Overlapping Hepatic and Neurological Toxicity Following Intentional Multidrug Poisoning with Acetaminophen, Metoclopramide, and Metronidazole: A Case Report.

INTRODUCTION

Polydrug overdose, defined as the simultaneous ingestion of multiple toxic substances, is increasingly encountered in emergency departments. Overlapping toxidromes often obscure the causative agents, complicating diagnosis and management. Acetaminophen (APAP) overdose can cause hepatotoxicity through N-acetyl-p-benzoquinone imine (NAPQI) formation, metoclopramide may precipitate acute extrapyramidal symptoms, and metronidazole can induce neurotoxicity, typically a cerebellar syndrome.

CASE SUMMARY: Young adult male medical student intentionally ingested 12 g of APAP, 170 mg of metoclopramide, and 8 g of metronidazole. He presented 24 hours later with repeated vomiting, tremor, rigidity, dysarthria, gait ataxia, and transient confusion. Vital signs were stable; laboratory tests showed transaminase elevation and coagulopathy. Peak AST/ALT were 100/76 U/L and INR peaked at 1.74. Management included oral N-acetylcysteine for APAP toxicity, intravenous diphenhydramine and diazepam for extrapyramidal symptoms, supportive ICU care, and psychiatric intervention. Coagulopathy was corrected with fresh frozen plasma. Neurological and hepatic abnormalities resolved within 72 hours, and the patient remained asymptomatic at 2-week follow-up. The patient recovered fully after N-acetylcysteine and supportive care, illustrating the diagnostic challenges of overlapping toxidromes.

CONCLUSION

This case highlights the diagnostic and therapeutic challenges of polydrug overdose with overlapping toxidromes. Rapid identification and agent-specific management, including NAC for APAP, symptomatic therapy for metoclopramide and metronidazole toxicity, and supportive care, resulted in full recovery without long-term sequelae. Emergency clinicians should maintain high suspicion for multiple co-ingestants and use targeted interventions to optimize outcomes.