKGROUND

Teicoplanin is a glycopeptide antibiotic currently used for the treatment of methicillin-resistant Staphylococcus aureus. The need for therapeutic drug monitoring of teicoplanin has been increasingly highlighted as important. It is generally accepted that whereas a plasma trough concentration (Cmin) of ≥10 mg/L is appropriate for the majority of infections, it should exceed 20 mg/L for severe infections. The target Cmin of teicoplanin in patients with febrile neutropenia (FN) has not been reported. The aim of this study was to estimate the target Cmin for the treatment of FN in patients with hematological malignancy.

METHODS

In this retrospective, single-center, observational cohort study, the records of 52 hospitalized patients with hematological malignancy who were treated with teicoplanin for FN due to bacteriologically documented or presumptive gram-positive infections were analyzed.

RESULTS

A significant difference in the first Cmin of teicoplanin was observed between the response and nonresponse groups in patients with bacteremia. The areas under the receiver operating characteristic curves were 0.80 for clinical efficacy. The cut-off value of teicoplanin Cmin on days 4-6 was 15.2 mg/L (sensitivity 80.0%, specificity 75.0%).

CONCLUSIONS

The authors propose a target teicoplanin Cmin of ≥15.2 mg/L for FN in patients with hematological malignancy.

Treatment option for sepsis in children in the era of antibiotic resistance

Sepsis caused by multidrug-resistant microorganisms is one of the most serious infectious diseases of childhood and poses significant challenges for pediatricians involved in management of critically ill children. This review discusses the use of pharmacokinetic/dynamic principles (i.e., prolonged infusion of β-lactams and vancomycin, once-daily administration of aminoglycosides and rationale of therapeutic drug monitoring) when prescribing antibiotics to critically ill patients. The potential of 'old' agents (i.e., colistin, fosfomycin) and newly approved antibiotics is critically reviewed. The pros and cons of combination antibacterial therapy are discussed and finally suggestions for the treatment of sepsis caused by multidrug-resistant organisms are provided.

Assessment of gentamicin 7 mg/kg once daily for pediatric patients with febrile neutropenia: a pilot project

Context. Use of once daily aminoglycosides continues to increase for the pediatric population, including oncology patients. Concerns have been identified and still need to be resolved including the optimal dose, frequency, and monitoring parameters.

Objective. We completed a study to determine if empiric use of gentamicin 7 mg/kg once daily in pediatric patients admitted with febrile neutropenia provided extrapolated peaks and drug-free intervals consistent with suggested preferred levels.

Design. A review of the patient’s chart was completed following their discharge from the hospital between September 2006 and October 2007.

Setting. A community hospital.

Patients. A consecutive sample of 17 encounters for pediatric patients admitted for febrile neutropenia that received once daily gentamicin.

Main outcome measures. Extrapolated peak levels and drug-free intervals.

Results. There were seven patients with a total of 17 encounters. The mean extrapolated peak level was 16.9 mg/L. The mean drug-free interval was 15.7 h. Both target peak and drug-free interval were obtained for two encounters (12%), which was one patient.

Conclusion. Gentamicin 7 mg/kg/dose once daily does not provide preferred levels for all pediatric febrile neutropenic patients. Further investigation is required to ensure that once daily gentamicin regimens for pediatric oncology patients provide adequate clinical success. J Oncol Pharm Practice (2009) 15: 211—216.

Extent of agreement in gentamicin concentration between serum that is drawn peripherally and from central venous catheters

OBJECTIVE

At our institution, patients who receive once-daily dosing of gentamicin have serum concentrations determined 3 and 6 hours after dose administration. Patients with single-lumen central venous catheters have the 3-hour samples drawn peripherally. The objective of this study was to evaluate the extent of agreement between peripheral and central venous catheter serum gentamicin concentrations drawn 3 hours after dose administration.

METHODS

In this prospective, observational study, patients provided both a peripheral and a central blood sample for determination of serum gentamicin concentration. The order of sampling (central venous catheter versus peripheral first) was randomized. Agreement was assessed by determination of the intraclass correlation coefficient and Bland-Altman analysis. The clinically acceptable targets for the lower limit of the intraclass correlation coefficient and Bland-Altman limits of agreement were defined a priori as >0.80 and +/-6%, respectively. Differences between the theoretical dose adjustments using the central venous catheter versus the peripheral sample result were described.

RESULTS

Forty-five pairs of samples were collected: 42 from single-lumen implantable central venous catheters (ports) and 3 from peripherally inserted central venous catheters. The intraclass correlation coefficient was 0.91. However, the Bland-Altman analysis resulted in a mean percentage difference (central venous catheter versus peripheral) of -0.92% and limits of agreement of -27.9% to 26.0%. The gentamicin dose adjustment based on the central venous catheter sample result would have led to clinically significant dose adjustments in 19 (42%) cases, when compared with the peripheral sample result.

CONCLUSIONS

These results indicate a lack of agreement between peripheral and single-lumen central venous catheter samples. In particular, ports are not appropriate sites for monitoring serum gentamicin concentrations.