CYP3A4

Transplantation

Cannabis

Metabolism

Psychiatry

Cytochrome P450

Anticonvulsant

Drug

Cannabidiol

CYP2C19

Epilepsy

Internal medicine

Pharmacology

Medicine

Tacrolimus

Drug interaction

American Journal of Transplantation

Cannabidiol (CBD), a major purified nonpsychoactive component of cannabis with anticonvulsant properties, was approved by the U.S. Food and Drug Administration (FDA) in June 2018 as an adjuvant treatment for refractory epilepsy (Epidiolex; GW Pharmaceuticals). CBD is metabolized by cytochrome P450 (CYP)3A4 and CYP2C19 with a growing body of evidence suggesting it is also a potent inhibitor of these pathways. We report for the first time a significant drug-drug interaction between the purified CBD product and tacrolimus. A participant in a CBD clinical trial for epilepsy who was also receiving tacrolimus showed an approximately 3-fold increase in dose-normalized tacrolimus concentrations while receiving 2000-2900 mg/day of CBD. Our report delineates an important concern for the transplant community with the increasing legalization of cannabis and advent of an FDA-approved CBD product. Larger studies are needed to better understand the impact of this drug-drug interaction in solid organ transplant recipients.

Evidence of a clinically significant drug-drug interaction between cannabidiol and tacrolimus