st-johns-wort
2 interactions related to st-johns-wort
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.
propranolol + st. john's wort
St. John's Wort induces several liver drug-metabolizing enzymes, including CYP1A2 and CYP3A4, plus the transporter P-glycoprotein. Propranolol is cleared mainly through CYP1A2 and CYP2D6, so regular St. John's Wort use can plausibly speed up its breakdown and weaken its effect. Direct studies of this specific pair are lacking; the concern is based on St. John's Wort's confirmed enzyme-inducing action, its documented lowering of theophylline (which shares propranolol's CYP1A2 pathway), and a case report of lost intraocular-pressure control in a glaucoma patient on a topical beta-blocker.