II. Background
- Acetaldehyde polymer used as a molluscicide, targeting small slugs and snails
- Highly toxic to small animals
- May cause serious toxicity in humans with large exposures
III. Mechanism: Toxicity
- Metaldehyde (and metabolites) decrease CNS GABA synthesis
- Metaldehyde metabolites increase MAO activity and increased oxygen free radicals
IV. Pharmacokinetics
- Routes of toxicity
- Ingestion and gastrointestinal absorption (within 1-4 hours)
- Transdermal
- Inhalational
- Enterohepatic recirculation increases Elimination Half-Life (up to 27 hours)
- Metaldehyde and its metabolites concentrate in the liver and CNS
- Metabolites
- Metaldehyde is hydrolyzed to acetaldehyde by hepatic CYP enzymes
VI. Adverse Effects: Neurotoxicity
-
Generalized Tonic Clonic Seizures
- Occurs with ingestions >100 mg/kg
- Intentional ingestions are associated with a higher risk of Seizures (RR 3)
-
Coma with increased mortality
- Occurs with ingestions >400 mg/kg
- Other neurologic adverse effects
- Facial Dystonia
- Altered Level of Consciousness
- Hyperreflexia
VII. Labs
- See Unknown Ingestion for toxicology labs (e.g. EKG, chemistry, bedside Glucose, acetaminphen level)
- Serum Metaldehyde levels are NOT typically available
VIII. Management
- Multidose Activated Charcoal for ingestions (due to enterohepatic circulation)
- Activated Charcoal 1 g/kg then 0.5 g/kg every 6 hours for 48 hours
- Requires alert, cooperative patient or secured airway (e.g. Endotracheal Intubation)
- Seizures (GABA Agonists)
- Disposition
- Observe patients for at least 6 hours
- Asymptomatic patients may be discharged after 6 hour observation
- Admit all symptomatic patients or intentional Overdose
IX. References
- Carroll and Yakey (2025) Crit Dec Emerg Med 39(7): 34
- Tan (2022) Acute Med Surg 9(1):e766 +PMID: 35769386 [PubMed]
- Bleakley (2008) Emerg Med J 25(6):381-2 +PMID: 18499834 [PubMed]