Objectives: To evaluate the antiemetic effect of a single dose of ondansetron and dexamethasone as a prophylaxis for chemotherapy induced acute nausea and emesis and factors associated with the control of acute nausea and emesis.
Material and Method: Patients who received single dose of 8 mg ondansetron and 20 mg dexamethasone as a prophylaxis for chemotherapy induced nausea and emesis at Department of Obstetrics and Gynecology, Bangkok Metropolitan Administration Medical College and Vajira Hospital, between October 2004 and April 2006 were identified. The assessment record of the drug efficacy had been evaluated in the first 24 hours after the start of chemotherapy in terms of control of vomiting, and nausea. Age of the patients, history of alcohol intake, type of cancer, regimen of chemotherapy and course of chemotherapy were analysed as possible factors associated with the control of nausea and emesis.
Results: Seventy-eight gynecologic-cancer patients receiving 353 cycles of chemotherapy were evaluated in this study. Completed control of acute vomiting and nausea were 68% and 57.2% respectively. Complete control of acute vomiting and nausea were 56.9% and 45.4% in patients of < 45 years compared to 78.8% and 68.7% in those with > 45 years. Complete control of acute vomiting and nausea were 59.2% and 48.7% in those receiving cisplatin-containing regimens compared to 86.7% and 75.2% in non-cisplatin containing regimens. Univariable and multivariable analysis showed that younger patients and those who received cisplatin-containing regimens had significant lower rates of complete control of both nausea and emesis. Patients receiving the first three courses of chemotherapy had significantly higher rate of complete control of nausea but not emesis as compared to those receiving chemotherapy after the third course.
Conclusion: A single intravenous dose of 8 mg of ondansetron and 20 mg of dexamethasone had good control of acute nausea and vomiting only in those who received non-cisplatin containing regimens and those older than 45 years.

Keywords: Chemotherapy induced emesis, Ondansetron, Dexamethasone, Cisplatin, Age