Pharmacology I - Opioids

Front 1

Which opioid has useful spasmolytic effects (muscle relaxant) but should NEVER be administered IV (causes histamine release and anaphylactoid reaction, collapse)?

Back 1

Meperidine (Pethidine)

Front 2

Which opioid causes nausea and vomiting, causes histamine release following rapid IV injection, and causes urinary retention through inhibition of ADH?

How to avoid problems associated with vomiting?

Back 2

Morphine

* no food night before surgery

Front 3

Which OPIOID has LONGER duration of action than morphine, and popular in equine b/c generally less behavorial side effects, and doesn't cause vomiting?

Back 3

Methadone

~ was developed for drug addicts

Front 4

Which opioid has an very FAST onset of 2-3 mins after IV, has a duration of action around 20 mins, is given by bolus, and produces bradycardia and respiratory depression?

(up to 50% drop in HR and can stop respiration)

Back 4

Fentanyl

Front 5

If dog or cat has been injected with too much fentanyl, has stopped breathing, accompanied by large drop in HR, what might one do to counteract this?

Back 5

* give atropine
(atropine treats bradycardia in emergency situations)
* put on breathing machine until effects wear off

Front 6

What are the two ways that opioids are classified?

Back 6

Pharmacological structure
Receptor affinity

Front 7

What are the four ways opioids can be classified concerning pharmacological structure?

Back 7

Endogenous opioid peptides
Opium alkaloids
Semi-synthetic opioids
Fully synthetic opioids

Front 8

In which animals is dysphoria and mania most common when administering opioids?

Back 8

Cats
Horses

Front 9

Can opioids be potent respiratory depressants, depressing both rate and tidal volume?

Back 9

Yes

Front 10

What kind of effect do opioids have on the cardiovascular system?

Back 10

Minimal effects at therapeutic doses

Front 11

Which opioid will almost always trigger vomiting?

Back 11

Morphine

Front 12

What effect do opioids have on the urinary system?

Back 12

urine retention

Front 13

Which animals show depressive effects in general when given opioids?

Back 13

Humans
Dogs
Monkeys
Rats
Rabbits
Birds

Front 14

Which animals show excitability at low doses of opioids?

Back 14

Horses
Pigs
Cattle
Sheep
Goats

Front 15

Why do cats have dysphoric effects when given opioids?

Back 15

Cats have deficiencies in glucuronidation pathways (how opioids are metabolized)
Also causes mydriasis

Front 16

What α2 agonist is licensed to use in horses and used in wild animal sedation (darts), and is administered alone or in combination with injected opioids?

Back 16

Detomidine

Front 17

What are the three general groups of opioid receptors?

Back 17

(OR) 1, 2, 3

Front 18

What opioid receptors activation produces supraspinal analgesia, spinal analgesia, respiratory depression, emesis, euphoria, addiction...?

Back 18

Receptors 3

Front 19

Which opioid is 10 times for potent that morphine and is not licensed in UK or Australia?

Back 19

Oxymorphone

~but drug action very similar to morphine, hydromorphine

Front 20

What opioid receptors are located principally in the limbic system and control analgesia and modulation of receptors 3?

Back 20

Receptors 1

Front 21

What opioid receptors are located principally in the cerebral cortex and spinal cord and control spinal analgesia, sedation, vasopressin release, diuresis, and miosis?

Back 21

Receptors 2

Front 22

Which opioid has an onset of action relatively slow after IV (20 mins), is a poor analgesic agent but good sedative and anti-tussive?

Back 22

Butorphanol

Front 23

What is the most commonly used opioid antagonist?

Back 23

Maloxone

Front 24

Which opioid is a reasonable analgesic for visceral or soft tissue pain, especially in cats, but has ceiling effect?

Back 24

Buprenorphine

Front 25

why is fentanyl available as patch? what is advantage?

is pharmokinetics of drug consistant?

Back 25

~b/c fentanyl is fast actiing, so way of slowing down absorption

* But onset and plasma concentration variable in animals
B/c were developed for abs. through human skin
* poor alternative to opioid CRI

Front 26

What potent synthetic opioid wears off immediately (after 3 minutes) regardless of infusion duration?
~Why is this?

Back 26

remifentanil - CST of 3 - 4 mins, independent of infusion duration, instant onset

~because NOT metabolized in liver; metabolized by pseudocholinesterases in plasma

Front 27

What potent synthetic opioids
~Used as premed for rapid-sequence induction protocol
~Onset of action 2 – 3 minutes

Back 27

Fentanyl

Front 28

Most commonly used opioid in vet medicine?

Back 28

Butorphanol (Torbugesic)

Front 29

Butorphanol (Torbugesic):
Advantages? What used for?

Back 29

good sedative and anti-tussive agent (cough suppressants e.g. for treating kennel cough)

Has been used to ‘reverse’ other opioids in case of overdose
(antagonizes 1 receptor and agonist for another opioid <- do we have know which?)

Front 30

Butorphanol (Torbugesic):
Short or long duration of action?

Back 30

short duration of action, takes about 30 minutes to kick in

Front 31

Disadvantage to Butorphanol (Torbugesic)?

Back 31

MIXED AGONIST-ANTAGONIST OPIOID

- antagonizes main opioid receptor,
so NOT RECOMMENDED AS AN ANALGESIC AGENT
- also will reverse action of other opioid acting on this receptor (but may be good thing)
- can cause dysphoria in horses
-very expensive

Front 32

What drug is partial agonist?

Back 32

BUPRENORPHINE

Front 33

When would you NOT want to use BUPRENORPHINE (Vetergesic)?

Why? What is duration of action?

Back 33

DO NOT USE WHEN AGGRESSIVE ANALGESIA IS REQUIRED! (if a lot of pain)

* both agonist and antagonist properties at μ receptor…high doses may be less effective than lower ones
* long duration of action difficult to displace from receptor…cannot enhance opioid analgesia if ineffective

Front 34

Routes of opioid administration? (8)

Back 34

1-3. Systemic (IV, IM, SC, continuous infusion)
4. transmucosal
5. epidural
6. intra-articular
7. topical
8. corneal