What antiemetic injection is effective for an elderly female patient with a history of cancer presenting with vomiting?

Antiemetic Injection for Elderly Female Cancer Patient with Vomiting

For an elderly female cancer patient with vomiting, start with ondansetron 8 mg IV as the first-line injectable antiemetic, combined with dexamethasone 12 mg IV for enhanced efficacy. 1, 2, 3

First-Line Injectable Antiemetic Regimen

Ondansetron (5-HT3 antagonist) is the preferred initial injectable antiemetic:

• Dose: 8 mg IV, administered 30 minutes before any additional chemotherapy or as treatment for active vomiting 1, 2, 3
• FDA-approved for prevention and treatment of chemotherapy-induced nausea and vomiting in patients aged 6 months and older 3
• Can be given as 8-12 mg IV (maximum 32 mg/day) 1

Add dexamethasone for combination therapy:

• Dose: 12 mg IV or PO once daily 1
• The combination of ondansetron plus dexamethasone provides 81% complete protection from emesis versus 64% with ondansetron alone 2
• This combination is superior to single-agent therapy across all emetogenic risk categories 1, 2

Alternative Injectable Options if Ondansetron Fails

Metoclopramide (dopamine antagonist):

• Dose: 10-40 mg IV every 4-6 hours 1, 4
• FDA-approved for prophylaxis of chemotherapy-induced vomiting 4
• Particularly useful for breakthrough vomiting despite prophylaxis 1
• Caution: Monitor for extrapyramidal side effects, especially in elderly patients; have diphenhydramine 25-50 mg available 1

Prochlorperazine:

• Dose: 10 mg IV every 4-6 hours 1
• Alternative dopamine antagonist with similar efficacy to metoclopramide 1

Haloperidol:

• Dose: 1-2 mg IV every 4-6 hours as needed 1
• Effective for refractory nausea and vomiting 1, 5
• Black box warning: Monitor for increased mortality risk in elderly dementia patients 1

Breakthrough Treatment Algorithm

If vomiting persists despite initial ondansetron:

1. Add an agent from a different drug class 1
2. First escalation: Add metoclopramide 10-40 mg IV every 4-6 hours 1
3. Second escalation: Add haloperidol 1-2 mg IV every 4-6 hours 1
4. Consider switching to a different 5-HT3 antagonist (granisetron 0.01 mg/kg IV, maximum 1 mg) 1

Additional Supportive Measures

Lorazepam for anxiety-related nausea:

• Dose: 0.5-2 mg IV every 4-6 hours as needed 1
• Particularly useful for anticipatory nausea or anxiety component 1, 6

H2 blocker or proton pump inhibitor:

• Add if patient has dyspepsia or reflux symptoms 1
• Many patients cannot distinguish heartburn from nausea 6

Critical Considerations for Elderly Patients

The elderly population requires special attention:

• Younger patients typically experience more nausea than older patients, but elderly patients may have reduced drug clearance 1
• Consider lower initial doses of olanzapine (5 mg instead of 10 mg) if used, due to increased sedation risk 1
• Monitor closely for extrapyramidal symptoms with dopamine antagonists 1
• Assess for polypharmacy and drug interactions, particularly with other CNS depressants 6

Common Pitfalls to Avoid

Do not use ondansetron alone for highly emetogenic chemotherapy:

• Always combine with dexamethasone for enhanced efficacy 1, 2
• Single-agent therapy has significantly lower complete response rates 2

Do not delay treatment:

• Antiemetics are most effective when given prophylactically, but for active vomiting, immediate IV administration is indicated 2, 6

Do not forget to assess for reversible causes:

• Check for bowel obstruction, electrolyte abnormalities, hypercalcemia, or CNS metastases 6
• Review all medications, particularly recent opioid additions 6

Maximum daily ondansetron dose:

• Do not exceed 32 mg IV per day due to QT prolongation risk 1