Table 1:
CYP450 system, cannabis and drug–drug interactions (DDIs)
| CYP450 isoenzymes | Involvement in hepatic metabolism of drugs (%) | Inducers potentially lowering cannabis effect | Inhibitors potentially increasing cannabis effect |
|---|---|---|---|
| Involved in CBD and THC metabolism | |||
| 2C9 | Rifampicin | Ketoconazole Fluconazole Amiodarone, benzbromarone Cimetidine |
|
| 2C19 | Artemisinin | Fluvoxamine Fluoxetine Omeprazole Ticlopidine Cimetidine Ketoconazole |
|
| 3A4 | 30%–40% | Azole antifungals, (eg, ketoconazole, fluconazole) Macrolide antimicrobials, (eg, erythromycin, clarithromycin) Selective serotonin re-uptake inhibitors (SSRIs) (eg, fluoxetine, paroxetine) Calcium channel blockers (eg, verapamil, diltiazem) Protease inhibitors Grapefruit juice Ciprofloxacin Cimetidine Propofol |
Rifampicin Rifabutin Carbamazepine phenytoin, phenobarbitone (13) |
| Involved only in CBD metabolism | |||
| 1A2 | Tobacco | Fluvoxamine Fluoxetine Ciprofloxacin Grapefruit juice Cimetidine Verapamil, diltiazem Estradiol, levonorgestrel Omeprazole |
|
| 2D6 | SSRIs (eg, fluoxetine) Propafenone Cimetidine Quinidine Terbinafine Amiodarone |
||
CYP450 = cytochrome P450; CBD = cannabidiol; THC = tetrahydrocannabinol