What is the proper dosing of Ondansetron (Zofran) for nausea?

From the Guidelines

Zofran (ondansetron) should be prescribed for nausea at a dose of 8 mg orally twice daily or 8 mg or 0.15 mg/kg IV, as recommended by the American Society of Clinical Oncology focused guideline update 1. When prescribing Zofran, it's essential to consider the emetic risk category of the patient's chemotherapy regimen.

• For high emetic risk, Zofran can be used in combination with other antiemetics such as aprepitant and dexamethasone.
• For moderate emetic risk, Zofran can be used alone or in combination with dexamethasone.
• For low emetic risk, dexamethasone is the preferred antiemetic, but Zofran can be used as an alternative. The medication comes in various forms, including regular tablets, orally disintegrating tablets (ODT), oral solution, and injectable forms.
• The ODT form is particularly useful for patients actively experiencing nausea who may have difficulty swallowing pills.
• Zofran works by blocking serotonin receptors in the brain and gut that trigger nausea and vomiting. Common side effects include headache, constipation, and occasionally QT interval prolongation on ECG, making it important to review a patient's cardiac history and medication list for potential interactions 1. The medication typically starts working within 30 minutes and lasts 4-8 hours.
• For maximum effectiveness, it's best taken at the first sign of nausea rather than waiting until symptoms become severe. It's also important to note that the safety and efficacy of Zofran in weekly or every-2-week chemotherapy regimens have not been evaluated, and the medication should be used with caution in these settings 1.

From the FDA Drug Label

In 2 randomized, double-blind, monotherapy trials, a single 24 mg oral dose of ondansetron tablets was superior to a relevant historical placebo control in the prevention of nausea and vomiting associated with highly emetogenic cancer chemotherapy, including cisplatin greater than or equal to 50 mg/m 2 A randomized, placebo-controlled, double-blind trial was conducted in the US in 67 patients receiving a cyclophosphamide-based chemotherapy regimen containing doxorubicin The first 8 mg dose of ondansetron tablets was administered 30 minutes before the start of chemotherapy, with a subsequent dose 8 hours after the first dose, followed by 8 mg of ondansetron tablets twice a day for 2 days after the completion of chemotherapy.

To prescribe Zofran (ondansetron) for nausea, the recommended dosage is:

• A single 24 mg oral dose for highly emetogenic chemotherapy
• 8 mg administered twice a day for moderately emetogenic chemotherapy 2

From the Research

Prescribing Zofran for Nausea

To prescribe Zofran (ondansetron) for nausea, consider the following:

• The dosage and administration of Zofran can vary depending on the patient's condition and the severity of nausea 3, 4, 5, 6.
• Zofran can be administered orally or intravenously, and the dosage can range from 4mg to 8mg per dose 4, 6.
• For chemotherapy-induced nausea and vomiting, Zofran is often used in combination with other antiemetic medications, such as dexamethasone and metoclopramide 3, 5.
• In the emergency department setting, Zofran has been shown to be effective in treating vomiting, but its effectiveness in treating nausea may be similar to that of prochlorperazine 6.

Comparison with Other Antiemetic Medications

Some key points to consider when comparing Zofran with other antiemetic medications:

• A study comparing Zofran with prochlorperazine found that both medications were effective in treating vomiting, but prochlorperazine may have better control of nausea 6.
• Another study found that Zofran was similar in efficacy to metoclopramide in treating nausea and vomiting in the emergency department setting 4.
• A randomized controlled trial found that a DEX-sparing regimen using Zofran and metoclopramide was noninferior to a 3-day dexamethasone regimen in preventing delayed chemotherapy-induced nausea and vomiting 5.

Patient-Specific Factors

When prescribing Zofran for nausea, consider the following patient-specific factors:

• The patient's medical history and current medications, as Zofran may interact with other medications 3, 4, 5, 6.
• The patient's renal function, as Zofran is primarily excreted by the kidneys 3, 4, 5, 6.
• The patient's pregnancy status, as Zofran has been used to treat nausea and vomiting in pregnancy, but its safety and efficacy have not been fully established 7.