THE EFFECT OF TIMING OF ONDANSETRON ADMINISTRATION IN OUTPATIENTS UNDERGOING OTOLARYNGOLOGIC SURGERY

A randomized, double-blind, placebo-controlled study was designed to c ompare the relative efficacy of prophylactic ondansetron, 4 mg intrave nously (IV), when administered before induction of anesthesia or at th e end of surgery to an outpatient population at high risk of developin g postoperative nausea and vomiting (PONV). Patients undergoing otolar yngologic surgery were randomly assigned to one of three different tre atment groups: Group I (placebo) received saline 5 mL prior to inducti on of anesthesia and again at the end of surgery; Group II received on dansetron 4 mg in 5 mL prior to induction of anesthesia and saline 5 m L at the end of surgery; and Group III received saline 5 mL prior to i nduction of anesthesia and ondansetron 4 mg at the end of surgery. All patients received the same general anesthetic technique. A standardiz ed regimen of rescue antiemetics was administered in the recovery room to patients with greater than or equal to 2 emetic episodes or at the patient's request for persistent nausea. Episodes of nausea and vomit ing, as well as the need for rescue antiemetics, were recorded for 24 h after the operation. The incidences of nausea and emesis in the reco very room after prophylactic ondansetron, 4 mg IV, administered either before induction (68% and 20%, respectively) or at the end of surgery (60% and 4%, respectively) were not significantly decreased compared to the placebo control group (80% and 12%, respectively). However, whe n ondansetron was administered at the end of the operation, it signifi cantly reduced the need for rescue antiemetics in the recovery room (3 6% vs 64% in the control group). The postanesthesia care unit and hosp ital discharge times were similar in all three study groups. One patie nt in Group II and one patient in Group III were hospitalized because of intractable symptoms related to PONV. After discharge from the ambu latory surgery unit, the incidence of nausea, vomiting, and the need f or rescue antiemetic drugs were similar in all three treatment groups. In conclusion, ondansetron (4 mg IV) was more effective in reducing t he need for rescue antiemetics in the recovery room when administered at the end versus prior to the start of otolaryngologic surgery. There fore, when ondansetron is used for antiemetic prophylaxis in outpatien ts undergoing otolaryngologic procedures, it should be administered at the end of the operation rather than prior to induction of anesthesia .