Module 6b: opiod analgesics

Question 1

Whats the difference between opiod and opiate

Answer 1

Opiod is general name of class-> inlcudes all drugs that act on opiod receptors

Opiates: naturally occuring opiods from opiod poppy-> morphine + codeine

Question 2

Name the 3 opioid receptors and give more info regarding most used one, location of it and function

Answer 2

MOP, DOP, KOP

MOP most opioid drug uses, located in CNS, responsible for majority of effects

Question 3

What are the 4 major effects of opioids

Answer 3

centrally mediated analgesia:
- decreased neural discharge
- intense in nature

Decreased sympathetic response

Sedation: contributes to anaesthesia

Cough suppression

Question 4

What are 6 opioid side effects?

Answer 4

respiratory depression
euphoria/dysphoria
prolonged recovery
GIT(nausea and vomiting, constipation)
Tolerance, addiction and withdrawal
Pruritis

Question 5

What are the uses of opioids in anaesthesia

Answer 5

Mainstay of intraoperative analgesia:
- Mainly fentanyl and morphine

Establishing pre-emptive analgesia

Maintaining intraoperative analgesia (IV boluses or infusion)

Dampening of intubation response (alfentanil)

Additive to LA in neuraxial blockade

Target controlled infusion of remifentanil for intraoperative analgesia

Opioid-based anaesthesia

Question 6

In what forms and for what can morphine be given?

Answer 6

IV: intraoperative analgesia, postoperative analgesia in high care, patient controlled analgesia pump

IM: postoperative analgesia in ward(4-6hrly), LABOUR ANALGESIA

Orally: severe chronic pain, palliative care cancer pain

Question 7

Give characteristics of codeine

Answer 7

weak opiate
pro-drug-> metabolized in liver into morphine
metabolism varies
usually given orally: combined, standalone, cough mixtures
addictive

Question 8

What are examples of semi-synthetic opioids

Answer 8

heroin(diamorphine)
oxycodone

Question 9

What are examples of synthetic opioids

Answer 9

pethidine
fentanyl + derivatives:
- alfentanil
- sulfentanil
-remifentanil

Question 10

Give characteristics about fentanyl

Answer 10

Other name: sublimaze
Most commonly used synthetic opioid in anaesthesia
Onset 10min
Intense analegsia for 30-45 min
Useful in pre-emptive surgical anaesthesia
Very potent(100x more than morphine)
Significant respiratory depression
High doses useful for cvs instability
Can be used in PCA/ added to local anaesthetic mix

Question 11

Give characteristics of alfentanil(Rapifen)

Answer 11

Fentanyl derivative
Rapid onset+offset(lasts 5 min)
Dose; 0.5mg-1mg IV
Does not cross placenta->USED IN GA IN C-SECTION/PRE-ECLAMPSIA
Blunts intubation response
Emergency rescue intraoperative analgesia

Question 12

Characteristics of sufentanil(Sufenta)

Answer 12

Similar effects to fentanyl
Very potent
few cardiovascular side-effects
Can be given via infusion intraoperatively:
- significant period of good postoperative analgesia
- patient will need high care monitoring post-op

Question 13

Characteristics of remifentanil(Ultiva)

Answer 13

Ultra short acting
Regardless of dose-> metabolised into inactive compounds after 10min
Spontaneous recovery
Must be given via infusion(requires infusion pump)

Question 14

What are the indications for remifentanil(ultiva)

Answer 14

sleep apnoea
morbid obesity
avoiding postoperative respiratory depression
deep intraoperative analgesia required

Question 15

Characteristics of tramadol

Answer 15

weak synthetic opiod
Has actions on noradrenergic and serotonin receptors
Given orally
Moderate to severe pain
Solo/combined with paracaetamol

Question 16

What is nalaxone?

Answer 16

Opiod antagonist which rapidly displaces opiods from receptors

Question 17

Where is nalaxone useful

Answer 17

emergency management of respiratroy depression

Neonates: opiod reversal in mothers who received opiods in labour/GA in pre-delivery