Plasma metoprolol and propranolol levels can be markedly raised (2- to 5-fold) by
propafenone.
Toxicity may develop.
Information is limited. Anticipate the need to reduce the dosage of metoprolol and propranolol. Monitor closely. It is possible that other
beta blockers that undergo liver
metabolism will interact similarly but not those largely excreted unchanged in the urine (e.g.
atenolol, nadolol). This needs confirmation.