Q: How long should be waited before drawing lidocaine level, if started as an IV infusion for termination of arrhythmias?

Answer:  24 hours

Lidocaine is a class IB antiarrhythmic used to treat premature ventricular contractions (PVCs), ventricular tachycardia, and fibrillation. The therapeutic level for lidocaine is 1.5-5.0 mcg/mL, and Lidocaine toxicity can be seen at levels greater than 5 mcg/mL including seizures, cardiovascular depression, AV block, and hypotension. If administered as an infusion levels can be drawn at any time after the steady state is reached which is usually attained within 18-24 hours.