Local Anesthetics

Question 1

LA MoA

Answer 1

• Block voltage gated Na channels
• Stop propogation of action potentials in axon fibers
• Un-ionized form can cross membrane
• LA are normally basic (pH 8-9)
  
  • Inflammed tissue is acidic and ionizes LA

Question 2

LA sensitivity to block

Answer 2

• More sensitive to LA
  
  • Small diameter fibers
  • Nociceptive fibers more than sensory input (touch/pressure, proprioception)
• Order of sensitivity to block most to least
  
  • Small myelinated–> non-myelinated–> large myelinated
  • So motor fibers are less affected than sensory

Question 3

LA Unwanted Effects

Answer 3

• Block of Na in CNS
  
  • confusion, agitation, convulsions, resp depression
• Block in heart
  
  • Blocks AP conduction and myocardial contraction
• Most (not COCAINE) cause severe vasodilation and drop in BP

Question 4

Lidocaine

Onset half life

found in 4

and even used in

Inherent

Answer 4

• rapid onset
• t 1/2 2 hrs
• Topical, transdermal, spray, injectable
• Used in IV for ventricular dysrhythmias
• inherent vasodilation properties

Question 5

Mepvicaine

Onset

Less inherent

Answer 5

Similar to lidocaine

Less inherent vasodilation

Question 6

Tetracaine

Onset

duration of action

less

Answer 6

Slower onset but longer duration of action than lido

Question 7

Bupvicaine

Action

Commonly used with

Answer 7

Longer action

Commonly used in epidurals together with opioid

Question 8

Cocaine

Dual action

Answer 8

• LA
• Catecholamine reuptake blocker
  
  • epi and dopamine
  • Sympathomimetic–> inc herat rate, vasoconstriction (HTN) inc body temp
  • Does not cause vasodilation

Question 9

GABA_A receptors and general anesthetics

Answer 9

• Most anesthetics potentiate GABA-A receptors
  
  • Not ketamine, cyclopropane, xenon
• Barbituates inc the duration R stay open
• Benzodiazepines inc the number that open
• Two-pore domain K channels
  
  • Volatile anesthetics potentiate these channels
  • not activated by iv
• NMDA receptors
  
  • N2O, ketamine block NMDA receptors

Question 10

Gen Anesthesia involves 3 neurological changes

Answer 10

Unconciousness

Loss of response to stimuli

Loss of reflexes

Question 11

Propofol

Type of anesthetic

used for

Answer 11

• General intravenous
• Induction anesthetic
  
  • preferred induction agent
• rapid onset and recovery with little symptoms

Question 12

Thiopental

Type

belongs to what class of drugs

solubility and metabolim

cqan cause

Answer 12

• Intravenous
• Induction
• Barbiturate
• High lipid solubility and slow metabolism
• can cause tissue necrosis

Question 13

Etomidate

Type of anes for

can cause

Answer 13

IV

Induction

Adrenal steroid suppression

Question 14

Midazolam

type for

belongs to what drug class

Answer 14

• IV
• Induction
• Benzodiazepines

Question 15

Fentanyl

type

agonist of

useful as

Answer 15

• IV
• Highly potent opioid agonist
• Useful analgesic

Question 16

Ketamine

type

onset

does not cause

Answer 16

• IV
• Slower onset
• Does not cause cardiovascular depression or resp supression

Question 17

Inhalation Anesthetic Agents

Properties

Answer 17

• Small, lipophilic, can readily cross alveolar membranes
• Most are volatile liquids at room temp (except N2O)
• Used to maintain anesthesia
• Rapid induction and recovery

Question 18

Nitrous Oxide

Answer 18

• Good analgesic properties but low potency as anesthetic

Question 19

Isoflurane

Type

Currently the…

Can cause

Answer 19

• Inhalation
• Most widely used volatile anesthetic
• Hypotension

Question 20

Halothane

Type

not used bc

Answer 20

Inhalation

not used bc of liver toxicity