Local Anesthetics, Amides vs Esters

Ester: Metabolized in the blood plasma and has a high incidence of allergy

  • Allergies to this drug stem from an atypical pseudocholinesterase which is a protein needed to metabolize these drugs
  • They tend to have a cross allergy meaning that if you are allergic to one ester drug you are likely going to be allergic to other esters

Amide: Metabolized in the liver like most other drugs, very low incidence of allergy

Individuals with liver disease or low liver function will have a hard time metabolizing the drug and more drug free in the body increasing its toxicity


Lidocaine/ Octocaine/ xylocaine

  • Starts to work quickly and spreads to tissues widely
  • Medium duration
  • Anesthetic characteristic will work longer with epinepherine
  • Available topically, IV, Block, Epidural, and as a viscous mouthwash solutions usually use d to treat sores and ulcers

Mepivicaine/ polocaine/ carbocaine

  • Available with levonordefrin which is like epinephrine to last longer and keep the anesthetic concentrated in treatment area
  • Works like lidocaine in terms of less vasodilation than other local anesthetics
  • Not available topically


  • Available with or without epinepherine, but even without epinephrine it has a longer duration than lidocaine
  • less toxic than lidocaine but also less potent
  • Risk of methemoglobinemia when drug metabolized into an active form of ortho-toluidine


  • Less toxic than lidocaine but more potent
  • Very long duration, need to be aware of risk for self harming patients or very young patients due to self inflicting injury when no sensation felt for extended periods


  • 5-10% metabolized in the liver and the rest in the blood plasma but still considered amide
  • methylparaben free
  • ability to be lipid soluble meaning it can cross lipid membrane barriers readily like the lipid membrane on our nerves


Procaine/ Novocaine

  • Very safe but high incidence of allergy
  • Not used in dentistry today
  • Very slow onset and high vasodilation without epinephrine
  • Used to treat IV arrhythmia and uncontrolled seizures


Not widely given in dentistry but if patient reports to allergy with this medication they likely are allergic to other esters


  • 10 times more potent than propoxycaine
  • Slow onset but long duration
  • Not widely used in dentistry

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