Unit 4: Local Anesthetics

Question 1

what was the first local anesthetic?

Answer 1

cocaine

cerebral stimulating qualities​

ophthalmology (1884)​

localized vasoconstriction: shrink nasal mucosa

Question 2

1st synthetic ester was ___

Answer 2

procaine

Question 3

1st synthetic amine was ____

Answer 3

lidocaine

Question 4

Name the class of antidysrythmIc drugs that are also LA

Answer 4

Antiarrhythmic Drug Classes:​

Class I - Sodium-channel blockers.​

Question 5

what is the introp dose of lidocaine?

Answer 5

1mg/kg over an hour

Question 6

what is the initial dose of lidocaine for induction?

Answer 6

1-2mg/kg over 2-4 minutes

Question 7

what is the drip dose for lidocaine?

Answer 7

1-2mg/kg/hr
stopped 12-72 hours after

Question 8

discuss the plasma lidocaine concentrations with the side effects

Answer 8

Question 9

local anesthetics (LAs) have a (1) _____ portion connected by a (2) _____ chain to the (3) ______ portion.

Answer 9

lipophilic
hydrocarbon
hydrophilic

Question 10

what are the two classess of local anesthetics?

Answer 10

amide and ester

Question 11

the standard LA is ____

Answer 11

lidocaine

Question 12

LA blocks pain and ____

Answer 12

motor

Question 13

when you give lidocaine the patient will often say it taste like ____

Answer 13

metal

Question 14

we give lidocaine to blunt the airway reflexes. What are those?

Answer 14

swallowing, gagging, coughing

Question 15

Lidocaine has vaso_____ properties

Answer 15

vasodilatory

Question 16

you give your pt lidocaine and they are having tinnitus and skeletal muscle twitching. What plasma lido concentration would you suspect?

Answer 16

5-10mcg/ml

Question 17

Bond between () & () classifies it as ester or amide

Answer 17

1 and 2

the hydocarbon/intermediate chain classifies it as ester or amide

esters have 1 i
amines have 2 i’s

Question 18

LA are weak ____ with a pH of 6

Answer 18

bases

Question 19

sodium bisulfite makes the LA more ____ with epi

Answer 19

soluble

Question 20

non ionize % is the largest indicator of ___ solublility

Answer 20

lipid

Question 21

the higher the nonionized% of the drug the more ____ the drug

Answer 21

lipid soluble it is

and sometimes potent

Question 22

bupivicaine is more potent than lidocaine even with a lower nonionized component? why?

Answer 22

lidocaine causes vasodilation and this causes it to travel away from the site of action

bupivicaine is also more lipid soluble

Question 23

liposomes do what? what are the drugs that do this(3)?
do they cause an increase or decrease in toxicity?

Answer 23

can be compared to an extended release

Question 24

what is the MOA of LA?

Answer 24

Binds to inactivated closed @ inner voltage-gated Na+ channels​

Block/inhibit Na+ passage in nerve membranes​

Question 25

LAs Block/inhibit Na+ passage in nerve membranes​, What 3 things does this cause?

Answer 25

Slowed rate of depolarization​ Does not reach threshold​ No action potential​

Question 26

what factors affect the LA blockade? (3)

Answer 26

Lipid solubility or non-ionized/unionized form​ Repetitively stimulated nerve​ (more sensitive, reacts well with LA) Diameter of the nerve​ (bigger the nerve the more drug we need)

Question 27

what are other targets of the LA besides the fast NA channels?

Answer 27

K channels Ca ion channels GPCR

Question 28

Answer 28

A

Question 29

minimum effective concentration (MEC) is ___

Answer 29

At least 2, preferably 3 Nodes of Ranvier (1 cm) blocked​ to gain numbness comparable to MAC with volatiles

Question 30

preganglionic B fibers are the ____

Answer 30

fastest Myelinated A (medium) and B fibers (faster) > Unmyelinated C fibers (small)

Question 31

what pt population have increase sensitivity to LA?

Answer 31

preg women because they have a decrease in plasma cholinesterase - you will give a lower dose, especially with the esters - can travel into the fetus, who has more acidic blood, and turns into ionized form and cause ion trapping - the fetus can become bradycardic and comatose

Question 32

usually all LA are ___% lipid soluble

Answer 32

50

Question 33

pKa’s closest to physiologic pH = most ______ OOA​

Answer 33

rapid

Question 34

what 4 factors influence absorption?

Answer 34

Site of injection​ Dosage​ Use of Epinephrine​ Pharmacologic characteristics of the drug​

Question 35

Rate of tissue distribution​ ***Lipid solubility is the _____ determinant of potency​

Answer 35

primary

Question 36

rate of clearance is dependent on what 2 things

Answer 36

CO and protein binding

Question 37

% bound of a drug is _____ related to % plasma

Answer 37

inversely

Question 38

the highest protein binding drug has the ____ metabolism

Answer 38

slowest

Question 39

describe metabolism of amides

Answer 39

Amides: Microsomal enzymes in the liver​ Most rapid: Prilocaine​ Intermediate: Lidocaine & Mepivacaine​ Slowest: Etidocaine, Bupivacaine & Ropivacaine​

Question 40

describe the metabolism of esters

Answer 40

Esters: Hydrolysis by cholinesterase enzyme in plasma > liver ​ except with Cocaine: Liver)​ Metabolite: para-aminobenzoic acid (PABA): allergies​ Amides are slower than esters​

Question 41

cocaine is an ester but is mainly metabolize in the ___

Answer 41

liver

Question 42

what is the usual reason pt have allergies to LA

Answer 42

PABA para-aminobenzoic acid this is the metabolite for ester LA, so if they have this allergy you will use an amide

Question 43

what are the three main LA that have first pass puml extraction

Answer 43

these are inactive once in the lungs Lidocaine, bupivacaine (dose dependent), and prilocaine​

Question 44

main elimination and clearance of LA is in the ___

Answer 44

kidney Poor water solubility​ Unchanged drug in urine = 5%​ Cocaine is 10 to 12%​ PABA through urine​

Question 45

Answer 45

true

Question 46

Answer 46

A and D clearance from primary site of action

Question 47

the higher the protein binding the ____ it is available to be metabolized

Answer 47

lesser