What pharmacology viva questions are testing
A pharmacology viva is not simply a memory test. You need to retrieve a fact, explain the mechanism, apply it to a patient or experiment, and identify the main safety issue. A weak answer often contains the right drug name but does not show how the drug produces its effect or when the treatment would be unsafe.
For each question, use this order:
- Name the drug or drug class.
- State the target and mechanism.
- Link the mechanism to the effect.
- Apply it to the situation.
- Finish with a key adverse effect, interaction or monitoring point.
For example, if asked about salbutamol in acute bronchoconstriction, do not stop at “it is a beta-2 agonist”. A complete answer is that it stimulates beta-2 adrenoceptors, increases adenylyl cyclase activity and intracellular cyclic AMP in airway smooth muscle, causes bronchodilation, acts quickly when inhaled, and can cause tremor, tachycardia and hypokalaemia.
That structure gives the examiner something assessable at each stage. It also prevents a common problem in oral assessments: giving a long list of facts without answering the actual question.
Set up a pharmacology viva board
Start with your own material rather than a generic list of drugs. Add lecture slides, practical notes, learning outcomes, drug tables and any feedback from previous oral assessments. Divide the material into sections that can become stations or question families.
A useful board might include pharmacokinetics, autonomic pharmacology, cardiovascular drugs, antimicrobials, endocrine drugs and adverse drug reactions. Each section should contain mechanisms, representative drugs, applications and safety points. Avoid putting every detail into one undifferentiated note. Viva preparation depends on being able to move between a drug, its mechanism and a practical scenario.
MySummaries turns those source notes into a study board. A board on this topic ends up looking like this:
| Concept | Core point | Application |
|---|---|---|
| Clearance | Volume of plasma cleared per unit time | Reduced clearance can increase steady-state concentration |
| Half-life | 0.693 × Vd / clearance | Determines time to approach steady state |
| Loading dose | Target concentration × Vd / bioavailability | Useful when a therapeutic effect is needed quickly |
ACE inhibitors reduce angiotensin II and aldosterone formation. Check renal function and potassium; cough and angioedema are important adverse effects.
- Salbutamol — beta-2 agonist; bronchodilation via increased cAMP
- Propranolol — non-selective beta blocker; avoid in asthma because it can cause bronchoconstriction
- Atropine — competitive muscarinic antagonist; increases heart rate and reduces secretions
- Insulin increases glucose uptake in skeletal muscle and adipose tissue and suppresses hepatic glucose output
- Levothyroxine is synthetic T4; excess treatment may cause symptoms of thyrotoxicosis
- Glucocorticoids alter gene transcription and suppress inflammatory mediators
- Aminoglycosides bind the 30S ribosomal subunit and cause misreading of mRNA
- Monitor renal function and drug concentrations because nephrotoxicity and ototoxicity are important risks
- Beta-lactams inhibit bacterial cell-wall cross-linking by binding penicillin-binding proteins
Use the board to identify the minimum answer for each topic. A minimum answer is not a paragraph copied from a textbook. It is the smallest set of facts that allows you to explain the drug accurately and safely.
Build a spoken answer framework
Before practising individual questions, create a repeatable opening and closing. For a drug-mechanism question, begin with the target. For a clinical safety question, begin with the immediate risk. For a pharmacokinetic question, begin by defining the parameter before discussing the formula.
For example:
- “The main target is…” for receptor and enzyme questions.
- “The immediate concern is…” for toxicity or overdose questions.
- “This changes concentration by affecting…” for pharmacokinetics.
- “I would monitor…” for a treatment or adverse-effect question.
A strong closing sentence often makes the answer sound complete: “Therefore, the benefit is bronchodilation, but the patient should be monitored for tremor, tachycardia and hypokalaemia.”
Do not use the same length of answer for every question. A definition may need two sentences. A case-based station may need a mechanism, application, differential explanation and safety plan. The aim is not to speak for as long as possible; it is to cover the points in an order the listener can follow.
The board's must-know view can reduce a large syllabus to the facts most likely to support an oral answer:
Station 1: explain a mechanism and apply it
The first station tests whether you can connect receptor pharmacology to a physiological effect. Do not list every beta blocker. Compare the relevant drugs and explain why the difference matters.
The following is one complete practice station, with criteria used for this practice session. These are not claimed to be universal marking rules for every pharmacology assessment.
