Premedication 3 - Opioids and Muscle Relaxants Flashcards
Which drug group are the strongest available analgesics? A) benzodiazepines B) Alpha 2 agonists C) Anticholinergics D) Opioids
D - opioids
T/F: opioids have minimal CV side effects and are suitable for most risk patients
True
A more potent drug requires
less dose for the same effect
3 classifications of opioids
Full agonists
Partial agonists
antagonists
Full opioid agonists
activate receptors and trigger full tissue response
Partial opioid agonists
activate receptors but do not trigger a full tissue response even at high doses
opioid antagonists
bind to receptors but do not trigger detectable tissue response
CNS effects of opioids
analgesia - excellent for acute pain decrease MAC inhalants sedation (depends on species and pain level) excitation, dysphoria tolerance dependence
T/F: all opioids trigger vomiting
false, they can trigger or inhibit vomiting
MoA of vomiting from opioids
water soluble opioids (morphine) enter brain slowly = cause vomiting
lipid soluble opioids (fentanyl) enter brain fast = no vomiting
Which of the following is FALSE regarding the CV effects of opioids?
A) suitable for most risk patients because no direct CV effects
B) improves CV function because allows reduction of anesthetic dose
C) may decrease HR and BP because reduction of sympathetic tone and increase of parasympathetic tone
D) treat the tachycardia with atropine
D - you would treat the bradycardia with atropine (opioids don’t cause tachycardia)
Resp effects of opioids?
resp depression
antitussive
may inhibit protective reflexes (coughing)
GI effects of opioids
defecation
obstipation
spasm of hepatic-pancreatic sphincter (Oddi)
Important other effects of opioids
hypothermia post OP hyperthermia in cats myosis (dogs), mydriasis (cats) inhibition of urination noise sensitivity
3 indications of opioid use
premedication
perioperative analgesia
treatment of acute and chronic pain
Describe important info about Morphine
cheap and strong analgesic, water soluble
causes vomiting
slow onset, long duration
metabolized in liver to an active metabolite
may cause histamine release
duration of epidural analgesia: 12-24h
Describe important info about Fentanyl
strong analgesic (full u agonist) fast onset, short duration no histamine release may accumulate after long infusion
Boluses of remifentanil can cause sudden _______
bradycardia
Describe butorphanol
antagonist on u and agonist on k receptors
weak and short acting analgesic
may antagonize full u agonists
Describe buprenorphine
partial u agonist
stronger than butorphanol but weaker than full u agonists
long acting
given to cats because less excitation than full u agonists
Describe Tramadol
PO
weak analgesic
inhibits NE and serotonin reuptake
metabolized in the liver, its metabolite is u opioid agonist
You are performing surgery on a dog and have given it buprenorphine as an analgesic. You are noticing severe respiratory depression. Which opioid antagonist could you give to reverse the respiratory depression?
Naloxone
______ is used to antagonize wild animals after long acting opioids
Naltrexone
Centrally acting muscle relaxant
Guaifenesin
T/F Guaifenesin is excellent for analgesia and sedation in large animals
False, is a muscle relaxant that offers no analgesia or unconsciousness
> 10% Guaifenesin can cause
thrombophlebitis or hemolysis
What is triple dip
GG + a2 agonist + ketamine
T/F: guaifenesin improves muscle relaxant effects of other premed drugs
True
