Cannabidiol has low affinity for the cannabinoid CB1 and CB2 receptors,[25][26] although it can act as an antagonist of CB1/CB2 agonists despite this low affinity.[26] Cannabidiol may be an antagonist of GPR55, a G protein-coupled receptor and putative cannabinoid receptor that is expressed in the caudate nucleus and putamen in the brain.[27] It also may act as an inverse agonist of GPR3, GPR6, and GPR12.[28] CBD has been shown to act as a serotonin 5-HT1A receptor partial agonist.[29] It is an allosteric modulator of the μ- and δ-opioid receptors as well.[30] The pharmacological effects of CBD may involve PPARγ agonism and intracellular calcium release.[7]
In the United States, the cannabidiol drug Epidiolex was approved by the Food and Drug Administration in 2018 for treatment of two epilepsy disorders.[12] Since cannabis is a Schedule I controlled substance in the United States, other CBD formulations remain illegal to prescribe for medical use or to use as an ingredient in foods or dietary supplements.[13] cannabidiol oil