A 62-year-old female is prescribed low-molecular-weight heparin (LMWH) for deep vein thrombosis prophylaxis following a total knee arthroplasty. What is the primary mechanism of action of low-molecular-weight heparin?

Potentiation of antithrombin III to selectively inhibit Factor Xa

Direct inhibition of free and clot-bound thrombin (Factor IIa)

Inhibition of vitamin K epoxide reductase

Direct binding and inhibition of Factor Xa without antithrombin III

A 62-year-old man with diabetes and hypertension (BP 158/96 mmHg) is started on ramipril 5 mg daily. Four weeks later he develops a dry persistent cough. The medication is changed to losartan. His colleague asks why ramipril causes cough but losartan does not, despite both blocking the RAAS. What is the mechanism by which ACE inhibitors (but not ARBs) cause cough?

Accumulation of bradykinin and substance P in the bronchial mucosa

Direct bronchospasm from angiotensin II blockade

Potassium retention causing airway smooth muscle contraction

Excess prostaglandin synthesis causing airway sensitisation

A 26-year-old woman with a history of asthma is bleeding after a caesarean delivery. Oxytocin and tranexamic acid have been given. The team is choosing a second-line uterotonic and is considering carboprost. Why should carboprost be avoided in this patient?

It cannot be given to a patient who has had a caesarean delivery

It must be given intravenously, which is unsafe during active bleeding

MCCQE Part I Pharmacology Questions: 10 Free Practice MCQs

Pharmacology questions test prescribing as a clinical act. The MCC objectives expect you to choose a drug for the indication, adjust for renal and hepatic function, and recognise interactions and adverse effects. They also cover therapeutic drug monitoring, antibiotic stewardship and the patient already on several medicines. The question often asks what to do next when a drug is causing harm, not which receptor it acts on.

Where candidates lose marks

Prescribing without checking renal function, pregnancy status or interacting medicines.
Failing to recognise a classic adverse effect such as angioedema with an ACE inhibitor or bleeding with an anticoagulant.
Continuing a drug that has caused harm instead of stopping it and documenting the reaction.
Using a broad spectrum antibiotic where narrow cover is indicated.

Guideline to follow: The MCCQE Part I follows Health Canada approved product monographs, Choosing Wisely Canada recommendations and Canadian antimicrobial stewardship guidance.

Ten MCCQE Part I-style pharmacology questions with the answer and the reasoning behind it. They come from the CA.med bank, which has 12 pharmacology questions and many more across every topic.

