Pilot trial of an antipsychotic medication for cannabis dependence showed reduced use and improved mood

In 21 cannabis-dependent patients given low-dose pericyazine (an antipsychotic) for 4 weeks, cannabis use, depression, anxiety, and insomnia all significantly decreased, though the open-label design limits conclusions.

Morley, Kirsten C et al.·Substance abuse and rehabilitation·2012·Preliminary EvidencePilot Study
RTHC-00593Pilot StudyPreliminary Evidence2012RETHINKTHC RESEARCH DATABASErethinkthc.com/research

Quick Facts

Study Type
Pilot Study
Evidence
Preliminary Evidence
Sample
N=21

What This Study Found

Twenty-one patients with cannabis dependence received pericyazine, a low-potency antipsychotic with sedative properties and low abuse potential, for 4 weeks in a community clinic setting. The dosing was flexible, up to 20 mg daily (8 tablets of 2.5 mg).

Significant reductions were observed in cannabis use, depression, anxiety, and insomnia severity across the treatment period. Pericyazine appeared to be well tolerated and easily administered in community clinics.

However, without a placebo control group, the authors could not conclude that the medication itself caused the improvements. Placebo effects, natural recovery, and the supportive clinical setting could all have contributed.

Key Numbers

21 patients. 4-week treatment. Up to 20 mg/day pericyazine. Significant reductions in cannabis use, depression, anxiety, insomnia. Well tolerated.

How They Did This

Naturalistic open-label case series. 21 patients enrolled for 4-week pericyazine treatment (up to 20 mg/day). Weekly medical review. Cannabis use, depression, anxiety, and insomnia measured with validated tools at baseline and follow-up. ECG and blood monitoring for safety.

Why This Research Matters

With no approved medications for cannabis dependence, any preliminary positive signal deserves attention. Pericyazine's sedative properties could address cannabis withdrawal symptoms (insomnia, anxiety) while its low abuse liability made it safe for addiction populations.

The Bigger Picture

This reflected clinical pragmatism in some parts of Australia, where pericyazine was already being used off-label for cannabis dependence despite no trial evidence. The pilot provided preliminary justification for a proper randomized trial.

What This Study Doesn't Tell Us

Open-label without placebo control. Very small sample. Only 4-week treatment period. Cannot attribute improvements to the medication. High likelihood of placebo effect and regression to the mean.

Questions This Raises

  • ?Would pericyazine outperform placebo in a randomized trial?
  • ?Are the benefits sustained beyond 4 weeks?
  • ?Would other low-potency antipsychotics work similarly?

Trust & Context

Key Stat:
Significant reductions in cannabis use, depression, anxiety, and insomnia
Evidence Grade:
Open-label pilot without control group. Provides preliminary safety and feasibility data but cannot determine efficacy.
Study Age:
Published in 2012. Pericyazine has not subsequently been validated for cannabis dependence in a randomized trial.
Original Title:
Pericyazine in the treatment of cannabis dependence in general practice: a naturalistic pilot trial.
Published In:
Substance abuse and rehabilitation, 3, 43-7 (2012)
Database ID:
RTHC-00593

Evidence Hierarchy

Meta-Analysis / Systematic Review
Randomized Controlled Trial
Cohort / Case-Control
Cross-Sectional / ObservationalSnapshot without intervening
This study
Case Report / Animal Study

A small preliminary study to test whether a larger study is feasible.

What do these levels mean? →

Frequently Asked Questions

Is there a medication for cannabis dependence?

No medication has been approved for cannabis dependence. This pilot tested pericyazine (an antipsychotic) and saw improvements, but without a placebo comparison group, the improvements could have been due to other factors. A randomized trial would be needed.

Why would an antipsychotic help with cannabis dependence?

Pericyazine has sedative properties that could address cannabis withdrawal symptoms like insomnia and anxiety. Its low abuse potential made it safe for use in addiction populations. However, it was not confirmed as effective in this preliminary study.

Read More on RethinkTHC

Cite This Study

RTHC-00593·https://rethinkthc.com/research/RTHC-00593

APA

Morley, Kirsten C; Haber, Paul S; Morgan, Madeleine L; Samara, Fares. (2012). Pericyazine in the treatment of cannabis dependence in general practice: a naturalistic pilot trial.. Substance abuse and rehabilitation, 3, 43-7. https://doi.org/10.2147/SAR.S30052

MLA

Morley, Kirsten C, et al. "Pericyazine in the treatment of cannabis dependence in general practice: a naturalistic pilot trial.." Substance abuse and rehabilitation, 2012. https://doi.org/10.2147/SAR.S30052

RethinkTHC

RethinkTHC Research Database. "Pericyazine in the treatment of cannabis dependence in gener..." RTHC-00593. Retrieved from https://rethinkthc.com/research/morley-2012-pericyazine-in-the-treatment

Access the Original Study

Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.

This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.