Some of our patients receive olanzapine (Zyprexa) as an antiemetic. Is this a typical use of this drug?

Olanzapine is an antipsychotic that affects dopamine, serotonin, catecholamines, acetylcholine, and histamine. Olanzapine-containing antiemetic regimens are 1 option in the National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology for prevention of nausea and vomiting with moderate or high emetic risk chemotherapy regimens.

In clinical studies, an olanzapine-containing regimen was similarly effective compared with an aprepitant containing regimen. Some studies have shown a trend toward less delayed nausea and vomiting with olanzapine-containing regimens; although in a phase 3 trial, this was not statistically significant.

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The typical prophylactic dosing in this setting is olanzapine 10 mg by mouth prior to chemotherapy, followed by 10 mg daily on days 2, 3, and 4. This is used in combination with dexamethasone 20 mg on day 1 and a 5-HT3 antagonist.

Adverse effects of olanzapine include sedation, dry mouth, and dizziness. I typically advise patients to take their doses on days 2 to 4 in the evening to better manage the sedation. Long-term continuous use of olanzapine may be associated with dyslipidemia, hyperglycemia, diabetes, and weight gain; however, these are not typically reported when olanzapine is used intermittently with chemotherapy as described above.