Ondansetron (Page 6 of 8)

14.2 Prevention of Postoperative Nausea and/or Vomiting

Adu lts

Adult surgical patients who received ondansetron immediately before the induction of general balanced anesthesia (barbiturate: thiopental, methohexital, or thiamylal; opioid: alfentanil or fentanyl; nitrous oxide; neuromuscular blockade: succinylcholine/curare and/or vecuronium or atracurium; and supplemental isoflurane) were evaluated in two double-blind US trials involving 554 patients. Ondansetron Injection (4 mg) intravenous given over 2 to 5 minutes was significantly more effective than placebo. The results of these trials are summarized in Table 10.

T able 10. Therapeutic Response in Prevention of Postoperative Nausea and/or Vomiting in Adult Patients

Ondansetron4 mgIntravenous

Placebo P- Value
Study 1

Emetic episodes:Number of patients

136 139
Treatment response over 24-h postoperative period
0 Emetic episodes 103 (76%) 64 (46%) <0.001
1 Emetic episode 13 (10%) 17 (12%)
More than 1 emetic episode/rescued 20 (15%) 58 (42%)

Nausea assessments:Number of patientsNo nausea over 24-h postoperative period

13456 (42%)

13639 (29%)

Study 2

Emetic episodes:Number of patients

136 143
Treatment response over 24-h postoperative period
0 Emetic episodes

85 (63%)

63 (44%)

0.002
1 Emetic episode 16 (12%) 29 (20%)
More than 1 emetic episode/rescued 35 (26%) 51 (36%)

Nausea assessments:Number of patientsNo nausea over 24-h postoperative period

12548 (38%)

13342 (32%)

The populations in Table 10 consisted mainly of females undergoing laparoscopic procedures.

In a placebo-controlled trial conducted in 468 males undergoing outpatient procedures, a single 4-mg intravenous ondansetron dose prevented postoperative vomiting over a 24-hour period in 79% of males receiving drug compared with 63% of males receiving placebo (P <0.001).

Two other placebo-controlled trials were conducted in 2,792 patients undergoing major abdominal or gynecological surgeries to evaluate a single 4-mg or 8-mg intravenous ondansetron dose for prevention of postoperative nausea and vomiting over a 24-hour period. At the 4-mg dosage, 59% of patients receiving ondansetron versus 45% receiving placebo in the first trial (P <0.001) and 41% of patients receiving ondansetron versus 30% receiving placebo in the second trial (P = 0.001) experienced no emetic episodes. No additional benefit was observed in patients who received intravenous ondansetron 8 mg compared with patients who received intravenous ondansetron 4 mg.

Ped iatrics

Three double-blind, placebo-controlled trials have been performed (one US, two foreign) in 1,049 male and female patients (aged 2 to 12 years) undergoing general anesthesia with nitrous oxide. The surgical procedures included tonsillectomy with or without adenoidectomy, strabismus surgery, herniorrhaphy, and orchidopexy. Patients were randomized to either single intravenous doses of ondansetron (0.1 mg/kg for pediatric patients weighing 40 kg or less, 4 mg for pediatric patients weighing more than 40 kg) or placebo. Study drug was administered over at least 30 seconds, immediately prior to or following anesthesia induction. Ondansetron was significantly more effective than placebo in preventing nausea and vomiting. The results of these trials are summarized in Table 11.

T able 11. Therapeutic Response in Prevention of Postoperative Nausea and/or Vomiting in Pediatric Patients Aged 2 to 12 Years

Treatment Response Over24 Hours

Ondansetronn (%)

Placebon (%)

P- Value
Study 1
Number of patients 205 210
0 Emetic episodes 140 (68%) 82 (39%) ≤0.001
Failurea 65 (32%) 128 (61%)
Study 2
Number of patients 112 110
0 Emetic episodes 68 (61%) 38 (35%) ≤0.001
Failurea 44 (39%) 72 (65%)
Study 3
Number of patients 206 206
0 Emetic episodes 123 (60%) 96 (47%) ≤0.01
Failurea 83 (40%) 110 (53%)
Nausea assessmentsb:
Number of patients 185 191
None 119 (64%) 99 (52%) ≤0.01

a Failure was one or more emetic episodes, rescued, or withdrawn.b Nausea measured as none, mild, or severe.

A double-blind, multicenter, placebo-controlled trial was conducted in 670 pediatric patients aged 1 month to 24 months who were undergoing routine surgery under general anesthesia. Seventy-five percent (75%) were males; 64% were white, 15% were black, 13% were American Hispanic, 2% were Asian, and 6% were “other race” patients. A single 0.1-mg/kg intravenous dose of ondansetron administered within 5 minutes following induction of anesthesia was statistically significantly more effective than placebo in preventing vomiting. In the placebo group, 28% of patients experienced vomiting compared with 11% of subjects who received ondansetron (P ≤0.01). Overall, 32 (10%) of placebo patients and 18 (5%) of patients who received ondansetron received antiemetic rescue medication(s) or prematurely withdrew from the trial.

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