Stemetil MD (Prochlorperazine) Prescribing Information
Recommended Adult Dosing
For acute nausea, vomiting, or dizziness, prescribe prochlorperazine 5-10 mg orally three times daily, with a maximum of 10 mg every 6 hours as needed. 1, 2
Standard Dosing Regimens by Indication:
- Dizziness/Vertigo: 5 mg three times daily (Stemetil MD-5 mg formulation), with mean effective dose of 14.9 mg/day for 7 days 2
- Nausea and Vomiting: 10 mg orally or IV every 6 hours as needed, with maximum 3-4 administrations daily 1
- Breakthrough Chemotherapy-Induced Nausea: 10 mg PO/IV every 6 hours or 25 mg suppository rectally every 12 hours 3
The buccal formulation achieves faster onset of action compared to oral tablets (significantly faster relief at p=0.04), making it preferable when rapid symptom control is needed 4.
Critical Contraindications and Warnings
Extrapyramidal symptoms (EPS) are the primary safety concern with prochlorperazine, occurring in 14% of patients and typically manifesting as akathisia within the first week of treatment. 5
High-Risk Populations Requiring Caution:
- Elderly patients: Higher risk of cognitive impairment, anticholinergic effects, and falls 6
- Patients with prostatic hypertrophy, elevated intraocular pressure, or existing cognitive impairment: Increased anticholinergic adverse effects 6
- Children: Predominantly neurological side-effects including dyskinesia, impaired consciousness, and pyramidal signs, independent of dosage 7
Monitoring Requirements:
- Keep diphenhydramine 25-50 mg readily available to treat acute dystonic reactions or akathisia if they occur 6
- Monitor for akathisia specifically within the first week of therapy, as this is the most common EPS manifestation 5
Common and Serious Side Effects
Neurological Effects (Most Concerning):
- Extrapyramidal symptoms: 14% incidence, primarily akathisia appearing within 7 days 5
- Dystonia and dyskinesia: Most frequent neurological sign in pediatric populations 7
- Neuroleptic malignant syndrome: Rare but serious, making chronic use inappropriate 6
Cardiovascular Effects:
- Hypotension and tachycardia: Particularly with IV administration 1
- QTc prolongation: Documented risk requiring ECG monitoring in susceptible patients 3
Other Common Effects:
- Anticholinergic effects: Dry mouth, urinary retention, constipation 6, 1
- Sedation and drowsiness: Less pronounced than promethazine (prochlorperazine superior with less drowsiness, p<0.05) 8
- Headache, asthenia, somnolence: Mild severity, typically self-resolving 2
Clinical Effectiveness Data
Real-world evidence demonstrates that prochlorperazine at mean dose of 14.9 mg/day for 7.2 days provides significant symptomatic relief (p<0.0001) for dizziness, nausea, vomiting, lightheadedness, and headache, with only 0.6% adverse drug reaction rate 2. The buccal formulation shows superior efficacy in reducing nausea frequency (p=0.02) and vomiting severity (p=0.05) at 24-36 hours compared to oral administration 4.
Key Clinical Pitfalls to Avoid
- Do not use chronically due to cumulative EPS risk and potential for neuroleptic malignant syndrome 6
- Avoid in pediatric populations unless benefits clearly outweigh the high risk of neurological side effects 7
- Consider alternative agents (ondansetron, olanzapine) if symptoms persist beyond 7 days or if EPS develops 3, 1
- Treat EPS immediately with orphenadrine or diphenhydramine rather than continuing therapy 7, 6