Effects of 5-mg dose of olanzapine for breakthrough nausea and vomiting in patients receiving carboplatin-based chemotherapy: a prospective trial

Background: Olanzapine 10 mg is recommended for breakthrough chemotherapy-induced nausea and vomiting. However, there is a possibility that 5 mg can be expected to be sufficiently effective. We aimed to investigate the efficacy and safety of olanzapine 5 mg for breakthrough chemotherapy-induced nausea and vomiting. Methods: A single-arm prospective trial of olanzapine 5 mg every 24 h for 72 h was conducted to treat breakthrough chemotherapy-induced nausea and vomiting in patients receiving carboplatin-based chemotherapy. The primary endpoint was total control (i.e., no emesis, no nausea, and no rescue medications) over 72 h. The secondary endpoints were early efficacy using the nausea scores at 30, 60, and 120 min after taking olanzapine from baseline and adverse events. Results: Among 84 potentially eligible patients, 19 patients who took olanzapine for breakthrough chemotherapy-induced nausea and vomiting were examined. The total control rate was 32% (95% CI: 13-57%), 65% (95% CI: 38-89%), 65% (95% CI: 38-89%), and 29% (95% CI: 10-56%) during 2-24, 24-48, 48-72 h, and overall period, respectively. The nausea scale significantly reduced after 30 min (P=0.0078), and the scale had been reduced by 67% from the baseline after 60 min. The adverse event of somnolence of any grade was observed in 13 (68%) patients, 6 (32%) of whom had grade 2 and 1 (5%) grade 3 somnolence. Conclusions: Olanzapine 5 mg did not show the expected effect on the complete disappearance of breakthrough chemotherapy-induced nausea and vomiting within 24 h.