Local anesthetics

Question 1

Lidocaine (Xylocaine) dose, max dose, onset, peak, duration?

Answer 1

dose: 1 - 1.5 mg/kg

max dose: 4.5 mg/kg (w/o epi); 7 mg/kg (w/ epi) or 300mg, whichever comes first

onset: 1 minute
peak: 2 minutes
duration: 10 - 20 minutes

Question 2

Lidocaine (Xylocaine) mechanism of action?

Answer 2

antiarrhythmic - suppresses automaticity of ventricular cells, decreasing diastolic depolarization and increasing the ventricular fibrillation threshold

and

local anesthetic - produces local anesthesia by reducing sodium permeability of sensory nerves, which blocks impulse generation and conduction

Question 3

How is lidocaine metabolized and eliminated?

Answer 3

hepatic metabolism

renal elimination

Question 4

Toxic effects of lidocaine occur when plasma levels reach what amount?

Answer 4

plasma levels > 5 mcg/mL

Question 5

Toxic effects of lidocaine…

Answer 5

pulmonary - respiratory depression / arrest (PL > 10 mcg/mL)

cardiac - hypotension and bradycardia (PL > 8 mcg/mL)

neuro - tinnitus and seizures (PL 5-10 mcg/mL); CNS depression (PL > 10 mcg/mL)

[PL = plasma level]

Question 6

Lidocaine in contraindicated in patients with this…

Answer 6

an amide allergy

Question 7

Lidocaine should be used cautiously in these patients…

Answer 7

liver disease

taking other antidysrhythmics

Question 8

Lidocaine (Xylocaine) is available in what strengths?

Answer 8

1% - 5mL vial

4% - 5mL ampule

2% - 100mg/5mL injection (prefilled syringe)

2% - 20mL viscous