Pharm Local Anesthetics

Front 1

Give the order of nerve suseptibility to block for myelinated somatic A fibers

Back 1

Small size >>> large: delta>gamma> beta> alpha

Front 2

Given that the order of block is from delta>gamma>beta>alpha for somatic A fibers, give the corresponding block associated with somatic A fibers.

Back 2

delta:fast pain, temp, touch> gamma:muscle tone > beta: touch, pressure > alpha: motor proprioception, reflexes

Front 3

Which fibers are most sensitive to block? Place in order

Back 3

C > B > A

Front 4

which are blocked first myelinated or non-myelinated nerves?

Back 4

myelinated

Front 5

which Na channel can bind anesthetic better, closed (resting), open, or open/inactive (desensitized)?

Back 5

open/inactive (desensitized)

Hint 5

None

Front 6

What effect does the binding of anesthetic have on desensitized Na channels?

Back 6

It stabilizes it in the desensitized state

Front 7

Which nerves in large nerve trunks are blocked first?

Back 7

the outer nerves are blocked first

Front 8

What form of an anesthetic can pass through the cell membrane?

Back 8

uncharge, thus pH and the drug pKa determine the relative amounts of drug on either side of the membrane

Front 9

When is the anesthetic effect of a drug terminated?

Back 9

when the drug is removed from the tissues

Front 10

What effect do vasoconstrictors, such as epinephrine, have on anesthetic action?

Back 10

they prolong action through reduced loss to the blood

Hint 10

None

Front 11

Once an anesthetic is in the blood what 2 things determine its distribution in different tissues?

Back 11

blood flow, hydrophobicity of the drug and tissues

Hint 11

None

Front 12

What effect do plasma esterase have on ester anesthetics such as procaine and tetracaine?

Back 12

produce inactive products, which are generally non-toxic, but can produce allergic responses

Front 13

what effect do hepatic enzymes have on amides, such as lidocaine and bupivacaine?

Back 13

Produces some active and/or toxic intermediates

Front 14

How can high plasma levels of anesthetic be produced? (3 ways)

Back 14

intravascular injection, repetitive admin, and impaired metabolism

Front 15

What are two toxicities related to high anesthetic plasma levels?

Back 15

CNS and cardio

Front 16

Which toxicity correlates with anesthetic potency, CNS or cardiac?

Back 16

CNS - potency is related to lipophilic properties, thus since the CNS is more lipophilic it will receive more drug --> more toxicity

Hint 16

None

Front 17

which anesthetic is most cardiotoxic?

Back 17

bupivacaine

Front 18

which occurs at lower plasma levels of anesthetic, CNS or cardiac?

Back 18

CNS

Front 19

Which produces more allergic responses esters or amides anesthetics?

Back 19

ester anesthetics

Front 20

What are the symptoms of esters?

Back 20

red and itchy eczematoid dermatitis or vesiculation

Front 21

What exactly causes the allergic rxn in ester use?

Back 21

the metabolite, PABA, which is also found in sunscreen

Front 22

How does a hydrophobic anesthetic effect the following? 1. onset... 2. potency... 3. tissue binding... 4. rate of metabolism

Back 22

1. Faster onset of block (with partitioning to the site of action), 2. greater potency (with greater toxicity), 3. inceased tissue binding, 4. decreased rate of metabolism

Hint 22

None

Front 23

What is the pKa of a hydrophilic anesthetic?

Back 23

between 8 and 9

Front 24

What is the state of most hydrophilic anesthetics at physiologic pH?

Back 24

charged

Front 25

How are hydrophilic anesthetic drugs supplied?

Back 25

in a acid pH so they will be neutral

Front 26

Local diffusion, Local pH, Tissue binding, local blood flow, and cardiac output, but NOT enzymatic half-life... all effect __________ of local anesthetic action.

Back 26

Local diffusion, Local pH, Tissue binding, local blood flow, and cardiac output, but NOT enzymatic half-life... all effect DURATION of local anesthetic action.

!!!!!!!!!!DURATION!!!!!!!!!

Hint 26

None

Front 27

What two things are associated with the function of total body clearance of anesthetics?

Back 27

liver and blood flow

Front 28

what is the formula for determining charged and uncharged form of anesthetics?

Back 28

log (cationic form/uncharged) = pKa -pH.. Thus a lower pKa with respect to higher pH will be neutral and able to cross the membrane... since most locals are weak bases, most of the drug will be in the form of a cation and not cross the membrane.

-or-

a negative number will produce more charged molecules = less available to cross the membrane... so infected tissue is less accessible to locals.

Hint 28

None

Front 29

What helps trap drug in cells?

Back 29

carbonate anhydrase (CO2 + H2O)

Front 30

What effect does a thicker myelin sheath have?

Back 30

greater nodal distance --> faster

Front 31

which are blocked faster, non-myelinated C fibers or mylinated A fibers?

Back 31

non-myelinated C fibers

Front 32

Which types of nerves are more sensitive to block, fast or slow firing frequency?

Back 32

Fast > slow (small>large, mylinated>non-myelinated, outer>inner)

Front 33

What effect does epinephrine have on anesthetics for the following? Duration, toxicity, extremeties

Back 33

epinephrine effects on… duration: increase, toxicity: decreases systemically, extremities: not in distal (vasoconstriction)

Front 34

What effect does calcium have on anesthetics for the efficacy?

Back 34

calcium decreases anesthetic efficacy

Front 35

What effect does hyperkalemia have on anesthetics for the effect?

Back 35

hyperkalemia increases anesthetic effect

Front 36

What effect does Low CO2 have on anesthetics for clearance?

Back 36

low CO2 produces decreased clearance of anesthetics

Front 37

What effect does infection have on anesthetics for tissue pH?

Back 37

lower pH --> see Henderson-hasselblach equation

Front 38

What drugs are used for anesthetic: tropical?

Back 38

benzocaine, tetracaine (systemic abs)

Front 39

What drugs are used for anesthetic: infiltration?

Back 39

procaine, lidocaine, bupivicaine, + epi ( at site, nerve ending)

Front 40

What drugs are used for anesthetic: field block?

Back 40

procaine, lidocaine, bupivicaine + epi (proximal nerve - less drug)

Front 41

What drugs are used for anesthetic: Nerve?

Back 41

procaine, lidocaine, bupivicaine, + epi (large bundle, damage if injected into the nerve)

Front 42

What drugs are used for anesthetic: spinal?

Back 42

tetracaine + lidocaine or bupivicaine (below L2… sympathetic > parasympathetic = hypotention… not very safe

Front 43

What drugs are used for anesthetic: epidural?

Back 43

lidocaine, bupivicaine (nerve roots, limited pH buffer)

Front 44

Name the 3 Locals that are ester metabolized. Name the 2 amine metabolized Locals

Back 44

Esters: procaine, tetracaine, benzocaine… Amine: Bupivicaine, lidocaine

Front 45

Which local is most CNS toxic?

Back 45

Tetracaine

Front 46

Which 2 drugs fall into these catagories: 1.Rapid onset/short acting… 2. Rapid onset/long acting.

Back 46

1.Rapid onset/short acting: Benzocaine… 2. Rapid onset/long acting: Bupivicaine.

Hint 46

None

Front 47

(1) Which 2 drugs fit into the following: 1. Short acting Local… 2. Intermediate acting Local... (2) what are the two short onset long long acting local anesthetics? why?

Back 47

(1) 1. Short acting Local: Procaine… 2. Intermediate acting Local: Tetracaine... (2) lidocaine and Bupivicaine, because the are metabolized by liver enzymes.

Hint 47

None