Local Anesthetics and Analgesics

Question 1

Mechanism of action for local anesthetics

Answer 1

Suppress pain by blocking sodium channels, thereby blocking impulse conduction along axons

Question 2

What is the onset for lidocaine?

Answer 2

less than 2 mins

Question 3

Why is lidocaine often given with epinephrine?

Answer 3

Prolong anesthesia
Reduce the risk of toxicity - slows absorption

Question 4

Lidocaine

Adverse effects

Answer 4

-Once in systemic circulation, can cause CNS excitation - from jitteriness to seizures, as level rise higher, CNS depression can occur - drowsiness to respiratory depression
-Cardiovascular - heart block, dysrhythmias, hypotension
-Hypotension with epidural or spinal anesthesia can be a problem

Question 5

When must epinephrine not be given along with lidocaine?

Answer 5

Avoid areas that have only one major blood supply, because clamping down blood flow could lead to tissue death (e.g. digital block or circumcision)

Question 6

Analgesics

Answer 6

Drugs that relieve pain without causing loss of consciousness

Question 7

Opioid

Answer 7

A general term defined as any drug, natural or synthetic, that has actions similar to morphine

Question 8

Opiate

Answer 8

Applies only to compounds present in opium

Question 9

3 main classes of opioid receptors

Answer 9

Mu receptors
Kappa receptors
Delta receptors

Question 10

Morphine

Adverse effects

Answer 10

-Respiratory depression
-Tolerance to respiratory depression can develop
-Increased depression with concurrent use of other drugs that have CNS depressant actions (e.g. alcohol, barbiturates, benzodiazepines)
-Constipation (no tolerance)
-Orthostatic hypotension
-Emesis (tolerance develops to this)
-Urinary retention
-Sedation (tolerance develops)

Question 11

Morphine

Onset

Answer 11

IV 7 mins
IM 30 mins
subQ up to 90 mins
may persist 4-5 hours

spinal injection - response may be delayed by hours

Question 12

Signs of morphine toxicity

Answer 12

-Coma
-Respiratory depression
-Pinpoint pupils

Question 13

Fentanyl potency

Answer 13

100 times the potency of morphine
Efficacy is the same

Question 14

Transdermal fentanyl (Duragesic) indication

Answer 14

Useful for patients with chronic severe pain and high degree of tolerance

Question 15

Meperidine (Demerol)

Half-life
Metabolite

Answer 15

Short half-life
Toxic metabolite acculumation

Question 16

Controlled-release oxycodone

Answer 16

OxyContin

Question 17

Buprenorphine (Subutex) forms

Answer 17

Sublingual film: Suboxone
7-day patch: Butrans

Question 18

Agonist-Antagonist Opioids

Answer 18

Buprenorphine (Subutex)
Nalbuphine (Nubain)

Question 19

ReVia

Answer 19

another trade name for naltrexone

Question 20

Methylnaltrexone

Answer 20

selective opioid antagonist that works on the GI tract and treats opioid-induced constipation in late-stage disease for patients on constant opioids

Question 21

What nerves /sensations are blocked most quickly by local anesthetics? Which nerves/sensations are blocked last?

Answer 21

pain, cold, hot, touch, deep pressure

Question 22

How do you safely apply topical anesthetics?

Answer 22

✿Apply the smallest amount needed over the smallest area possible
✿Avoid application to broken or irritated skin
✿Avoid strenuous exercise, wrapping the site, and heating the site, all of which can accelerate absorption by increasing skin temperature

Question 23

Refers to a condition where there is a delay or complete interruption of electrical signals in the heart’s conduction system, affecting the normal rhythm and coordination of heartbeats

Answer 23

Heart block

Question 24

Heart Block
Signs and Symptoms

Answer 24

Fatigue, dizziness, fainting, or irregular heartbeats