How it is examined
The CICM First Part written section is two papers, each with 10 short answer questions and 50 multiple choice questions, over 2.5 hours. Candidates who reach the Angoff standard in both the SAQs and the MCQs progress to cross-table vivas: 2 minutes of reading, then 10 minutes with the examiners on basic sciences applied to intensive care, including monitoring equipment. Up to five attempts are allowed. Check the CICM website and syllabus for current details.
SAQs ask you to define and explain terms, draw concentration-time curves, or describe how critical illness alters kinetics.
Pharmacokinetics
| Term | Meaning | ICU relevance |
|---|---|---|
| Volume of distribution | Amount in body / plasma concentration | Increased in fluid overload and sepsis for hydrophilic drugs |
| Clearance | Volume of plasma cleared per unit time | Augmented renal clearance; reduced in AKI |
| Half-life | 0.693 x Vd / clearance | Determines time to steady state |
| Context-sensitive half-time | Time to 50% fall after infusion | Fentanyl accumulates with long infusions |
| Protein binding | Fraction bound to albumin or alpha-1 acid glycoprotein | Hypoalbuminaemia raises free fraction |
| Extraction ratio | Fraction removed by an organ | High-extraction drugs depend on blood flow |
Pharmacodynamics
- Dose-response curves: potency (EC50) versus efficacy (Emax).
- Competitive antagonists shift the curve right without lowering maximum effect.
- Non-competitive antagonists lower maximum effect.
- Tachyphylaxis and tolerance.
- Time-dependent versus concentration-dependent antibiotic killing.
Critical illness and kinetics
- Sepsis increases Vd for hydrophilic drugs such as beta-lactams and aminoglycosides, so loading doses are needed.
- Augmented renal clearance can make standard beta-lactam doses subtherapeutic.
- AKI and CRRT change clearance; dosing follows the circuit and drug properties.
- ECMO circuits sequester lipophilic and highly protein-bound drugs.
Practice questions
SAQ-style practice
Define context-sensitive half-time and explain its clinical relevance for sedative infusions.
Show a model answer outline
- Definition: time for plasma concentration to fall by 50% after stopping an infusion maintaining a steady concentration.
- Depends on infusion duration and drug distribution, not just elimination half-life.
- Fentanyl rises sharply with long infusions; remifentanil stays short due to esterase metabolism.
- Relevant to waking and extubation planning.
Worked MCQ · Loading dose
Which parameter determines the loading dose needed to reach a target plasma concentration?
- A Clearance
- B Volume of distribution
- C Half-life
- D Oral bioavailability alone
- E Plasma protein binding alone
Show the reasoning
Answer B. Loading dose = target concentration x Vd (divided by bioavailability for non-IV routes). Clearance determines the maintenance dose.
Common mistakes
- Defining terms without explaining relevance.
- Confusing potency and efficacy.
- Forgetting units.
- Ignoring altered kinetics in critical illness.
- Unlabelled concentration-time curves.
Free sample pharmacokinetics and pharmacodynamics questions
Questions from our Intensive care (CICM) bank. Choose your answer, then open the explanation.
Local anaesthetic with pKa closer to 7.4 has:
- AFaster onset
- BLower toxicity
- CSlower onset
- DLonger duration only
- EHigher potency
Show answer and explanation
Answer A. A pKa closer to physiological pH means more unionised drug, which crosses the nerve membrane faster. Lignocaine (7.9) is faster than bupivacaine (8.1). Duration relates to protein binding; potency to lipid solubility.
Learning point: LA onset: pKa; potency: lipid solubility; duration: protein binding.
A local anaesthetic with a pKa of 7.9 is injected into infected, acidic tissue. What happens?
- ALess drug is ionised and onset is faster
- BMore drug is ionised and onset is slower
- CThe drug becomes more lipid soluble
- DIonisation is unchanged
- EPotency increases
Show answer and explanation
Answer B. Local anaesthetics are weak bases. In acidic tissue, more drug is ionised and cannot cross the nerve membrane, delaying onset and reducing effectiveness.
Learning point: Weak bases are more ionised in acidic tissue.
What does a large volume of distribution indicate?
- AExtensive tissue binding
- BShort half-life
- CRapid renal clearance
- DHigh protein binding in plasma
- EDrug confined to plasma
Show answer and explanation
Answer A. Vd = dose/plasma concentration. A large Vd (for example amiodarone, fentanyl) implies extensive tissue distribution. High plasma protein binding gives a small Vd.
Learning point: Large Vd: tissue binding.
Practise more pharmacokinetics and pharmacodynamics questions free
Every pharmacokinetics and pharmacodynamics subtopic in our bank
The bank holds 21 pharmacokinetics and pharmacodynamics questions across 21 subtopics. You can filter by any of them, build a custom block and track your accuracy subtopic by subtopic.
- Agonists1
- Augmented renal clearance1
- Bioavailability1
- Clearance1
- Competitive antagonism1
- Context-sensitive half-time1
- CYP inhibitors1
- Drug in pregnancy1
- Enzyme induction1
- Half-life1
- Hepatic extraction ratio1
- Loading dose1
- Partial agonist1
- pKa1
- pKa and ionisation1
- Protein binding1
- Renal dosing1
- Steady state1
- Therapeutic index1
- Volume of distribution1
- Zero-order kinetics1
Common questions
Is PK/PD a large part of the First Part?
Pharmacology principles are a core part of the CICM First Part syllabus.
Do I need equations?
Yes. Know the relationships between Vd, clearance, half-life and dosing.
What about extracorporeal therapies?
Know the principles of how CRRT and ECMO alter drug handling.
Sources
Clinical content is summarised from current Australian guidance at the date above. Guidelines change, so always check the latest edition.