Free timed mock exam

1 / 10
A 38-year-old woman with post-traumatic stress disorder has completed a course of trauma-focused cognitive behavioural therapy but continues to have intrusive memories and hyperarousal. She and her physician decide to try medication.
Which medication has good evidence of efficacy for the core symptoms of post-traumatic stress disorder?
Show answer
Answer: C. Paroxetine
Why: Where medication is used for post-traumatic stress disorder, the agents with good evidence for core symptoms are the SSRIs fluoxetine, paroxetine and sertraline, and the SNRI venlafaxine XR. Benzodiazepines are not effective for core symptoms, and early benzodiazepine use after trauma has not been beneficial and may increase the risk of developing the disorder. Divalproex has negative evidence. Combination treatment with an SSRI plus psychotherapy has not consistently proved superior to psychotherapy alone in small trials, so the role of combining treatment requires further study.
- A. Benzodiazepines such as clonazepam have not shown benefit for core symptoms, and early benzodiazepine use after trauma may increase the risk of developing the disorder.
- B. Beta-blocker treatment has not been established for core post-traumatic stress symptoms, and its use to prevent the disorder has shown conflicting results.
- D. This anticonvulsant has not demonstrated efficacy for the core symptoms of post-traumatic stress disorder.
Sources: Canadian clinical practice guidelines for the management of anxiety, posttraumatic stress and obsessive-compulsive disorders
2 / 10
A 33-year-old woman has ongoing postpartum bleeding from a poorly contracted uterus. A nurse asks which route of misoprostol should be used, noting that the ward stock is available only as tablets.
According to the SOGC postpartum haemorrhage guideline, which route of misoprostol should be used for prevention or treatment of postpartum haemorrhage?
Show answer
Answer: D. Sublingual or oral
Why: Guideline No. 431 limits misoprostol to the sublingual and oral routes for both prevention and treatment of postpartum haemorrhage. Pharmacokinetic data show that sublingual administration has the highest bioavailability and a rapid onset, while the rectal route has the lowest bioavailability and a slower onset and is specifically discouraged. Misoprostol is also not an intravenous or intramyometrial agent, which distinguishes it from carboprost. Doses above 400 micrograms are not required, and 200 micrograms may be sufficient.
- A. The rectal route is inferior in both onset and bioavailability and should not be used, so it is not an acceptable alternative here.
- B. Misoprostol is supplied as tablets for mucosal administration and is not given by the intravenous route in this setting.
- C. Injection into the uterine muscle belongs to carboprost, not to misoprostol, which the guideline gives by the mucosal routes.
Sources: SOGC Clinical Practice Guideline No. 431: Postpartum Haemorrhage and Haemorrhagic Shock (2022)
3 / 10
A 62-year-old man with symptomatic intermittent claudication secondary to peripheral arterial disease is reviewed for cardiovascular risk reduction.
Which antiplatelet is first-line for secondary prevention of peripheral arterial disease in this patient?
Show answer
Answer: A. Clopidogrel
Why: Canadian guidelines recommend Clopidogrel 75 mg once daily (or Aspirin 80 mg/day) as secondary prevention in patients with symptomatic peripheral arterial disease (PAD).
- B. Second line if Clopidogrel contraindicated.
- C. Anticoagulant, not routine for PAD.
- D. Rarely used now.
Sources: Canadian Cardiovascular Society (CCS) Guidelines
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4 / 10
A 62-year-old female is prescribed low-molecular-weight heparin (LMWH) for deep vein thrombosis prophylaxis following a total knee arthroplasty.
What is the primary mechanism of action of low-molecular-weight heparin?
Show answer
Answer: B. Potentiation of antithrombin III to selectively inhibit Factor Xa
Why: Low-molecular-weight heparin (LMWH) works by binding to antithrombin III, causing a conformational change that increases antithrombin's ability to selectively inactivate Factor Xa. Unlike unfractionated heparin, LMWH has a lesser effect on thrombin (Factor IIa) because of its shorter polysaccharide chain.
- A. This is the mechanism of direct thrombin inhibitors such as dabigatran or argatroban.
- C. This is the mechanism of action of warfarin, which decreases synthesis of Factors II, VII, IX, and X.
- D. This is the mechanism of direct oral anticoagulants (DOACs) such as rivaroxaban and apixaban.
Sources: Thrombosis Canada Guidelines / AMH
5 / 10
A 62-year-old man with diabetes and hypertension (BP 158/96 mmHg) is started on ramipril 5 mg daily. Four weeks later he develops a dry persistent cough. The medication is changed to losartan. His colleague asks why ramipril causes cough but losartan does not, despite both blocking the RAAS.
What is the mechanism by which ACE inhibitors (but not ARBs) cause cough?
Show answer
Answer: A. Accumulation of bradykinin and substance P in the bronchial mucosa
Why: ACE inhibitor cough occurs in 10-20% of patients (higher prevalence in East Asian patients, up to 40%). Mechanism: ACE inhibits angiotensin I→II conversion AND degrades bradykinin; inhibition of ACE leads to bradykinin and substance P accumulation → cough hypersensitivity via tracheo-bronchial C-fibres. Treatment: switch to ARB (e.g. losartan, valsartan), same RAAS benefit without cough. ACE-inhibitor cough is not a contraindication to ARBs.
- B. ARBs also block angiotensin II effects (at the AT1 receptor) but do NOT cause cough, ruling out angiotensin II-mediated bronchospasm as the mechanism.
- C. Both ACE inhibitors and ARBs can cause hyperkalaemia (via RAAS inhibition), but potassium retention does not cause cough through airway smooth muscle mechanisms.
