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.
^ Jump up to: a b c "FDA warns company marketing unapproved cannabidiol products with unsubstantiated claims to treat cancer, Alzheimer's disease, opioid withdrawal, pain and pet anxiety". US Food and Drug Administration. July 23, 2019. Retrieved July 24, 2019. Unlike drugs approved by the FDA, the manufacturing process of these products has not been subject to FDA review as part of the drug approval process, and there has been no FDA evaluation of whether these products are effective for their intended use, what the proper dosage is, how they could interact with FDA-approved drugs, or whether they have dangerous side effects or other safety concerns. cannabidiol oil