Examiner
Compare salbutamol and propranolol. Explain their receptor actions, the main physiological effects, and why propranolol may be unsafe in a patient with asthma.
You correctly identified salbutamol as a beta-2 agonist and propranolol as a non-selective beta blocker, but you did not clearly distinguish beta-1 from beta-2 effects at first.
ImproveState the receptor selectivity before describing the physiological response.
You linked beta-2 stimulation to bronchodilation and recognised the asthma risk, but the explanation of bronchoconstriction was brief.
ImproveExplain that beta-2 blockade removes bronchodilator tone and may also blunt the response to rescue beta-2 agonists.
You mentioned tremor and tachycardia but omitted hypokalaemia with salbutamol and masking of hypoglycaemia with propranolol.
ImproveGive one important adverse effect for each drug and one monitoring or counselling point.
The answer was understandable and within the time, although it moved between effects and adverse effects before finishing the comparison.
ImproveUse the order drug, receptor, effect, clinical use, safety for both drugs.
A strong answerSalbutamol is a relatively selective beta-2 adrenoceptor agonist. Beta-2 stimulation activates adenylyl cyclase, increases cyclic AMP and relaxes airway smooth muscle, producing bronchodilation; tremor, tachycardia and hypokalaemia can occur. Propranolol blocks both beta-1 and beta-2 receptors, reducing cardiac rate and contractility but also blocking beta-2-mediated bronchodilation. It may therefore precipitate bronchoconstriction and reduce the response to inhaled salbutamol, so a non-selective beta blocker is generally avoided in a patient with asthma unless there is a compelling reason and specialist oversight.
The answer does not need to claim that one drug is always “better”. It needs to explain the pharmacological difference that changes the clinical decision. If the question is purely laboratory-based, the same method applies: identify the receptor, predict the physiological response, then mention the variable that could alter the result.
Station 2: use pharmacokinetics to explain a dose decision
Pharmacokinetic viva questions often expose confusion between half-life, clearance and volume of distribution. Define each term before using it. A drug with a large volume of distribution is widely distributed outside plasma; a drug with low clearance remains in the body longer, all else being equal.
Examiner
A patient has a drug with a large volume of distribution and reduced renal clearance. Explain how these two factors affect the loading dose, maintenance dose and dosing interval.
You correctly linked volume of distribution to the loading dose and clearance to the maintenance dose.
ImproveState the loading-dose relationship explicitly: target concentration × volume of distribution, adjusted for bioavailability.
You recognised accumulation with reduced renal clearance and suggested dose reduction, which was appropriate.
ImproveMake clear that the exact adjustment depends on the drug, renal function and therapeutic index.
You mentioned plasma concentration monitoring but did not say when it is most useful.
ImproveName a narrow-therapeutic-index example such as gentamicin or digoxin and link monitoring to toxicity or efficacy.
The explanation was logically ordered and used the equations accurately, with a small amount of repetition.
ImproveGive the principle once, then apply it to the patient.
A strong answerA large volume of distribution means that more drug is outside the plasma, so a larger loading dose may be needed to achieve the desired initial plasma concentration; the relationship is loading dose = target concentration × volume of distribution, adjusted for bioavailability. Reduced renal clearance lowers drug elimination and prolongs the half-life, so the maintenance dose usually needs to be reduced, the dosing interval lengthened, or both. Repeated standard doses may accumulate and cause toxicity. The adjustment must be based on the individual drug, renal function, therapeutic index and, where appropriate, measured concentrations.
A common follow-up is “Does the loading dose need to be reduced in renal impairment?” The safest answer is that renal impairment mainly changes clearance and therefore maintenance dosing. The loading dose is determined principally by volume of distribution, although altered fluid balance, protein binding and the drug's distribution may change the practical calculation.
If you forget an equation, state the relationship in words rather than inventing a number. A clear explanation of what increases or decreases a parameter is more useful than a confidently stated but incorrect formula.
Station 3: respond to toxicity safely
Toxicity stations reward prioritisation. Start with the immediate physiological danger, not the antidote. In opioid toxicity, respiratory depression is the urgent problem. Naloxone is important, but it does not replace airway management, oxygenation and ventilation when those are needed.
Examiner
A drowsy patient has pinpoint pupils and a respiratory rate of 6 per minute after receiving morphine. Talk through your pharmacological interpretation and immediate management.
You identified opioid toxicity from the reduced respiratory rate, reduced consciousness and miosis.
