From the Guidelines
Ondansetron (Zofran) in combination with dexamethasone is the best anti-emetic regimen for post-surgical nausea in most cases, as it provides a multimodal approach to preventing postoperative nausea and vomiting (PONV). The typical adult dose of ondansetron is 4mg IV or 8mg orally, which can be repeated every 8 hours as needed, while dexamethasone is typically given at a dose of 4-8mg IV 1. For prevention, ondansetron is often given just before the end of surgery, and for treatment, it can be administered as soon as nausea develops. Ondansetron works by blocking serotonin 5-HT3 receptors in the chemoreceptor trigger zone and gastrointestinal tract, effectively preventing the nausea reflex, while dexamethasone has anti-inflammatory properties and can help reduce the incidence of PONV 1.
Alternative Options and Considerations
Alternative options include metoclopramide (10mg IV) which increases gastric emptying, but it may have more side effects compared to ondansetron and dexamethasone. For patients with risk factors like previous post-operative nausea and vomiting, female gender, non-smoker status, or motion sickness history, a multimodal approach combining different anti-emetics may be more effective. If ondansetron is contraindicated or ineffective, scopolamine patches applied behind the ear or promethazine 12.5-25mg IV are reasonable alternatives, though they may cause more sedation.
Multimodal Approach
A multimodal approach to PONV prophylaxis, including the use of two or more antiemetic drugs, is recommended to decrease the incidence of PONV and improve efficacy 1. This approach can include a combination of ondansetron, dexamethasone, and other antiemetic drugs, as well as non-pharmacological interventions such as total intravenous anesthesia (TIVA) and multimodal analgesia.
Risk Assessment and Screening
All patients should have a risk assessment for PONV using a scoring system such as the Apfel score, and receive prophylaxis based on their risk factors 1. Patients with a high risk of PONV should receive 2-3 antiemetics, while those with a low risk may receive a single antiemetic or no prophylaxis at all.
Evidence and Recommendations
The evidence for the use of ondansetron and dexamethasone in combination for PONV prophylaxis is strong, with a high level of evidence and a strong grade of recommendation 1. The use of a multimodal approach to PONV prophylaxis, including the use of two or more antiemetic drugs, is also recommended, with a high level of evidence and a strong grade of recommendation 1.
From the FDA Drug Label
Ondansetron Injection is indicated for the prevention of postoperative nausea and/or vomiting. As with other antiemetics, routine prophylaxis is not recommended for patients in whom there is little expectation that nausea and/or vomiting will occur postoperatively In patients in whom nausea and/or vomiting must be avoided postoperatively, Ondansetron Injection is recommended even when the incidence of postoperative nausea and/or vomiting is low.
The best anti-emetic for post-surgical nausea is ondansetron (IV), as it is specifically indicated for the prevention of postoperative nausea and/or vomiting.
- Key benefits of ondansetron include:
- Prevention of postoperative nausea and/or vomiting
- Effective in patients undergoing various types of surgery, including outpatient procedures and major abdominal or gynecological surgeries
- Approved for patients aged 1 month and older
- Dosage: a single 4-mg intravenous dose is recommended for adults, while pediatric patients receive 0.1 mg/kg for those weighing 40 kg or less, or 4 mg for those weighing more than 40 kg 2, 2.
From the Research
Anti-emetic Options for Post-Surgical Nausea
- Ondansetron, a 5-HT3 receptor antagonist, has been shown to be effective in treating postoperative nausea and vomiting in several studies 3, 4, 5.
- The optimal dose of ondansetron for postoperative nausea and vomiting has been found to be 4 mg 3.
- Ondansetron has been compared to placebo in several studies, and has been found to be significantly more effective in reducing nausea and preventing further emesis 3, 4, 5.
- Other 5-HT3 receptor antagonists, such as granisetron, have also been found to be effective in preventing postoperative nausea and vomiting 6.
Combination Therapy
- The combination of dexamethasone with a 5-HT3 receptor antagonist, such as ondansetron or granisetron, has been found to be more effective in preventing postoperative nausea and vomiting than either agent alone 7.
- Dexamethasone has been found to be effective in preventing postoperative nausea and vomiting, with a number needed to treat of 7.1 for early vomiting and 4.3 for late nausea 7.
- The combination of dexamethasone with a 5-HT3 receptor antagonist has been found to have a number needed to treat of 7.7 for late nausea and 7.8 for late vomiting 7.
Safety and Efficacy
- Ondansetron has been found to be well-tolerated, with a similar side effect profile to placebo 3, 4, 5.
- Dexamethasone has been found to be safe, with no reports of adverse effects in several studies 7.
- The combination of dexamethasone with a 5-HT3 receptor antagonist has been found to be safe and effective, with no reports of adverse effects 7.