FACEM Pharmacology Fundamentals 3

Question 1

The 'ceiling effect' of buprenorphine as an analgesic is best explained by its pharmacology as a:

Accepted Answer

Partial agonist at mu-opioid receptors with high receptor affinity

Answer

Buprenorphine's partial agonist activity means increasing the dose beyond a ceiling provides no additional analgesia, and its high affinity makes displacement by naloxone difficult.

Question 2

Which ion channel mechanism explains the local anaesthetic action of lignocaine (lidocaine)?

Accepted Answer

Inhibition of voltage-gated sodium channels in the inactivated state

Answer

Local anaesthetics block voltage-gated sodium channels preferentially in the inactivated state, preventing action potential propagation in nerve fibres.

Question 3

A patient receives a drug with a volume of distribution (Vd) of 500 L. This large Vd most likely indicates:

Accepted Answer

The drug is extensively distributed into peripheral tissues

Answer

A large Vd (much greater than total body water ~42L) indicates extensive drug distribution into peripheral tissues, often due to high lipid solubility or tissue binding.

Question 4

Ketamine's dissociative anaesthetic properties are primarily mediated through:

Accepted Answer

NMDA receptor antagonism

Answer

Ketamine acts primarily as a non-competitive NMDA (N-methyl-D-aspartate) receptor antagonist, blocking glutamate-mediated excitatory neurotransmission.

Question 5

When two drugs are said to have a 'synergistic' interaction, this means:

Accepted Answer

The combined effect is greater than the sum of individual effects

Answer

Synergism occurs when the combined effect exceeds simple additivity (effect > drug A + drug B alone), as seen with opioids combined with benzodiazepines for sedation.

(FACEM) Fellowship of the Australasian College for Emergency Medicine Practice Test

(FACEM) Fellowship of the Australasian College for Emergency Medicine Practice Test

FACEM Pharmacology Fundamentals 3