Analgesics

Question 1

Define acute/nociceptive pain.

Answer 1

Short-term pain, with an easily identifiable cause.

Question 2

Define chronic/neuropathic pain.

Answer 2

Pain which persists. Constant and intermittent.

Question 3

Define allodynia.

Answer 3

Pain from a stimulus that does not usually cause pain.

Question 4

Define parasthesis.

Answer 4

Painful feelings e.g pins and needles. With no apparent stimulus.

Question 5

What are 3 classes of drugs used for analgesia?

Answer 5

Opioids. Antidepressants/Antiepileptics. Local Anaesthetics.

Question 6

What is the mechanism of action for opioids?

Answer 6

Act at the level of the spinal cord and the CNS. Decrease neurotransmitter release and block postsynaptic receptors. Activate inhibitory pathways.

Question 7

What are the advantages of using opioids?

Answer 7

Highly effective, range of durations of effects, variety of routes.

Question 8

What are the side effects of opioids?

Answer 8

N&V, constipation, drowsiness, respiratory depression, hypotension, sedation, dependance.

Question 9

What can opioids interact with?

Answer 9

Alcohol, MAOIs, SSRIs

Question 10

What are opioid μ-receptors?

Answer 10

Involves CNS, spinal cord, Peripheral sensory neurons and GI tract. Responsible for most of the analgesic effects. Most opioids are μ-receptor agonists.

Question 11

Examples of opioids?

Answer 11

Morphine, methadone, codein, tramadol, fentanyl

Question 12

What are the 2 types of antidepressants that can be used for analgesia?

Answer 12

Serotonin and noradrenaline reuptake inhibitors (SNRI).

Selective Serotonin Reuptake Inhibitors (SSRI).

Question 13

What are SNRIs used for?

Answer 13

Highly effective for neuropathic pain.

Question 14

What are examples of SNRI drugs?

Answer 14

Venlafaxine - prescribed for diabetic neuropathy, Duloextine - prescribed for peripheral neuropathy.

Question 15

What are example of SSRI drugs?

Answer 15

Paroxetine, Citalopram.

Question 16

How do SNRI/SSRI work?

Answer 16

Prevent the recycling of neurotransmitters and enhance the signal.

Question 17

What are the side effects of SNRIs?

Answer 17

Nausea, insomnia, sedation, headache, dizziness. Can cause: epilepsy, cardiac disease, diabetes.

Question 18

How do antiepileptic drugs work for analgesia?

Answer 18

Inhibit voltage gated sodium channels. Inhibit voltage gated calcium channels. Inhibit Glutamate and GABA receptors. This inhibits action potentials firing and limits neuronal excitation.

Question 19

What is carbamazepine?

Answer 19

Antiepileptic drug. Used to treat different types of neuralgia and diabetic neuropathies.

Question 20

What are the side effects of carbamazepine?

Answer 20

Dizziness, drowsiness, fatigue, nausea, hepatoxicity, renal impairment, skin reactions, anorexia, tremor.

Question 21

What is Gabapentin?

Answer 21

An anti epileptic drug. Used to treat neuropathy of the face, neuralgia, sciatic type pain, neuropathy.

Question 22

What are the side effects of gabapentin?

Answer 22

Anorexia, dyspepsia, tremor.

Question 23

How do local anaesthetics work?

Answer 23

Inhibit voltage gated sodium channels or NMDA receptors. Prevent nerve-cell communication. Inhibit firing and prevent impulse transmission.

Question 24

What is the name of the local anaesthetic that blocks sodium channels?

Answer 24

Lidocaine. IV.

Question 25

What are the side effects of lidocaine?

Answer 25

CNS effects, respiratory depression, convulsions, hypotension, bradycardia.

Question 26

What does Ketamine do?

Answer 26

Blocker of Glutamate receptors (NMDA).

Question 27

What are the side effects of ketamine?

Answer 27

HTN, tachycardia, tremor, myocardial depression.