What is the treatment for a quetiapine (Seroquel) overdose?

Quetiapine Overdose Management

In acute quetiapine overdose, immediately establish airway protection with intubation if the patient shows altered mental status, followed by gastric lavage (if intubated and presenting early), activated charcoal administration, continuous cardiac monitoring, and aggressive supportive care with IV fluids—avoiding epinephrine or dopamine for hypotension due to alpha-blockade. 1

Immediate Stabilization and Decontamination

Airway management is the absolute priority, as quetiapine overdose causes rapid progression to coma with risk of aspiration. 1, 2, 3

• Intubate early if the patient shows any signs of decreased consciousness, as deterioration can be sudden and unpredictable—patients can progress from awake and ambulatory to unresponsive within 1-2 hours post-ingestion. 2, 3
• Perform gastric lavage only after intubation if the patient is unconscious, as the risk of obtundation, seizure, or dystonic reaction creates significant aspiration risk with induced emesis. 1
• Administer activated charcoal with a laxative as soon as airway is secured. 1
• Be aware that pharmacobezoars can form, particularly with massive overdoses (>10g), causing delayed absorption and prolonged toxicity lasting 5-7 days despite initial treatment. 4

Cardiovascular Monitoring and Management

Continuous electrocardiographic monitoring is mandatory to detect arrhythmias and QT prolongation. 1, 2

• Expect tachycardia and hypotension as the primary cardiovascular manifestations, resulting from exaggeration of quetiapine's known pharmacological effects. 1, 2, 5
• Monitor for QTc prolongation, which can occur with overdose and may persist for 2-3 days. 1, 2, 6
• Treat hypotension with IV fluids and sympathomimetic agents, but absolutely avoid epinephrine and dopamine, as beta-stimulation will worsen hypotension in the setting of quetiapine-induced alpha-blockade. 1
• Do NOT use disopyramide, procainamide, or quinidine if antiarrhythmic therapy is needed, as these carry theoretical hazard of additive QT-prolonging effects. 1
• Avoid bretylium, as its alpha-adrenergic-blocking properties are additive to quetiapine, resulting in problematic hypotension. 1

Specific Clinical Considerations

There is no specific antidote to quetiapine—management is entirely supportive. 1

• Anticipate prolonged altered mental status: Even with massive overdoses (up to 36g reported), patients typically recover completely, though coma may persist for up to 5 days with pharmacobezoar formation. 4, 5
• Monitor for hypokalemia and heart block, which have been reported with large overdoses (>9000mg). 1
• Check blood glucose, as hyperglycemia is a recognized complication of quetiapine overdose. 5
• Administer anticholinergic medication only if severe extrapyramidal symptoms develop. 1
• Consider multiple drug involvement in all cases, as polypharmacy overdoses are common. 1

Disposition and Monitoring Duration

All quetiapine overdose patients requiring hospitalization must be admitted to an intensive care unit. 2

• Continue close medical supervision and monitoring until the patient fully recovers, which may take 2-3 days for cardiovascular effects (tachycardia, QTc prolongation) even in uncomplicated cases. 1, 2
• Extend monitoring to 5-7 days if pharmacobezoar is suspected on imaging or if clinical deterioration occurs after initial improvement, as delayed absorption can cause secondary peaks in serum concentrations. 4
• Obtain serum quetiapine levels if available, though management decisions should not be delayed waiting for results—levels can reach 5940 ng/mL at 40 hours post-ingestion with pharmacobezoars. 4

Critical Pitfalls to Avoid

• Never use epinephrine or dopamine for hypotension—these will paradoxically worsen blood pressure due to unopposed beta-stimulation in the presence of alpha-blockade. 1
• Do not delay intubation—the window between alert and comatose can be as short as 1 hour, and aspiration risk is high. 2, 3
• Do not discharge early—even patients who appear to recover quickly require extended observation for delayed cardiovascular effects and potential pharmacobezoar-related secondary deterioration. 2, 4