|US||Ambiguous (Federal) (see Legality)|
Explicitly legal in many states
|Canada||Rx Only (Schedule II)|
|AU||Rx Only (Schedule 4)|
|EMA||Trials ongoing (Epidiolex)|
|Scientific Status||Benefits well established|
|Addiction Risk||Minimal (not psychoactive)|
|Therapeutic Index||Very High (1:1000+)|
|Brand names||Epidiolex (approval pending)|
Sativex (nabiximols) (with THC)
Cannabidiol (CBD) is a substance extracted from cannabis believed to have a wide variety of medicinal uses. Unlike THC, CBD does not have a psychoactive "high" effect, and is believed to have little to no potential for abuse or psychological addiction.
Cannabidiol may help prevent neurodegeneration from heavy alcohol use.
The dosage of CBD will depend on the method of administration. CBD has an intranasal bioavailability of about 34% to 46%, a vaporization BA of about 40%, and an oral BA of only 6% due to first-pass metabolism. Thus, an inhaled dose is approximately 6-8 times more potent than a dose in pill form. This differs from THC, which has a high oral bioavailability.
Doses during Phase III trials of Epidiolex ranged from 25 mg/kg to 50 mg/kg per day, taken orally. This equates to over 1,000 mg per day for a 50 kg adult (equivalent to 125 mg inhaled/vaporized), far greater than the doses typically recommended for relief of pain and nausea.
CBD has been shown to have beneficial effects for schizophrenic patients at doses of 200 mg to 800 mg (equivalent to 25 mg to 100 mg inhaled/vaporized). The study showed that CBD had comparable therapeutic effects to amisulpride, an atypical antipsychotic. Amisulpride is an approved drug for the treatment of schizophrenia and other disorders.
The legal status of cannabidiol in the United States, at the federal level, is ambiguous. Cannabis is a Schedule I substance, but cannabidiol is unlisted. CBD is legal when extracted from "industrial hemp" (defined as having 0.3% or less delta-9-THC), but not from "cannabis plants." Many states have explicitly legalized CBD, including CBD extracted from cannabis plants with minimal THC content that are considered non-psychoactive, although not necessarily meeting the federal definition of industrial hemp.
Because hemp is rarely grown commercially in the United States (despite growing naturally in many areas) due to strict licensing rules and restrictions on interstate transportation, hemp-derived CBD is typically imported from other countries.
Pure cannibidiol is not a controlled substance in the UK, and is currently undergoing trials for epilepsy. In late 2016, the MHRA issued a statement recognizing the medicinal effects of CBD. The MHRA has also established a timeline for the regulation of CBD.
The Wales NHS has approved the use of cannabidiol.
Cannabigerol (CBG) and tetrahydrocannabivarin (THCV), both found in the cannabis plant, also act as CB1 antagonists. Although they are less studied, they may have benefits similar to those of CBD.
Two CB1 antagonists, ibipinabant and otenabant, have been developed in preliminary research. However, these drugs were never brought to market, due to the negative postmarketing effects documented with rimonabant. Rimonabant, however, is an inverse agonist of CB1, not an antagonist. Rimonabant is also an opioid antagonist. Thus, rimonabant has a different pharmacological profile than ibipinabant and otenabant, as well as the natural compounds CBD, CBG, and THCV.