Lidocaine Dosing Calculator

The Lidocaine Dosing Calculator determines maximum safe doses of lidocaine for local anesthesia and intravenous applications. Lidocaine (lignocaine) is the most widely used local anesthetic worldwide and one of the most versatile drugs in medicine, serving as a local anesthetic, antiarrhythmic agent, and increasingly as an intravenous analgesic. Understanding maximum dosing limits is critical for preventing local anesthetic systemic toxicity (LAST), a potentially fatal complication.

Lidocaine was synthesized in 1943 by Nils Lofgren and Bengt Lundqvist in Sweden, becoming the first amino amide local anesthetic. Its superior safety profile compared to earlier ester-type anesthetics (cocaine, procaine) revolutionized surgical and procedural anesthesia. Today, lidocaine remains the first-line local anesthetic for infiltration, nerve blocks, topical anesthesia, and emergency antiarrhythmic therapy.

For local anesthesia, the maximum recommended dose depends on whether epinephrine is co-administered. Plain lidocaine: 4.5 mg/kg with an absolute maximum of 300 mg. With epinephrine (1:100,000 or 1:200,000): 7.0 mg/kg with an absolute maximum of 500 mg. Epinephrine causes local vasoconstriction, slowing lidocaine absorption into the systemic circulation, effectively increasing the safe dose threshold and prolonging the duration of anesthesia.

Common concentrations used in clinical practice include 0.5% (5 mg/mL) for infiltration of large areas, 1% (10 mg/mL) for standard infiltration and nerve blocks, and 2% (20 mg/mL) for dental blocks and procedures requiring more concentrated solutions. Understanding the relationship between percentage, mg/mL concentration, and total volume is essential for safe dosing: a 1% solution contains 10 mg/mL, so 30 mL of 1% lidocaine equals 300 mg total dose.

For intravenous antiarrhythmic use, lidocaine is a Class Ib antiarrhythmic agent indicated for ventricular tachycardia and ventricular fibrillation refractory to amiodarone or procainamide. The loading dose is 1.0-1.5 mg/kg IV push, with additional boluses of 0.5-0.75 mg/kg every 5-10 minutes up to a maximum of 3 mg/kg. A maintenance infusion of 1-4 mg/min follows to prevent recurrence.

Intravenous lidocaine infusion for perioperative analgesia has emerged as a significant opioid-sparing strategy. The typical protocol involves a 1.5 mg/kg bolus followed by 1-2 mg/kg/hour infusion during surgery and continuing for 24-48 hours postoperatively. Multiple systematic reviews have demonstrated reduced postoperative pain scores, opioid consumption, nausea, and length of hospital stay, particularly after abdominal surgery.

Local anesthetic systemic toxicity (LAST) occurs when lidocaine reaches toxic serum levels, typically >5 mcg/mL. Early symptoms include perioral numbness, tinnitus, metallic taste, and visual disturbances. Progression leads to seizures, cardiovascular collapse, and cardiac arrest. Treatment includes lipid emulsion therapy (Intralipid 20%), airway management, and seizure control with benzodiazepines. Prevention through careful dose calculation and aspiration before injection is paramount.

This calculator provides maximum dose calculations with safety caps for all major lidocaine applications, including volume conversion based on solution concentration.