Clinical features of seven patients poisoned with a tolfenpyrad-based insecticide in Thailand.

Introduction: Tolfenpyrad, a novel insecticide originating from Japan and first approved in 2002, has been marketed in numerous countries. Data on tolfenpyrad exposure in humans are limited. This study aimed to characterize the clinical features and outcomes of acute poisoning from tolfenpyrad-based insecticides in Thailand.

Methods: This retrospective study analyzed cases of tolfenpyrad exposure reported to the Ramathibodi Poison Center from 2012 to 2022.

Results: A total of seven patients were identified, with the majority being male (n = 5). Deliberate tolfenpyrad exposure accounted for three cases. The median age was 33 (range 1-46) years. Severe systemic effects were evident at presentation in the four patients ingesting tolfenpyrad. These included altered mental status (n = 4), mydriasis (n = 2), cardiac arrest (n = 1), hypotension (n = 4), bradycardia (n = 2), and high anion gap metabolic acidosis (n = 4). The median time from exposure to hospital presentation was 30 (range 15-60) minutes. All four patients ingesting tolfenpyrad died, whereas the three patients exposed via inhalation and dermally developed only mild clinical effects, and all were discharged following supportive care.

Discussion: We observed many of the clinical features reported previously, including vomiting, mydriasis, altered mental status, metabolic acidosis, and hypotension. We also noted a combination of bradycardia and hypotension while not observing respiratory depression.

Conclusions: Tolfenpyrad insecticide poisoning has been reported infrequently. Rapid systemic toxicity can follow ingestion, resulting in a high mortality. Larger-scale studies are essential to identify predictors of severity and determine the optimal treatment for tolfenpyrad-poisoned patients.