What are the clinical consequences and emergency management of ingesting ten diclofenac tablets?

Acute Diclofenac Overdose: Clinical Consequences and Emergency Management

Ingestion of 10 diclofenac tablets (250-1000 mg depending on tablet strength) typically causes central nervous system toxicity including disorientation, hallucinations, loss of consciousness, and potentially respiratory arrest requiring aggressive supportive care with mechanical ventilation. 1

Immediate Clinical Manifestations

The primary toxicity from diclofenac overdose affects the central nervous system rather than causing direct cardiovascular collapse at presentation. 1

CNS Toxicity (Most Common)

• Disorientation and altered mental status develop as the earliest manifestations 1
• Hallucinations may occur with moderate overdoses 1
• Loss of consciousness progressing to respiratory arrest represents the most life-threatening acute complication 1
• Symptoms typically manifest within hours of ingestion 1

Cardiovascular Effects

• ECG abnormalities including QTc prolongation, QRS widening, and tachycardia can develop, particularly at 12-24 hours post-ingestion 2
• Direct myocardial damage with oxidative stress and mitochondrial injury may occur with high doses 2, 3
• Cardiovascular toxicity is generally delayed compared to CNS effects 2

Gastrointestinal Symptoms

• Nausea and vomiting are expected but typically less severe than the CNS manifestations 1, 4
• Gastrointestinal bleeding risk exists but is not the primary acute concern in overdose 5

Emergency Management Algorithm

Immediate Stabilization (First Hour)

1. Airway protection is the absolute priority - prepare for rapid sequence intubation given high risk of respiratory arrest 1
2. Establish IV access and continuous cardiac monitoring with serial ECGs to detect QTc prolongation and arrhythmias 2
3. Administer activated charcoal if patient presents within 1-2 hours of ingestion and airway is protected 1
4. Obtain baseline labs: complete metabolic panel (renal function), liver enzymes, complete blood count, coagulation studies 3

Supportive Care (Hours 1-24)

• Mechanical ventilation should be initiated promptly for respiratory depression or inability to protect airway 1
• Aggressive fluid resuscitation to maintain renal perfusion and prevent acute kidney injury 5
• Continuous monitoring of mental status, respiratory rate, oxygen saturation, and cardiac rhythm 1, 2
• Serial ECGs at 1,6,12, and 24 hours to monitor for delayed cardiac toxicity 2

No Specific Antidote Available

• There is no reversal agent for diclofenac toxicity - management is entirely supportive 1
• Unlike opioid overdose (naloxone) or benzodiazepine overdose (flumazenil), no pharmacologic antagonist exists 5

Expected Clinical Course and Prognosis

Most patients recover fully within 24 hours with aggressive supportive care and no serious long-term sequelae. 1

Recovery Timeline

• Consciousness typically returns within 24 hours with supportive management 1
• Extubation is usually possible within 24 hours if respiratory arrest occurred 1
• Complete neurological recovery is expected in the absence of prolonged hypoxia 1

Delayed Complications to Monitor (24-72 Hours)

• Hepatotoxicity may develop with delayed onset, requiring serial liver enzyme monitoring 3
• Acute kidney injury from acute tubular necrosis, particularly if hypotension occurred 5
• Cardiac arrhythmias may manifest in the 12-24 hour window 2

Critical Pitfalls to Avoid

Common Management Errors

• Underestimating respiratory depression risk - have intubation equipment immediately available 1
• Failing to protect airway before activated charcoal - aspiration risk is extremely high in altered patients 1
• Inadequate monitoring duration - cardiac and hepatic toxicity may be delayed beyond initial presentation 2, 3
• Premature discharge - patients require minimum 24-hour observation even if initially asymptomatic 1, 2

High-Risk Patient Populations

• Elderly patients have increased susceptibility to both CNS and cardiovascular toxicity 5, 6
• Patients with pre-existing cardiac disease face substantially higher risk of arrhythmias and cardiac arrest 5, 6
• Patients with renal insufficiency may have prolonged drug elimination and worse outcomes 5
• Concurrent ingestion with other NSAIDs (as in the reported case with ibuprofen and indomethacin) dramatically increases toxicity 1

Dose-Dependent Toxicity Considerations

Standard therapeutic dosing is 100-200 mg daily in divided doses. 5, 4

• 10 tablets of 25 mg (250 mg total) = 1.25-2.5x maximum daily dose
• 10 tablets of 50 mg (500 mg total) = 2.5-5x maximum daily dose
• 10 tablets of 75 mg (750 mg total) = 3.75-7.5x maximum daily dose
• 10 tablets of 100 mg (1000 mg total) = 5-10x maximum daily dose

The case report documenting severe CNS toxicity involved 375 mg (approximately 2.5x maximum daily dose), suggesting significant toxicity can occur at relatively modest overdoses. 1