What is the onset and duration of action of lidocaine with epinephrine (adrenaline) for local anesthesia?

Onset and Duration of Action of Lidocaine with Epinephrine

Lidocaine with epinephrine takes approximately 2-5 minutes to onset and provides anesthesia for 90-200 minutes. 1

Onset of Action

• Lidocaine with epinephrine has an onset of action of 2-5 minutes for topical anesthesia 1
• For infiltrative anesthesia, lidocaine has a faster onset (approximately 1 minute) compared to alternatives like diphenhydramine (5 minutes) 1
• The maximum vasoconstriction effect from epinephrine occurs much later than commonly believed - approximately 25.9 minutes after injection (not the traditionally taught 7-10 minutes) 2

Duration of Action

• Lidocaine with epinephrine provides anesthesia for approximately 90-200 minutes 1
• The addition of epinephrine significantly prolongs the duration of lidocaine's anesthetic effect compared to plain lidocaine 3
• Epinephrine extends lidocaine's action by:
  • Causing vasoconstriction that slows systemic absorption 1
  • Increasing the amount of lidocaine in the slow-decaying component in neural tissue by 3-4 fold 4
  • Enhancing the intensity of analgesia throughout the duration of action 4

Pharmacokinetic Considerations

• Epinephrine concentrations between 1:50,000 and 1:400,000 are equally effective for vasoconstriction 5
• The duration of anesthesia with lidocaine-epinephrine is proportional to the lidocaine concentration 5
• Low-dose epinephrine (25 μg) provides similar analgesia duration as higher doses (200 μg) but with more stable hemodynamics 6

Clinical Applications

• For optimal surgical visualization and hemostasis, incision should ideally be made 25 minutes after injection to allow for maximum vasoconstriction 2
• The maximum safe dose of lidocaine with epinephrine for infiltration is 7 mg/kg in adults 1
• For children, the recommended maximum dose of lidocaine with epinephrine is 3.0-4.5 mg/kg 1

Important Considerations

• When using lidocaine with epinephrine, be aware of potential toxicity signs including circumoral numbness, facial tingling, slurred speech, metallic taste, and auditory changes 1
• Avoid using lidocaine with epinephrine within 4 hours of other local anesthetic interventions to prevent cumulative toxicity 1
• Buffering lidocaine with sodium bicarbonate (typically in a 1:9 or 1:10 ratio) can decrease injection pain while maintaining effectiveness 1