| To obtain emergency consultation with a medical toxicologist, in the United States, call 1-800-222-1222 for the nearest regional poison control center. Contact information for poison control centers around the world is available at the WHO website and in the UpToDate topic on regional poison control centers (society guideline links). |
| Clinical and laboratory features |
- Toxicity varies by drug. Bupropion and venlafaxine most toxic in overdose: may cause seizures or cardiac conduction abnormalities.
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- Additional potential complications include serotonin syndrome and arrhythmias.
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- Potential signs and symptoms include:
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- CNS - Sedation, coma, tremor; agitation (bupropion)
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- Cardiopulmonary - Tachycardia, hypertension
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- Gastrointestinal - Abdominal tenderness, vomiting, diarrhea
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- Neuromuscular - Clonus (ankle), hyperreflexia
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- ECG may reveal prolonged QTc interval or evidence of sodium channel blockade. Signs of severe sodium channel blockade include:
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- Prolongation of the QRS complex ≥120 milliseconds
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- Terminal R wave of 3 mm or more in lead aVR
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- Ratio of terminal R wave to S wave of 0.7 or more in lead aVR
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| Management |
- Most atypical antidepressant ingestions cause minimal toxicity; supportive care is generally sufficient. Determine drug and amount ingested, formulation, timing, and coingestants.
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- Secure airway, breathing, and circulation; intubate as clinically indicated.
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- To awake patients protecting their airway, may give one dose of activated charcoal (1 g/kg; standard adult dose is 50 g).
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- Avoid giving additional serotonergic agents.
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- Treat seizures with benzodiazepines (eg, diazepam, lorazepam). Initial diazepam dose for adults is 5 to 10 mg IV, given every 5 to 10 minutes (children >5 years: 1 to 2 mg; children <5 years: 0.2 to 0.5 mg).
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- Treat prolonged QRS interval with sodium bicarbonate: 1 to 2 mEq/kg IV push (typically, 50 to 100 mEq for an adult). Doses may be repeated as needed until the QRS interval narrows or the blood pH reaches 7.55. If QRS narrows with bicarbonate bolus, infuse bicarbonate (refer to dosing details in topic).
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- Observe patients with prolonged QTc for development of torsades de pointes. Treat torsades de pointes with magnesium sulfate (Mg): initial dose 2 g IV over 2 minutes; may repeat after 10 minutes; infusion may be needed.
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- For management of serotonin syndrome, refer to separate UpToDate topic.
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