supplements. Epilepsy From the results seen in humans with drugs such as Epidiolex and Sativex in scientific studies and reviews, it could be expected that CBD-based products would be helpful to manage seizures in dogs. However, despite the numerous case reports presented by veterinary neurologists supporting the benefits of CBD as adjunctive therapy, , published controlled studies have not shown a statistically significant decrease in the number of seizures across the groups receiving CBD. Further research in this area is required before any clear conclusion can be drawn. Pharmacokinetics The oral bioavailability of CBD varies greatly across species and it is linked to the presentation and the time of administration. A 24-hour kinetic examination in dogs showed that the absorption of the cannabidiolic acid (CBDA) does occur, and that this molecule is absorbed least twice as well as CBD post oral ingestion. It was found that the major metabolites of CBD in humans (7-OH-CBD and 7-COOH-CBD) are not prevalent in dogs, while 6-OH-CBD was found to be the primary metabolite in dogs receiving a CBD-enriched cannabis-derived herbal extract, suggesting that canine and human CBD metabolic route might be somewhat different. Pharmacology Pharmacodynamics Cannabidiol has low affinity for the cannabinoid CB and CB receptors, although it acts as an antagonist of CB/CB agonists, despite this low affinity. The core effect of antagonism of CB receptors is reduced binding affinity of THC and any of its related isomers. 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. It also may act as an inverse agonist of GPR3, GPR6, and GPR12. CBD has been shown to act as a serotonin 5-HT receptor partial agonist. At higher concentrations, CBD acts as an inverse agonist of 5-HT receptors. It is an allosteric modulator of the μ- and δ-opioid receptors as well. The pharmacological effects of CBD may involve PPARγ agonism, inhibition of voltage-gated cation channels, and intracellular calcium release. Pharmacokinetics The oral bioavailability of cannabidiol is approximately 6% in humans, 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 the cytochrome P450 enzymes CYP2B6, CYP2C19, CYP2D6, CYP2J2, and CYP3A4, and by the isoenzymes UGT1A7, UGT1A9, and UGT2B7, forming a variety of metabolites such as