A role for cannabidiol in psychiatry? Keep calm and follow the drug development rules

Abstract

Along with tetrahydrocannabinol (THC), cannabidiol (CBD) is one of the main pharmacological components of Cannabis sativa and indica. Unlike THC, which binds CB1 receptors, CBD does not cause any dependence, and acts mostly via 5-HT1A and TPRV1 receptors (De Gregorio et al. 2018). Khoury et al. (2019) recently published a systematic review on the role of cannabidiol in psychiatry in the World Journal of Biological Psychiatry. After analysing 609 articles, they found six case reports, seven randomised clinical trials and 21 registered clinical trials, with a total of 201 subjects included. They then classified the level of evidence following criteria A (the highest) to C2 (the lowest), following the WFSBP task forces standards (Bandelow et al. 2008). Their results indicated that, while it seems clear that CBD has no efficacy in major depressive and bipolar disorders, the level of evidence for cannabis withdrawal is B, cannabis addiction is C2, and treatment of positive symptoms in schizophrenia and anxiety in social anxiety disorder is C1. The most frequently reported side effects were sedation and dizziness without any severe adverse events. They also reported many RCT registered trials (from clinicaltrials.gov databases) whose results are still unpublished or incomplete. Altogether, the evidence regarding efficacy and safety of CBD in psychiatry is still scarce. The scarcity of conclusions about the use of CBD in psychiatry is due to the following factors: