Material and Method: A phase II prospective open label clinical trial was conducted in tertiary care based hospital. Forty-six cancer patients diagnosed with solid tumors were enrolled to receive at least one cycle of highly emetogenic chemotherapy (HEC) every two to four weeks. Each patient was provided standard antiemetic consisting of the generic form of ondansetron plus corticosteroids and metoclopramide according to clinical practice guideline. Olanzapine was administered as 5 mg orally every 12 hours for two doses in patients experiencing breakthrough emesis for at least one episode despite standard prevention. The efficacy and tolerability were evaluated every six hours for 24 hours (utilizing Index of Nausea, Vomiting and Retching: INVR tool).

Results: Of 46 evaluable patients receiving HEC and additional olanzapine between September 2009 and July 2010, the complete response of breakthrough emesis, retching, and nausea control among patients were 60.9%, 71.7%, and 50.0%, respectively. Adverse events reported were mild and tolerable including dizziness, fatigue, and dyspepsia.

Conclusion: Olanzapine is considered to be safe and effective treatment of breakthrough vomiting in cancer patients undergoing highly emetogenic chemotherapy in the present study.

Keywords: Olanzapine, Chemotherapy induced nausea and vomiting, Breakthrough vomiting, Ondansetron, Metoclopramide, Dexamethasone