ImproveSay explicitly that opioid receptor activity has caused central respiratory depression.
You started with airway and breathing assessment and included assisted ventilation if required.
ImproveKeep airway, breathing and circulation before discussing the antidote.
You named naloxone and explained that it should be titrated to restore adequate ventilation rather than necessarily full consciousness.
ImproveMention the risk of recurrent toxicity because naloxone may wear off before the opioid.
You correctly described competitive antagonism at opioid receptors and included observation, but did not discuss withdrawal in detail.
ImproveAdd acute withdrawal, pain recurrence and the need for repeated doses or infusion in selected cases.
A strong answerThis is consistent with opioid-induced central respiratory depression, with miosis and reduced consciousness supporting the diagnosis. I would assess and support the airway and breathing immediately, give oxygen as appropriate and provide assisted ventilation if ventilation is inadequate. Naloxone is a competitive opioid receptor antagonist and should be given in titrated doses to restore adequate respiratory effort, not simply to make the patient fully awake. I would reassess frequently because naloxone may have a shorter duration than the opioid, and I would watch for acute withdrawal, recurrent sedation and return of pain.
The crucial distinction is between reversing a sign and correcting the danger. “Give naloxone” alone is incomplete. A strong answer makes clear what you will do if the patient remains inadequately ventilated and what you will monitor after the initial response.
Repair the wording that loses marks
When you review a recording, mark only phrases that are vague, incomplete or pharmacologically wrong. Do not rewrite every sentence. One specific correction is easier to practise than a page of general feedback.
For the beta-adrenoceptor station, the transcript might show this:
Salbutamol works on beta receptors and opens the airways. Propranolol blocks beta receptors, so I would be cautious in asthma. It can also affect the heart. I would monitor the patient and use an alternative if necessary.
Propranolol blocks beta receptors, so I would be cautious in asthma.
The statement does not identify non-selective beta blockade, beta-2 blockade, bronchoconstriction or reduced response to rescue salbutamol.
Say: Propranolol blocks beta-1 and beta-2 receptors; beta-2 blockade can cause bronchoconstriction and blunt the response to inhaled salbutamol, so it is generally avoided in asthma unless there is a compelling reason.Notice the correction is not “say more”. It supplies the missing causal chain: drug, receptor, physiological effect and consequence for treatment. That is the level of detail to add when a marker says an answer is too brief.
A knowledge gap should be treated differently from thin wording. If you cannot explain why aminoglycosides are nephrotoxic or why ACE inhibitors can increase potassium, return to the source notes and make a new card. If you know the mechanism but say “it affects the kidneys”, practise the sentence aloud until it contains the relevant mechanism and monitoring point.
A short examiner-style debrief can help you hear the difference between a correct fact and a complete answer:
You identified the opioid toxidrome correctly, but the answer became safe only when you prioritised ventilation before naming naloxone.
A weekly method for pharmacology viva practice
Use three types of session rather than repeating the same notes.
Session one: retrieval
Choose one board section and answer six short prompts aloud. Examples include:
- What is the mechanism of ACE inhibitors?
- Why can aminoglycosides cause toxicity?
- What determines a drug's half-life?
- How does insulin lower plasma glucose?
- Why can warfarin interact with other medicines?
- What is the difference between an agonist and an antagonist?
Give yourself 30–60 seconds per answer. Stop when you have covered the mechanism, application and safety point. Mark the answer as secure, partial or incorrect.
Session two: comparison
Compare pairs that are easily confused: salbutamol and propranolol, heparin and warfarin, beta-lactams and aminoglycosides, insulin and metformin, competitive and non-competitive antagonists. Comparison forces you to identify the feature that changes the indication or risk.
Session three: full stations
Record three answers under a time limit. Include one mechanism question, one calculation or pharmacokinetic question and one toxicity or adverse-effect scenario. Listen once for scientific accuracy and once for organisation. Make one remediation card from each important error.
The useful output is not a percentage alone. It is a list of sentences you could not say accurately under pressure. Those sentences should become the next day's practice.
How MySummaries helps
MySummaries can turn your pharmacology PDFs, slides and handwritten notes into a board, then use that board for flashcards, written questions, examiner-voice lectures and recorded oral practice. For this task, the important link is between a missed spoken point and the next revision action: a vague mechanism can become a focused card, while an incomplete toxicity answer can become a new viva station.