Drug Interaction Report

MONITOR: Amide-type local anesthetics (e.g., lidocaine, bupivacaine, ropivacaine) may have additive cardiac effects when coadministered with class I antiarrhythmic agents. In general, the toxic effects of amide-type anesthetics when coadministered with structurally related antiarrhythmic agents are additive and potentially synergistic which may lead to bradycardia, chest pain, heart block, arrhythmias, ECG abnormalities, and cardiac arrest. The clinical significance of the interaction has not been established.

MANAGEMENT: If coadministration of amide-type local anesthetics with class I antiarrhythmic agents (e.g., procainamide, mexiletine, disopyramide) is required, caution and clinical monitoring are recommended for additive cardiac effects. Advise patients to contact their physician if they experience adverse effects such as chest pain, palpitations, nausea, vomiting, lightheadedness, nervousness, dizziness, or tremors.

Ethanol may increase the acetylation of procainamide. Subtherapeutic plasma levels of procainamide may result in some patients. Because the acetylated metabolite of procainamide also possesses antiarrhythmic properties, the clinical effects are unclear.