Anagesics

Question 1

Name the order of the pain pathway

Answer 1

Nocicepter
....
Dorsal Horn
...
Spinothalamic Tract
...
Ventral Posterior Nucleus (Thalamus)
...
Sensory Cortex

Question 2

Name some categories of Analgesics

Answer 2

• NSAIDS
• Opioids (Modify the transmission of pain signams and the subjective perception of pain)
• Antidepressants/Antiepeleptics (used in neuropathic pain that is resistant to opioids)
• Local Anasthetics (effective in severe crescendo pain)

Question 3

What is the mechanism of action for Opioid Analgesics

Answer 3

They act on the spinal cord and the CNS:

• Decrease neuritransmitter release
• Blck postsynaptic receptors
• Activate inhibitory pathways

Question 4

Name some positives and negatives of Opioids

Answer 4

Advantages:

• effective
• array of durations of effects
• range of routes (IV, Trasdermal)

Disadvantages:

• Lots of SE
• Cautions/Contradictions (respiratory depression)
• Interactions (alcohol, SSRI, Carbamazepine, Cimetidine)

Question 5

True or False…

Most Opioids are receptor agonists.

Answer 5

TRUE

Most are μ receptor agonists.

Question 6

When are Opioid Antagonists useful?

Answer 6

They can be used to block the action of opiates . For example in heroin/morphine overdose:

• Naltrexone
• Naloxone

Question 7

What are the types of Opioid Receptors?

Answer 7

There are 3 main types:

• Kapa receptors (CNS, Spinal Cord, Peipheral Sensory Neurons)
• Delta (CNS, PSensory Neurons
• μ (moo) - CNS, Spinal Cord, PSensory Neurons, GI tract (MOST ANALGESIC OPIOIDS ARE μ RECE{PTOR AGONISTS)

Question 8

Name some Opioid drugs and their routes…

Answer 8

• Morphine (oral, iv, intrathecal, sc
• Diamorphine (oral, iv)
• Hydromorphone (oral iv)
• Methadone (oral)
• Pethidine (oral, iv, im)

Question 9

Name some Antidepressants that can be used as analgesics…

Answer 9

SNRI- Selective Noradrenaline Reuptake Inhibitors (venaflaxine, Duloxetine)

SSRI- Selective Seretonin Reuptake Inhibitors (citalopram, Paroxetine)

Question 10

What drug seems to work well as an analgesic in a disease environment ?
Such as HIV related pain

Answer 10

SSRI-

such as citalopram, paroxetine

Question 11

Which antidepressant is effective in Neuropathic pain

Answer 11

SNRI -

Such as Venlafaxine, Duloxetine

Question 12

How do Antidepressants work as analgesics?

Answer 12

They mediate descending inhibition of ascending pain pathways in the brain+ spine

Also prevent the re-uptake of neurotransmitters so it enhances the signal.

Question 13

Name some SE of SNRI’s

Answer 13

Duloxetine- Nausea, somnolence, Insomnia, Dizziness
Venlafaxine- Nausea, sedation, headache, dizziness

Also has -cautions/contradictions: Epilepsy, Heart disease, diabetes, angle closure glaucoma, pregnancy/ breast feeding.
-Interactions: alcohol can increase sedation, NSAIDS can incerease risk of bleeding ect..

Question 14

True or false

SSRIs can have interactions with epileptics.

Answer 14

TRUE

Can antagonise anticonvulsant effects of anti-epileptics. Causing a risk of fits.

Question 15

How do anti- elileptics work in the treatment of Pain?

Answer 15

They inhibit voltage gated Na and Ca2 channels. Also inhibit Glutamate, Aninobutyric acid (GABA) and Glycine receptors,

This causes

• inhibition of action potentials firing
• Prevents Impulse transmission
• Limits Neuronol exciteation
• Enhance neuronal Inhibition

Question 16

Name some Antiepileptics used as anagesics…

Answer 16

Carbamazepine

Gabapentin (current drug of choice due to limited side effects)

Question 17

What is the Mechanism of Local Anaesthetics in analgesia

Answer 17

They inhibit the voltage gated Na channels of NMDA receptors which prevents nerve- nerve cell communication

They inhibit firing and prevent impulse transmission.

Question 18

Give some examples of Local Anaesthetics and their SE

Answer 18

Lidocaine (Xylocaine)
CNS effects (confusion), respiratory depression, convulsants, lowPB, bradycardia

Ketamine (Ketalar)
hypertension, tachy, tremor, myocardial depression

Question 19

Which class of Analgesics inhibit neuron firing and prevent impulses firing?

Answer 19

Local anaesthetics :

• Ketamine
• Lidocaine

Question 20

Which class of Analgesics inhibit Na and Ca channelse and also inhibit Glutamate and aminobutyric acid (GABA)

Answer 20

Antiepeleptics:

Gabapentin
Carbamazepine

Question 21

Which anti-epileptic is preferred due to it’s lack of SE

Answer 21

Gabapentin as it’s only SE are dyspepsia and tremor compared to the long list of SE associated with Carbamazepine.

Question 22

Which class of analgesic does this apply to:

‘seretonin and noradrenaline mediate descending inhibition of ascending pain pathways in the brain and spinal cord’

Answer 22

Antidepressants as analgesics:

SNRIs - Venlafaxine, Duloxetine

SSRIs - Paroxetine, Citalopram

Question 23

Which class of analgesics does this represent?

• Decrease Neurotransmitter release
• Mimic our Endogenous Ligands ‘enkephalins’
• Signal Transduncion (Gprotein couples receptors)
• Act as supressors
• Act as Agonists at opioid Receptors (3 types)

Answer 23

Opioid Analgesics:

They act on 3 receptors
Kapa, Delta and Moo

ie

• Morphine
• Oramorph