What are the doses of Ondansetron (Zofran)?

From the Guidelines

Ondansetron is typically dosed at 8 mg orally twice daily for the prevention and treatment of nausea and vomiting in adults, as recommended by the American Society of Clinical Oncology 1. The dosing of ondansetron can vary depending on the specific clinical context, such as the emetic risk category of the chemotherapy regimen.

• For high-emetic-risk chemotherapy, ondansetron can be dosed at 8 mg orally twice daily or 8 mg intravenously, in combination with other antiemetic agents such as a neurokinin 1 (NK1) receptor antagonist and dexamethasone 1.
• For moderate-emetic-risk chemotherapy, ondansetron can be dosed at 8 mg orally twice daily or 8 mg intravenously, in combination with dexamethasone 1. It's worth noting that the National Comprehensive Cancer Network (NCCN) guidelines also recommend ondansetron as part of an antiemetic regimen for chemotherapy-induced nausea and vomiting, with dosing ranging from 8-16 mg orally or intravenously, depending on the specific regimen and emetic risk category 1. In terms of administration, ondansetron can be given orally, intravenously, or via other routes such as orally dissolving tablets or soluble films.
• The choice of administration route and dosing schedule should be individualized based on patient-specific factors, such as renal function, hepatic function, and ability to swallow tablets. Overall, the goal of ondansetron dosing is to prevent or minimize nausea and vomiting, while also minimizing the risk of adverse effects and optimizing patient quality of life.

From the FDA Drug Label

Ondansetron Tablets USP, are available in the following strengths: 4 mg – white, oval, film-coated tablets engraved with “4” on one side and “NO” on other side. 8 mg – yellow, oval, film-coated tablets engraved with “8” on one side and “NO” on the other side. In a double-blind US trial in 336 patients receiving a cyclophosphamide-based chemotherapy regimen containing either methotrexate or doxorubicin, ondansetron tablets 8 mg administered twice a day, was as effective as ondansetron tablets 8 mg administered 3 times a day in preventing nausea and vomiting The first 8 mg dose was administered 30 minutes before the start of emetogenic chemotherapy, with a subsequent 8 mg dose 8 hours after the first dose, followed by 8 mg administered twice a day for 2 days after the completion of chemotherapy The first 8 mg dose was administered 30 minutes before the start of emetogenic chemotherapy, with subsequent 8 mg doses at 4 hours and 8 hours after the first dose, followed by 8 mg administered 3 times a day for 2 days after the completion of chemotherapy. Ondansetron Tablets 8 mg Twice Daily a (n = 165) 8 mg Three Times a Dayb (n = 171) In single-arm trials, 148 patients receiving cyclophosphamide-based chemotherapy were re-treated with ondansetron tablets 8 mg three times daily during subsequent chemotherapy for a total of 396 re-treatment courses The initial dose of ondansetron tablets injection ranged from 0. 04 to 0.87 mg per kg (total dose of 2. 16 mg to 12 mg) followed by the administration of oral doses of ondansetron tablets ranging from 4 to 24 mg daily for 3 days. In 2 trials the response rates to ondansetron tablets 4 mg three times a day in patients younger than 12 years was similar to ondansetron tablets 8 mg three times daily in patients 12 to 18 years. 8 mg of ondansetron tablets administered 1. 5 hours before each fraction of radiotherapy for 4 days was significantly more effective than placebo in preventing vomiting induced by total body irradiation. Patients received the first dose of ondansetron tablets (8 mg) or metoclopramide (10 mg) 1 to 2 hours before radiotherapy. Patients received the first dose of ondansetron tablets (8 mg) or prochlorperazine (10 mg) 1 to 2 hours before the first daily radiotherapy fraction, with subsequent 8 mg doses approximately every 8 hours on each day of radiotherapy. ondansetron tablets 16 mg as a single dose or placebo was administered one hour before the induction of general balanced anesthesia

The recommended doses of ondansetron are:

• 8 mg administered twice a day
• 8 mg administered three times a day
• 4 mg to 24 mg daily for 3 days in pediatric patients
• 8 mg administered 1.5 hours before each fraction of radiotherapy for 4 days
• 8 mg administered 1 to 2 hours before radiotherapy
• 16 mg as a single dose administered one hour before the induction of general balanced anesthesia 2 2

From the Research

Ondansetron Doses

• The provided studies do not specifically mention the doses of ondansetron used for chemotherapy-induced and postoperative nausea and vomiting.
• However, the studies discuss the efficacy of ondansetron in comparison to other antiemetic agents, such as granisetron, metoclopramide, and dexamethasone 3, 4, 5.
• One study mentions that ondansetron is effective in preventing nausea and vomiting caused by chemotherapy and radiotherapy, but does not provide specific dose information 3.
• Another study discusses the use of ondansetron in combination with dexamethasone for the prevention of acute and delayed nausea and vomiting, but again does not provide dose information 6.
• A network meta-analysis study compares the efficacy of different antiemetic treatment combinations, including ondansetron, but does not provide specific dose information 7.

Efficacy of Ondansetron

• Ondansetron has been shown to be effective in preventing chemotherapy-induced nausea and vomiting, particularly when used in combination with other antiemetic agents such as dexamethasone 3, 6.
• The drug has also been shown to be effective in preventing postoperative nausea and vomiting 3, 5.
• However, the efficacy of ondansetron can vary depending on the specific context and patient population, and more research is needed to fully understand its effects 4, 7.

Comparison to Other Antiemetic Agents

• Ondansetron has been compared to other antiemetic agents, such as granisetron and metoclopramide, in several studies 3, 4, 5.
• The results of these studies suggest that ondansetron is generally effective in preventing nausea and vomiting, but its efficacy can vary depending on the specific context and patient population 4, 7.
• One study found that ondansetron and granisetron had equal antiemetic efficacy in reducing or eliminating chemotherapy-induced nausea and vomiting 4.