Medizinische Interaktionen

Interactions

THC and CBD are metabolized by CYP3A4 and CYP2C9

CBD, but not THC, is metabolized by CYP2C19

THC is a CYP1A2 inducer. Theoretically, THC can decrease serum concentrations of clozapine, duloxetine, naproxen, cyclobenzaprine, olanzapine, haloperidol, and chlorpromazine, amongst others.

CBD is a potent inhibitor of CYP3A4 and CYP2D6.

As CYP3A4 metabolizes about a quarter of all drugs, CBD may increase serum concentrations of:  

• Macrolides
• Calcium channel blockers
• Benzodiazepines
• Cyclosporine
• Sildenafil (and other PDE5 inhibitors)
• Antihistamines
• Haloperidol
• Antiretrovirals
• Some statins (atorvastatin and simvastatin, but not pravastatin or rosuvastatin)

CYP2D6 metabolizes many antidepressants, so CBD may increase serum concentrations of:

•  SSRIs
• Tricyclic antidepressants
• beta-blockers
• opioids (including codeine and oxycodone)

However, in practical terms THC and CBD are very safe to be taken simultaneously with most drugs. The most important interactions are as follows:

• THC and CBD increase warfarin levels.
• Frequent cannabis use has been associated with increased INR.

• Alcohol may increase THC levels.

• Smoked cannabis can decrease theophylline levels. 

• In children treated with CBD for epilepsy, CBD increased clobazam levels.