Suspected acute meperidine toxicity in a dog

Area of Science:

• Veterinary Anesthesiology
• Clinical Pharmacology
• Toxicology

Background:

• Meperidine is an opioid analgesic commonly used in veterinary medicine.
• Accidental overdose can lead to adverse effects, including central nervous system (CNS) excitation.
• Understanding the specific mechanisms of meperidine toxicity is crucial for effective management.

Observation:

• A Coton De Tulear dog received a ten-fold overdose of meperidine.
• The overdose resulted in profound CNS excitement, unresponsiveness, and muscle twitches.
• Initial treatment with naloxone and diazepam showed limited efficacy, with diazepam ultimately controlling the excitatory signs.

Findings:

• Normeperidine, a metabolite of meperidine, is implicated in CNS excitatory effects.
• These excitatory effects are not mediated by mu-opioid receptors, explaining naloxone's initial ineffectiveness.
• Benzodiazepines, such as diazepam, were effective in reversing the clinical signs of normeperidine excitotoxicity.

Implications:

• The use of naloxone should be carefully considered in cases of suspected normeperidine excitotoxicity.
• Benzodiazepines represent a potential therapeutic option for managing meperidine-induced CNS excitement in dogs.
• This case highlights the importance of accurate drug dosing and awareness of metabolite-specific toxicities in veterinary anesthesia.