Cannabinoids, Antidepressants Ineffective For Cannabis Use Disorder

Data on pharmacologic therapies for cannabis use disorder (CUD) are scarce, but available evidence suggests that several drug classes used off-label for CUD, including cannabinoids and antidepressants, are not effective for this purpose, according to a systematic review of the literature.

From 2002 to 2014, the prevalence of daily cannabis use in the United States doubled, according to national survey data. "Because of increasing access to and use of cannabis in the general population, along with a high prevalence of CUD among current cannabis users, an urgent need exists for more research to identify effective pharmacologic treatments, the reviewers write in Annals of Internal Medicine.

The US Food and Drug Administration has not approved any pharmacotherapy for CUD, although cannabinoids, antidepressants, anxiolytics, and glutamatergic modulators have been proposed for off-label use.

Dr. Karli Kondo and colleagues from the VA Portland Health Care System in Oregon reviewed 26 pharmacotherapy trials of adults or adolescents with CUD to determine the benefits and risks of various therapies for CUD.

Therapies included antidepressants (escitalopram, fluoxetine, bupropion, nefazodone, venlafaxine, vilazodone); antipsychotics (clazapine, ziprasidone); an anxiolytic (buspirone); mood stabilizers (divalproex, lithium); a cognitive-enhancing agent (atomoxetine); cannabinoids (dronabinol, nabilone, nabiximols); anticonvulsants (gapabentin, topiramate); a glutamatergic modulator (N-acetylcysteine); hormones (oxytocin, progesterone); a fatty acid amide hydrolase inhibitor; and a cholinesterase inhibitor (galantamine).

Across all trials, the evidence was largely inadequate to determine whether medication is helpful in treating CUD, the researchers found.

There was low-strength evidence that antidepressants do not reduce cannabis use or keep patients in treatment. There was low- to moderate-strength evidence that buspirone does not improve outcomes and that cannabinoids do not increase abstinence rates (moderate-strength evidence), reduce cannabis use (low-strength evidence), or increase treatment retention (low). There was not enough evidence to comment on effects of all other drug classes.

Across all drug studies, there was no consistent evidence of increased harm.

The evidence base overall was limited due to small number of studies investigating most drug classes, small sample sizes, high attrition rates, and other methodological flaws in nearly half the trials included in the review.

"A need exists for high-quality research examining the effectiveness of pharmacotherapies for CUD; many of the existing studies are hampered by poor methodological quality or reporting," Dr. Kondo and colleagues conclude.

Dr. Kondo did not respond to a request for comment by press time.

The study was funded by the US Department of Veterans Affairs. The authors have disclosed no relevant conflicts of interest.

—Reuters Staff

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