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Flashcards in Local Anesthetics - the drugs Deck (62)
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1

Its metabolite interferes with efficacy of sulfonamide antibiotics

Procaine

2

what LAs have significant 1st pass effect by the lungs

Bupivicaine

Lidoicaine

Prilocaine

3

Chloroprocaine duration after infiltration

30 min to 1 hr

4

LAs that come as pure enantiometrs

Ropivacaine

Levobupivacaine

*advantage = less toxic, easier to resuscitate in case of toxicity

5

What is the dose of Lidocaine for epidural placement? 

It depends on the level of blockade required and the density of blockade required. If you want profound motor blockade at T4 for example and the epidural is placed at the L2-3 interspace that is about 10 segments. Say this person is average size – I would give 1.5ml per segments I wanted blocked – so I would give 15cc of 2% lidocaine. 15cc X 20mg/cc = 300mg of lidocaine.  I would need to make sure that this amount did not exceed the maximum dose allowed which is 5mg/kg for plain lidocaine. If the patient was 70kg that is 350mg – so 15cc is O.K. If I wanted to give more I might add epi which would increase my maximum dose to 7mg/kg or 490mg. 

6

Chloroprocaine Max Dose

12 mg/kg

7

Lidocaine uses?

  • Regional/ neuraxial block
  • Cough suppression
  • Attenuate ICP/BP raise during laryngoscopy
  • Attenuate reflex bronchospasm that may occur with airway instrumentation
  • Suppress ventricular dysrhythmias

8

Tetracaine Max Dose

3 mg/kg

9

Cocaine toxicity sxs

cocaine ↓ reuptake of NE → leads to ↑ concentrations of NE

  • restlessness, tremors, seizures & euphoria
  • tachycardia/MI

10

LAs that come in racemic mixtures

Bupivacaine

Mepivacaine

11

Arrange LAs in the order of non-ionization %

cocaine, lidocaine, mepivacaine, chloroprocaine, prilocaine, ropivacaine, tetracaine, procaine

Procaine 3%

Chloroprocaine 5%

Tetracaine 7%

Cocaine 7%

Bupivacaine/Levobupivacaine 17%

Ropivacaine 17%

Lidocaine 24%

Prilocaine 24 %

Mepivacaine 39%

12

Bupivacaine E½t

3.5 hrs

13

LA great for differential nerve block (sensory>motor)

great for OB

Bupivacaine

14

when do you redose lidocaine (epidural)?

lidocaine lasts about 1.5-2 hours etc

15

Ropivacaine max spinal dose 

15-20

16

Bupivacaine DOA after spinal

1.5 to 3.5 hr

17

List max doses of LAs

Bupivacaine, cocaine, tetracaine, ropivacaine, etidocaine, lidocaine, mepivacaine, choroprocaine

Bupivacaine 2.5 mg/kg

Cocaine 3 mg/kg

Tetracaine 3 mg/kg

Ropivacaine 3 mg/kg (3.5 w epi)

Etidocaine 4 mg/kg

Lidocaine 4 mg/kg (7 w epi)

Mepivacaine 4 mg/kg (7 w epi)

Chloroprocaine 12 mg/kg

18

Prilocaine duration after infiltration

1 -2 hrs

19

Mepivacaine duration after infiltration

1.5 - 3 hr

20

LAs with pKa in the ≈ 8s

Bupivacaine/Levobupivacaine 8.1

Ropivacaine 8.1

Cocaine 8.5

Tetracaine 8.5

Chloroprocaine 8.7

Procaine 8.9

21

which has more CNS toxicity poptential

lidocaine or mepivacaine

mepivacaine

22

Does lidocaine have an active metabolite?

YES.

2 Monoethylglycinexylidide (80% activity)

(Mono-ethyl-glycine-xylidide)

xylidide (10% activity)

23

Bupivacaine (Levobupivacaine) 

duration after infiltration

4-8 hrs

24

LAs with pKa in the ≈7s

Mepivacaine 7.6

Etidocaine 7.7

Lidocaine 7.9 

Prilocaine 7.9

25

Shortest DOA for epidural

Chloroprocaine

26

Ropivacaine duration after infiltration

4-8 hrs

27

LA toxicity s/s?

CNS

circumoral numbness, tinnitus, vision changes, dizzy, slurred speech, restless, muscle twitching (especially in the face), seizures (which cause CNS depression, apnea, hypotension)

CV

hypotension, myocardial depression, AV block

Note: bupivacaine is most CV toxic

28

Lidocaine max spinal dose 

30-100 mg

29

Bupivacaine pros and cons?

Pro

highly protein bound

  • low incidence of neuro complications with spinal
  • longer DOA (good for post-op pain and labor)

Also, A alpha, beta, and gamma fibers are not completely blocked, so sensory is blocked and motor is not completely blocked.

Con

TOXICITY! very cardio toxic; pressure is still felt, that can freak people out

30

metabolism of prilocaine.

Rapid metabolism

TOXIC metabolite ortho-toluidine

Must be avoided in OB due to metabolite

Big doses will convert hgb to methemoglobin (treated with methylene blue)