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Pharmacokinetics of i.v. and rectal methohexitone in children
S Björkman1, J Gabrielsson, H Quaynor
1Hospital Pharmacy, Malmö allmänna sjukhus, Sweden.
Insights
Methohexitone
Area of Science:
- Pharmacology
- Anesthesiology
- Pediatric Medicine
Background:
- Methohexitone is an anesthetic agent used in pediatric surgery.
- Understanding its pharmacokinetic profile in children is crucial for safe and effective anesthesia.
- Previous studies on pediatric methohexitone pharmacokinetics are limited.
Purpose of the Study:
- To investigate the pharmacokinetics of methohexitone in healthy children.
- To compare intravenous (IV) and rectal administration routes.
- To determine key pharmacokinetic parameters like half-life, clearance, and bioavailability.
Main Methods:
- 15 healthy children undergoing minor surgery were studied.
- Six children received IV methohexitone (1-2 mg/kg).
- Nine children received rectal methohexitone (20-25 mg/kg).
- Plasma concentrations were analyzed using a three-compartment pharmacokinetic model for IV data.
- The model was adapted for rectal administration data.
Main Results:
- Intravenous methohexitone exhibited a mean elimination half-life of 193 ± 75 min, longer than previously reported for children but consistent with adults.
- Mean clearance was 17.9 ± 8.3 ml/min/kg, and volume of distribution at steady state was 2.1 ± 0.24 L/kg.
- Rectal administration resulted in a mean bioavailability of 17%, with significant inter-individual variability (six-fold).
Conclusions:
- Methohexitone's pharmacokinetic profile in children, particularly its elimination half-life, is similar to adults.
- Rectal administration of methohexitone shows lower bioavailability and high variability in children.
- These findings are important for optimizing anesthetic drug administration in pediatric patients.
Abstract:
The pharmacokinetics of methohexitone were investigated in 15 healthy children undergoing minor surgery under inhalation anaesthesia. Six received 1% methohexitone 1-2 mg kg-1 i.v. and nine received 10% methohexitone 20-25 mg kg-1 per rectum. On i.v. administration, three-compartment pharmacokinetics generally applied. The mean elimination half-life of methohexitone was 193 +/- 75 min; that is, considerably longer than previously reported for children, but in good agreement with findings in adults. The mean clearance was 17.9 +/- 8.3 ml min-1 kg-1, the volume of distribution at steady state was 2.1 +/- 0.24 litre kg-1 and the mean residence time was 134 +/- 47 min. The pharmacokinetic model used for the i.v. data was easily modified to suit the plasma concentration curves obtained on rectal administration. The mean bioavailability of methohexitone administered per rectum was 17%, with a six-fold variation between individuals.