Seminar - Analgesia

Question 1

List the steps of the pain pathway.

Answer 1

Transduction, Transmission, Modulation, Projection, and Perception.

Question 2

What agents act on Transduction?

Answer 2

Local anesthetics, NSAIDs, Opioids

Question 3

What agents act on Transmission?

Answer 3

Local anesthetics
Maybe alpha 2 agonists and NDMA antagonists

Question 4

What agents act on modulation?

Answer 4

Local anesthetics, maybe NSAIDS, opioids, alpha 2 agonists, NMDA antagonists

Question 5

What agents act on projection?

Answer 5

Nada

Question 6

What agents act on perception?

Answer 6

General anesthetics, Opioids, Alpha 2 agonists

Question 7

What is the function of cyclo-oxygenase inhibitors (COX)?

Answer 7

Block action of arachidonic acid to prostaglandin

Question 8

What analgesic is best for bone pain?

Answer 8

NSAIDs

Question 9

Describe acetylsalicylic acid (aspirin) for analgesia in rodents.

Answer 9

Analgesic, antipyretic, and anti-inflammatory.
Gastric bleeding and ulcers, prolongs bleeding time, CNS toxicity or hepatic injury.
Metabolized by liver, excreted in urine.
Lasts for 4 hours.

Question 10

Is acetaminophen an NSAID?

Answer 10

Eh, it’s not a COX inhibitor like most NSAIDS.

Question 11

Describe acetaminophen for analgesic in rodents.

Answer 11

Analgesic and antipyretic, but only weak anti-inflammatory properties.
Fewer side effects than aspirin. Administering in rodent drinking water likely not effective at treating pain.

Question 12

Describe flunixin meglumine for analgesia.

Answer 12

Analgesic, antipyretic, and anti-inflammatory.
Reduces inflammatory pain through activation of spinal opioid receptors.
May cause GI disruption, occasionally associated with renal, hepatic, or CNS effects.

Question 13

Describe phenylbutazone for analgesia.

Answer 13

Potent anti-inflammatory with analgesia. Antipyretic effects less than aspirin.
May cause GI bleeding, CNS toxicity, blood dyscrasias in some species (dogs, horses?).
Metabolized in liver by glucuronidation, may induce hepatic microsomal enzymes

Question 14

Describe ibuprofen for analgesia.

Answer 14

Effects similar to aspirin, but with fewer side effects.
Not associated with hepatic toxicity, but can cause GI or CNS disturbance.
Metabolized by liver and excreted in urine.

Question 15

Describe ketorolac for analgesia.

Answer 15

Most potent NSAID known.
Excellent aqueous solubility and lack of tissue irritability. May have effect on bone metabolism and healing.
Non-COX selective, can cause gastric lesions.

Question 16

Describe ketamine as an analgesic.

Answer 16

“Incomplete.” Prevents sensitization (windup) of nociceptive pathways by blocking the effects of glutamate, an excitatory neurotransmitter at the NMDA receptor.

Question 17

What is clonidine?

Answer 17

Alpha-2 agonist.

Question 18

How do alpha-2 agonists exert their sedative and analgesic effects?

Answer 18

Sedative - Cerebral a-2 adrenoceptors
Analgesic - Cerebral and spinal a-2 adrenoceptors

Question 19

What does binding of the opioid mu receptor result in?

Answer 19

Analgesia, resp depression, miosis, reduced GI motility, and a feeling of well-being

Question 20

What does binding of the delta opioid receptor result in?

Answer 20

Analgesia and poorly defined positive reinforcing effects

Question 21

What does binding of the kappa opioid receptor result in?

Answer 21

Analgesia, dysphoria, and moderate miosis and resp depression.

Question 22

What types of pain are opioids most useful for?

Answer 22

Somatic and visceral

Question 23

What opioids are agonists of the mu, delta, and kappa receptors?

Answer 23

Morphine, Fentanyl, and Oxymorphone

Question 24

What opioids are mu antagonists and kappa agonists?

Answer 24

Butorphanol, pentazocine, and nalbuphine

Question 25

What is buprenorphine?

Answer 25

Partial mu agonist, kappa antagoist.

Question 26

What is naloxone?

Answer 26

Mu, delta, and kappa antagonist

Question 27

What is nalorphine?

Answer 27

Mu antagonist, kappa agonists

Question 28

What are the only kappa antagonists?

Answer 28

Buprenorphine and naloxone

Question 29

Describe morphine analgesia.

Answer 29

Sedation w/o excitement. 2-4h duration.

Question 30

What opioid is recommended over others for severe pain?

Answer 30

Morphine

Question 31

Describe meperidine (demerol, pethidine) analgesia.

Answer 31

Mu agonist. Half the analgesic potency of morphine. Greater tendency to produce excitement. 2-3 hour duration.

Question 32

What do opiate agonists-antagonists tend to have? What does this result in?

Answer 32

Ceiling effect. May diminish the effects of a pure agonist.

Question 33

Generally, what are opiate agonist-antagonists used for?

Answer 33

Reserved for mild to moderate pain. May be more effective than pure agonists for visceral pain.

Question 34

Describe butorphanol analgesia.

Answer 34

Kappa agonist, mu antagonist. 2-5x potency of morphine. 6h duration

Question 35

What are the side effects of Bup HCl?

Answer 35

Stimulates activity, increases temp, decreases food and water intake.

Question 36

How do pentazocine and nalbuphine compare to butorphanol?

Answer 36

All kappa agonists, mu antagonists. Pentazocine is similar to butorphanol, nalbuphine has more potent mu agonistic activity than butorphanol.

Question 37

How do opiate reversal work?

Answer 37

Not completely known, likely competitive antagonists.