Two fatal cases of lacosamide poisoning with contrasting postmortem findings: implications for forensic toxicology

Lacosamide is a third-generation antiepileptic drug with expanding clinical use worldwide. Although generally considered safe, it has occasionally resulted in fatal intoxications; however, detailed postmortem data remain limited. Here, we describe two fatal cases of acute lacosamide poisoning with contrasting postmortem findings. In case 1, the cardiac blood concentration was extremely high (200 µg/mL). The gastric contents contained no visible solid residue at autopsy, although computed tomography images revealed hyperdense material in the stomach, extending toward the pyloric region. The cardiac blood included soft clots. The direct cause of death was presumed to be acute lacosamide poisoning. The cardiac/peripheral blood concentration ratio was 1.67, which exceeded previously reported values. In case 2, the cardiac blood concentration (74 µg/mL) was within the range reported in fatal cases. The gastric contents showed visible white powder, which was limited to the stomach cavity. The cardiac blood was a dark-reddish liquid. The urinary concentration was higher compared with that in case 1, which was consistent with rapid renal excretion. Alcohol intake and underlying sick sinus syndrome likely contributed to the fatal outcome. The cardiac/peripheral blood concentration ratio was 1.12, which was a comparable value to those previously reported. These cases demonstrate variability in the postmortem findings of fatal lacosamide poisoning, which highlights the importance of interpreting gastric, urinary, and coagulation findings along with blood levels. Given the increasing use of lacosamide, it is necessary to incorporate this substance into forensic toxicology screening protocols to aid in the precise diagnosis of drug-related fatalities.