Results of a prospective, randomized, double-blind, placebo-controlled, dose-ranging trial to determine the effective dose of ramosetron for the prevention of vomiting after tonsillectomy in children.

BACKGROUND

Postoperative vomiting (POV) is an important adverse effect of anesthesia and surgery, and children undergoing tonsillectomy may be particularly at risk.

OBJECTIVE

The aim of this study was to determine the effective dose of ramosetron, a 5-hydroxytryptamine type 3 receptor antagonist, for prophylaxis of severe POV (> or =2 episodes) in children undergoing general anesthesia for tonsillectomy.

METHODS

Standard general anesthetic technique and postoperative analgesia were used in this prospective, randomized, double-blind, placebo-controlled, dose-ranging trial of pediatric patients. Patients who had experienced POV, had taken an antiemetic medication within 24 hours before surgery of had a history of motion sickness were excluded. Only patients aged 4 to 10 years were included, because of their ability to answer questions. Patients received a single administration of either i.v. placebo or i.v. ramosetron at 3, 6, or 12 microg/kg immediately after the end of surgery. During the first 48 hours after anesthesia, episodes of retching, vomiting, and adverse events were recorded by nursing staff blinded to treatment assignment.

RESULTS

Eighty children (20 in each group)--42 girls and 38 boys--were enrolled. There were no differences in patient demographic characteristics among the treatment groups. The rates of complete response (no vomiting, retching, or need for another antiemetic medication) from 0 to 24 hours after anesthesia were 35% (7/20) with ramosetron 3 microg/kg, 90% (18/20) with ramosetron 6 micro/kg, and 90% (18/20) with ramosetron 12 microg/kg compared with placebo (30% [620], P=NS, P=0.001, and P=0.001 vs placebo, respectively); the corresponding rates from 24 to 48 hours after anesthesia were 35% (7/20), 90% (18/20), and 95% (19/20) compared with placebo (35% [7/20]; P=NS, P=0.001, and P=0.001 vs placebo, respectively). No difference in antiemetic efficacy was observed between ramosetron 6 and 12 microg/kg. No clinically serious adverse events attributable to the study drug were observed in any group.

CONCLUSIONS

In the pediatric population studied, ramosetron 6 microg/kg was effective for the prevention of vomiting after tonsillectomy from 0 to 48 hours after anesthesia. Increasing the dose to 12 microg/kg did not appear to provide further benefit.