5. Opioids

Question 1

Opium vs ipioid?

Answer 1

Opium: Natural extract of the poppy Papaver somniferum. It contains morphine and other related compounds.
Opioid: any substance (natural or synthetic) that produces morphine like effects which are blocked by a morphine antagonist
Aka narcotics (don’t use this word)

Question 2

What are opioids?

Answer 2

• Huge family of drugs
• Administered principally for their analgesic action
• Weak v. Strong
(weak opioids have a “ceiling effect” where escalation of the dose typically causes SE without improving analgesia)
• Duration of action
• Potency

Question 3

Strong opioids examples”

Answer 3

MORPHINE
Oxycodone 
Diamorphine 
Fentanyl (Lipophilic drug)
Pethidine (on it's way out. Originally anticholinergic drug)
Remifentanil 
Methadone

Question 4

Weak opioids examples?

Answer 4

CODEINE
Hydrocodeine
Tramadol
(Loperamide)

Question 5

Opioid antagonists?

Answer 5

Naloxone

Naltrexone

Question 6

Opioid administration?

Answer 6

Transdermal patch
IV
Subcutaneous
Transmucosal lozenges
Oral (not great for systemic reaching)

Question 7

What is the oral bioavailability for the following opioids:
Morphine?
Oxycodone?
Fentanyl?
Codeine?
Tramadol?

Answer 7

Morphine: 30%
Oxycodone: 70%
Fentanyl: 50%
Codeine: 60%
Tramadol: 70%

Question 8

What are the different opioid receptors?

Answer 8

Mu Opioid Peptide receptors (MOP)
Kappa Opioid Peptide receptor (KOP)
Delta Opioid Peptide receptor (DOP)
Nociception Opioid Peptide receptor (NOP)

Question 9

What are the precursors for the endogenous opioids?

Answer 9

POMC: Pro-opiomelanocortin
PENK: Proenkephalin
PDYN: Prodynorphin
ACTH: Adenocorticotrophic hormone

Question 10

What is the action of opioids at cellular level?

Answer 10

Bind to opioid g-protein-coupled receptor
Receptor activation by opioid receptor ligands –> intracellular transduction pathways e.g.
-K+ efflex ++++
-Ca2+ influx inhibition -
-Adenylyl cyclase inhibition
So… Reduces NT release

Question 11

CVS actions of opioids

Answer 11

Bp down
DR down (due to SAN direct effect and sympathetic system activation)

Question 12

GIT actions of opioids

Answer 12

Nausea/Vomiting:

1. CTZ
2. Vestibular apparatus
3. Decrease motility

Constipation (use laxative?)

Question 13

Respiration action of opioids?

Answer 13

DEPRESSION
Increase pCO2
Anti tussive action
RR down
Tidal vol down

Question 14

Renal action of opioids?

Answer 14

Urinary retention

Question 15

CNS action of opioids?

Answer 15

Sedation (good or bad??)

Analgesia: Useful clinical effect

Euphoria: Risk of misuse/abuse so needs to be controlled

Question 16

Visual action of opioids

Answer 16

Meoisis (PS, contraction)

Leads to –> Pinpoint pupil

Question 17

Name 5 strong opioids?

Answer 17

Morphine 
Fentanyl
Oxycodone
Diamorphine
Pethidine

Question 18

Name 2 weak opioids?

Answer 18

Codeine

Tramadol

Question 19

What is the parenteral and oral dose of morphine?

Answer 19

Parenteral: 10mg (0.1mg/kg)
Oral: 30mg (0.3mg/kg)

Question 20

What is the parenteral and oral dose of fentanyl?

Answer 20

Parenteral: 100 micrograms
Oral: NA

Question 21

What is an antagonist?

Answer 21

A drug with a high affinity for the receptor but no intrinsic activity

Question 22

Key consideration when prescribing opioids?

Answer 22

THEY ARE CONTROLLED DRUGS under Misuse of Drugs Act 1971