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 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.
Schizophrenia. Research on the use of cannabidiol for psychotic symptoms in people with schizophrenia is mixed. Some early research suggests that taking cannabidiol four times daily for 4 weeks improves psychotic symptoms and might be as effective as the antipsychotic medication amisulpride. But other early research suggests that taking cannabidiol for 14 days is not beneficial. The mixed results might be related to the cannabidiol dose used and duration of treatment.
Until 2017, products containing cannabidiol marketed for medical purposes were classed as medicines by the UK regulatory body, the Medicines and Healthcare products Regulatory Agency (MHRA) and could not be marketed without regulatory approval for the medical claims. As of 2018, cannabis oil is legal to possess, buy, and sell in the UK, providing the product does not contain more than 0.3% THC and is not advertised as providing a medicinal benefit.