The AUC of propafenone is increased by more than 200% with co-administration of propranolol.
The metabolism of propranolol is reduced by co-administration of quinidine, leading to a 2- to 3-fold increased blood concentrations and greater beta-blockade.
The metabolism of lidocaine is inhibited by co-administration of propranolol, resulting in a 25% increase in lidocaine concentrations.
Propafenone has negative inotropic and beta-blocking properties that can be additive to those of propranolol.
Quinidine increases the concentration of propranolol and produces a greater degree of clinical beta-blockade and may cause postural hypotension.
Disopyramide is a Type I antiarrhythmic drug with potent negative inotropic and chronotropic effects and has been associated with severe bradycardia, asystole and heart failure when administered with propranolol.
Amiodarone is an antiarrhythmic agent with negative chronotropic properties that may be additive to those seen with propranolol.
The clearance of lidocaine is reduced when administered with propranolol. Lidocaine toxicity has been reported following co-administration with propranolol.
Caution should be exercised when administering propranolol with drugs that slow A-V nodal conduction, e.g., digitalis, lidocaine and calcium channel blockers.