A Review of Human Studies Assessing Cannabidiol’s (CBD) Therapeutic Actions and Potential, C. Michael White, 2019

A Review of Human Studies Assessing Cannabidiol’s (CBD) Therapeutic Actions and Potential

C. Michael White

The Journal of Clinical Pharmacology, 2019, 59, (7) 923–934

Doi : 10.1002/jcph.1387



Cannabidiol (CBD) is a highly touted product for many different disorders among the lay press. Numerous CBD products are available, ranging from a US Food and Drug Administration (FDA) approved product called Epidiolex to products created for medical marijuana dispensaries and products sold in smoke shops, convenience stores, and over the Internet.The legal status of the non–FDA approved products differs depending on the source of the CBD and the state,while the consistency and quality of the non–FDA-approved products vary markedly.Without independent laboratory verification, it is impossible to know whether the labeled CBD dosage in non–FDA-approved CBD products is correct, that the delta-9-tetrahydrocannabinol content is <0.3%, and that it is free of adulteration and contamination. On the Internet, CBD has been touted for many ailments for which it has not been studied, and in those diseases with evaluable human data, it generally has weak or very weak evidence.

The control of refractory seizures is a clear exception, with strong evidence of CBD’s benefit. Acute CBD dosing before anxiety-provoking events like public speaking and the chronic use of CBD in schizophrenia are promising but not proven. CBD is not risk free, with adverse events (primarily somnolence and gastrointestinal in nature) and drug interactions. CBD has been shown to increase liver function tests and needs further study to assess its impact on suicidal ideation.

Keywords : anxiety, cannabidiol, cannabis, CBD, psychosis, seizures


Cannabis sativa (marijuana) has been evaluated for the treatment of many diseases and disorders, but
the altered sensory and time perception (the “high”) provided by the delta-9-tetrahydrocannabinol (delta-9- THC) component has been a barrier to wider adoption of the product by patients and medical professionals.1 Employers may test workers or prospective workers for delta-9-THC in their hair, nails, or urine, with positive findings resulting in suspension, termination, or not being hired.1 Finally, regulatory restrictions at the federal level and in some states make delta-9-THC–containing products illegal to possess or to transport across state lines, even for legitimate medical purposes such as seizures, nausea/vomiting, and pain/spasticity.2,3

Cannabidiol (CBD) is the second most prevalent bioactive constituent of the Cannabis sativa plant, and unlike in some animal species, does not convert to delta-9-THC in the human body.2 In vitro, animal, and human studies suggest mechanisms of action for CBD directly or tangentially related to the endocannabinoid system, as delineated in Table 1.2–10 There has been an incredible amount of media coverage on the health benefits of CBD, with CBD products heralded as medical breakthroughs or even miracles for all types of diseases.11,12

Medical professionals may be interested in CBD as a new therapy for patients with limited traditional
options or are asked about CBD products by patients, family, and acquaintances for a host of ailments. Similarly, medical professionals might be interested in recommending CBD to patients in lieu of the medical marijuana the patient is seeking. Finally, patients may not be forthcoming about using CBD products in addition to or as a substitute for your prescribed therapy. This article provides the information medical professionals need to understand quality control issues with CBD products, CBD’s pharmacokinetics and drug interaction potential, and the benefits and risks associated with using CBD for seizures, anxiety, schizophrenia, pain/spasticity, and Parkinson disease. This review will not assess the efficacy or safety of combined delta-9-THC–CBD products because the specific impact of CBD in the products cannot be determined.