Lidocaine

See critical care quick reference for drug doses by weight.

General

• Also known internationally as lignocaine
• Type: Local anesthetics; Antiarrhythmics
• Dosage Forms: Local injection, transdermal, intravenous, inhaled, viscous
• Common Trade Names: Xylocaine, P-Care, ReadySharp Lidocaine, Xylocard

Adult Dosing

Local Anesthetic

• Maximum without epinepherine: 5mg/kg (max 300mg)
• Maximum with epinepherine: 7mg/kg (max 500mg)

Antiarrhythmic

• Loading dose = 1-1.5mg/kg
  • Additional boluses of 0.5-0.75mg/kg q5-10min up to max of 3mg/kg
  • If effective start infusion of 2mg/min
• Indications
  • Treatment of ventricular arrhythmias and ectopy
    • Considered 2nd-line to amiodarone for treatment of V-fib and pulseless v-tach

Pediatric Dosing

Local Anesthetic

• Without epinepherine: 5mg/kg (max 300mg)
• With epinepherine: 7mg/kg (max 500mg)

Antiarrhythmic

See critical care quick reference for drug doses by weight.

Special Populations

• Pregnancy Rating: American B, Australia A
• Lactation: Not expected to cause any adverse effect
• Renal Dosing
  • Adult: No adjustment provided in manufacturer's labelling but accumulation of metabolites may be increased in renal dysfunction
  • Pediatric: No adjustment provided in manufacturer's labelling
• Hepatic Dosing
  • Adult: Reduce maintenance infusion when used IV (0.75 mg/minute). Monitor concentration.
  • Pediatric: Use with caution. Reduce dose.

Contraindications

• Allergy to amide anesthetics
  • Note that these allergies are rare and are often caused by preservative, so a preservative-free formulation may be appropriate
  • Note that allergy to amide anesthetics does not suggest allergy to ester anesthetics
• High SA or AV block (without pacemaker)
• Concurrent treatment with Class I anti-dysrhythmic agents
• Wolff-Parkinson-White syndrome

Adverse Reactions

Local

• Dermatologic
  • Itching or irritation
  • Depigmentation
  • Rash/urticaria
  • Edema
  • Venous inflammation

Serious

• Local Anesthetic Systemic Toxicity (LAST)
  • Rare during infiltration of local anesthetic
  • CNS toxicity
    • Metallic taste
    • Tinnitus
    • Tingling of lips
    • Dizziness
    • Anxiety
    • Confusion
    • Lethargy
    • Loss of consciousness
    • Seizures
    • Nausea/vomiting
  • Cardiovascular toxicity
    • Bradycardia
    • Decreased myocardial contractility
    • Atrioventricular block
    • Vasodilation
    • Ventricular arrhythmias
    • Cardiac arrest
• Bronchospasm
• Respiratory depression or arrest
• Methemoglobinemia

Pharmacology

• Pharmacokinetics
  • Onset of action = 45-90s
  • Duration of action = 10-20min (antiarrythmic IV); 30-90 min (subcutaneous)
  • Half-life 90 - 120 minutes
    • Prolonged in hepatic impairment or congestive heart failure
• Metabolism
  • Primarily hepatic
• Excretion
  • Urine
• Mechanism of Action
  • Class Ib antiarrythmic
    • Binds to fast Na channels in inactive state thereby raising the depolarization threshold
    • Acts preferentially on ischemic tissue
      • Elevates V-fib threshold
      • Suppresses ventricular ectopy
  • Little effect on vascular tone, contractility, or cardiac output

Comments

• To decrease pain on injection for local anesthesia, may use bicarbonate buffered solution (!:10 cc)
  • Shorter shelf-life due to decreased stability
• Inject through wound edges whenever possible
  • Avoid injecting through intact skin when possible

See Also

• Local anesthetic systemic toxicity
• Critical care quick reference