Flecainide Toxicity Secondary to Accidental Overdose: A Pediatric Case Report of Two Brothers

Evidence of exposure to flecainide in a newborn by keratinous matrices testing and interpretation of the findings

Pediatric poisoning represents a serious problem all around the world. Abuse or neglect of children by adults must be highlighted in children exposed to drugs to which they would not normally have access. Usually, segmental hair analysis would allow in these contexts to determine whether the exposure was unique or repetitive. Hair and nail samples from a 9-month-old girl were received in our laboratory for analysis, after the child was hospitalized due to severe dehydration caused by her mother's neglect. At the admission, flecainide, an antiarrhythmic never prescribed to the child, was identified in the daughter urine. Using an LC-MS/MS method, flecainide tested positive in the child's hair at the following concentrations: 66 pg/mg (root to 1 cm), 61 pg/mg (1-2 cm), and 125 pg/mg (2-3 cm). Traces below the limit of quantification (1 pg/mg) were also present in the nail clippings. These concentrations are much lower than those obtained in adults under daily treatment. Given the different pharmacokinetic and dynamic parameters in children, the different rate of hair growth, and the greater porosity of the hair, which makes it more prone to external contamination, the interpretation of hair findings in children remains very complicated. In this case, it can be assumed that the presence of the drug in the urine indicates systemic incorporation and that administration had occurred for some months (three positive segments). The interpretation of hair tests from young children needs a global review of all the findings, as a positive result cannot stand alone to claim repetitive exposures.

Pediatric antiarrhythmics and toxicity: A clinical review

Antiarrhythmic medications are fundamental in the acute and chronic management of pediatric arrhythmias. Particularly in the pediatric patient population, associated antiarrhythmic toxicities represent important potential adverse effects. Emergency medicine clinicians must be skilled in the detection, workup, and management of antiarrhythmic toxicity. This is a clinical review of the indications, pharmacology, adverse effects, and toxicologic treatment of antiarrhythmics commonly used in the pediatric patient population.

Flecainide toxicity: ECG changes associated with supratherapeutic levels in milk-fed infants

Flecainide is a class 1C antiarrhythmic and is highly effective for treating a wide range of arrhythmias. It is not licensed for children under the age of 12 years, but has been used safely for years in young children, particularly when first-line agents are not effective. Although toxicity does occur in both adult and paediatric populations, there have been very few reported instances of flecainide toxicity in neonates and children. Supratherapeutic levels of flecainide manifests on ECG with prolongation of the PR interval, QRS duration and QT, and can lead to life-threatening arrhythmias. In milk-fed infants receiving flecainide, regular feeding patterns are paramount to achieve a steady therapeutic state, as milk and dairy products are known to reduce the absorption of flecainide. This case series details four milk-fed infants admitted with ECG changes secondary to flecainide toxicity.