Pharmacology Practice Questions: 10 Worked MCQs

How to use these pharmacology practice questions

These questions cover core pharmacology rather than a named national examination. They are written in single-best-answer style and test the decisions that commonly distinguish recall from applied understanding: mechanism, pharmacokinetics, adverse effects, interactions and safe prescribing.

Choose an answer in each question, then read the explanation immediately afterwards. For every error, identify the type of mistake:

• Mechanism error: you selected the wrong target or pathway.
• Application error: you knew the fact but did not apply it to the case.
• Safety error: you missed toxicity, contraindication or monitoring.
• Kinetics error: you confused absorption, distribution, metabolism, elimination or receptor behaviour.

The explanations use standard pharmacology principles. Always check local product information and prescribing guidance for doses, contraindications and monitoring requirements.

Pharmacology practice questions

Question 1 — drug metabolism and interactions

This tests whether you can connect an enzyme interaction with a clinically important change in drug exposure. Answer the question before reading the explanation.

A patient taking warfarin is prescribed trimethoprim–sulfamethoxazole for a urinary tract infection. Five days later, the INR is substantially higher than the patient's previous result. Which explanation is most likely?

The important reasoning is not simply that the INR rose after a new medicine. Sulfamethoxazole can inhibit CYP2C9-mediated warfarin metabolism, while antibiotic effects on gut bacteria may further reduce vitamin K availability. In practice, the patient needs prompt review and INR monitoring rather than an assumption that the interaction is harmless.

Question 2 — receptor pharmacology

This tests the effect of a competitive antagonist on a full agonist dose–response curve.

A reversible competitive antagonist is added to a tissue preparation containing a full agonist. What change is expected?

This distinction is frequently examined because it separates potency from efficacy. The agonist's apparent potency falls, but its efficacy is unchanged. A fall in the maximum response points instead towards an insurmountable antagonist, irreversible binding, or loss of functional receptors.

Question 3 — adverse drug effects

This tests recognition of a characteristic adverse effect and its mechanism.

A patient develops a persistent dry cough several weeks after starting an antihypertensive. Which drug is the most likely cause?

Do not explain this adverse effect as a direct increase in angiotensin II. ACE inhibitors reduce angiotensin II formation and also reduce bradykinin breakdown. If an ACE inhibitor is stopped because of cough, the choice of an alternative depends on the patient's clinical circumstances and local guidance.

Question 4 — pharmacokinetics

This tests the meaning of zero-order elimination.

Which statement best describes a drug eliminated by zero-order kinetics over the relevant concentration range?

Phenytoin is a classic example of capacity-limited elimination over part of its therapeutic range. This is why concentration changes should not be assumed to follow a simple proportional relationship with dose. Always interpret drug concentrations with the dose, timing of sampling, adherence, formulation and clinical response.

Question 5 — antimicrobial pharmacology

This tests a major toxicity associated with an antibiotic class.

Which adverse-effect combination is most characteristic of gentamicin?

The class clue is useful: aminoglycosides bind the bacterial 30S ribosomal subunit and have concentration-dependent antibacterial activity, but their toxicity limits use. Risk is affected by renal function, treatment duration and exposure to other nephrotoxic or ototoxic medicines.

Question 6 — antidotes

This tests whether you can match an anticoagulant with its reversal agent.

A patient has serious bleeding while receiving unfractionated heparin. Which medicine directly neutralises the anticoagulant effect?

An answer that merely says “give an antidote” misses the pharmacological matching step. Keep the pairs separate in revision: unfractionated heparin–protamine, vitamin K antagonists–vitamin K-based reversal strategies, dabigatran–idarucizumab, and factor Xa inhibitor reversal according to the medicine, indication and local guidance.

Question 7 — toxicity and electrolytes

This tests a clinically important factor that increases digoxin toxicity.

Which abnormality increases the risk of digoxin toxicity at a given digoxin concentration?

This is a good example of why a serum concentration is not interpreted in isolation. Renal impairment, interacting medicines and electrolyte abnormalities can change risk even when the measured concentration does not look extreme. Look for gastrointestinal, visual and cardiac features as well as the laboratory result.

Question 8 — glucocorticoids

This tests the mechanism behind a common long-term glucocorticoid safety issue.

Why should long-term systemic prednisolone generally be reduced gradually rather than stopped suddenly?

The need for tapering depends on factors such as dose, duration, treatment pattern and the patient's condition. Do not turn this principle into an automatic schedule: the prescribing clinician should follow the indication and current local guidance, particularly if the patient is acutely unwell.

Question 9 — diabetes medicines

This tests the immediate adverse effect most directly linked to insulin excess.

Which adverse effect is most directly caused by an excessive dose of insulin?

A complete answer links the drug to the physiological change: insulin lowers circulating glucose by increasing uptake and reducing hepatic glucose production. When revising, separate predictable dose-related effects from immunological reactions and from complications of the underlying disease.

Question 10 — folate rescue

This tests the purpose of folinic acid in methotrexate treatment.

What is the main pharmacological rationale for giving folinic acid after methotrexate in situations where rescue is required?

The key distinction is between folic acid supplementation used in some treatment regimens and folinic acid rescue after significant methotrexate exposure or high-dose therapy. Timing, dose and route are clinically important, so follow the relevant protocol rather than applying a memorised generic schedule.

What to do with your errors

Ten questions are enough to expose patterns, but not enough to prove mastery. After marking, group errors by mechanism rather than simply counting the total score. A learner who scores eight out of ten but misses both pharmacokinetics questions needs a different next session from one who misses two antidote questions.

A useful review sequence is:

1. State the drug or class involved.
2. Name the molecular target or physiological process.
3. Predict the main clinical effect.
4. Add the important toxicity, interaction or monitoring point.
5. Re-answer the question without looking at the options.

A question set on this topic can be organised into a board so that mechanisms, adverse effects, kinetics and antidotes are kept separate. A board on this topic ends up looking like this:

The percentage here should be read as performance on the platform's practice work, not as a result from any external examination. The most useful next step is to convert the lowest section into short retrieval questions with one answer each.

When the same mark is lost twice, reduce the error to one precise prompt rather than rereading an entire chapter. For example, do not write “revise anticoagulants”. Write the question that would have prevented the error:

Answer the remediation prompt aloud, then explain why the nearest distractor is wrong. That second step checks whether you understand the distinction or have only memorised a pair of words.

How MySummaries helps

MySummaries can turn your own pharmacology notes, lecture slides and photographed revision pages into a focused board, then generate question drills, spaced-repetition cards and written practice marked against that material. For this task, use the weak areas to decide which section to revise next, and keep missed questions in the remediation tray rather than restarting the whole topic. Start at MySummaries.