DM1 Pt7-5 Acute Pain Control - Opioids

Question 1

What are the major classes of analgesic drugs used for acute pain management in cats?

Answer 1

Opioids, NSAIDs, Alpha-2 adrenoreceptor agonists, Ketamine, Local anaesthetics, and Tramadol.

Question 2

Why are opioids widely used for pain management in cats?

Answer 2

Opioids are used due to their safety, efficacy, ability to be redosed, and their versatility in administration.

Question 3

What is the role of opioids in peri-operative pain management?

Answer 3

Opioids form the backbone of peri-operative analgesic techniques and are critical in premedication, sedation, and pain relief.

Question 4

What is the historical significance of opioids?

Answer 4

Opioids, derived from the poppy plant (Papaver Somniferum), have been used for pain and pleasure for nearly 6 millennia.

Question 5

How are opioids different from NSAIDs in dosing?

Answer 5

Unlike NSAIDs, opioids can be redosed to achieve the desired level of analgesia.

Question 6

What are the legal requirements for full µ (mu) opioid agonists (Schedule 2 Controlled Drugs) in the UK?

Answer 6

Full µ agonists must be stored in a locked cabinet, accessed only by a responsible person, and recorded in a Controlled Drugs Register.

Question 7

What are the legal differences between Schedule 2 and Schedule 3 opioids?

Answer 7

Schedule 3 drugs, like buprenorphine, require safe custody but do not need to be recorded in a Controlled Drugs Register.

Question 8

Why do some veterinary practices prefer to stock Schedule 3 opioids?

Answer 8

Due to less stringent legal requirements, some practices only stock buprenorphine and butorphanol instead of full µ agonists (Schedule 2).

Question 9

What limitation does the absence of full µ agonists create in veterinary practices?

Answer 9

The lack of full µ agonists imposes a significant limitation on managing moderate to severe pain in cats.

Question 10

What are the storage and record-keeping requirements for Schedule 2 Controlled Drugs?

Answer 10

These drugs must be stored in a locked cabinet, and all transactions must be recorded in a Controlled Drugs Register within 24 hours of dispensing.

Question 11

What are the clinical effects of opioids in cats?

Answer 11

Analgesia, sedation, euphoria, cough suppression, bradycardia, respiratory depression, vomiting, reduced gut motility, and pupil dilation.

Question 12

How do opioids affect the cardiovascular system?

Answer 12

Opioids can cause bradycardia by stimulating vagal tone, which can be managed by giving anticholinergics like atropine.

Question 13

What is the effect of opioids on the respiratory system in animals?

Answer 13

Respiratory depression is unlikely with clinical doses in awake animals but can occur with opioids like fentanyl during anesthesia.

Question 14

Why should morphine be avoided in certain animals?

Answer 14

Morphine can cause vomiting by stimulating the chemoreceptor trigger zone and should be avoided in animals with raised intracranial or intraocular pressure.

Question 15

How do opioids affect the gastrointestinal system?

Answer 15

Opioids reduce gut motility and stimulate GI sphincters, which can lead to constipation.

Question 16

What are the effects of opioids on the eyes?

Answer 16

In most species, opioids cause pupil constriction, but in cats, opioids cause pupil dilation.

Question 17

What risk do opioids pose during pregnancy?

Answer 17

Opioids can cross the placenta and cause respiratory depression in neonates during caesarean sections.

Question 18

What are the three recognized opioid receptors?

Answer 18

The three opioid receptors are Mu (µ), Kappa (κ), and Delta (δ), which are found in the brain, spinal cord, and peripheral tissues.

Question 19

Which opioid receptor provides the most potent analgesia in cats?

Answer 19

The Mu (µ) receptor provides the most potent analgesia in cats.

Question 20

What are the different classifications of opioids based on their receptor activity?

Answer 20

Full agonists (e.g., methadone, fentanyl), partial agonists (e.g., buprenorphine), and antagonists (e.g., naloxone).

Question 21

What is the difference between opioid potency and efficacy?

Answer 21

Potency refers to the concentration required to elicit a response, while efficacy refers to the maximum effect a drug can achieve.

Question 22

Why is buprenorphine more potent but less efficacious than morphine or methadone?

Answer 22

Buprenorphine requires a lower concentration to elicit a response (higher potency) but cannot achieve the same maximum analgesia (lower efficacy) as morphine or methadone.

Question 23

What is the interaction between partial and full Mu receptor agonists?

Answer 23

Buprenorphine (partial agonist) binds tightly to Mu receptors, potentially limiting the efficacy of full Mu agonists like morphine or methadone administered later.

Question 24

When should buprenorphine not be used for premedication?

Answer 24

Buprenorphine should not be used if administration of full Mu agonists like fentanyl is anticipated during anesthesia.

Question 25

How should additional analgesia be given after buprenorphine if the animal remains in pain?

Answer 25

Full Mu agonists should be administered, but higher doses or more frequent administration may be required for effective analgesia.

Question 26

What are the different durations of action for opioids in cats?

Answer 26

Ultra-short acting (e.g. remifentanil), short-acting (e.g. fentanyl), medium-acting (e.g. methadone, morphine), and long-acting (e.g. buprenorphine).

Question 27

How long do medium-acting opioids like methadone or morphine last?

Answer 27

Methadone and morphine last approximately 3-4 hours in cats and dogs.

Question 28

What is the benefit of long-acting opioids like buprenorphine?

Answer 28

Buprenorphine lasts 6 hours, reducing the need for frequent dosing, especially overnight.

Question 29

How are fentanyl and buprenorphine administered transdermally in cats?

Answer 29

The patches are applied to clipped, clean skin (e.g. thigh or tail) and can last up to 3 days but take 12-24 hours to become effective.

Question 30

What is important to monitor when using opioid patches in cats?

Answer 30

Monitor for signs of pain and administer additional analgesics if necessary, as plasma drug absorption can vary between individuals.

Question 31

What is the historical concern about opioid use in cats?

Answer 31

Opioids were historically believed to cause excitement and mania in cats, but at clinical doses, this does not occur when the cat is in pain.

Question 32

What difference exists between opioid effects in cats vs dogs?

Answer 32

Opioids cause pupillary dilation in cats but have no significant MAC reduction effect (i.e., no reduction in volatile anesthetic concentration).