Cannabidiol in Humans—The Quest for Therapeutic Targets

Summary & key facts

Researchers looked at 34 human studies to see what cannabidiol or CBD does. About half the studies gave CBD to healthy people and half gave it to patients with conditions like multiple sclerosis, psychosis, social anxiety, pain, insomnia and epilepsy. The results are mixed. Very high doses of inhaled or injected CBD seem needed to block the effects of THC, the part of cannabis that makes people feel high. Some studies find that oral CBD at fairly high daily doses, roughly 150 to 600 mg, may help social anxiety, sleep problems and seizures, but it can also cause mental drowsiness. The authors say the findings are still preliminary and that how the body handles CBD and how CBD affects the brain could explain the mixed results.

Key facts:

• The review combined 34 randomized or crossover studies in humans that tested CBD either alone or with THC.
• Sixteen studies tested CBD in healthy people and 18 tested it in patients with conditions such as multiple sclerosis, psychotic disorders, social anxiety, pain, insomnia and epilepsy.
• When CBD was inhaled or given by vein, very high doses were needed to reduce the effects of a lower dose of THC.
• Studies that gave CBD by mouth or as a mouth spray sometimes found that CBD made THC effects last longer or feel stronger, and other studies found the opposite.
• Early clinical trials suggest that high daily oral doses of CBD, about 150 to 600 mg a day, may help with social anxiety, sleep problems and epileptic seizures in some people.
• Those same high oral doses were also linked to mental sedation, meaning people felt mentally slowed or drowsy in some studies.
• The authors note that differences in how the body absorbs CBD and how CBD acts in the brain could explain why studies do not all agree.

Abstract

Cannabidiol (CBD), a major phytocannabinoid constituent of cannabis, is attracting growing attention in medicine for its anxiolytic, antipsychotic, antiemetic and anti-inflammatory properties. However, up to this point, a comprehensive literature review of the effects of CBD in humans is lacking. The aim of the present systematic review is to examine the randomized and crossover studies that administered CBD to healthy controls and to clinical patients. A systematic search was performed in the electronic databases PubMed and EMBASE using the key word "cannabidiol". Both monotherapy and combination studies (e.g., CBD + ∆9-THC) were included. A total of 34 studies were identified: 16 of these were experimental studies, conducted in healthy subjects, and 18 were conducted in clinical populations, including multiple sclerosis (six studies), schizophrenia and bipolar mania (four studies), social anxiety disorder (two studies), neuropathic and cancer pain (two studies), cancer anorexia (one study), Huntington's disease (one study), insomnia (one study), and epilepsy (one study). Experimental studies indicate that a high-dose of inhaled/intravenous CBD is required to inhibit the effects of a lower dose of ∆9-THC. Moreover, some experimental and clinical studies suggest that oral/oromucosal CBD may prolong and/or intensify ∆9-THC-induced effects, whereas others suggest that it may inhibit ∆9-THC-induced effects. Finally, preliminary clinical trials suggest that high-dose oral CBD (150-600 mg/d) may exert a therapeutic effect for social anxiety disorder, insomnia and epilepsy, but also that it may cause mental sedation. Potential pharmacokinetic and pharmacodynamic explanations for these results are discussed.

Topics

Cannabis and Cannabinoid Research Sleep and Wakefulness Research

Categories

Health Sciences Medicine Pharmacology

Tags

Antipsychotic Anxiety Anxiolytic Bipolar disorder Cannabidiol Cannabis Clinical trial Internal medicine Lithium (medication) Mania Medicine Neuropathic pain Pharmacology Psychiatry Schizophrenia (object-oriented programming)

Substances

Cannabis

Conditions & symptoms

Anxiety Chronic Pain Sleep disorder Anxiety or worry Chronic pain Poor sleep