Recommended Dosage and Usage of Thorazine (Chlorpromazine)
For adult patients with psychotic disorders, the recommended dosage of Thorazine (chlorpromazine) is 25 mg orally three times daily initially, with gradual increases as needed until symptoms are controlled, typically reaching an effective maintenance dose of 200-400 mg daily. 1
Adult Dosing Guidelines
Psychotic Disorders
Initial dosage:
- Outpatients: 10 mg three to four times daily, or 25 mg twice to three times daily
- More severe cases: 25 mg three times daily, with increases of 20-50 mg at semi-weekly intervals
- Hospitalized patients (acute schizophrenic/manic states): Begin with injectable form until controlled, then transition to oral dosing
Maintenance dosage:
- Typical effective dose: 200-400 mg daily
- Some patients may require higher dosages (up to 800-1000 mg daily)
- Generally little therapeutic benefit exceeding 1000 mg daily for extended periods 1
Other Indications
- Nausea and vomiting: 10-25 mg every 4-6 hours as needed 1
- Presurgical apprehension: 25-50 mg, 2-3 hours before operation 1
- Intractable hiccups: 25-50 mg three to four times daily 1
- Acute intermittent porphyria: 25-50 mg three to four times daily 1
- Delirium management: 12.5-25 mg orally or per rectum initially, with scheduled dosing every 6-12 hours if needed 2
Pediatric Dosing
- Age restriction: Generally should not be used in children under 6 months of age except in potentially life-saving situations 1
- Severe behavioral problems:
- Oral: 0.25 mg/lb body weight every 4-6 hours as needed
- Example: 10 mg every 4-6 hours for a 40 lb child 1
- Nausea and vomiting: 0.25 mg/lb body weight every 4-6 hours 1
- Presurgical apprehension: 0.25 mg/lb body weight orally 2-3 hours before operation 1
Special Populations
Elderly Patients
- Lower doses are generally sufficient
- Increased susceptibility to hypotension and neuromuscular reactions
- Dosage should be increased more gradually
- Close monitoring required 1
Debilitated or Emaciated Patients
- Increase dosage more gradually
- Use doses in the lower range 1
Administration Routes
- Oral: Tablets (including 100 mg and 200 mg for severe conditions)
- Rectal: Suppositories available for patients unable to take oral medication
- Parenteral: Intramuscular or intravenous options available when oral administration is not possible 1
Adverse Effects and Monitoring
Common Adverse Effects
- Sedation and anticholinergic effects 2
- Extrapyramidal symptoms (EPSEs) 2
- Orthostatic hypotension 2
- QTc interval prolongation 2
- Increased risk of ventricular arrhythmia and sudden cardiac death (adjusted OR 1.45,95% CI 0.93 to 2.27) 2
Monitoring Requirements
- Blood pressure (risk of orthostatic hypotension)
- ECG monitoring (QTc prolongation)
- Extrapyramidal symptoms
- Mental status and sedation level 2
Contraindications and Precautions
- Use with caution in patients with:
- Renal and hepatic impairment
- Cardiovascular disease
- History of seizures
- Parkinson's disease or dementia with Lewy bodies (increased risk of EPSEs) 2
Comparative Efficacy
- In the management of delirium, chlorpromazine is considered a first-generation antipsychotic option 2
- For emesis control in cancer patients, studies show chlorpromazine plus dexamethasone achieves total control of emesis in approximately 33.3% of patients 3
- For schizophrenia, lower doses (≤400 mg/day) compared to high doses (>800 mg/day) show fewer extrapyramidal side effects but may be less effective for symptom control 4
Practical Considerations
- Titrate dose gradually to find the lowest effective maintenance level
- For long-term therapy, gradually reduce dosage after symptoms have been controlled for a reasonable period
- Parenteral use may cause local irritation
- The 100 mg and 200 mg tablets are specifically for severe neuropsychiatric conditions 1
Remember that chlorpromazine is associated with significant side effects, particularly extrapyramidal symptoms, sedation, and cardiovascular effects. Close monitoring is essential, especially when initiating therapy or adjusting doses.