Cannabidiol Use in Refractory Epilepsy

Marcia L. Buck, PharmD, FCCP, FPPAG, BCPPS


Pediatr Pharm. 2018;24(11) 

In This Article


Cannabidiol is well absorbed after oral administration, with a time to maximum concentration (Tmax) of 2.5 to 5 hours. Administration of CBD with a high-fat, high-calorie meal increases the maximum plasma concentrations by 5-fold and reduces variability in absorption, but adequate concentrations are achieved in both fed and fasting states. Cannabidiol is widely distributed, with > 94% protein binding. It is extensively metabolized, primarily in the liver, via cytochrome P450 (CYP) and uridine 5' diphospho-glucuronosyltransferase (UGT) enzymes CYP3A4, CYP2C19, UGT1A7, UGT1A9, and UGT2B7. The only active metabolite, 7-OH-CBD, has an area under the concentration-time curve (AUC) 38% lower than the parent compound. Cannabidiol has an elimination half-life of 56–61 hours in adults. Patients with moderate to severe hepatic impairment (Child-Pugh classes B or C) have reduced clearance, with AUC values 2.5 to 5-fold higher than healthy adults.[2–4]