cyp2d6
5 interactions related to cyp2d6
carvedilol + st. john's wort
Carvedilol is partly broken down by liver enzymes (including CYP2C9 and CYP3A4) and is also a P-glycoprotein substrate. St. John's Wort induces several of these enzymes and P-glycoprotein, which can speed carvedilol clearance and lower its blood levels, potentially weakening its blood-pressure and heart-failure effects. The interaction is mechanism-based and extrapolated from St. John's Wort's effect on similar drugs; no direct human study of this specific pair has been published.
fluoxetine + kava
Kava carries a well-documented risk of serious, unpredictable liver injury and acts as a central nervous system depressant, so combining it with fluoxetine raises concern about additive sedation and liver harm. Kava also inhibits the liver enzymes that clear fluoxetine, though this has only been shown in laboratory studies and any rise in fluoxetine levels in people remains theoretical.
alcohol + codeine
Codeine and alcohol are both central nervous system depressants. Taken together they add up, slowing breathing and deepening sedation, with the risk of dangerous or fatal respiratory depression. The danger is amplified for people who convert codeine to morphine unusually fast (CYP2D6 ultra-rapid metabolizers), who can experience strong opioid effects from ordinary doses.
cbd + beta-blockers
CBD weakly inhibits CYP2D6, the liver enzyme that clears beta-blockers such as metoprolol, propranolol, and carvedilol, so in theory it could nudge their plasma levels up. CBD also has a mild blood-pressure-lowering effect of its own. Both actions point in the same direction as the beta-blocker, but the CYP2D6 effect is weak and its real-world clinical significance has not been demonstrated in humans.
nortriptyline + st. john's wort
St. John's wort induces the liver enzymes (chiefly CYP3A4, via the pregnane X receptor) that help clear nortriptyline, which can lower nortriptyline blood levels and weaken its antidepressant effect. The herb also adds serotonergic activity, which gives an additive, theoretical increase in the risk of serotonin syndrome.