Local Anesthetics

Front 1

Name the three parts of local anesthetics

Back 1

ionizable "head", link of an ester or amide connecting chain, and non polar tail which contains a phenyl ring.

Front 2

Are anesthetics weak acids or weak bases

Back 2

Weak bases

Front 3

What kind of amino group does the LA have. What is the pKa range? are they hydrophilic or hydrophobic? And are they ionic or cat-ioninc

Back 3

Clinically the LAs contain a tertiary amino group, pKa range of 7.5-9, as hydrophilic, cationic group.

Front 4

Name the 4 ester local anesthetics

Back 4

cocaine, procaine, benzocaine, tetracaine (and chloroprocaine - not listed in book)

Front 5

Name the 3 amide type local anesthetics

Back 5

Lidocaine, mepivacaine, and bupivacaine.

Front 6

What kind of channels do LA preferentailly block?

Back 6

voltage dependent sodium channels (in nerve and muscle membranes, when admin peripherally)

Front 7

where is the receptor side for LA

Back 7

occurs within the sodium channel nearest the cytoplasmic side of the membrane.

Front 8

What does epinephrine do when added to LA

Back 8

constricts bl vessels, counter acts effect on the smooth muscle.

Front 9

Describe 2 ways LA gets to the sodium channel

Back 9

Anesthetics bind and block Na+ channel. Local anesthetics go to receptor site 2 ways. 1) polar route - round about way - diffuses cell membrane until increased conc in cytosol fluid and then goes in channel. 2) Lipid route, goes into bilayer without going into cytosol.

Front 10

True or False. The open/inactive states are more receptive to cytosol anesthetics

Back 10

True

Front 11

List the 3 different states of membrane depolarization

Back 11

resting state, open state, inactivated state.

Front 12

True or False, Bupivacaine blocks Na+ when nerve is inactive

Back 12

True

Front 13

yes or no. if using the lipid route, does the NA+ channel have to be open?

Back 13

yes

Front 14

Bupivacaine blocks Na+ at (decreased or increased) frequency than lidocaine. Lidocaine blocks Na+ at (decreased or increased) frequency than Bupivacaine

Back 14

Bupivacaine blocks Na+ at (decreased ) frequency than lidocaine. Lidocaine blocks Na+ at (increased) frequency than Bupivacaine

Front 15

True or False, lidocaine decreases the heart rate

Back 15

true. It blocks heart rhythm. This drug is given IV because it is highly metabolized.

Front 16

True or false. Lidocaine is lipophilic compared with bupivicaine

Back 16

False. Bupivicaine is very lipophilic compared with lidocaine.

Front 17

True or False. Bupivacaine occurs in the normal frquency range of the myocardium, it can be expected to modify the NORMAL cardiac rhythm

Back 17

True

Front 18

True or False. Lidocaine only displays its maximal blocking activity at much higher than normal beat frequencies, explaining its selective blockage of tachycardias.

Back 18

True

Front 19

Can Bupivacaine be cardiotoxic? explain?

Back 19

yes. due to its slow rate of dissociation from the myocardial sodium channel.

Front 20

Name 5 factors that control the time course and intensity of local anesthesia

Back 20

1) method of administration and dose, 2) lipid solubility, 3) membrane permeability barriers, 4) ionization, 5) vascular absorption.

Front 21

Does epinephrine slow absorption because of vasoconstriction? What does it do to the rate and intensity of nerve block and the duration of action?

Back 21

Increases the rate of intensity of nerve block and prolongs the duration of action.

Front 22

True or False: There are specific pharmacological antagonists when LAs are incorrectly infect or absorbed too rapidly

Back 22

False, there are no specific pharmacological Antagonists. Treatment includes artificial respiration with pure oxygen and administration of anticonvulsant (valium)---patient can stop breathing if drug is redistributed to other parts of the body (skeletal muscle and adipose) Make sure you have O2 and defibrillation. Have to keep oxygenated for redistribution to take place.

Front 23

In order, list the pharmacological effects with increased lidocaine plasma concentration

Back 23

1) anti-arrhythmic,
2) lightheadedness, tinnitus, circumoral and Tongue numbness, 3) visual disturbances,
4) convulsions, muscular Twitching,
5) coma,
6) respiratory arrest,
7) Cardiovascular depression

Front 24

Pick one: allergic reactions most (frequent or rare) with para-amino benzoic acid ester LAs and (frequent or rare) with Amide Type LAs

Back 24

Are allergic reactions most (frequent) with para-amino benzoic acid ester LAs and (rare) with Amide Type LAs

Front 25

What are Ester LA's hydrolyzed by?

Back 25

plasma (non-specific) cholinsterase ((Once in blood vessels))

Front 26

Where are Amide LAs dealkylated and hydrolyzed in?

Back 26

The liver.

The cytochrome p450 removes the Alkyeal group, The amylase takes out the amide group.

The metabolism is not what determines how well the work, it is how well they are absorbed.

Front 27

What is the major factor determining the duration of local anesthesia?

Back 27

Vascular absorption.

Front 28

What 2 things is metabolism impt in controlling?

Back 28

1) antiarrhythmic duration of action of procainamide and lidocaine 2) fetal CNS depression due to absorption of LA from maternal circulation

Front 29

Which amide has the methyl group

Back 29

Mepivacaine

Front 30

Which amide has the butyl group

Back 30

Bupivacaine.

Front 31

What two LAs lipophillic are potent, block nerve impulse, they are most toxic and dangerous. But useful only for spinal anesthesia (largely, but not totally

Back 31

Benzocaine (#1), and Tetracaine (#2)

Front 32

what is the major determinant of the rate of recovery from an accidental intravascular injection of local anesthetic:

Back 32

Re-distribution to other tissues.

Front 33

Which Methods of Local Anesthetic Administration: Mucous membranes are highly permeable to the unionized forms of LAs, where as healthy skin is not. Care should be taken not to adminster more than the recommended dose for a given LA, as it can readily enter the systemic circulation by this route and cause confusions or respiratory failure.

Back 33

Topical

Front 34

Which Methods of Local Anesthetic Administration: Most common means of injecting LAs. When injected, nerve endings and small nerve bundles can be totally paralyzed allowing the patients to be oblivious to painful stimuli

Back 34

Infiltration

Front 35

Which Methods of Local Anesthetic Administration: When a more extensive region is to be operated upon, LA can be injected NEXT to a large nerve bundle which carries all the sensory information from that region to the CNS. This method is less predictable and requires precise knowledge of the anatomical location of the nerve to be paralyzed.

Back 35

Nerve Block

Front 36

Which Methods of Local Anesthetic Administration: The LA solution is injected near the dorsal root of the spinal cord, where sensory nerves enter the spinal cord. The LA then diffuses into the dorsal root and adjacent part of the spinal cord. This method is capable to blocking all sensation below the segment exposed to the LA. Its ADVANTAGE is that it does nto involve needle penetration of the dura.: its DISADVANTAGE is that the intensity and duration of anesthesia is less predictable than spinal anesthesia.

Back 36

Epidural

Front 37

Which Methods of Local Anesthetic Administration: The anesthetic is injected intrathecally, so it can diffuse through the CSF to motor as well as sensory neurons of a given spinal segment. Anesthesia is predictable and complete enough such that major surgery can be carried out with little or no inhalational general anesthetic.

Back 37

Spinal

Front 38

Which Methods of Local Anesthetic Administration: LA can be injected into a limb whose venous return has been limited with a tourniquet; this technique is very useful for re-setting bone fractures.

Back 38

Intravenous