Chlorpromazine versus placebo for schizophrenia

Area of Science:

• Psychiatry and Pharmacology
• Clinical Trials and Evidence-Based Medicine
• Schizophrenia Treatment Research

Background:

• Chlorpromazine, developed in the 1950s, is a foundational treatment for schizophrenia.
• Its continued use necessitates a thorough evaluation of its efficacy and safety profile.

Purpose of the Study:

• To systematically review randomized controlled trials comparing chlorpromazine to placebo for schizophrenia.
• To quantify the effects of chlorpromazine on key outcomes including relapse, overall improvement, and adverse events.

Main Methods:

• Comprehensive electronic database searches (e.g., MEDLINE, EMBASE, PsycLIT) from inception to 1999.
• Inclusion of randomized controlled trials (RCTs) of chlorpromazine versus placebo in schizophrenia patients.
• Data extraction and analysis using relative risk (RR) and number needed to treat/harm (NNT/NNH) where possible.

Main Results:

• Chlorpromazine significantly reduces relapse rates (RR 0.65, NNT 3) and promotes global improvement (RR 0.76, NNT 7) compared to placebo.
• However, it is associated with numerous adverse effects, including sedation (NNH 6), movement disorders (NNH 24), parkinsonism (NNH 10), dizziness (NNH 12), and weight gain (NNH 3).
• Fewer patients receiving chlorpromazine discontinued treatment early (RR 0.76).

Conclusions:

• Despite a notable placebo response (40%), chlorpromazine remains a benchmark treatment for psychosis, supported by quantified evidence.
• Chlorpromazine is an established, albeit imperfect, therapeutic option for schizophrenia.
• This evidence supports informed decision-making for clinicians and patients regarding its judicious use.