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Pharmacokinetics of two per cent rectal methohexitone in children
R B Forbes1, D J Murray, J B Dillman
1Department of Anesthesia, University of Iowa College of Medicine, Iowa City 52242.
Insights
Rectal methohexitone effectively sedates children for anesthesia. Higher doses (25-30 mg/kg) ensure faster sleep onset and reliable sedation, with individualized dosing recommended.
Area of Science:
- Anesthesiology
- Pediatric Pharmacology
Background:
- Rectal methohexitone is a common anesthetic induction agent in children.
- Optimizing dosage for effective and safe sedation is crucial.
Purpose of the Study:
- To evaluate the relationship between rectal methohexitone dosage and anesthetic onset in children.
- To determine plasma methohexitone concentrations at various doses.
- To assess the safety and efficacy of different rectal methohexitone doses.
Main Methods:
- Sixty children (1-6 years) received rectal methohexitone (15, 20, 25, or 30 mg/kg).
- Onset of sleep was assessed by a blinded observer.
- Plasma methohexitone levels were measured at 15, 30, 45, and 120 minutes.
Main Results:
- Fifty of 60 children achieved sleep within 15 minutes.
- Higher doses (25-30 mg/kg) led to more reliable and faster sleep onset.
- Plasma methohexitone concentrations were significantly higher with 30 mg/kg compared to lower doses up to 120 minutes.
- No significant difference in complication incidence across doses.
Conclusions:
- Dose-dependent efficacy of rectal methohexitone for pediatric anesthesia induction.
- 25-30 mg/kg rectal methohexitone is recommended for reliable sedation.
- Individualized dosing based on clinical needs is advised for optimal anesthetic outcomes.
Abstract:
Plasma methohexitone concentrations were determined in 60 children, aged one to six years, following administration of 15 mg.kg-1, 20 mg.kg-1, 25 mg.kg-1 or 30 mg.kg-1 two per cent rectal methohexitone. Time to the onset of sleep was determined by a blinded observer and venous blood samples obtained 15, 30, 45 and 120 minutes following drug administration. Fifty of 60 children were asleep within 15 minutes. Nine of the ten children that did not fall asleep were sedate and could be separated easily from their parents to undergo inhalational induction of anesthesia. Time to the onset of sleep was inversely related to the dose of rectal methohexitone administered. Sleep was achieved more reliably following the use of 25 to 30 mg.kg-1 rectal methohexitone. In addition, plasma methohexitone concentrations following 30 mg.kg-1 rectal methohexitone were significantly higher for up to 120 minutes following drug administration than the plasma concentrations achieved after 15 mg.kg-1 or 20 mg.kg-1 methohexitone. There was no difference in the incidence of complications. The authors recommend that clinical circumstances be carefully considered and the dose of rectal methohexitone administered be individualized to meet the specific anaesthetic requirements of each child.