Objectives Although amiodarone is an effective treatment for severe paediatric arrhythmias, uncertainties about adverse effects such as hypotension, bradycardia and excessive serum drug concentrations persist. Therefore, the aims of this study were to: (a) determine serum concentrations of intravenous (IV) amiodarone following a widely implemented dosing regimen of 5 mg/kg bolus plus a 10 mg/kg/day continuous infusion and (b) generate descriptive data on safety parameters such as hypotension, bradycardia or corrected QT (QTc) prolongation during this regimen.

Design Prospective observational study.

Setting Paediatric intensive care unit.

Patients Twenty paediatric patients (median age, 0.23 years; range, 6 days–15.04 years) with arrhythmia secondary to or without cardiac surgery.

Interventions None.

Main outcome measures Amiodarone serum concentrations, blood pressure, heart rate, QTc intervals.

Results Amiodarone serum concentrations increased markedly during bolus, followed by rapid decreases during maintenance infusion. All patients had serum concentrations regarded as effective in adults (median concentration range: 1.30–2.06 µM/L during maintenance phase). Amiodarone suppressed arrhythmias in 18 (90%) patients. Mean QTc intervals for pretherapy, during and post-therapy periods were 443 ms, 458 ms and 467 ms, respectively. Eight patients had hypotension.

Conclusions Amiodarone was effective in the majority of children in this small cohort.