Lidocaine

Xylocaine

Amide local anesthetic / class IB antiarrhythmic

Blocks voltage-gated Na⁺ channels in nerves (LA) and cardiac myocytes (antiarrhythmic).

Indications

•Local infiltration
•Spinal/epidural
•IV regional (Bier block)
•Topical airway
•Antiarrhythmic
•IV infusion for postop pain

Dosing

Context	Adult	Pediatric
Infiltration	Max 4.5 mg/kg plain; 7 mg/kg with epi	—
Topical airway	4% nebulized 4 mL	—
IV bolus antiarrhythmic	1–1.5 mg/kg IV, repeat 0.5 mg/kg q5–10 min (max 3 mg/kg)	—
IV infusion analgesia	1–2 mg/kg bolus then 1–3 mg/kg/hr	—
Bier block	0.5% 40–50 mL preservative-free	—

Maximum dose

4.5 mg/kg plain (absolute max 300 mg) · 7 mg/kg with epi (absolute max 500 mg)

Max-dose calculator

single-injection infiltration / block

Patient weight (kg)

Plain

300 mg

Capped at absolute max 300 mg

With epinephrine

490 mg

Concentration	Max volume (plain)	Max volume (with epi)
0.5% (5 mg/mL)	60 mL	98 mL
1% (10 mg/mL)	30 mL	49 mL
1.5% (15 mg/mL)	20 mL	32.7 mL
2% (20 mg/mL)	15 mL	24.5 mL

Infiltration/block max only — not the IV antiarrhythmic (≤3 mg/kg) or infusion limits. Education only — confirm against the package insert. Max doses are not additive across agents; account for total LA when mixing.

Pharmacokinetics

Onset 1–5 min (depending on route). Duration 60–120 min. Hepatic CYP metabolism.

Side effects

!LAST (perioral numbness → tinnitus → seizures → arrhythmia → cardiac arrest)
!Transient neurologic symptoms (intrathecal lidocaine — back/leg pain hours after spinal)
!Methemoglobinemia (high doses, prilocaine more so)

Contraindications

×Heart block (without pacer) — high-dose IV
×Allergy to amide LAs (rare)

Clinical pearls

★Add bicarb 1 mEq per 10 mL to alkalinize → faster onset, less burning.
★Avoid intrathecal lidocaine if possible — TNS rate up to 14%; bupivacaine better choice.
★IV lidocaine infusion: opioid-sparing for laparoscopic surgery.