ANESTHETICS


LOCAL ANESTHETICS:

 All have following structure:

  1. Lipophilic---Benzene------Ester OR
  2. Moiety Ring Amide

All are weak bases; must be un-ionized to be absorbed; ionized to be pharmacologically active

Amides:
  1. Lidocaine-Lasts 30-60min; Concentrations > 1% do not increase effectiveness or duration of anesthesia
  2. Bupivacaine (Marcaine)-More potent and longer-acting than lidocaine, mepivacaine, or procaine; tight therapeutic index; lasts 1.5-2h; higher risk of toicity with systemic absorption; Contraindicated in pregnant comen
  3. Mepivacaine-Lasts 1-2.5h

Esters: More frequent allergic reactions than Amides (metabolized to PABA), so used less frequently

  1. Procaine (Novocaine)-2.3 mg/kg
  2. Tetracaine-Lasts 1.5-3h (topical only; not for local injection)
  3. Chloroprocaine (Nesacaine)-Lasts 30-60min

Systemic toxicity:

  1. CNS: confusion, dizziness, tinnitue, perioral paresthesia, sedation, nystagmus, siezures, LOC
  2. Cardiovascular: Ventricular arrhythmias, hypotension
Allergies:
Addiiton of epinephrine:

(Sources include Core Content Review of  Family Medicine, 2012)