What are the available oral (PO) antiemetics?

Available Oral (PO) Antiemetics

The available oral antiemetics include 5-HT3 antagonists (ondansetron, granisetron, tropisetron, dolasetron), dopamine antagonists (metoclopramide, prochlorperazine, domperidone, metopimazine), corticosteroids (dexamethasone, prednisolone, methylprednisolone), neurokinin antagonists (aprepitant), and benzodiazepines (lorazepam). 1

5-HT3 (Serotonin) Antagonists

• Ondansetron: 16-24 mg PO once daily 1
• Granisetron: 2 mg PO once daily 1
• Tropisetron: 5 mg PO once daily 1
• Dolasetron: 100 mg PO once daily 1

Dopamine Antagonists

• Metoclopramide: 20-30 mg PO 3-4 times daily 1, 2
• Prochlorperazine: 10-20 mg PO 3-4 times daily 1
• Domperidone: 20 mg PO 3-4 times daily 1
• Metopimazine: 15-30 mg PO 3-4 times daily 1
• Levosulpiride: Used as third-line therapy 2

Corticosteroids

• Dexamethasone: 20 mg PO once daily 1, 3
• Prednisolone: 100-150 mg PO once daily 1
• Methylprednisolone: 100 mg PO once daily 1

Neurokinin (NK1) Antagonists

• Aprepitant: 125 mg PO on day 1, followed by 80 mg PO on days 2 and 3 after chemotherapy 1, 3, 4

Others

• Lorazepam: 1-2 mg PO 1-4 times daily 1, 3
• Olanzapine: Used as second-line therapy for nausea and vomiting in advanced cancer 2
• Methotrimeprazine: Used as second-line therapy for nausea and vomiting in advanced cancer 2

Administration Considerations

• For routine use, oral formulations are recommended over intravenous administration 1
• Antiemetics should be administered prophylactically 30-60 minutes before the start of chemotherapy 1, 3
• If a patient is actively vomiting, intravenous administration is preferred over oral 3

Special Considerations

• When aprepitant is combined with corticosteroids, the corticosteroid dose should be reduced by 50% due to drug interactions 1, 3
• For refractory nausea and vomiting, consider adding dopamine antagonists to serotonin antagonists and corticosteroids 1, 3
• For anticipatory nausea and vomiting, lorazepam or behavioral techniques may be beneficial 1, 3
• Always consider other potential causes of nausea and vomiting (e.g., radiotherapy, metabolic disorders, electrolyte disturbances, constipation, gastrointestinal obstruction) 1, 3

Efficacy Considerations

• The combination of a 5-HT3 antagonist, dexamethasone, and aprepitant is considered the standard of care for prevention of chemotherapy-induced nausea and vomiting in high-risk settings 3, 5
• First-line antiemetics for nausea and vomiting in advanced cancer are metoclopramide and haloperidol 2
• Second-line medications for advanced cancer include methotrimeprazine and olanzapine 2