Amide Local Anesthetics

Amide local anesthetics are used commonly to anesthetize body parts by local infiltration or by surface absorption in order to relieve painful conditions or to assist in completion of procedures.  Amides are metabolized by the liver and have fast onset of action.  Systemic toxicity is more likely for amide anesthetics than esters.

(A hint for classifying amide vs ester anesthetics: all amide anesthetics have 2 i's in their spelling.)

Class Drugs

• Lidocaine

• Bupivacaine

• Ropivacaine

• Mepivacaine

• Prilocaine

Class Mechanism of Action

Block nerve conduction sensory impulses from the periphery to the CNS

• Blockade of sodium ion channels

Prevents action potential from initiating and sending signals to the brain

• Causes vasodilation

This side effect is mitigated by co-administration of epinephrine, which limits diffusion by causing vasoconstriction

Class Application

Local anesthesia

• Via: topical administration, infiltration, nerve blocks, or neuraxial blocks (epidurals, etc.)

Class Adverse Effects

Systemic toxicity

• May be caused by overdose of local injection or iv injection of appropriate doses

• Treatment is generally supportive

Airway management

• Treatment of seizures

• Treatment of cardiac arrhythmias

• In severe cases lipid emulsion therapy rescue is indicated

Allergy

• Allergies are rare to local anesthetics, esters are more allergenic than amides

• Allergy to one amide does not rule out use of other amides

Drug Table

Drug Name	Application	Comments	Image
Lidocaine			"Lid" "Cane"
Bupivacaine			"Up Arrow" "Cane"
Ropivacaine			"Rope" "Cane"
Mepivacaine			"Map" "IV" "Cane"
Prilocaine			"Pry Bar" "Cane"