A randomized controlled non-inferiority study comparing the antiemetic effect between intravenous granisetron and oral azasetron based on estimated 5-HT3 receptor occupancy.

BACKGROUND The acute antiemetic effect was compared between oral azasetron and intravenous granisetron based on the 5-hydroxytryptamine(3) (5-HT(3)) receptor occupancy theory. PATIENTS AND METHODS Receptor occupancy was estimated from reported data on plasma concentrations and affinity constants to 5-HT(3) receptor. A randomized non-inferiority study comparing acute antiemetic effects between oral azasetron and intravenous granisetron was performed in 105 patients receiving the first course of carboplatin-based chemotherapy for lung cancer. RESULTS Azasetron exhibited the highest 5-HT(3) receptor occupancy among various first-generation 5-HT(3) antagonists. The complete response to oral azasetron was shown to be non-inferior to that of intravenous granisetron, in which the risk difference was 0.0004 (95% confidence interval: -0.0519-0.0527). The lower limit of the confidence intervals did not exceed the negative non-inferiority margin (-0.1). The complete response during the overall period was not different (68% versus 67%). CONCLUSION Oral azasetron was found to be non-inferior to intravenous granisetron in the acute antiemetic effect against moderately emetogenic chemotherapy.