Agricultural avermectins: An uncommon but potentially fatal cause of pesticide poisoning

Study objective: Avermectins have been used in the control of parasites and insects; however, human data concerning poisoning are lacking. This study investigated the clinical spectrum of avermectin poisoning. Methods: A retrospective study was conducted to evaluate patients with aver mectin poisoning reported to a poison center from September 1993 through De cember 1997. Results: Eighteen patients with abamectin (Agri-Mek; 2% wt/wt abamectin) ex posure and 1 with ivermectin (Ivomec; 1% wt/vol ivermectin) ingestion were identified. There were 14 male and 5 female patients, ranging in age from 1 5 to 83 years. Most patients were exposed as a result of attempted suicide (14). Oral ingestion (15) was the most common route of exposure. Four patie nts were asymptomatic, and 8 had minor symptoms after a mean ingestion of 2 3 mg/kg abamectin (4.2 to 67 mg/kg), or after dermal and inhalation contact . Seven patients manifested severe symptoms, such as coma (7), aspiration w ith respiratory failure (4), and hypotension (3), after a mean ingestion of 100.7 mg/kg avermectin (15.4 mg/kg far ivermectin and 114.9 mg/kg for abam ectin). All 7 patients received intensive supportive care; 1 patient died 1 8 days later as a result of multiple organ failure. Conclusion: Ingestion of a large dose of avermectin may be associated with life-threatening coma, hypotension, and subsequent aspiration.