Abstract:  Objective To investigate the efficacy and safety of the first-generation 5-HT3 receptor antagonist（5-HT3RA） Tropisetron （TRO） and the second-generation 5-HT3RA Palonosetron （PAL），respectively，combined with Dexamethasone （DXM） in the prevention of chemotherapy-induced nausea and vomiting. Methods A total of 192 patients with cancer，treated in the Guangxi Medical University Cancer Hospital from January 2015 to December 2018 through highly emetogenic chemotherapy，were investigated and selected into the PAL group and TRO group by a randomized self-crossover method. Among them，the antiemetic scheme of the PAL group was the PAL+DXM，and the TRO group was the TRO+DXM. The incidence of nausea，vomiting and antemetic adverse reactions were compared between the two groups. Results There was no significant difference in the incidence rate of nausea and vomiting between the PAL group and TRO group （all P>0.05） during acute phase（d1）. In the delayed phase（d2-d5） and whole phase（d1-d5），the nausea rate in the PAL group were markedly lower than that in the TRO group （all P<0.05）. In the delayed phase（d3-d4） and whole phase，vomiting rate in the PAL group were also lower than that in the TRO group （all P<0.05）. 57.3% of patients in the TRO group had to use 5-HT3RA repeatedly，which was significantly higher than 39.3% in the PAL group （P<0.05）. The adverse reactions of antiemetic drugs included constipation，abdominal distension，headache，and hiccups，while the incidence of adverse reactions was similar between the two groups（P>0.05）. Conclusions The second-generation of 5-HT3RA PAL is better than the first-generation of 5-HT3RA TRO in the prevention of delayed chemotherapy-induced nausea and vomiting.

Key words: 5-HT3 receptor antagonist, Chemotherapy, Nausea, Vomiting, Adverse reaction