Opioid revision

Question 1

What is the oral bioavailability of morphine?

Answer 1

30%

though good absorption, high first pass

Question 2

What is the ratio that indicates solubility?

Answer 2

octanol : buffer coefficient

Question 3

Mechanisms of action of pethidine?

Answer 3

opioid agent, but also anti-cholinergic, 5HT, LA activity, a2 activity

Question 4

Protein binding of morphine?

Answer 4

30%

Question 5

What is the CSHT of fentanyl at 4 hours?

Answer 5

260 mins

Question 6

oxycodone

• Oral bioavailability
• VD
• Protein binding

Answer 6

80%
2.6 L/kg
40%

Question 7

Notable metabolites of oxycodone?

Answer 7

noroxycodone and oxymorphone, both active

Question 8

Mechanism of action of opioid agonist?

Answer 8

GPCR, Gi -> decreased cAMP -> closure of voltage-gated calcium channels

hyperpolarisation of the membrane by increasing potassium conductance

Question 9

At 200 mins, CSHT of

• alfentanil
• sufentanil
• remifentanil

Answer 9

60 mins
30 mins
4 mins

Question 10

Compare metabolism of tramadol and tapentadol

Answer 10

Tramadol - CYP2D6, active metabolite ODMT renal excreted.

Tapentadol - glucuronidation, inactive metabolite renal excreted

Question 11

MoA of buprenorphine?

Answer 11

partial agonist u receptor with higher affinity and slower dissociation than full agonist opioids

K-receptor antagonist properties