Lipid Therapy for Selected Toxins

INTRODUCTION: The use of intravenous lipid emulsions (IVLE) has received much recent attention as potential antidote for a variety of lipophilic drug intoxications in veterinary medicine. Several case reports have shown promise, but to date few placebocontrolled studies have been performed. Potential toxicants that may respond to IVLE therapy include local anesthetics (such as lidocaine and bupivacaine), permethrin, muscle relaxers (such as baclofen), some anti-depressants, and avermectin parasiticides such as ivermectin. The original study by Weinberg et al in 2006, demonstrated that IVLE administered to rats increased survival after bupivacaine-induced cardiac arrest. A follow-up study using a canine model showed that IVLE administration increased survival in bupivacaine overdose. A normal sinus rhythm was established after 5 minutes in all dogs that were given IVLE, while no dogs receiving saline placebo survived. Subsequent studies in rabbits, mice, and dogs also showed that IVLE improved resuscitative efforts and survival in verapamil, propranolol, and clomipramine intoxications compared to standard resuscitative interventions alone. Two clinical case reports exists in the veterinary literature. One involves moxidectin toxicity and the successful use of IVLE. In this case report, a puppy was exposed to moxidectin, and shortly thereafter developed vomiting, ataxia, seizures and tremors. Seizure activity was treated with intravenous diazepam but the patient became comatose, requiring mechanical ventilation. IVLE therapy was initiated 10 hours post exposure, and within 2 hours of initiation of IVLE therapy the patient's condition improved to the point that he was able to be extubated. The patient was discharged 2 days after admission with no further neurological signs. The second report concerns a 5 year-old cat given a SQ overdose of lidocaine who made a complete recovery after an IV lipid infusion.