Clinical Overview
Chlorpromazine is the prototypical phenothiazine antipsychotic, historically significant as the first effective treatment for schizophrenia. While largely superseded by newer antipsychotics, it remains indicated for schizophrenia, manic episodes, severe behavioral problems, and nausea/vomiting. It is considered a low-potency typical antipsychotic with significant sedating and anticholinergic effects.
Primary Clinical Applications
Chlorpromazine is indicated for schizophrenia, manic episodes of bipolar disorder, severe behavioral problems in children, and intractable hiccups. It is also used for nausea and vomiting, particularly in surgical and cancer patients. Its broad spectrum of activity makes it useful in various psychiatric and medical conditions.
Mechanism and Clinical Profile
Chlorpromazine blocks dopamine D2 receptors, providing antipsychotic effects, but also has significant activity at histamine, alpha-adrenergic, and cholinergic receptors. This broad receptor activity accounts for its effectiveness but also its extensive side effect profile including sedation, hypotension, and anticholinergic effects.
Historical Importance and Current Use
As the first effective antipsychotic, chlorpromazine revolutionized psychiatric treatment and established the foundation for modern psychopharmacology. While newer agents are generally preferred, it remains valuable for specific situations and serves as a reference standard for antipsychotic potency (chlorpromazine equivalents).
Prescribing Information
Dosing & Administration
Schizophrenia/Psychosis – Adults:
- Outpatients – Initial: 30-75 mg daily in divided doses
- Inpatients – Initial: 25 mg three times daily
- Titration: Increase gradually every 2-3 days
- Maintenance: 200-800 mg daily in divided doses
- Maximum: 2000 mg daily for severe cases
Elderly:
- Initial: 10-25 mg twice daily
- Titrate slowly based on response and tolerance
Nausea and Vomiting:
- Oral: 10-25 mg every 4-6 hours as needed
- IM: 25-50 mg every 3-4 hours as needed
Intractable Hiccups:
- Oral: 25-50 mg three to four times daily
Indications
- Treatment of schizophrenia
- Control of manic episodes in bipolar disorder
- Severe behavioral problems in children
- Nausea and vomiting
- Intractable hiccups
- Preoperative sedation
Contraindications
- Hypersensitivity to phenothiazines
- Severe CNS depression or comatose states
- Bone marrow suppression
- Pheochromocytoma
- Severe liver or cardiac disease
Warnings & Precautions
- Boxed Warning: Increased mortality in elderly patients with dementia-related psychosis
- Tardive dyskinesia: Risk increases with duration of treatment
- Neuroleptic malignant syndrome: Rare but potentially fatal
- Orthostatic hypotension: Significant risk due to alpha-blockade
- Anticholinergic effects: Dry mouth, constipation, urinary retention
- Photosensitivity: Increased risk of sunburn
- Blood dyscrasias: Monitor CBC periodically
Drug Interactions
- CNS depressants: Enhanced sedation and respiratory depression
- Anticholinergics: Additive anticholinergic effects
- Antihypertensives: Enhanced hypotensive effects
- Lithium: Increased risk of extrapyramidal symptoms
- Tramadol: Increased seizure risk
Adverse Reactions
Common:
- Sedation, dizziness, dry mouth, constipation
- Orthostatic hypotension, weight gain
- Extrapyramidal symptoms (less common than high-potency antipsychotics)
Serious:
- Tardive dyskinesia, neuroleptic malignant syndrome
- Agranulocytosis, liver toxicity
Special Populations
- Elderly: Increased mortality risk in dementia-related psychosis
- Hepatic Impairment: Use with caution, may require dose reduction
- Pregnancy: Category C – use only if benefits outweigh risks
- Sun exposure: Counsel patients about photosensitivity risk
Medical Disclaimer: This information is for educational purposes only and is not intended as medical advice. Always consult with qualified healthcare professionals before making any treatment decisions. Individual patient circumstances may vary significantly.
