Can a 2000mg quetiapine overdose be lethal?

Quetiapine Overdose Lethality

A 2000mg quetiapine overdose can be lethal, though death is uncommon—survival has been reported with doses up to 36 grams, but fatalities have occurred with as little as 13.6 grams in clinical trials. 1, 2

Mortality Risk Assessment

The lethality of quetiapine overdose is unpredictable and depends on multiple factors:

• Deaths have been documented in clinical trials following overdose of 13.6 grams of quetiapine alone, and there are very rare post-marketing reports of death from quetiapine overdose 1
• Survival is possible with massive overdoses: A patient survived a 36-gram ingestion (18 times the dose in question) with complete recovery, and another survived 24 grams despite developing hypotension and seizures 2, 3
• Three deaths occurred in a California case series of 945 adult quetiapine overdoses; all three fatalities presented with coma, tachycardia, and respiratory depression requiring ventilatory support 4

Life-Threatening Complications

The primary mechanisms of death are respiratory depression, cardiovascular collapse, and aspiration 1, 4:

• Central nervous system depression occurs in 76% of cases (drowsiness) with 10% progressing to coma 4
• Respiratory depression requiring mechanical ventilation occurs in approximately 5% of overdoses 3, 4
• Cardiovascular effects include tachycardia (56% of cases), hypotension (18%), and QTc prolongation, though torsades de pointes is rare 1, 3, 4
• Seizures occur in approximately 2% of cases 3, 4

Critical Management Priorities

Immediate airway protection and cardiovascular monitoring are essential 1:

• Establish and maintain airway with bag-mask ventilation; proceed to endotracheal intubation if the patient is unconscious or has respiratory depression 1
• Gastric lavage (after intubation if unconscious) and activated charcoal with laxative should be considered, though the risk of aspiration is significant given the potential for obtundation and seizures 1
• Continuous ECG monitoring is mandatory to detect arrhythmias, particularly QT prolongation 1
• Treat hypotension with IV fluids and/or sympathomimetic agents, but avoid epinephrine and dopamine as beta-stimulation may worsen hypotension due to quetiapine's alpha-blockade 1

Prognostic Indicators

Patients with pre-existing cardiovascular disease face increased risk 1:

• A reported dose <3 grams AND Glasgow Coma Scale score of 15 at least 4 hours post-ingestion predicts patients unlikely to require ICU admission or hospital stay >24 hours 3
• At 2000mg (2 grams), the patient is below this threshold, but close monitoring is still required as individual responses vary 3
• Reported dose and peak quetiapine concentrations correlate significantly with ICU admission and prolonged hospital stay 3

Important Caveats

• No specific antidote exists for quetiapine overdose; management is entirely supportive 1
• Polypharmacy overdoses carry higher risk—if other CNS depressants (opioids, alcohol, benzodiazepines) are co-ingested, lethality increases substantially 1
• Intralipid therapy has been reported in case reports for severe quetiapine overdose with rapid improvement, though evidence is limited to case reports 5
• Close medical supervision must continue until full recovery, as delayed complications can occur 1