The possibility of potentiating the effect of Rytmonorm by local anaesthetics given simultaneously (eg, implantation of pacemaker, surgical or dental procedures) or by other drugs which inhibit the heart rate and/or contractility (eg, β-adrenergic blockers, tricyclic antidepressants) should be borne in mind.
Rises in propranolol, metoprolol, desipramine, cyclosporin or digoxin plasma levels, respectively, under concomitant administration of Rytmonorm have been reported. If symptoms of such overdosage occur, plasma concentrations should be determined and doses reduced, if required.
There have been reports of rises of the propafenone plasma concentrations when cimetidine was taken simultaneously.
Oral anticoagulants may interact with propafenone (potentiation of the effect of the anticoagulants). It is therefore recommended to thoroughly check the clotting parameters of such patients.
Decreases propafenone plasma concentration when used simultaneously with phenobarbital or rifampicin, possibly in subtherapeutic levels.