What is the dosage and usage of prochlorperazine for treating nausea and vomiting, and schizophrenia?

Prochlorperazine Dosage and Usage for Nausea/Vomiting and Schizophrenia

For nausea and vomiting, prochlorperazine is typically administered at 5-10 mg orally every 6-8 hours as needed, while for schizophrenia, higher doses of 15-40 mg daily divided in multiple doses are recommended. 1

Nausea and Vomiting Treatment

Dosage Options:

• Oral administration:
  • 5-10 mg every 6 hours as needed 2
  • 10 mg pretreatment (optional) for chemotherapy-induced nausea 2
• Intravenous administration:
  • 5-10 mg every 6-8 hours 2
  • 2.5 mg slow IV push (can repeat after 20 minutes if needed) for rapid control 3
• Rectal administration:
  • 25 mg suppository every 12 hours 2

Clinical Considerations:

1. Efficacy: Prochlorperazine works significantly better than promethazine for relieving symptoms of nausea and vomiting more quickly and completely in emergency department patients 4

2. Onset of action: Mean time to cessation of vomiting with IV administration is approximately 8.5 minutes versus 35 minutes for intramuscular administration 3

3. Specific indications:

   • Low to moderate emetogenic potential chemotherapy 2
   • Postoperative nausea and vomiting 2
   • Opioid-induced nausea 5
   • Acute nausea in emergency settings 3, 4, 6
   • Cyclic vomiting syndrome 2

4. Administration route options: Virtually all prochlorperazine formulations can be given intravenously at similar doses if the patient is unable to take oral medication 2

5. Buccal formulation advantage: Buccal administration produces plasma concentrations more than twice as high as an oral tablet, with less than half the variability 7

Schizophrenia Treatment

Dosage:

• FDA-approved for the treatment of schizophrenia 1
• Higher doses than for antiemetic use are typically required
• Dosing should be individualized based on response and tolerability

Important Adverse Effects and Precautions

Common adverse effects:

• Extrapyramidal symptoms: Particularly akathisia, which can occur within a week of starting treatment 5
• CNS depression 2
• Anticholinergic effects 2

Monitoring and precautions:

• Monitor for dystonic reactions: Use diphenhydramine 25-50 mg PO or IV every 4-6 hours for dystonic reactions 2
• Caution in specific populations: Patients with history of leukopenia, neutropenia, dementia, glaucoma, or seizure disorder 2
• Duration limitations: When used for non-psychotic anxiety, should not be administered at doses of more than 20 mg per day or for longer than 12 weeks due to risk of persistent tardive dyskinesia 1

Risk of extrapyramidal symptoms:

The incidence of extrapyramidal symptoms with prochlorperazine (14%) is significantly higher than with newer atypical antipsychotics like perospirone (0%) when used as antiemetics 5. Careful monitoring is essential, particularly for akathisia.

Alternative Antiemetics to Consider

When prochlorperazine causes side effects or is ineffective:

• 5-HT3 antagonists (ondansetron, granisetron)
• NK-1 receptor antagonists (aprepitant)
• Other phenothiazines (promethazine, chlorpromazine)
• Atypical antipsychotics with lower extrapyramidal side effect profiles 5

Administration in Special Circumstances

• Peripheral IV administration: Can cause tissue injury, including gangrene or thrombophlebitis 2
• Buccal administration: May provide higher and more consistent plasma levels with reduced metabolite formation 7

Always consider the risk-benefit profile when prescribing prochlorperazine, particularly for extended periods, due to the risk of tardive dyskinesia and other extrapyramidal symptoms.