This cream should be used with caution together with dental injection anaesthesia, other local anaesthetics or agents structurally related to local anaesthetics of amide type eg, antiarrhythmic drugs (eg, mexiletine), as the toxic effects of these drugs are additive. Patients treated with class III antiarrhythmic drugs (eg, amiodarone) should be closely observed and ECG monitoring should be considered, as the cardiac effects of lidocaine and class III antiarrhythmic drugs can be additive. Drugs that inhibit the metabolism of lidocaine (eg, cimetidine or ?-blockers) may cause potentially toxic plasma concentrations when lidocaine is given in repeated high doses over a long...