Purpose: This study was conducted to determine the optimal dose titration of ramosetron to prevent the Rhodes Index of Nausea, Vomiting, and Retching (RINVR).
Methods: Patients treated with folic acid, 5-fluorouracil, and oxaliplatin were randomized into three groups (0.3 mg, 0.45 mg, and 0.6 mg ramosetron before chemotherapy). The pharmacokinetics and pharmacodynamics using RINVR were evaluated.
Results: Seventeen, 15, and 18 patients received ramosetron at doses of 0.3 mg, 0.45 mg, and 0.6 mg, respectively. T max (h), C max (ng/mL), and AUClast (ng·h/mL) were associated with dose escalation significantly, showing a reverse correlation with the RINVR during chemotherapy. Acute CINV was observed in four patients (22.2%), two patients (14.3%), and one (5.6%) patient and a delayed CINV on day 7 was found in eight (47%), three (21.4%), and five (27.8%) patients in each group. The complete response rate was increased with dose escalation (35.3%, 50.0%, and 72.2% in each group) and also showed the tendency for decreasing moderate-to-severe CINV.
Conclusions: This study shows a trend regarding the dose-response relationship for ramosetron to prevent CINV, including delayed emesis. It suggested that dose escalation should be considered in patients with CINV in a subsequent cycle of chemotherapy, and an individual approach using RINVR could be useful to monitor CINV.