Potential mutual intensified effects w/ medicines containing lignocaine or other local anaesth (amide type). Possible increased effect on the heart w/ antiarrhythmics [eg, mexiletine, tocainide, β-blockers (eg, propranolol) or Ca-channel blockers (eg, diltiazem & verapamil)]. Increased cardiac effects of class III antiarrhythmics (eg, amiodarone). Increased risk of side effects w/ H
2-blockers (eg, cimetidine). Potential mutual intensified effects w/ medicines that may induce methemoglobinemia.