Why is olanzapine (Zyprexa), an antipsychotic, being used to prevent nausea? — Name withheld on request

Olanzapine is an atypical antipsychotic approved for the treatment of multiple mental health conditions. It affects multiple neurotransmitters, including dopamine, serotonin, acetylcholine, histamine and catecholamines. Due to its effects on dopamine and serotonin, researchers began studying the use of olanzapine in the prevention of chemotherapy-induced nausea/vomiting (CINV).

Multiple phase 3 randomized controlled trials have compared antiemetic regimens containing olanzapine with those containing an NK1 antagonist (eg, aprepitant [Emend]) for use with moderate and highly emetic chemotherapy regimens. In these trials, the olanzapine-containing regimen was found to be as effective as the NK1 antagonist-containing regimen in preventing CINV. Olanzapine has also been evaluated as a breakthrough medication for patients already experiencing CINV and has been shown effective; however, there is more robust data supporting its use as a preventative.

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Olanzapine may not be appropriate for all patients, including those at risk of falls, the elderly, and patients taking antipsychotics for other indications. However, it can be quite effective in patients for whom it is appropriate.