Amiodarone/N-desethylamiodarone population pharmacokinetics in paediatric patients.

The population pharmacokinetics of amiodarone and its active metabolite, N-desethylamiodarone (DEA) were investigated in paediatric patients with arrhythmias, mainly supraventricular tachycardias. A total of 55 patients from the Department of Pediatric Intensive Care and Pediatric Cardiology at Necker-Enfants malades Hospital (Paris, France) provided 72 concentrations for both amiodarone and DEA following repeated oral or intravenous administration. Blood samples drawn for biological analyses were used for drug concentrations. Plasma amiodarone concentrations were measured by a liquid chromatography method coupled with mass spectrometry and the data were modelled using the software Monolix 2019R2. Parent pharmacokinetics was described with a 2-compartment open model and the metabolite formation was connected to the central parent compartment. Parameter estimates scaled allometrically on bodyweight (normalized to 70 kg) were, respectively (% relative standard errors, RSEs), 6.32 (31%) and 7.14 L/h (26%) for elimination (CL) and intercompartmental clearances and 167 (31%) and 3930 (32%) L for V1 and V2 . Oral bioavailability was 0.362 (21.5%). The clearance between subject variability (ω, square root of the variance) was 0.462 (RSE 21%). The proportional residual variabilities were respectively 0.453 (RSE 13%) and 0.423 (RSE 12%) for amiodarone and DEA respectively. The terminal half-lives were 34 and 14.5 days for amiodarone and DEA, respectively. A dosage schedule was established for 3 weight bands in 2 time periods. The high pharmacokinetic variability suggests that therapeutic drug monitoring might be useful to improve individual efficacy and safety.

Risk factors of mortality and recoarctation after coarctation repair in infancy.

OBJECTIVES: The main challenge of aortic coarctation (CoA) repair in infants is to obtain durable results without morbidity. We aimed to describe predictors of aortic arch reintervention after aortic CoA repair. METHODS: Between January 2000 and March 2014, we retrospectively included consecutive infants with isolated CoA or CoA with ventricular septal defect (CoA + VSD) who had surgical repair of the aortic arch before 3 months of age. RESULTS: Five hundred and thirty patients were included: 308 (58%) patients had isolated CoA and 222 (42%) patients had CoA + VSD. Three hundred and eighty-five patients (72.6%) had CoA repair, 51 patients (9.6%) had CoA repair with closure of VSD and 94 patients (17.8%) had CoA repair with pulmonary artery banding. Mean age at operation was 13 ± 1.6 days, with 294 patients (55.5%) operated on before 2 weeks. Median follow-up was 7.57 years. Sixty-one patients (11.5%) needed reintervention on the aortic arch. Freedom from aortic arch reintervention was 90% at 1 year and 88.5% at 5 years. Proportions of aortic arch reintervention were similar in the different surgical strategy groups (P = 0.80). However, in patients receiving prostaglandin E1 (PGE1), the end-to-end repair was at higher risk of recoarctation compared to the extended end-to-side repair (P = 0.033). The risk factors of aortic arch reintervention were age at repair <15 days (P = 0.034) and the need for PGE1 infusion at surgery (P = 0.0043). CONCLUSIONS: CoA repair in young infants has an overall good outcome. The use of PGE1 may modify the aortic arch anatomy and mask the boundaries of the resection to be performed. PGE1 treatment should be studied more specifically in another study to improve preoperative management.