Pharmacokinetics and Pharmacodynamics
Drug absorption, distribution, protein binding, clearance, compartments, elimination, receptors, dose-response and interactions.
How to prepare for the current Primary FRCA MCQ
Build mechanisms first, practise calculations with units, connect equipment to failure modes and finish every SBA by choosing the single best answer to the exact lead-in.
Core concepts
Concept 1
Absorption, distribution, protein binding, metabolism and clearance determine the concentration reaching the effect site over time.
Exam cue: Ask whether a change affects loading dose, maintenance dose, effect-site equilibration or more than one of these.
Concept 2
Receptor affinity, efficacy, potency, dose–response shape and patient variability determine the resulting clinical effect.
Exam cue: Separate potency from efficacy and redistribution from elimination.
Risk pitfalls and guardrails
Using elimination half-life alone to predict recovery after a prolonged infusion.
Guardrail: Do not choose an option merely because it states a true fact; choose the one that best answers the exact lead-in under the stated conditions.
Assuming that a more potent drug can necessarily produce a greater maximum effect.
Guardrail: Do not choose an option merely because it states a true fact; choose the one that best answers the exact lead-in under the stated conditions.
Memory anchors
What mainly determines a loading dose?
Target concentration and apparent volume of distribution, adjusted for bioavailability where relevant.
What mainly determines a maintenance dose rate?
Target concentration and clearance.
What is context-sensitive half-time?
The time for plasma concentration to halve after an infusion stops, considered in relation to infusion duration.
What distinguishes potency from efficacy?
Potency is the concentration or dose needed for an effect; efficacy is the maximum effect achievable.
What does a competitive antagonist usually do?
It shifts the agonist concentration–response curve right without reducing the achievable maximum when sufficient agonist can be given.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
After an intravenous bolus, a drug amount falls from 100 mg to 50 mg in 2 hours by first-order elimination. What is its elimination half-life?
Which pharmacokinetic variable relates the amount of drug in the body to its measured plasma concentration?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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