Local Anesthetics



Local Anesthetics






▪Ester Local Anesthetics

Metabolized by pseudocholinesterase to PABA; have incr risk of allergy.


Procaine (Novocaine)

0.5-1%

Onset fast, SDOA 25-30 min, low potency.

Spinal, PNB.


Cloroprocaine (Nesacaine)

1%-3%

Fastest onset, SDOA, low potency, least toxic.

EPIDURAL (not spinal), caudal, PNB.


Tetracaine (Pontocaine)

0.5%-1%

Onset slow, LDOA 2-5 hr, high potency.

SPINAL (not epidural), intense motor block , poor sensory.

0.5% tetracaine can be neurotoxic in continuous spinal anesthesia.


Cocaine

Blocks NE reuptake; vasoconstrictor, sig syst. absorption occurs.

Topical


Benzocaine

Topical anesthetic; causes metheglobinemia.



Cetacaine

Tetracaine and benzocaine; causes metheglobinemia.

Higher % more likely to get motor block, lower % gets sensory/SNS block.








Dose Chart for Esters




















































Ester

%

Use

Onset

DOA

Max mg w/Epi


Procaine

10

Spinal

Fast

0.5-1

200


Chloroprocaine

2

PNB

Fast

0.5-1

800/1000

2-3

Epid

Fast

0.5-1

800/1000


Tetracaine

0.5

Spinal

Fast

2-6

20


Cocaine

4-10

Top

Fast

0.5-1

150


Benzocaine

≥ 20

Top

Fast

0.5-1

200



▪Amide Local Anesthetics

Breakdown via amidases, metab by CP450 (much slower than ester hydrolysis).


Lidocaine (Xylocaine)

0.5-5%

Onset rapid, mod DOA (0.5-2 hrs), mod potency/toxicity.

Epidural, spinal, caudal, PNB, topical, local.

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Sep 9, 2016 | Posted by in ANESTHESIA | Comments Off on Local Anesthetics

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