P73 Paediatric population pharmacokinetic modeling for gentamicin – is the current dose recommendation justified?

BackgroundMonitoring of gentamicin serum trough level (Cmin) is standard practice in children to prevent toxicity by accumulation1. Cmin < 2 mg/L are recommended. Peak serum concentration (Cmax) is not routinely measured although Cmax between 10 and 12 mg/L have been recommended balancing efficac...

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Bibliographic Details
Published in:Archives of disease in childhood 2019-06, Vol.104 (6), p.e47-e47
Main Authors: Paioni, P, Berger, C, Krämer, SD
Format: Article
Language:English
Subjects:
Body height
Children
Cystic fibrosis
Dosage
Drug dosages
Gentamicin
Intravenous administration
Neonates
Patients
Pediatrics
Serum levels
Therapeutic drug monitoring
Toxicity
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Summary:BackgroundMonitoring of gentamicin serum trough level (Cmin) is standard practice in children to prevent toxicity by accumulation1. Cmin < 2 mg/L are recommended. Peak serum concentration (Cmax) is not routinely measured although Cmax between 10 and 12 mg/L have been recommended balancing efficacy and toxicity2,3. We aimed to develop a population pharmacokinetic (PK) model for gentamicin in children to optimise current dosing regimens.MethodsAll patients receiving once daily intravenous gentamicin (5 mg/kg in children < 7 days and 7.5 mg/kg in children >7 days of age) at the University Children’s Hospital Zurich between 10/2017 and 01/2019 were eligible for this study. Children with cystic fibrosis and renal replacement procedures were excluded. Routine Cmin were measured in all patients before administration of the second or third dose. Additional gentamicin serum levels were measured 30 min (C30) and 4 h after the second dose in patients giving written informed consent. Data were analysed by non-linear mixed-effects modeling.Results165 patients (median age 34 days; IQR 15–56 days) were included in the study. A total number of 103 C30 and 166 Cmin measurements were available, respectively. C30 (mean 19.7 mg/L, SD ±6.1 mg/L) was >12 mg/L in 94/103 (91%) and Cmin >2 mg/mL in 3/166 (1.8%) measurements. The PK model successfully predicted most C30 >12 mg/L but performed poorly at the through levels.ConclusionsOur current gentamicin dosing regimen rarely leads to accumulation but most Cmax are above optimal range. The latter was successfully modelled. Although no evidence for a Cmax upper limit exists, toxicity has been associated with high drug exposure3. This calls for an adjustment of our dosing regimen using our PK model based on body height or weight in order to lower exposure. Further studies investigating the relationship between Cmax levels and clinical outcome and additional data for PK model testing are needed for validation.ReferencesRitz N, Bielicki J, Pfister M, van den Anker J. Therapeutic Drug Monitoring for Anti-infective Agents in Pediatrics: The Way Forward. Pediatr Infect Dis J. 2016;35(5):570–572.Chattopadhyay B. Newborns and gentamicin-how much and how often? J Antimicrob Chemother. 2002;49(1):13–16.Touw DJ, Westerman EM, Sprij AJ. Therapeutic drug monitoring of aminoglycosides in neonates. Clin Pharmacokinet. 2009;48(2):71–88.Disclosure(s)Nothing to disclose
ISSN:0003-9888
1468-2044
DOI:10.1136/archdischild-2019-esdppp.111