2 Pharm: Local Anesthetics

Front 1

local anesthetics gen

Back 1

local anesthetics gen:
- reversible blockade of nerve impulse conduction
- progressive conc blocks:
1. autonomic
2. somatic sensory
3. somatic motor
- recovery: occurs spontaneously, in reverse order

Front 2

cocaine

Back 2

cocaine:
- ester of benzoic acid, erythroxylon coca tree of Andes
- 1860: isolated by Nieman
- 1884: topical anesthetic for cornea

Front 3

procaine

Back 3

procaine:
- first local anesthetic syn by Einhorn (1905)

Front 4

lidocaine

Back 4

lidocaine:
- syn by Lofgren (1943)
- prototype local with which others compared

Front 5

parts of basic molecule

Back 5

parts of basic molecule:
1. lipophilic end
2. intermediate part
3. hydrophilic end

Front 6

lipophilic end of basic molecule

Back 6

lipophilic end of basic molecule:
- usually unsaturated aromatic ring, eg paraminobenzoic acid
- essential for activity
- classified by how end connected to intermediate chain:
1. ester (-CO-) bond -or-
2. amide (-NHC-) bond

Front 7

ester compounds:

Back 7

ester compounds:
-caines
1. chloropro-
2. pro-
3. tetra-
4. topical anesthesia: co-, benzo-, buta-, hexyl-, propara-, cyclomethy-

Front 8

vasoconstrictors

Back 8

vasoconstrictors:
1. epi: 1: 200K or 5 ug/ml
2. phenylephrine: 1: 20K
3. cobefrin
4. hyaluronidase

Front 9

intermediate and hydrophilic end of basic molecule

Back 9

1. intermediate part: hydrocarbon chain, alkyl (OCH2) group
- increasing length of chain: inc potency and toxicity
2. hydrophilic end: secondary or tertiary amine

Front 10

ester group

Back 10

ester group:
- benzoic acid derivatives
- hydrolyzed by plasma and liver esterases

Front 11

amide group

Back 11

amide group:
- aniline derivatives
- met by microsomal liver enz

Front 12

commercial prep

Back 12

commercial prep:
1. HCl salts: pH 6, make basic (non-ionized) soluble in water
2. epi: (1:200K) prolongs duration and intensity of analgesia
3. hyaluronidase: inc diffusion, faster onset, shorten duration
4. hya, epi and procaine: double are of desensitization, inc duration
5. new: no epi and hya

Front 13

amide compounds

Back 13

amide compounds:
- caines:
1. lido, xylo, ultra, sera
2. mepiva- (carbo-): long-acting
3. bupiva- (mar-)
4. etido-
5. prilo-
6. dibu-

Front 14

pharmacokinetics

Back 14

pharmacokinetics:
1. weak bases (non-ionized): made soluble by acid salts which make the cations
2. active: ionized and non-ionized
3. non-ionized: faster onset of action
4. high lipid solubility: high potency, long-acting eg tetracaine, bupivicaine and etidocaine

Front 15

non-depolarizing block

Back 15

non-depolarizing block:
- inhibits depol:
1. prevents Na entry into cell
2. threshold not reached, no AP propagation
3. doesn't alter resting mem pot or threshold pot

Front 16

nerve fibers

Back 16

nerve fibers:
1. large diam: more resistant
2. B (of autonomic): more sensitive than pain conducting C and delta
- exception preganglionic SNS B: blocked with low conc
3. pain fibers (sensory block): C and delta, but motor fx to touch ( alpha or A and beta) may remain unaffected

Front 17

allergic rxn

Back 17

allergic rxn:
1. para-aminobenzoic acid: metabolite of ester compounds
2. methylparaben: preservative of ester and amide compounds

Front 18

systemic toxicity

Back 18

systemic toxicity:
- some spp more prone:
1. eq: procaine
2. primates: lidocaine
- tongue numbness, restlessness, muscle twitching, depressed respiration

Front 19

lidocaine uses

Back 19

lidocaine uses:
1. sx drip: fibrillation prevention
2. SQ: prevents sloughing by irritating inj such as guafenesin
3. ER: unknown cause of tachycardia (no epi)

Front 20

topical anesthesia

Back 20

topical anesthesia:
- skin burns
- itching
- prevention of laryngospasm: ET placement

Front 21

local infiltration

Back 21

local infiltration:
- nerve blocks