What is the initial dosing for Thorazine (chlorpromazine) in severe psychosis?

Initial Dosing for Thorazine (Chlorpromazine) in Severe Psychosis

For severe psychosis, the initial dosing of Thorazine (chlorpromazine) for hospitalized patients is 25 mg IM, which may be followed by an additional 25-50 mg injection in 1 hour if necessary, gradually increasing over several days up to 400 mg every 4-6 hours in exceptionally severe cases until the patient is controlled. 1

Dosing Recommendations Based on Treatment Setting

Hospitalized Patients with Acute Schizophrenic or Manic States

• Initial treatment: 25 mg IM
• If necessary, give additional 25-50 mg injection in 1 hour
• Increase subsequent IM doses gradually over several days up to 400 mg every 4-6 hours in exceptionally severe cases
• Usually, patients become quiet and cooperative within 24-48 hours, at which point oral doses may be substituted 1

Oral Dosing After Initial Control

• Once the patient is stabilized on IM dosing, transition to oral therapy:
• Initial oral dose: 25-50 mg three times daily
• Gradually increase until effective dose is reached, usually 400 mg daily for less acutely disturbed patients 2
• Maximum improvement may not be seen for weeks or even months
• Continue optimum dosage for 2 weeks, then gradually reduce to lowest effective maintenance level 2

Special Considerations

Dosing Adjustments

• Elderly patients: Use lower doses as they are more susceptible to hypotension and neuromuscular reactions 2, 1
• Debilitated or emaciated patients: Increase dosage more gradually 2

Monitoring and Side Effects

• Monitor for hypotension, particularly during initial dosing and dose increases 1
• Watch for extrapyramidal symptoms, which should be avoided to encourage future medication adherence 3
• The therapeutic dose equivalent is considered to be 600 mg of chlorpromazine per day 3

Important Dosing Principles

1. Adequate trial duration: Each antipsychotic treatment episode should last at least 6 weeks at a therapeutic dose to be deemed adequate 3

2. Gradual dose increases: After initial titration, increase doses only at widely spaced intervals (usually 14-21 days) if response has been inadequate 4

3. Dose limitations: Increase doses only within the limits of sedation and extrapyramidal side effects 4

Common Pitfalls to Avoid

• Rapid dose escalation: This increases risk of side effects without necessarily improving efficacy
• Inadequate dosing: Daily dosage of 200 mg is not unusual, and some patients require higher dosages (e.g., 800 mg daily is not uncommon in discharged mental patients) 2
• Premature determination of treatment failure: Allow sufficient time (at least 4-6 weeks) at therapeutic doses before determining efficacy 4

Alternative Approaches

If chlorpromazine is ineffective or poorly tolerated after adequate trials, consider atypical antipsychotics which may have better side effect profiles, particularly regarding extrapyramidal symptoms 3

Remember that chlorpromazine is a typical antipsychotic agent with significant side effects involving the cholinergic, cardiovascular, and extrapyramidal systems, and there is an inherent risk of irreversible tardive dyskinesia with long-term use 3.