What is the recommended dosage and management of Compazine (prochlorperazine) for nausea and vomiting?

Prochlorperazine (Compazine) for Nausea and Vomiting Management

Prochlorperazine is an effective first-line dopamine antagonist for managing nausea and vomiting, with recommended oral dosing of 5-10 mg 3-4 times daily (not exceeding 40 mg/day) or intramuscular dosing of 5-10 mg every 3-4 hours (not exceeding 40 mg/day). 1, 2

Adult Dosing Recommendations

Oral Administration

• Standard dosage: 5-10 mg 3-4 times daily 1
• Maximum daily dose: 40 mg (use higher doses only in resistant cases) 1
• For elderly patients: Start at lower dosages and increase gradually due to higher susceptibility to hypotension and neuromuscular reactions 1

Parenteral Administration

• Intramuscular (IM): 5-10 mg injected deeply into upper outer quadrant of buttock every 3-4 hours as needed 2
• Intravenous (IV): 2.5-10 mg by slow IV injection or infusion at a rate not exceeding 5 mg/minute 2
  • May be administered undiluted or diluted in isotonic solution
  • Single IV dose should not exceed 10 mg
  • Total IV dosage should not exceed 40 mg per day
  • IV administration has shown faster relief (mean time to cessation of vomiting: 8.5 minutes) compared to IM administration (35 minutes) 3

Pediatric Dosing

• Not recommended for children under 20 pounds or under 2 years of age 1, 2
• Weight-based oral dosing:
  • 20-29 lbs: 2.5 mg 1-2 times daily (max 7.5 mg/day)
  • 30-39 lbs: 2.5 mg 2-3 times daily (max 10 mg/day)
  • 40-85 lbs: 2.5 mg 3 times daily or 5 mg twice daily (max 15 mg/day) 1

Clinical Efficacy

• Prochlorperazine has been shown to be more effective than promethazine for relieving nausea and vomiting more quickly and completely in emergency department patients 4
• Works through inhibition of dopaminergic pathways in the chemoreceptor trigger zone 5

Monitoring and Adverse Effects

Common Side Effects

• Sedation (though less than with promethazine) 4
• Hypotension, particularly with IV administration 2
• Extrapyramidal symptoms, particularly akathisia (14% incidence reported) 6
  • Monitor for restlessness, inability to sit still, or other movement disorders
  • Can develop within a week of starting treatment
  • Can be treated with diphenhydramine if symptoms occur 7

Precautions

• Use lower doses in elderly, debilitated, or emaciated patients 1
• Monitor for QT prolongation, especially with IV administration 7
• Avoid subcutaneous administration due to local irritation 2

Alternative Antiemetic Options

When prochlorperazine is ineffective or contraindicated:

1. Add a second agent such as ondansetron (5-HT3 antagonist) 5
2. Consider other antiemetics:
   • Haloperidol: 0.5-2 mg every 3-6 hours 5
   • Chlorpromazine: 12.5-25 mg IV or 25-50 mg orally every 3-4 hours 5
   • Metoclopramide: 5-20 mg three to four times daily 5
   • Ondansetron: 4-8 mg two to three times daily 5, 8

Special Considerations

• For refractory nausea and vomiting, multimodal analgesia is recommended 5
• For bowel obstruction caused by cancer, consider adding octreotide 5
• For patients with cardiac disease, use caution due to potential QT prolongation 8
• For patients with renal impairment, dose adjustments may be required 8

Prochlorperazine remains a valuable first-line agent for nausea and vomiting management with demonstrated efficacy, but careful monitoring for extrapyramidal symptoms is essential, particularly in the first week of treatment.