Aim: To evaluate the antiemetic efficacy and safety of 
olanzapine in Japanese women with nausea and/or vomiting 
refractory to the standard antiemetic regimen. 
Methods: We retrospectively reviewed the medical records 
of consecutive female patients with early breast cancer who 
underwent highly emetogenic chemotherapy at our hospital 
from January 2009 to March 2013. Patients with grade 2 or 
3 nausea and/or vomiting despite receiving standard 
antiemetics (5-hydroxytryptamine3 receptor antagonists and 
dexamethasone 20 mg on day 1, and 4 mg dexamethasone 
on days 2 and 3) in the first chemotherapy cycle received an 
additional 2.5–10 mg olanzapine from days 1 to 3 in the 
subsequent cycles. We assessed patient characteristics, 
olanzapine dose, nausea and vomiting grades before and 
after adding olanzapine, and adverse effects. 
Results: We reviewed 20 patients with poor control in the 
first chemotherapy cycle, despite receiving standard 
antiemetics, who received olanzapine from the second 
cycle. Nausea and vomiting improved in 75% and 70% of 
cases, respectively, despite poor control during the first cycle, while an additional 10% of cases achieved a complete 
response (no emesis, no rescue) in the second cycle. No 
grade 3/4 adverse events were noted, but 50% and 30% of 
subjects complained of grade 1/2 drowsiness and dizziness, 
respectively, prompting a reduction in the olanzapine dose. 
Efficacy was retained at the lower dose. 
Conclusion: Olanzapine has excellent antiemetic efficacy 
in Japanese women with chemotherapy-induced nausea and 
vomiting refractory to standard antiemetics. The 
recommended dose of olanzapine for Japanese women 
appears to be lower than for Caucasians.