What is the management for an overdose of Olanzapine (olanzapine) 10 mg, approximately 10 tablets consumed within 1 hour?

Management of Olanzapine Overdose (100 mg ingested 1 hour ago)

For an acute olanzapine overdose of approximately 100 mg (10 tablets of 10 mg) presenting within 1 hour, immediately establish airway protection, provide supportive care with continuous monitoring, and avoid specific antidotes as none exist—most patients recover fully within 48 hours with supportive management alone. 1

Immediate Assessment and Stabilization

Airway and Breathing

• Establish and maintain an airway immediately with adequate oxygenation and ventilation 1
• Prepare for potential intubation if the patient develops significant CNS depression, as respiratory depression can occur with moderate to severe overdoses 1, 2
• Monitor respiratory rate continuously, as respiratory depression/arrest has been reported in symptomatic olanzapine overdoses 1

Cardiovascular Monitoring

• Commence continuous electrocardiographic monitoring immediately to detect possible arrhythmias, including supraventricular tachycardia and cardiac conduction abnormalities 1
• Monitor for tachycardia (occurs in >10% of symptomatic cases) and hypotension 1
• Check vital signs frequently, though they are usually within normal limits following overdoses 1

Expected Clinical Presentation at This Dose

Anticipated Symptoms

At 100 mg ingested dose, expect moderate poisoning severity with the following manifestations:

• Fluctuating mental status between somnolence and agitation—this is characteristic of moderate olanzapine overdoses (doses >120 mg show this pattern in 35% of cases) 2
• Somnolence (occurs in 77% of cases) 2
• Agitation/aggressiveness (occurs in 42% of cases and >10% of symptomatic overdoses) 1, 2
• Miosis (occurs in 31% of cases, particularly with moderate poisoning) 2
• Dysarthria (>10% incidence in symptomatic patients) 1
• Tachycardia (>10% incidence) 1
• Extrapyramidal symptoms 1

Critical Warning Signs

Watch specifically for these potentially serious complications:

• Reduced level of consciousness ranging from sedation to coma 1
• Seizures/convulsions (reported in severe cases) 1, 3
• Aspiration risk 1
• Cardiac arrhythmias 1
• Delirium 1
• Cerebral edema (rare but reported with elevated intracranial pressure) 3

Specific Management Steps

Gastrointestinal Decontamination

• Consider activated charcoal if the patient presents within 1 hour and can protect their airway or after airway protection is secured
• Do not induce vomiting given the risk of rapid CNS depression 1

Supportive Care (Primary Treatment)

There is no specific antidote to olanzapine overdose 1. Management is entirely supportive:

• Maintain adequate hydration and electrolyte balance
• Monitor blood glucose, as hyperglycemia has been reported (glucose levels up to 350 mg/dL documented) 4
• Check creatine phosphokinase levels, as elevations occur (up to 1992 mg/dL reported) 4
• Monitor for metabolic acidosis 4
• Assess for leukocytosis 4

Avoid Specific Interventions

• Do NOT administer flumazenil—olanzapine is not a benzodiazepine, and flumazenil has no role in this overdose 5
• Avoid combining with benzodiazepines if possible, as fatalities have been reported with concurrent use of benzodiazepines with high-dose olanzapine 5

Monitoring Duration and Disposition

Expected Recovery Timeline

• Most patients recover fully within 48 hours with supportive care alone 2
• Symptoms are transient and rarely require specific therapeutic interventions beyond monitoring 2
• However, prolonged toxicity can occur—serum concentrations may remain elevated for several days, potentially causing coma requiring ventilatory support for extended periods 6

Laboratory Monitoring

• Serum olanzapine concentrations >0.1 mg/L are toxic, and >1 mg/L can be fatal 7
• At 100 mg ingested dose, expect moderate severity (Poisoning Severity Score typically "moderate") 2
• Serial monitoring may show concentrations remaining elevated at 4,8, and 12 hours post-ingestion 4

Admission Criteria

• Admit all patients with moderate to severe symptoms for continuous monitoring
• Intensive care unit admission is warranted for patients with:
  • Coma or significantly depressed consciousness 4, 6
  • Respiratory depression requiring ventilatory support 6
  • Cardiac arrhythmias 1
  • Seizures 3
  • Signs of cerebral edema 3

Special Considerations

Cerebral Edema Management

If cerebral edema develops (rare but documented):

• Administer intravenous mannitol for raised intracranial pressure 3
• Consider head CT if neurological deterioration occurs 3
• Cranial pressure-lowering treatment can improve outcomes 3

Contact Poison Control

Contact a Certified Poison Control Center (1-800-222-1222) for the most up-to-date management guidance 1

Multiple Drug Involvement

Always consider the possibility of co-ingestion with other substances, particularly given that overdose with multiple drugs is common 5, 1