special subjects
Cannabidiol (CBD)
Drug Interactions
CBD is metabolized by the cytochrome p450 (CYP) enzymes CYP3A4 and CYP2C19. Coadministration with medications that are metabolized by or inhibit CYP3A4 or CYP2C19 can increase plasma concentrations of these medications or of CBD, which may result in increasing their effects and a greater risk of adverse reactions ( References ). CBD may increase the serum concentration and effects of a number of drugs including the following: Antiseizure medications (eg,brivaracetam,carbamazepine,clobazam,topiramate) Immunosuppressants used to prevent rejection after an organ transplant (eg,cyclosporine,tacrolimus) Anticoagulants (eg,warfarin) Tricyclic antidepressants Proton pump inhibitors (eg,omeprazole); diarrhea may occur Nicotine, prolonging duration of action ofnicotine Lithium, causing or increasinglithiumtoxicity Ketamine, possibly enhancing antidepressant effects Methadone Levothyroxine CBD can cause sleepiness and drowsiness, so taking both CBD and sedatives (eg, benzodiazepines,phenobarbital,morphine, alcohol) may make people too drowsy. Information on interactions is emerging. Any medication that has a narrow therapeutic index (eg,amiodarone) warrants caution and close monitoring with CBD use due to the possibility of drug interactions. Acetaminophen,valproic acid, and CBD can cause liver injury, so the combination of CBD andacetaminophenorvalproic acidmight increase the chance of liver injury. A number of drugs, including antiseizure medications andrifampin, may lower the serum concentration of CBD. Tricyclic antidepressants may increase serum concentrations of CBD and thus may increase adverse effects of CBD. (See also table.) 