EXAM 2 APPLEYARD

Question 1

opiods act through which receptors

Answer 1

mu, delta, and kappa

Question 2

most clinically used opioids act through which receptor?

Answer 2

mu

Question 3

mu receptor is what kind of receptor?

Answer 3

GPCR

Question 4

mu receptor is primarly inhibitory/exciatory

Answer 4

inhibitory

Question 5

affinity

Answer 5

ability to bind to the recepto

Question 6

efficacy

Answer 6

ability to activate the receptor

Question 7

Rx

Etorphine

Answer 7

a full agonist at the mu receptor with high efficacy for activating the receptor.

Question 8

Rx

Naloxone

Answer 8

an mu antagonist and therefore has no efficacy to activate the receptor and blocks the effects of agonists

Question 9

Rx

Buprenorphine

Answer 9

a partial mu agonist so has a low efficacy for the mu receptor. It will cause some analgesia, but less than morphine and if given at the same time as a full agonist it will partially antagonize the full agonist’s effect.

Question 10

opioid effects

Answer 10

1. analgesia
2. sedation
3. calming and euphoria
4. anti-tussive

Question 11

How do opiods cause analgesia?

Answer 11

Morphine-like opioid drugs activate opioid receptors to decrease pain transmission and perception

Acts at multiple levels in the nociception pathway

Question 12

species differences with opioid sedation

Answer 12

sedation is greater in dogs than in cats

Question 13

adverse effects with opioid use for sedation

Answer 13

can cause excitement!
cats, horses, and some breeds of dogs (huskies, malamutes) are more susceptible to dysphoria or agitation. Sheep, cattle, and swine can also show excitation

Question 14

how do opioids cause anti-tussive effects?

Answer 14

Inhibition of cough center of medulla oblongata

Question 15

general adverse effects of opioids

Answer 15

Vomiting and defacation
Decrease GI motility, e.g. constipation
Respiratory depression
Bradycardia
Urinary retention
Miosis – dogs, humans
Mydriasis – cats, sheep, horses

Question 16

vomiting and defecation can occur following
administration of opioids, especially when given ??

Answer 16

as a pre-anesthetic to animals not in pain.

Question 17

physiologic mechanism for opioid induced vomiting and defecation

Answer 17

Initial stimulation of medullary chemoreceptor trigger
zone (CTZ), followed by delayed suppression of
inhibition of medullary vomiting center

Immediate defecation can result from an initial
increase in GI tone. However, then opioids normally
cause constipation.

Question 18

Rx

Morphine

Answer 18

original opioid purified from poppies and it is the standard to which other opioids are compared. Can stimulate histamine release. Lasts up to 4 hours, useful for traumas and surgeries.

Question 19

Rx

Hydropmorphone

Answer 19

5-7X more potent than morphine. Doesn’t cause histamine release.

Question 20

Rx

Fentanyl

Answer 20

100X more potent than morphine. Doesn’t cause histamine release. Used during surgeries and
can be given as a transdermal patch post-operatively.

Question 21

Rx

Tramadol:

Answer 21

1/6000 affinity of morphine for the mu receptor. May cause analgesia through activation of
alpha2 receptors and by inhibiting NE and 5HT reuptake. Also may cause analgesia through active
metabolite (M1) that does have affinity for the mu opioid receptor. There is a debate about how effective it
is.

Question 22

Rx

Nalaxone

Answer 22

Competitive antagonist at all three (μ, δ, κ) opiate receptors (weak on δ). Highly effective for rapid opioid reversal.

Question 22

mechanism of opioid resp depression

Answer 22

Opioids decrease the sensitivity of the respiratory
center in the medulla oblongata (brainstem) to CO2
Normally the cause of death in an overdose

Question 22

mechanism of opioid induced bradycardia

Answer 22

bradycardia probably due to opioid-inducedmedullary vagal stimulation.

Question 22

Why is it important to know that most opioids are lipophilic?

Answer 22

they can cross the placenta and therefore respiratory depressant effects can be seen in the fetus and should be monitored.

Question 23

temperature effects of opioids?

Answer 23

hypothermia - dogs, rabbits, guinea pigs hyperthermia - cats (only with mu agonists, not kappa agonists)

Question 24

mechanism of urinary retention with opioids. What administration route is this most common with?

Answer 24

Increase detrusor muscle and sphincter tone Especially common after epidural morphine – may need to manually express or catheterize

Question 25

Miosis in what animals with opioid use?

Answer 25

dogs, humans

Question 26

mydriasis in what animals with opioid use

Answer 26

cats, sheep, horses

Question 27

neuroendocrine effects of opioid use?

Answer 27

1. increase vasopressin (antidiuretic hormone) release --> oliguria 2. decrease gonadotropin release 3. increase prolactin release

Question 29

histamine release is most common with what route of opioid administration and what type of opioid?

Answer 29

Particularly with IV administration of morphine

Question 30

cardinal signs of opioid overdose

Answer 30

Miosis (pin-point pupils) if dog, dilation in cats Respiratory depression – leading to failure Coma

Question 31

concerns with long term opioid treatment

Answer 31

development of tolerance development of dependence

Question 32

acute signs of opioid withdrawl?

Answer 32

Hyperthermia, tremors, salivation Retching, vomiting, diarrhea

Question 33

opioid routes of administration

Answer 33

1. Oral 2. Injection, IV, SC, IM 3. Spinal/epidural 4. Patch

Question 34

downside of oral administration of opioids

Answer 34

many have substantial first-pass metabolism following oral administration