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

Esters: more frequent allergic rxns; met'zed to PABA

1. Procaine (Novocaine)--2.3 mg/kg
2. Tetracaine--2.5 mg/kg; lasts about 3h
3. 2-Chloroprocain--lasts about 45min

Amides:

1. Lidocaine--6.4mg/kg; lasts 60-90min
2. Mepivacaine--1.3-4mg/kg; lasts about 3h
3. Bupivacaine--tight therapeutic index; lasts about 3h

Systemic toxicity: If due to bupivacaine, tx with IV Bretylium or ultra short-acting barbiturates

1. CNS: confusion, dizziness, tinnitue, perioral paresthesia, sedation, nystagmus, siezures, LOC
2. CV: Ventricular arrhythmias, hypotension