Low-dose intravenous clonidine in children: plasma concentrations and haemodynamic response
H T Bergendahl1, S Eksborg, P A Lönnqvist
1Department of Paediatric Anaesthesiology and Intensive care, St Görans Paediatric Hospital, Stockholm, Sweden.
Insights
Low doses of intravenous clonidine (0.625 and 1.25 micrograms/kg) effectively reduced blood pressure in paediatric patients. This study found moderate blood pressure reduction without a clear dose-dependent or plasma-concentration effect.
Area of Science:
- Anesthesiology
- Pediatric Pharmacology
Background:
- Alpha-2 agonist clonidine shows beneficial perioperative effects in children.
- Previous studies indicate similar pharmacokinetics in pediatric and adult patients.
- A prior study demonstrated significant blood pressure reduction with 2.5 micrograms/kg clonidine.
Purpose of the Study:
- To evaluate dose-dependent and plasma-dependent hemodynamic changes with lower clonidine doses.
- To assess the effects of intravenous clonidine 0.625 and 1.25 micrograms/kg in pediatric patients.
Main Methods:
- Prospective, single-blind, controlled clinical trial.
- 24 pediatric patients (13-78 months) randomized into control, 0.625 mcg/kg, and 1.25 mcg/kg clonidine groups.
- Non-invasive blood pressure and heart rate monitored; plasma clonidine concentrations analyzed.
Main Results:
- All groups showed a decrease in mean arterial blood pressure (MABP) from baseline.
- Clonidine groups exhibited significantly greater blood pressure reduction compared to the control group.
- No significant effect on heart rate was observed, likely due to atropine premedication.
Conclusions:
- Low intravenous doses of clonidine (0.625 and 1.25 micrograms/kg) reduce blood pressure in pediatric patients.
- A plasma concentration-dependent blood pressure effect could not be established.
- The observed blood pressure reductions were of moderate magnitude.
Abstract:
The beneficial perioperative effects of the alpha-2 agonist clonidine have recently been verified in paediatric patients, and the pharmacokinetics have been found to be similar to what has been reported in adults. In a previous study we found that 2.5 micrograms/kg of clonidine causes a significant reduction in blood pressure. The aim of the present study was to evaluate if even lower doses of clonidine are associated with dose dependent or plasma-dependent haemodynamic changes. In a prospective, single, blind, controlled clinical trial, 24 paediatric patients (age range: 13-78 months) were randomised into three groups: control, intravenous clonidine 0.625 microgram/kg and intravenous clonidine 1.25 micrograms/kg respectively. Non-invasive blood pressure and heart rate were recorded at 3-min intervals for 30 min. Plasma concentrations of clonidine were analysed at 15 and 30 min post-injection. A decrease in MABP compared to baseline values was observed in all groups. A significantly greater reduction in blood pressure was seen in all groups receiving clonidine compared to control. In conclusion, low doses of clonidine (0.625 and 1.25 micrograms/kg) were found capable of causing a blood pressure reduction compared to control. We could not establish a plasma concentration dependent blood pressure effect. The observed blood pressure reductions caused by clonidine were of moderate magnitude. No effect on heart rate was observed, a finding which most likely is explained by the inclusion of atropine in the premedication.
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