Stemetil (Prochlorperazine): Indications, Contraindications, and Uses
Stemetil (prochlorperazine) is indicated for control of severe nausea and vomiting, treatment of schizophrenia, and short-term treatment of generalized non-psychotic anxiety (≤12 weeks at ≤20 mg/day). 1
Primary Indications
1. Severe Nausea and Vomiting
Prochlorperazine is FDA-approved for controlling severe nausea and vomiting from various causes 1. The evidence supports its use in multiple clinical contexts:
Chemotherapy-Induced Nausea/Vomiting (CINV): Used as breakthrough therapy for grade 1-2 and grade 3 emetogenic chemotherapy at 10 mg orally every 6 hours as needed 2. Also recommended at 10 mg PO/IV every 6 hours or 25 mg suppository PR every 12 hours for breakthrough CINV 3, 4
Acute Migraine: Prochlorperazine effectively relieves headache pain and associated nausea 5. A 2019 meta-analysis demonstrated it was more effective than placebo (OR=7.23), metoclopramide (OR=2.89), and other active comparators (OR=3.70) for headache relief in emergency departments 6
Acute Vomiting in Emergency Settings: IV prochlorperazine 2.5 mg given over one minute controls vomiting with mean cessation time of 8.5 minutes versus 35 minutes for IM administration 7
Dizziness-Associated Nausea: Effective at 5 mg three times daily (mean dose 14.9 mg/day) for managing acute dizziness with associated nausea and vomiting 8
2. Schizophrenia
Approved for treatment of schizophrenia 1
3. Non-Psychotic Anxiety
Effective for short-term treatment (maximum 12 weeks) at doses ≤20 mg/day. Critical limitation: Should not be first-line due to risk of irreversible tardive dyskinesia at higher doses or longer duration 1
Absolute Contraindications
Do not use prochlorperazine in the following situations 1:
- Known hypersensitivity to phenothiazines
- Comatose states
- Presence of large amounts of CNS depressants (alcohol, barbiturates, narcotics)
- Pediatric surgery
- Children under 2 years of age or under 20 lbs
- Children for conditions where dosage has not been established
Important Precautions and Warnings
Hematologic Risks
Monitor complete blood count (CBC) frequently in first months of therapy, especially in patients with pre-existing low WBC or history of drug-induced leukopenia/neutropenia. Discontinue immediately if WBC declines without other causative factors 1
Extrapyramidal Symptoms (EPS)
- Incidence in children: 9% (single-dose), 4% (multiple-dose) 9
- Adults: Significantly increased risk of akathisia/dystonia (OR=2.55) compared to other antiemetics 6
- Monitor for dystonic reactions; treat with diphenhydramine 25-50 mg PO/IV every 4-6 hours 3
Cardiovascular Precautions
- Hypotension risk: Keep patients lying down for at least 30 minutes after injection 1
- Use cautiously in patients with impaired cardiovascular systems
- If hypotension occurs, use Levophed or Neo-Synephrine; avoid epinephrine (may cause paradoxical further lowering of blood pressure) 1
Masking of Other Conditions
The antiemetic action may mask signs/symptoms of:
- Drug overdosage
- Intestinal obstruction
- Brain tumor
- Reye's syndrome
- Chemotherapy drug toxicity 1
Other Significant Risks
- Tardive dyskinesia: Risk increases with doses >20 mg/day or duration >12 weeks for anxiety treatment 1
- Neuroleptic malignant syndrome: Rare but serious 9
- Aspiration risk: Reported in post-surgical patients 1
- Use with caution in glaucoma patients (anticholinergic effects) 1
- Use with caution in extreme heat exposure (impairs thermoregulation) 1
Dosing Recommendations
For Nausea/Vomiting
- Oral: 10 mg every 6 hours as needed 2
- IV: 2.5-5 mg over one minute 7; or 10 mg IV every 4-6 hours 3
- Rectal: 25 mg suppository every 12 hours 3, 4
For Acute Migraine
- 10 mg PO or IV pretreatment 5
For Dizziness
- 5 mg three times daily (mean effective dose 14.9 mg/day for 7.2 days) 8
Drug Interactions
- Phenothiazines diminish oral anticoagulant effects 1
- Propranolol: Increased plasma levels of both drugs 1
- Anticonvulsants: May lower seizure threshold; may interfere with phenytoin metabolism causing toxicity 1
- Thiazide diuretics: Accentuate orthostatic hypotension 1
- Guanethidine: Antihypertensive effects may be counteracted 1
Common Adverse Effects
Based on prospective studies and meta-analyses:
- Sedation: 10% (multiple-dose studies) 9
- EPS: 4-9% 9
- Overall adverse events: OR=5.79 versus placebo 6
- Headache, asthenia, somnolence (mild, self-resolving) 8
Serious adverse events are rare but include seizure, neuroleptic malignant syndrome, autonomic collapse, and tardive dyskinesia 9. Five pediatric fatalities have been reported in association with prochlorperazine use 9.