FANZCA Core Knowledge and Fundamentals 2 — Questions and Answers
Question 1: Which pharmacokinetic parameter best describes the relationship between drug dose and plasma concentration at steady state?
- Volume of distribution
- Clearance (Correct answer)
- Half-life
- Bioavailability
Correct answer: Clearance
Clearance determines steady-state plasma concentration because Css = dose rate / clearance, making it the primary determinant of drug exposure at steady state.
Question 2: A patient receives propofol via a target-controlled infusion (TCI). The Marsh model uses which variable as its primary input for volume of distribution calculations?
- Lean body weight
- Total body weight (Correct answer)
- Ideal body weight
- Body surface area
Correct answer: Total body weight
The Marsh model uses total body weight as its primary input, which can lead to overdosing in obese patients compared to models like Schnider that use age and lean body weight.
Question 3: What is the mechanism by which neostigmine reverses non-depolarising neuromuscular blockade?
- Direct agonism at nicotinic receptors
- Inhibition of acetylcholinesterase (Correct answer)
- Competitive displacement at the neuromuscular junction
- Increased acetylcholine synthesis
Correct answer: Inhibition of acetylcholinesterase
Neostigmine inhibits acetylcholinesterase, increasing synaptic acetylcholine concentration to competitively overcome the neuromuscular block.
Question 4: Which opioid receptor subtype is primarily responsible for analgesia at the spinal cord level?
- Delta (δ)
- Kappa (κ)
- Mu (μ) (Correct answer)
- Nociceptin/orphanin FQ (NOP)
Correct answer: Mu (μ)
Mu (μ) receptors mediate the predominant analgesic effects of opioids at both spinal and supraspinal levels, as well as respiratory depression and euphoria.
Question 5: Context-sensitive half-time differs from elimination half-life because it accounts for:
- Renal clearance of the drug
- Redistribution from peripheral compartments after infusion cessation (Correct answer)
- Hepatic first-pass metabolism
- Protein binding changes over time
Correct answer: Redistribution from peripheral compartments after infusion cessation
Context-sensitive half-time reflects the time for plasma concentration to fall 50% after stopping an infusion, incorporating redistribution from peripheral tissue compartments which increases with infusion duration.
Question 6: Rocuronium at a dose of 1.2 mg/kg is used for rapid sequence intubation. Its onset is most attributable to:
- High lipid solubility
- High plasma protein binding
- Large concentration gradient at the neuromuscular junction (Correct answer)
- Slow hepatic metabolism
Correct answer: Large concentration gradient at the neuromuscular junction
The large dose creates a steep concentration gradient driving rapid diffusion to the neuromuscular junction, achieving onset comparable to succinylcholine despite rocuronium's slower intrinsic potency.
Question 7: Which volatile anaesthetic agent has the lowest blood:gas partition coefficient among currently used agents?
- Isoflurane
- Sevoflurane
- Desflurane (Correct answer)
- Halothane
Correct answer: Desflurane
Desflurane has a blood:gas partition coefficient of approximately 0.45, the lowest among currently used volatile agents, resulting in the fastest induction and emergence.
FANZCA Core Knowledge and Fundamentals 2
Which pharmacokinetic parameter best describes the relationship between drug dose and plasma concentration at steady state?