Poisoning by illegal rodenticides containing acetylcholinesterase inhibitors (chumbinho): a prospective case series

Objective. To describe a prospective case series of poisonings caused by ingestion of illegal rodenticides containing acetylcholinesterase inhibitors, mainly chumbinho, followed-up by the Campinas PCC for a period of 1 year. Case series. Seventy-six cases were included, of which 53.9% were males. Age ranged from 2 to 74 years (median = 36 years). The main circumstances leading to poisoning were intentional (suicide attempts 92.1%; homicide attempts 5.3%), and 65.8% were admitted less than 2 hours after ingestion. Most of the patients (96.1%) showed cholinergic muscarinic manifestations, particularly salivation (86.8%), myosis (77.6%), sweating (50%), and bronchorrhea (35.5%). Atropine was used in 82.9% of patients (median = 2 days), intubation and mechanical ventilation in 46.1% (median = 3 days), and the median length of the hospital stay was 4 days. Plasma samples obtained upon admission in 59 cases revealed (LC-MS/MS): aldicarb (55), carbofuran (2), aldicarb and carbofuran (1), no active component (1). In most of the plasma and urine samples collected upon admission, the highest concentrations (ng/mL) obtained were for the active metabolite aldicarb sulphoxide (plasma, median = 831, IIQ = 99.2-2885; urine, median = 9800, IIQ = 2000-15000) than aldicarb (plasma, median = 237, IIQ = 35.7-851; urine, median = 584, IIQ = 166-1230), indicating rapid metabolism. The excretion of aldicarb and its metabolites was rapid since these compounds were rarely detected in plasma samples 48 hours after admission. Sequential cholinesterase analysis in 14 patients revealed almost complete reactivation in the first 48 hours post-admission, compatible for poisoning by carbamates. Based on the Poisoning Severity Score, the cases were classified as asymptomatic (5.3%), minor (11.8%), moderate (35.5%), severe (43.4%), and fatal (3.9%). Conclusions. Most poisonings involved aldicarb and resulted from suicide attempts; the poisonings were generally severe, with a mortality of 3.9%. Aldicarb was rapidly absorbed, metabolized, and excreted.