What is the typical dosage of Thorazine (chlorpromazine) for treating psychotic disorders?

Thorazine (Chlorpromazine) Dosage for Psychotic Disorders

For adults with psychotic disorders, the recommended initial oral dose of Thorazine (chlorpromazine) is 25 mg three times daily, gradually increasing to an effective maintenance dose of 200-800 mg/day based on symptom control and tolerability. 1

Initial Dosing Strategy

Outpatient Setting

• Start with 10 mg three or four times daily, or 25 mg twice or three times daily 1
• Increase gradually until effective dose is reached, typically 400 mg daily for less acutely disturbed patients 1

Hospitalized Patients with Acute Psychosis

• Initial treatment may begin with chlorpromazine injection until patient is controlled 1
• Once patient becomes quiet and cooperative (usually within 24-48 hours), switch to oral dosing 1
• Begin with 500 mg/day, which is generally sufficient 1
• While doses may be increased up to 2,000 mg/day, there is usually little therapeutic gain exceeding 1,000 mg/day for extended periods 1

Dose Titration and Monitoring

• After initial titration, increase dose only at widely spaced intervals (14-21 days) if response is inadequate 2
• Increase dosage only within the limits of sedation and extrapyramidal side effects 2
• For adequate therapeutic trial, maintain at therapeutic dose for at least 6 weeks before determining efficacy 2
• If no response after 4-6 weeks at therapeutic dose, consider switching to another antipsychotic 2

Special Populations

Elderly Patients

• Use lower dosages as elderly patients are more susceptible to hypotension and neuromuscular reactions 1
• Observe elderly patients closely and increase dosage more gradually 1

Debilitated or Emaciated Patients

• Increase dosage more gradually in these vulnerable populations 1
• Lower dosage ranges are typically sufficient 1

Maintenance Therapy

• After symptoms are controlled, gradually reduce dosage to the lowest effective maintenance level 1
• Daily dosage of 200 mg is not unusual for maintenance therapy 1
• Some patients require higher maintenance dosages (e.g., 800 mg daily is not uncommon in discharged mental patients) 1

Treatment Resistance Considerations

• Treatment resistance is defined as failure of at least two adequate antipsychotic trials (each lasting at least 6 weeks at therapeutic doses) 2
• For treatment-resistant cases, a trial of clozapine should be considered 2
• The minimum therapeutic dose of chlorpromazine is considered to be 600 mg/day (or equivalent) when evaluating treatment resistance 2

Side Effect Management

• Monitor closely for extrapyramidal symptoms, which are more common at higher doses 3
• Be vigilant for hypotension, particularly when initiating therapy or increasing doses 4
• Weight gain is a common side effect that should be monitored 5
• Sedation is a prominent side effect that may affect adherence and functioning 5

Important Clinical Considerations

• First-generation and second-generation antipsychotics are not distinct categories from either pharmacological or clinical perspective 2
• Dose-response curves for both acute treatment and relapse prevention follow a hyperbolic pattern 6
• Ensure adequate duration of treatment before determining lack of efficacy (minimum 6 weeks) 2
• Consider adherence issues when evaluating apparent treatment resistance 2

By following these dosing guidelines and monitoring protocols, clinicians can optimize the therapeutic benefits of chlorpromazine while minimizing adverse effects in patients with psychotic disorders.