From the Guidelines
Management of an olanzapine overdose requires immediate medical attention in an emergency department setting, focusing on supportive care, including airway protection, hemodynamic stabilization, and continuous cardiac monitoring. The initial approach should prioritize stabilization of vital functions. According to the guidelines for managing delirium, which can be relevant in the context of olanzapine overdose due to its potential to cause altered mental status, medications like olanzapine itself are used in controlled settings for delirium management but would not be indicated in the case of an overdose 1.
Key considerations in managing an olanzapine overdose include:
- Airway protection and hemodynamic stabilization
- Continuous cardiac monitoring due to the risk of QT prolongation
- Administration of activated charcoal (1 g/kg) if the patient presents within 1-2 hours of ingestion and has a protected airway
- Gastric lavage may be considered for massive ingestions if performed early
- Use of benzodiazepines such as lorazepam or diazepam for agitation or seizures
- External cooling measures for hyperthermia
- Management of anticholinergic effects, which can be severe, with careful consideration of physostigmine in extreme cases
- IV fluids for hypotension, with vasopressors added if necessary
It's crucial to note that olanzapine overdose can lead to significant CNS depression, anticholinergic effects, and cardiovascular complications due to its broad receptor antagonism profile, including dopamine, serotonin, histamine, and muscarinic receptors 1. There is no specific antidote for olanzapine overdose, making supportive care and close monitoring for at least 24 hours essential due to the drug's long half-life.
From the FDA Drug Label
Charcoal — The administration of activated charcoal (1 g) reduced the Cmax and AUC of oral olanzapine by about 60%. As peak olanzapine levels are not typically obtained until about 6 hours after dosing, charcoal may be a useful treatment for olanzapine overdose
The management of an overdose of Olanzapine may include the administration of activated charcoal, as it has been shown to reduce the peak levels and area under the curve of olanzapine by about 60% 2.
From the Research
Management of Olanzapine Overdose
The management of an overdose of olanzapine, an atypical antipsychotic, is primarily supportive, as there is no specific antidote for olanzapine toxicity 3, 4, 5, 6.
Clinical Presentation
The clinical presentation of olanzapine overdose can vary, but common symptoms include:
- Somnolence (77%) 3
- Agitation (42-81%) 3, 5, 6
- Miosis (31-65%) 3, 5, 6
- Tachycardia (73-85%) 5, 6
- Hypertension (73%) 5
- Coma (54%) 5
- Delirium (54%) 6
Treatment
Treatment for olanzapine overdose typically involves:
- Supportive care, including monitoring of vital signs and cardiac function 4, 5, 6
- Management of symptoms, such as agitation and delirium, with benzodiazepines or other sedatives 6
- Respiratory support, including mechanical ventilation, if necessary 4, 5
- Cardiac monitoring, as olanzapine can cause QT prolongation and other cardiac arrhythmias 7
Special Considerations
Special considerations in the management of olanzapine overdose include:
- The potential for prolonged toxicity, with some patients requiring several days of supportive care 4, 5
- The risk of severe outcomes, including coma and respiratory depression, particularly in patients who ingest large doses of olanzapine 4, 5, 6
- The importance of monitoring for adverse effects, such as hypotension and bradycardia, particularly in patients receiving intravenous olanzapine 7