What is the accuracy of serum salicylate levels in diagnosing ibuprofen (nonsteroidal anti-inflammatory drug (NSAID)) overdose?

Serum Salicylate Testing Has No Utility in Ibuprofen Overdose

Serum salicylate testing is completely irrelevant for diagnosing or managing ibuprofen overdose, as ibuprofen is a propionic acid derivative NSAID that is chemically unrelated to salicylates and will not be detected by salicylate testing. 1

Understanding Ibuprofen Overdose

• Ibuprofen overdose manifestations typically include gastrointestinal upset, dizziness, and mild sedation, with severe cases potentially developing metabolic acidosis, renal failure, respiratory depression, and cardiovascular collapse 2, 3
• The FDA drug label for ibuprofen indicates that symptoms are unlikely after ingestion of less than 100 mg/kg, but may become life-threatening when more than 400 mg/kg is ingested 1, 4
• Reported serum ibuprofen concentrations in fatal overdoses have ranged from 260-600 μg/mL (therapeutic range: 10-50 μg/mL) 3, 5

Diagnostic Testing in Ibuprofen Overdose

• Serum salicylate testing has no role in diagnosing or managing ibuprofen overdose as these are completely different drug classes 1
• Appropriate laboratory tests for suspected ibuprofen overdose should include:
  • Complete blood count (to assess for thrombocytopenia) 6
  • Comprehensive metabolic panel (to evaluate liver and kidney function) 6, 7
  • Arterial blood gas (to assess for metabolic acidosis) 3, 7
  • Serum ibuprofen levels (if available, though not typically needed for management decisions) 4

Management of Ibuprofen Overdose

• Treatment is primarily supportive, focusing on:
  • Gastric decontamination with activated charcoal if presenting within 1 hour of ingestion 4
  • Correction of metabolic acidosis 3, 7
  • Maintenance of adequate hydration 1
  • Monitoring of renal function 6, 7
• In severe cases with multi-organ failure, more aggressive interventions may be required:
  • Vasopressor support for hypotension 3
  • Mechanical ventilation for respiratory failure 7
  • Renal replacement therapy for acute kidney injury 3, 7

Clinical Pearls and Pitfalls

• A common pitfall is confusing different NSAID classes - ibuprofen (propionic acid derivative) is chemically distinct from aspirin (salicylate) 8
• Naloxone has been reported to reverse CNS depression in some cases of ibuprofen overdose, suggesting an opioid-like mechanism may contribute to CNS effects 2
• Patients with massive ibuprofen overdose may develop a triad of metabolic acidosis, renal failure, and CNS depression that can progress to cardiovascular collapse 3, 7
• The risk of mortality increases with delayed presentation, pre-existing medical conditions, and extremely high serum concentrations 3, 5