What is the recommended dosage per day of ondansetron (antiemetic) and pantoprazole (proton pump inhibitor)?

Recommended Daily Dosages

For ondansetron, use 8 mg orally twice daily (total 16 mg/day) or 8-16 mg IV once daily for chemotherapy-induced nausea, and for pantoprazole, use 40 mg once daily for gastrointestinal prophylaxis. 1

Ondansetron Dosing by Clinical Context

Chemotherapy-Induced Nausea and Vomiting

High Emetogenic Risk Chemotherapy:

• 16-24 mg orally once daily OR 8-16 mg IV once daily 1
• Must be combined with dexamethasone 12 mg and an NK1 receptor antagonist 1
• Continue for 2-3 days after chemotherapy completion 2
• Maximum daily dose: 32 mg via any route 3

Moderate Emetogenic Risk Chemotherapy:

• 8 mg orally twice daily (total 16 mg/day) OR 8 mg IV 1, 2
• First dose 30 minutes before chemotherapy 2
• Combine with dexamethasone 8-12 mg for enhanced efficacy 3
• Continue for 1-2 days after chemotherapy completion 2

Low Emetogenic Risk Chemotherapy:

• 8 mg orally twice daily OR 8 mg IV on day of chemotherapy only 3
• No subsequent day dosing typically required 2

Radiation-Induced Nausea and Vomiting

Upper Abdomen or Total Body Irradiation:

• 8 mg orally 2-3 times daily 1
• May add dexamethasone 4 mg daily for modest additional benefit 1
• Continue daily on radiation days plus 1-2 days after completion 3

Breakthrough/Rescue Dosing

• Titrate up to maximum 16 mg oral or IV daily 3
• Add dopamine antagonist (metoclopramide or prochlorperazine) if ondansetron alone is insufficient 1, 3
• Consider adding dexamethasone if not already prescribed 3

Pantoprazole Dosing

Standard Gastrointestinal Prophylaxis

• 40 mg orally or IV once daily 1
• This dose is equivalent to omeprazole 20 mg, esomeprazole 20 mg, lansoprazole 30 mg, or rabeprazole 20 mg 1
• The 40 mg dose demonstrates comparable efficacy to 80 mg for reflux esophagitis with 78% healing at 4 weeks and 95% at 8 weeks 4

Alternative H2 Antagonist Option

• Famotidine 20 mg orally or IV twice daily (if H2 antagonist preferred over PPI) 1
• Equivalent to ranitidine 150 mg twice daily or cimetidine 300 mg three-four times daily 1

Critical Prescribing Considerations

Ondansetron Safety Limits:

• Single IV doses should not exceed 16 mg due to QT prolongation risk 3
• Maximum total daily dose is 32 mg via any route 3
• Administer at least 30 minutes before chemotherapy or 1 hour before anesthesia 3

Combination Therapy Requirements:

• Ondansetron monotherapy is inadequate for high-risk scenarios 3
• Triple therapy (ondansetron + NK1 antagonist + dexamethasone) is mandatory for highly emetogenic chemotherapy 1, 3
• Combination with dexamethasone significantly improves efficacy compared to ondansetron alone 2

Drug Interaction Caution:

• Pantoprazole doses exceeding 40 mg (or equivalent PPIs) may decrease glecaprevir concentrations when co-administered with direct-acting antivirals 1
• Pantoprazole demonstrates minimal cytochrome P450 interactions and does not require dose adjustment with concomitant medications 5, 6

Special Population Considerations:

• Pantoprazole requires no dose adjustment in renal failure 6
• In severe liver cirrhosis, pantoprazole half-life increases to 7-9 hours but standard 40 mg dosing remains appropriate 6
• Minimize corticosteroid use in patients receiving immunotherapy to avoid attenuating immunotherapy benefits 2