Cannabidiol can be taken into the body in multiple ways, including by inhalation of cannabis smoke or vapor, as an aerosol spray into the cheek, and by mouth. It may be supplied as CBD oil containing only CBD as the active ingredient (no included tetrahydrocannabinol [THC] or terpenes), a full-plant CBD-dominant hemp extract oil, capsules, dried cannabis, or as a prescription liquid solution. CBD does not have the same psychoactivity as THC, and may change the effects of THC on the body if both are present. As of 2018, the mechanism of action for its biological effects has not been determined.
The two main receptors in the endocannabinoid system are CB1 and CB2. Where THC directly affects these receptors, CBD has a subtler, more indirect approach. Instead of attaching to these receptors, CBD affects how these receptors signal the body and its chemicals. Furthermore, CBD increases the production of the body’s own cannabinoids by blocking the enzymes that can break them down.
The oral bioavailability of CBD is 13 to 19%, while its bioavailability via inhalation is 11 to 45% (mean 31%). The elimination half-life of CBD is 18–32 hours. Cannabidiol is metabolized in the liver as well as in the intestines by CYP2C19 and CYP3A4 enzymes, and UGT1A7, UGT1A9, and UGT2B7 isoforms. CBD may have a wide margin in dosing.
Cannabidiol has antipsychotic effects. The exact cause for these effects is not clear. But cannabidiol seems to prevent the breakdown of a chemical in the brain that affects pain, mood, and mental function. Preventing the breakdown of this chemical and increasing its levels in the blood seems to reduce psychotic symptoms associated with conditions such as schizophrenia. Cannabidiol might also block some of the psychoactive effects of delta-9-tetrahydrocannabinol (THC). Also, cannabidiol seems to reduce pain and anxiety.
^ Jump up to: a b c Campos AC, Moreira FA, Gomes FV, Del Bel EA, Guimarães FS (December 2012). "Multiple mechanisms involved in the large-spectrum therapeutic potential of cannabidiol in psychiatric disorders". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences (Review). 367 (1607): 3364–78. doi:10.1098/rstb.2011.0389. PMC 3481531. PMID 23108553.
Various strains of "medical marijuana" are found to have a significant variation in the ratios of CBD-to-THC, and are known to contain other non-psychotropic cannabinoids. Any psychoactive marijuana, regardless of its CBD content, is derived from the flower (or bud) of the genus Cannabis. As defined by U.S. federal law, non-psychoactive hemp (also commonly-termed industrial hemp), regardless of its CBD content, is any part of the cannabis plant, whether growing or not, containing a ∆-9 tetrahydrocannabinol concentration of no more than 0.3% on a dry-weight basis. Certain standards are required for legal growing, cultivating, and producing the hemp plant. The Colorado Industrial Hemp Program registers growers of industrial hemp and samples crops to verify that the dry-weight THC concentration does not exceed 0.3%.
In nature, Cannabis ruderalis typically has the lowest levels of THC, Cannabis sativa has a higher level of THC than it has CBD, and Cannabis indica has a higher level of CBD than it has THC. However, since man has been cultivating cannabis (and especially Cannabis sativa) for thousands of years, the effects of artificial selections have led to several different types of cannabis even within the same species, depending on the purpose the cannabis was cultivated for.
E-cigarettes aren't thought of as 100% safe, but most experts think they're less dangerous than cigarettes, says Neal Benowitz, MD, a nicotine researcher at the University of California at San Francisco. Cigarette smoking kills almost half a million people a year in the United States. Most of the harm comes from the thousands of chemicals that are burned and inhaled in the smoke, he explains.
In the United States, the cannabidiol drug Epidiolex was approved by the Food and Drug Administration in 2018 for treatment of two epilepsy disorders. The side effects of long-term use of the drug include somnolence, decreased appetite, diarrhea, fatigue, malaise, weakness, and sleeping problems. As of mid-2019 in the United States, CBD is a Schedule I controlled substance that is illegal for use in human foods, dietary supplements, other consumer products, or pet foods.