Pharmacotherapies for cannabis use disorder.

RATIONALE

Globally, cannabis use is prevalent and widespread. There are currently no pharmacotherapies approved for the treatment of cannabis use disorder (a problematic pattern of cannabis use that leads to clinically significant impairment or distress). This is the second update of a Cochrane Review first published in the Cochrane Library in Issue 12, 2014.

OBJECTIVES

To assess the effectiveness and safety of pharmacotherapies as compared with each other, placebo or no pharmacotherapy (supportive care) for reducing symptoms of cannabis withdrawal and promoting cessation or reduction of cannabis use.

SEARCH METHODS

We updated our searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and PsycINFO in May 2024.

ELIGIBILITY CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of medications to treat cannabis withdrawal and/or to promote cessation or reduction of cannabis use, in comparison with other medications, placebo or no medication in people diagnosed as cannabis dependent or who are likely to be dependent.

OUTCOMES

Critical outcomes were: 1) abstinence at the end of treatment; 2) intensity of withdrawal including craving; 3) nature, incidence and frequency of adverse events (AE) and 4) severe AE (SAE); 5) withdrawal from treatment due to adverse effects and whether the planned medication regimen was modified in response to adverse effects; 6) completion of scheduled treatment. Important outcomes were: 1) cannabis use at the end of treatment; 2) number of participants engaged in further treatment; 3) economic outcomes.

RISK OF BIAS

We assessed the risk of bias in results included in meta-analyses using the risk of bias 2 (RoB 2) tool.

SYNTHESIS METHODS

We synthesised results for each outcome using random-effect meta-analysis where possible. Where this was not possible due to the nature of the data, we reported results narratively. We used GRADE to assess the certainty of evidence.

INCLUDED STUDIES

We included 37 RCTs (3201 participants). Most were undertaken in the USA (29), Australia (4), Israel (2), Canada (1) and the United Kingdom (1), mainly recruiting adults (mean age 22-41 years), with four studies only including young people (mean age 17-21 years). In 32 studies, most of the participants were male (56-92%). Five studies targeted participants with comorbidities (depression (2), bipolar disorder (1), and attention deficit hyperactivity disorder (1)). Eleven studies received study medicines from the manufacturing company and none were funded by pharmaceutical companies. Thirty-six studies compared active medications and placebo; one study compared four active medications. Medications were diverse, as were the outcomes reported, which limited the potential for synthesis.

SYNTHESIS OF RESULTS

Abstinence at end of treatment was no more likely with Δ⁹-tetrahydrocannabinol (THC) preparations (risk ratio (RR) 1.04, 95% CI 0.71 to 1.52; 4 studies, 290 participants; moderate-certainty evidence) or N-acetylcysteine (RR 1.17, 95% CI 0.73 to 1.88; 2 studies, 270 participants; moderate-certainty evidence), and may be no more likely with cannabidiol (RR 2.23, 95% CI 0.54 to 9.32; 1 study, 68 participants; low-certainty evidence) or with anticonvulsant and mood stabilisers (RR 1.23, 95% CI 0.52 to 2.92; 1 study, 29 participants; very low-certainty evidence), when compared with placebo, but the evidence is uncertain. AE and SAE. There was probably little to no difference in the likelihood of AEs in participants treated with THC preparations (RR 1.05, 95% CI 0.88 to 1.26; 5 studies, 507 participants), cannabidiol (RR 1.01, 95% CI 0.81 to 1.25; 2 studies, 57 participants), N-acetylcysteine (RR 0.82, 95% CI 0.63 to 1.07; 2 studies, 418 participants), PF-04457845 (RR 0.98, 95% CI 0.87 to 1.11; 2 studies, 298 participants) (all moderate-certainty evidence) and there may be little to no difference in participants treated with anticonvulsants and mood stabilisers (RR 0.96, 95% CI 0.81 to 1.13; 4 studies, 331 participants) or oxytocin (RR 0.50, 95% CI 0.06 to 4.47; 1 study, 16 participants) (both low-certainty evidence), compared with placebo. SAE may be no more likely with THC preparations (RR 0.99, 95% CI 0.25 to 3.9; 7 studies, 584 participants), N-acetylcysteine (RR 0.16, 95% CI 0.02 to 1.33; 2 studies, 418 participants), PF-04457845 (RR 4.83, 95% CI 0.23 to 99.48; 2 studies, 298 participants), compared with placebo (all low-certainty evidence). Withdrawal from treatment due to adverse effects was more likely with anticonvulsants and mood stabilisers (RR 2.88, 95% CI 1.05 to 7.86; 5 studies, 257 participants; very low-certainty evidence), but the evidence is uncertain. There may be little to no difference in the likelihood of withdrawal from treatment due to adverse effects with THC preparations (RR 1.77, 95%CI 0.4 to 7.85; 5 studies, 507 participants), N-acetylcysteine (RR 0.61, 95% CI 0.03 to 12.53; 2 studies, 418 participants) compared with placebo (both low-certainty evidence). We found that completion of treatment was probably not more likely with cannabidiol (RR 1.02, 95% CI 0.89 to 1.17; 2 studies, 92 participants), anticonvulsant and mood stabilisers (RR 0.86, 95% CI 0.72 to 1.03; 6 studies, 407 participants), N-acetylcysteine (RR 1.08, 95% CI 0.95 to 1.23; 2 studies, 418 participants), or PF-04457845 (RR 0.96, 95% CI 0.85 to 1.07; 2 studies, 298 participants) (all moderate-certainty evidence) and there may be little to no difference in participants treated with THC (RR 1.11, 95% CI 0.93 to 1.32; 7 studies, 582 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

There is incomplete evidence for all the clinically-important pharmacotherapies investigated and, for half of their outcomes, the quality of the evidence was low (44%) or very low (11%). Given the limited evidence of efficacy, those pharmacotherapies should still be considered experimental for treating cannabis use disorder. The greater withdrawal from treatment due to adverse effects seen with anticonvulsants and mood stabilisers may limit their therapeutic value.

FUNDING

FS, TP, JS: Received funding from the National Institute for Health and Care Research to directly support the conduct of this review. SN: National Health and Medical Research Council to directly support her time in the conduct of this review.

REGISTRATION

Protocol [and previous versions] available via DOI: 10.1002/14651858.CD008940 [DOI: 10.1002/14651858.CD008940.pub2 and DOI: 10.1002/14651858.CD008940.pub3].

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