Part 1-PharmacoDynamicsTWO

Question 1

Inclusion of more ______ in solution has specific benefits: Greater stability, Increased solubility of the initially powdered, drug in water, Ease of sterilization

Answer 1

CATIONS

Question 2

The _________ (____) is a measure of a molecules AFFINITY of hydrogen ions

Answer 2

dissociation constant (pKa)

Question 3

When pH of solution = _____ of the local anesthetic, 50% is cation form and 50% is base form

Answer 3

pKa

Question 4

What is more important in clinical practice-diffusion of the LA molecule or binding to the receptor site?

Answer 4

diffusion!

Question 5

________ of anesthetic action is related to pKa of the LA*

Answer 5

Rate of onset

Question 6

The _______ the pKa, the longer the onset of anesthesia*

Answer 6

HIGHER

Question 7

LA with a high pKa value has very few molecules available in the ______ form at a tissue pH of 7.4

Answer 7

base

Question 8

What are the typical pKa ranges of LA’s?

Answer 8

7.7-8.1

Question 9

Some anesthetics fall outside of the range of usefulness as injectables (pKa is very _____) but are still effective as topical anesthetics…Example: Benzocaine = pKa of ____

Answer 9

LOW (a low affinity for H+ ions, and therefore penetrates really well as base, but does not want to become cation for profound anesthesia!)…Benzocaine - pKa of 3.5

Question 10

Why is bu-piv-a-caine such a long acting anesthetic?

Answer 10

lots of base diffuses and converts to cation to block the signal

Question 11

The higher the percentage of uncharged base at time of injection, the ______ the anesthetic penetrates the membrane.

Answer 11

quicker

Question 12

Most LA solutions have pH between ___ and ___

Answer 12

5.5-7

Question 13

Repeat concept: LA solutions that contain vasoconstrictor are acidified to slow _______ – prolongs period of effectiveness of drug…WHAT IS THE preservative used?

Answer 13

oxidation…SODIUM BISULFATE

Question 14

Which part of the LA solution can cause allergies?

Answer 14

Sodium Bisulfate perservative

Question 15

Whats faster in onset-LA with vasoconstrictor or plain LA?

Answer 15

Plain…it is less acidic (no preservatives)

Question 16

What is the way LA can get past the impenetrable barrier of intact skin?

Answer 16

E…M….L….A….eutectic mixture of local anesthetics…REAL slow

Question 17

Topicals with pH between 5.5 to 6.5 lowers regional pH to below normal = less ____ formed, Diffusion through to free nerve endings is _____, Nerve block is _______

Answer 17

base…limited…ineffective

Question 18

Increasing pH of the topical anesthetic provides more base form (RN) Increases _______ of the topical anesthetic 􏰀 Shelf life ______ as drug pH increases

Answer 18

POTENCY….decreases

Question 19

A peripheral nerve is composed of _______ to ________ of tightly packed axons

Answer 19

hundreds to thousands

Question 20

ANATOMY REVIEW!!! Single nerve cell is called a _______

Answer 20

nerve fiber

Question 21

ANATOMY REVIEW!!! What covers each individual nerve fiber?

Answer 21

endoneurium

Question 22

ANATOMY REVIEW!!! Whats the name for bundles of 500 to 1000 nerve fibers??

Answer 22

Fasciculi

Question 23

ANATOMY REVIEW!!! What covers the fasciculi?

Answer 23

PeriNeurium

Question 24

ANATOMY REVIEW!!! What is the innermost layer of the perineurium?

Answer 24

Perilemma

Question 25

ANATOMY REVIEW!!! What is the alveolar connective tissue supporting fasciculi and carrying nutrient vessels?

Answer 25

Epineurium

Question 26

ANATOMY REVIEW!!! What is the outer layer of the Epineurium?

Answer 26

Epieneural sheath

Question 27

Which anatomical component of the nerve is the GREATEST barrier to the penetration of LA?

Answer 27

Perineurium (covering the 500-1000 bundles of fibers)

Question 28

Fasciculi that are located near the surface of the nerve are called _________

Answer 28

mantle bundles

Question 29

What are the first type of individual fibers that are reached by LA?

Answer 29

mantle bundles

Question 30

Fasciculi found closer to the center of the nerve are called ________

Answer 30

core bundles

Question 31

interesting.....Nerve fibers in ______ bundles innervate structures in close proximity to them.....Fibers in _____ bundles innervate structures some distance away from them

Answer 31

mantle = close....core = distance

Question 32

EXAMPLE: Inferior alveolar nerve block given near entrance to the mandibular canal: Fibers in mantle layer innervate ______ region Fibers in core layer innervate ______ mandible (lips, chin and anterior teeth)

Answer 32

molar....anterior

Question 33

Structures receiving ____ bundle innervation anesthetize later and with more difficulty

Answer 33

core

Question 34

Lack of labial and mental soft tissue signs and symptoms of anesthesia after administration of inferior alveolar nerve block indicates that _____ bundles have not yet been adequately anesthetized

Answer 34

core

Question 35

In NO clinical situation are ALL fibers within a peripheral nerve ______

Answer 35

blocked

Question 36

What are the two factors for complete block of nerves?

Answer 36

adequate volume and concentration of LA

Question 37

________ time : Time from deposition of the anesthetic solution to complete conduction blockade

Answer 37

INDUCTION time

Question 38

Review: Drugs with a _____ pKa possess a more rapid onset of action

Answer 38

lower

Question 39

What is the cause of potency in an LA? Duration of action?

Answer 39

potency = lipid solubility.....duration = degree of protein binding

Question 40

INTERESTING!!! Proteins constitute ___% of nerve membrane

Answer 40

10%

Question 41

What property of LA naturally shortens its own duration of action?

Answer 41

vasodilation

Question 42

Recovery from LA- which bundles are going to recover faster?

Answer 42

mantle much faster than core

Question 43

Where does recovery from LA first occur?

Answer 43

proximal to the injection site

Question 44

_______ is slower process than induction

Answer 44

Recovery

Question 45

What is happening with the bundles when the Pt can start to feel the LA wearing off? What can we do about it??

Answer 45

the mantle bundles are losing their LA...more LA administered will diffuse and numb again

Question 46

WHAT IS increasing tolerance to a drug that is administered repeatedly??

Answer 46

Tachyphylaxis!!! (second injection)

Question 47

________ is more likely to develop if nerve function is allowed to return before second injection*

Answer 47

Tachyphylaxis

Question 48

Three factors that affect the rate of removal of an LA: 1. Degree of ______ binding 2._______ at the injection site 3. Presence or absence of ________

Answer 48

protein....vascularity.....vasoconstrictor

Question 49

a new first- in-class local anesthetic reversal agent...WHAT is the name and what is its MECH of action?

Answer 49

ORA - VERSE...its a VASODILATOR

Question 50

Oraverse: Not recommended for children less than __ yrs and/or less than ___lbs

Answer 50

6yrs...33lbs

Question 51

Oraverse: What is contraindicated?....What does the label look like?

Answer 51

NO contraindications!....Label is GREEN

Question 52

What is the ratio used with OraVerse to LA? What is the MAX?

Answer 52

1:1 ratio, but limit 2 OraVerse