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

Full agonist at mu-opioid receptors

Answer

Pure antagonist at all opioid receptors

Answer

Kappa-selective agonist

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

Blockade of potassium channels during repolarization

Answer

Activation of GABA-A chloride channels

Answer

Blockade of calcium channels at the neuromuscular junction

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

The drug is confined to the plasma compartment

Answer

The drug is 100% protein-bound in plasma

Answer

The drug has poor lipid solubility

Question 4

Ketamine's dissociative anaesthetic properties are primarily mediated through:

Accepted Answer

NMDA receptor antagonism

Answer

GABA-A receptor potentiation

Answer

Sigma opioid receptor agonism

Answer

Alpha-2 adrenoceptor agonism

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

Each drug reduces the other's plasma concentration

Answer

Both drugs compete for the same receptor

Answer

One drug accelerates hepatic metabolism of the other

Question 6

The primary mechanism by which probenecid increases serum urate levels when co-administered with penicillin is:

Accepted Answer

Inhibition of renal tubular secretion of penicillin

Answer

Induction of CYP3A4 increasing penicillin metabolism

Answer

Displacement of penicillin from plasma proteins

Answer

Reduction of penicillin bioavailability

Question 7

In the context of enzyme kinetics, 'Km' (Michaelis constant) represents:

Accepted Answer

The substrate concentration at which reaction velocity is half maximal

Answer

The maximum rate of enzymatic reaction

Answer

The total number of active enzyme molecules

Answer

The equilibrium constant for enzyme-product dissociation