- D. While bradykinin stimulates prostaglandin synthesis as a downstream effect, the primary and direct mechanism of ACE-inhibitor cough is bradykinin accumulation itself, not prostaglandin excess. NSAIDs (which block prostaglandin synthesis) do not reliably eliminate ACE-inhibitor cough.
Sources: Pharmacology: Goodman & Gilman's The Pharmacological Basis of Therapeutics; CPS (Canadian Pharmacists Association), Ramipril monograph
6 / 10
A 45-year-old woman is diagnosed with Graves' disease. She is started on Carbimazole.
What is the most serious side effect she needs to be urgently warned about?
Show answer
Answer: D. Agranulocytosis
Why: Carbimazole can cause agranulocytosis (neutropenia). Patients must be educated to seek medical attention if they develop symptoms of infection like sore throat or fever.
- A. Weight gain may occur as metabolism normalises, but it is not an emergency.
- B. Palpitations are a symptom of the disease, not a side effect of Carbimazole.
- C. Alopecia can occur but is not life-threatening.
Sources: CPS / Canadian Drug Guide Carbimazole
7 / 10
A 26-year-old woman with a history of asthma is bleeding after a caesarean delivery. Oxytocin and tranexamic acid have been given. The team is choosing a second-line uterotonic and is considering carboprost.
Why should carboprost be avoided in this patient?
Show answer
Answer: C. It can cause bronchospasm
Why: Guideline No. 431 notes that carboprost, a prostaglandin F2 alpha, causes contractions of myometrial and intestinal smooth muscle and can be given intramuscularly or intramyometrially but not intravenously. Because it is an F class prostaglandin it can provoke bronchospasm and should not be used in patients with asthma, which is why it is unsuitable for this patient. Its common gastrointestinal effects, including diarrhoea, are managed by giving loperamide alongside it. It is not contraindicated by a previous caesarean delivery.
- A. Carboprost is used for postpartum haemorrhage after either caesarean or vaginal delivery, so the mode of delivery is not the concern here.
- B. Carboprost is given by intramuscular or intramyometrial injection and cannot be given intravenously, which is the reverse of this statement.
- D. Diarrhoea is the notable adverse effect that loperamide is given to counter; potassium disturbance is not the reason to avoid the drug.
Sources: SOGC Clinical Practice Guideline No. 431: Postpartum Haemorrhage and Haemorrhagic Shock (2022)
8 / 10
A 60-year-old male with heart failure with reduced ejection fraction (HFrEF) remains breathless despite optimal therapy with Ramipril, Bisoprolol, and Spironolactone.
According to the Canadian Cardiovascular Society (CCS) Heart Failure guidelines, what is the next most appropriate pharmacological step?
Show answer
Answer: A. Sacubitril-Valsartan
Why: The Canadian Cardiovascular Society (CCS) guidelines recommend replacing an ACE inhibitor or ARB with an Angiotensin Receptor-Neprilysin Inhibitor (ARNI) such as Sacubitril-Valsartan (Entresto) in patients with symptomatic HFrEF (LVEF <= 40%) who remain symptomatic despite optimal medical therapy.
- B. Used for symptom control, not first-line prognosis improvement.
- C. Symptom control only.
- D. Contraindicated in HFrEF.
Sources: CCS Heart Failure Guidelines
9 / 10
A 30-year-old patient diagnosed with Major Depressive Disorder is initiated on sertraline 50 mg daily following CANMAT clinical practice guidelines.
What is the typical time frame for therapeutic effect?
Show answer
Answer: B. 2-4 weeks
Why: According to CANMAT guidelines, patients initiating SSRI antidepressant therapy like sertraline must be educated that clinical onset of antidepressant response requires 2 to 4 weeks, with full trial assessment at 6 to 8 weeks. Option A (2-4 days) and Option D (immediately) are pharmacologically impossible due to neuroreceptor adaptation lag; Option C (3 months) represents an inappropriately long wait before assessing response.
- A. Too soon.
- C. Too long.
- D. Placebo effect maybe, but not pharmacological.
Sources: CANMAT Clinical Guidelines for the Management of Major Depressive Disorder
10 / 10
A 31-year-old man is diagnosed with panic disorder. He has two or three unexpected panic attacks each week. He has no other medical or psychiatric conditions and takes no other medication.
Which is a recommended first-line pharmacotherapy for his panic disorder?
Show answer
Answer: A. Sertraline
Why: First-line pharmacotherapy for panic disorder includes the SSRIs citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, paroxetine CR and sertraline, and the SNRI venlafaxine XR. Cognitive behavioural therapy, alone or combined with pharmacotherapy, is also a first-line treatment. If response to an optimal dose of a first-line agent is inadequate, or the agent is not tolerated, treatment should be switched to another first-line agent before second-line options such as the tricyclics, mirtazapine, reboxetine or benzodiazepines are considered. Buspirone, propranolol, tiagabine and trazodone are not recommended for panic disorder.
- B. This agent has not shown efficacy in panic disorder and is listed among the treatments that are not recommended.
- C. This benzodiazepine is effective but is a second-line option, reserved largely for short-term use or early treatment while an antidepressant takes effect, because of the risk of dependence.
- D. Beta-blockade has not demonstrated efficacy for panic disorder and is not recommended.
Sources: Canadian clinical practice guidelines for the management of anxiety, posttraumatic stress and obsessive-compulsive disorders

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MCCQE Part I Pharmacology Questions: 10 Free Practice MCQs

Where candidates lose marks

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