Pharmacokinetics of S-ketamine during prolonged sedation at the pediatric intensive care unit

Robert B Flint, Carole N M Brouwer, Anne S C Kränzlin, Loraine Lie-A-Huen, Albert P Bos, Ron A A Mathôt*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

3 Citations (Scopus)

Abstract

BACKGROUND: S-ketamine is the S(+)-enantiomer of the racemic mixture ketamine, an anesthetic drug providing both sedation and analgesia. In clinical practice, significant interpatient variability in drug effect of S-ketamine is observed during long-term sedation.

AIMS: The aim of this study was to evaluate the pharmacokinetic variability of S-ketamine in children aged 0-18 years during long-term sedation. Twenty-five children (median age: 0.42 years, range: 0.02-12.5) received continuous intravenous administrations of 0.3-3.6 mg/kg/h S-ketamine for sedation during mechanical ventilation. Infusion rates were adjusted to the desired level of sedation and analgesia based on the COMFORT-B score and Visual Analog Scale. Blood samples were drawn once daily at random time-points, and at 1 and 4 hours after discontinuation of S-ketamine infusion. Time profiles of plasma concentrations of S-ketamine and active metabolite S-norketamine were analyzed using nonlinear mixed-effects modeling software. Clearance and volume of distribution were allometrically scaled using the ¾ power model.

RESULTS: A total of 86 blood samples were collected. A 2-compartment and 1-compartment model adequately described the PK of S-ketamine and S-norketamine, respectively. The typical parameter estimates for clearance and central and peripheral volumes of distribution were: CLS-KETAMINE =112 L/h/70 kg, V1S-KETAMINE =7.7 L/70 kg, V2S-KETAMINE =545L/70 kg, QS-kETAMINE =196 L/h/70 kg, and CLS-NORKETAMINE =53 L/h/70 kg. Interpatient variability of CLS-KETAMINE and CLS-NORKETAMINE was considerable with values of 40% and 104%, respectively, leading to marked variability in steady-state plasma concentrations.

CONCLUSION: Substantial interpatient variability in pharmacokinetics in children complicates the development of adequate dosage regimen for continuous sedation.

Original languageEnglish
Pages (from-to)1098-1107
Number of pages10
JournalPaediatric Anaesthesia
Volume27
Issue number11
Early online date13 Oct 2017
DOIs
Publication statusPublished - Nov 2017
Externally publishedYes

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