Investigating the CYP450‐Catalyzed Metabolism of Cannabidiol and Its Implications for Drug Safety

Cannabidiol (CBD) is a naturally occurring phytocannabinoid derived from Cannabis sativa. It was recently FDA-approved as Epidiolex® for the treatment of seizures associated with Lennox-Gastaut or Dravet syndrome in patients aged two and older. CBD’s rise in popularity among consumer products and supplements has led to an increase in safety events and concerns for toxicity. Epidiolex® is known to cause dose-dependent hepatotoxicity, and monitoring of serum transaminases and bilirubin is recommended for six months following treatment initiation. Cannabidiol is reported to undergo hepatic metabolism by cytochromes P450 (CYP) 2C19 and CYP3A4, and UDP-glucuronosyltransferases (UGT) 1A7, UGT1A9, and UGT2B7, respectively. However, the relative enzyme contributions have not been described. The objectives of this project were to determine the specific roles of P450 and UGT enzymes in CBD metabolism with respect to formation of the active metabolite 7-hydroxy-CBD (7-OH-CBD) and glucuronides, and to investigate the effect of CYP2C19 activity on formation of 7-OH-CBD in human liver microsomes. Cannabidiol (1 μM) was incubated with pooled human liver microsomes (0.2 mg/mL protein) in the presence and absence of enzyme cofactors NADPH and UDPGA over time (0–60 min). Cannabidiol and its 7-hydroxy metabolite were detected and quantified using LC-MS/MS. The results from substrate depletion studies indicated that P450 enzymes were faster than UGT enzymes in metabolizing CBD (depletion rate constant = 0.12 min−1 with NADPH versus 0.05 min−1 with UDPGA). Formation of 7-OH-CBD increased rapidly in incubations supplemented with NADPH, followed by a gradual reduction in metabolite generation. Based on substrate depletion data in the presence of UDPGA, UGTs appeared to play a slightly lesser role in CBD metabolism. To determine the influence of CYP2C19 activity on CBD metabolism, a sample of individual CYP2C19-genotyped human liver microsomes with poor, rapid, and ultrarapid metabolizing phenotypes were incubated with CBD (1 μM) for 0–30 min. Interestingly, CYP2C19 genotype appeared to influence CBD metabolite generation, with CYP2C19 poor metabolizers producing significantly less 7-OH-CBD compared to rapid and ultrarapid metabolizers. Future work will investigate the metabolism, transport, and toxicity of cannabidiol in human hepatocytes. Support or Funding Information This work is supported by the UNC-Chapel Hill Royster Society of Fellows and the UNC Eshelman School of Pharmacy Faculty Start-Up Funds. Figure 1Open in figure viewerPowerPoint Oxidative Metabolism of Cannabidiol