Letter to the Editor  Courrier des lecteurs Antidote for bromethalin poisoning Dear Editor, We read with great interest the recent Special Report by Dr. Coppock (Can Vet J 2013;54:557–558), on the deadly consequences of accidental ingestion by veterinary patients of bromethalin rodenticide, a commonly used potent, long-acting (days) neurotoxin for which no known antidote exists (1,2). However, given the hydrophobic (lipid-soluble) characteristics of bromethalin (log P, 6.78), we propose that intravenous or intraosseous administration of lipid emulsion using a well-­ established protocol (aka Lipid Rescue) could be a therapeutic option for veterinary patients with bromethalin toxicosis and should be initiated as soon as possible at point-of-care (3). Intravenous administration of commercially available lipid emulsion (e.g., Intralipid® 20%; a parenteral nutritional supplement approved worldwide) is a relatively new, safe, and efficacious treatment modality for severe cardiovascular and neurological toxicity provoked by accidental and intentional poisoning with lipophilic drugs (3). This emerging intervention is already used successfully in dogs, cats, and other animals poisoned by ivermectin, moxidectin, permethrin, baclofen, lidocaine, and other lipophilic drugs (4,5). Treated animals often exhibit prompt recovery with no reported acute adverse events nor long-term sequelae (4,5). Although the exact mechanism(s) of action underlying the salutary effects of lipid emulsion in the CNS of these cases is uncertain (3), it is possible that the circulating lipid emulsion entraps bromethalin (viz, the “lipid sink”) and then shuttle it to other sites for catabolism and excretion from the body. At the cellular level, free fatty acids released from lipid emulsion could also rescue mitochondria from the toxic effects of bromethalin in the CNS by inhibiting mitochondrial

­ ermeability transition pore opening thereby promoting recovp ery of veterinary patients (1–3). Finally, we encourage healthcare providers who treat bromethalin-intoxicated veterinary patients with lipid emulsion to report their experience in the literature.

References 1. Coppock R. Advisory: Bromethalin rodenticide — No known antidote. Can Vet J 2013;54:557–558. 2. Peterson ME. Bromethalin. Top Companion Anim Med 2013;28:21–23. 3. Weinberg GL. Lipid emulsion infusion: Resuscitation for local anesthetic and other drug overdose. Anesthesiology 2012;117:180–187. 4. Fernandez AL, Lee JA, Rahilly L, Hovda L, Brutlag AG, Engebretsen K. The use of intravenous lipid emulsion as an antidote in veterinary toxicology. J Vet Emerg Crit Care (San Antonio) 2011;21:309–320. 5. Kaplan A, Whelan M. The use of IV lipid emulsion for lipophilic drug toxicities. J Am Anim Hosp Assoc 2012;48:221–227.

Israel Rubinstein, MD Professor of Medicine Department of Medicine University of Illinois at Chicago College of Medicine and Jesse Brown VA Medical Center Chicago, Illinois 60612, USA [email protected] Guy Weinberg, MD Professor of Anesthesiology Department of Anesthesiology University of Illinois at Chicago College of Medicine and Jesse Brown VA Medical Center Chicago, Illinois 60612, USA [email protected]

Constructive and professional comments made in the spirit of intellectual debate are welcomed by the Editor. Writers are expected to be respectful of others and to ensure that letters are considerate and courteous. The Editor reserves the right to remove comments deemed to be inflammatory or disrespectful. CVJ / VOL 55 / JANUARY 2014

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