Pharmacology of Pain Control

Question 1

what does somatic pain feel like?

Answer 1

Localised aching, gnawing, throbbing

Question 2

Examples of somatic pain (3)

Answer 2

Sunburn
Muscle spasticity
Bone metastasis

Question 3

What does visceral pain feel like?

Answer 3

Poorly localised, deep, aching, cramping, pressure

Question 4

Examples of visceral pain?

Answer 4

Bowel obstruction, pancreatic cancer, pancreatitis

Question 5

What does neuropathic pain feel like?

Answer 5

electric shock, burning, shooting, altered sensation

Question 6

sites analgesics can act on (4)

Answer 6

Injury site
Local nerve conduction
Transmission in dorsal horn
Centrally

Question 7

adjuvants to analgesics

Answer 7

drugs designed for other conditions (off label use)
secondary treatment along w/analgesics
smaller dose of analgesics e.g. steroids, antidepressants, anxiolytics

Question 8

Any drug or agent with affinity for opioid receptors and reversed by …

Answer 8

Naloxone

Question 9

Where are opioid receptors located?

Answer 9

CNS, enteric plexus gut, immune cells, peripheral sensory nerves

Question 10

mu receptors endogenous ligand

Answer 10

beta-endorphine

Question 11

what effects do mu receptors have? (5)

Answer 11

analgesia
respiratory depression
euphoria
dysphoria
hallucinations

Question 12

other effects of opioids

Answer 12

respiratory depression
suppress cough
CTZ stimulation
miosis
constipation
histamine release
hormonal change
SA node depression

Question 13

what effect does opioid stimulation of CTZ cause?

Answer 13

nausea and vomiting

Question 14

How do opioids cause constipation?

Answer 14

delay gastric emptying and inhibit peristalsis

Question 15

how do opioids cause miosis?

Answer 15

Excitatory action on PNS innervation of pupils

Question 16

What is drug tolerance?

Answer 16

increased resistance to a drug’s effects over time so increased doses required to cause same effect

Question 17

What is physical dependence ?

Answer 17

sudden withdrawal of a drug provokes withdrawal syndrome, physiological effects

Question 18

Drug addiction - define

Answer 18

Pattern of behaviour characterised by craving of psychic effect of a drug

Question 19

Signs of opioid overdose?

Answer 19

coma, respiratory depression, pinpoint pupils, confusion, myoclonic jerks

Question 20

Morphine metabolism

Answer 20

By the liver and excreted by the kidneys, in renal failure toxic metabolites can accumulate

Question 21

Oxycodone metabolism and excretion

Answer 21

metabolised extensively in liver, excreted by the kidneys, less toxic metabolites, still need caution in renal failure

Question 22

Renal failure - fentanyl, morphine or oxycodone?

Answer 22

Fentanyl
Oxycodone with caution
Not morphine as metabolites can accumulate

Question 23

1st choice opioids

Answer 23

Morphine

Question 24

alfentanil - what is this?

Answer 24

fentanyl derivative, metabolised in liver, 3rd line opioid, very specialist

Question 25

Fentanyl (transdermal)

Answer 25

potent opioid patch, wide variability in drug delivery

Question 26

Indications of a syringe driver

Answer 26

palliative care

loss of ability to absorb oral medication e.g. NBM, vomiting

Question 27

Opioid switch

Answer 27

Substituting one opioid for another to achieve better balance of analgesia and side effects

Question 28

What is opioid rotation?

Answer 28

Rotating around one opioid to another or alternative route based on patient preference or to improve side effects