A 70-year-old man with non-valvular atrial fibrillation on apixaban has an NSTEMI and receives a drug-eluting stent. His bleeding risk is moderate. Which long-term antithrombotic regimen is recommended after the first week?

Warfarin, aspirin and clopidogrel

Apixaban, aspirin and ticagrelor

Aspirin plus ticagrelor, stopping apixaban

A 54-year-old man had a drug-eluting stent placed for an NSTEMI and was discharged on aspirin and clopidogrel. Three months later he has stent thrombosis despite taking his tablets regularly. Genotyping shows he is homozygous for a loss-of-function CYP2C19 allele. What is the best change in his antiplatelet therapy?

Replace clopidogrel with ticagrelor

Replace clopidogrel with dipyridamole

Replace aspirin with cilostazol

Antiarrhythmics, anticoagulants and antiplatelets

23 NEET-PG practice questions on Antiarrhythmics, anticoagulants and antiplatelets, part of Pharmacology. The first 23 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Medium
A 72-year-old woman on dabigatran for atrial fibrillation falls at home. CT shows an acute subdural haematoma, and the neurosurgeon plans evacuation. Which agent specifically reverses her anticoagulant?
1. AIdarucizumab
2. BPhytomenadione (vitamin K)
3. CAndexanet alfa
4. DProtamine sulfate
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Answer: A · Idarucizumab
Dabigatran is a direct thrombin inhibitor. Idarucizumab is a humanised monoclonal antibody fragment that binds dabigatran with very high affinity and neutralises it within minutes, allowing urgent surgery. Where it is not available, prothrombin complex concentrate is used, and dabigatran can also be removed by haemodialysis. Andexanet alfa is the matching antidote for the factor Xa inhibitors rivaroxaban and apixaban.
- B: Vitamin K reverses warfarin; dabigatran does not act on vitamin K-dependent factors.
- C: Andexanet alfa reverses factor Xa inhibitors, not dabigatran.
- D: Protamine neutralises heparin and does not bind dabigatran.
Question 2 · Hard
A 68-year-old woman is on day 5 of fondaparinux for a DVT after a hip fracture. She develops a large rectus sheath haematoma. The surgical resident reviews four statements: 1. Protamine fully neutralises unfractionated heparin. 2. Protamine fully neutralises fondaparinux. 3. Heparin-induced thrombocytopenia is less common with LMWH than with unfractionated heparin. 4. Fondaparinux inhibits factor Xa through antithrombin, with no direct effect on thrombin. Which statements are correct?
1. A3 and 4 only
2. B1 and 2 only
3. C1, 3 and 4 only
4. D1 and 4 only
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Answer: C · 1, 3 and 4 only
Statements 1, 3 and 4 are correct. Protamine binds the long, highly charged chains of unfractionated heparin and neutralises it fully, but it binds the short chains of LMWH only partly and does not bind fondaparinux, a synthetic pentasaccharide, at all. Fondaparinux carries only the antithrombin-binding pentasaccharide, too short to bridge antithrombin and thrombin, so it acts on factor Xa alone. HIT is less common with LMWH, and fondaparinux rarely causes it. Bleeding on fondaparinux is managed with supportive care and, if life-threatening, prothrombin complex concentrate or recombinant factor VIIa, because no specific antidote is in routine use.
- A: Omits statement 1; protamine does fully neutralise unfractionated heparin.
- B: Includes the false statement 2 and omits statements 3 and 4.
- D: Omits statement 3; HIT is less common with LMWH than with unfractionated heparin.
Question 3 · Hard
A 70-year-old man with non-valvular atrial fibrillation on apixaban has an NSTEMI and receives a drug-eluting stent. His bleeding risk is moderate. Which long-term antithrombotic regimen is recommended after the first week?
1. AWarfarin, aspirin and clopidogrel
2. BApixaban plus clopidogrel
3. CApixaban, aspirin and ticagrelor
4. DAspirin plus ticagrelor, stopping apixaban
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Answer: B · Apixaban plus clopidogrel
Patients with AF who need PCI need an anticoagulant to prevent stroke and a P2Y12 inhibitor to prevent stent thrombosis. Triple therapy with aspirin roughly doubles bleeding, so current guidance limits aspirin to the peri-PCI period (usually up to a week) and then continues a DOAC with clopidogrel, usually for up to 12 months, followed by the DOAC alone. Clopidogrel is preferred over ticagrelor or prasugrel in combination with an anticoagulant because it causes less bleeding. Dual antiplatelet therapy without an anticoagulant does not protect against stroke from AF.
- A: Warfarin-based triple therapy bleeds more than a DOAC with clopidogrel.
- C: Long-term triple therapy with ticagrelor carries a high bleeding risk.
- D: Dual antiplatelet therapy does not prevent cardioembolic stroke in AF.
Question 4 · Medium
A 54-year-old man had a drug-eluting stent placed for an NSTEMI and was discharged on aspirin and clopidogrel. Three months later he has stent thrombosis despite taking his tablets regularly. Genotyping shows he is homozygous for a loss-of-function CYP2C19 allele. What is the best change in his antiplatelet therapy?
1. AReplace clopidogrel with ticagrelor
2. BDouble the dose of clopidogrel
3. CReplace clopidogrel with dipyridamole
4. DReplace aspirin with cilostazol
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Answer: A · Replace clopidogrel with ticagrelor
Clopidogrel is a prodrug that needs two oxidation steps in the liver, mainly by CYP2C19, to form the active thiol that irreversibly blocks the platelet P2Y12 receptor. Poor metabolisers make little active drug and have more stent thrombosis. Ticagrelor acts directly and reversibly on P2Y12 without activation, and prasugrel is activated by other enzymes, so either is effective in these patients. Higher clopidogrel doses do not reliably overcome the poor-metaboliser state.
- B: Doubling the dose does not reliably restore platelet inhibition in poor metabolisers.
- C: Dipyridamole is a weak antiplatelet and is not used after coronary stenting.
- D: Cilostazol does not replace P2Y12 inhibition after stenting.
Question 5 · Medium
A 65-year-old woman with heart failure takes sotalol for atrial fibrillation and furosemide. She is brought to casualty after brief blackouts. Serum potassium is 2.8 mmol/L. The monitor shows runs of polymorphic ventricular tachycardia in which the QRS axis twists around the baseline; between runs the QTc is 590 ms. She has a pulse and BP 108/70 mmHg. Which drug should be given first?
1. AIV magnesium sulfate
2. BIV amiodarone
3. CIV procainamide
4. DIV adenosine
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Answer: A · IV magnesium sulfate
This is torsades de pointes caused by QT prolongation from sotalol (a class III drug with beta-blocking action), made worse by diuretic-induced hypokalaemia. IV magnesium sulfate is the first-line treatment even if serum magnesium is normal; it suppresses the early afterdepolarisations that trigger the rhythm. Potassium is corrected to the high-normal range, sotalol is stopped, and isoprenaline or temporary pacing to raise the heart rate is used if torsades recurs. Pulseless torsades needs defibrillation.
- B: Amiodarone also prolongs the QT and can perpetuate torsades.
- C: Procainamide is a class Ia drug that prolongs the QT.
- D: Adenosine has no role in ventricular tachycardia of this kind.
Question 6 · Medium
A 66-year-old man on warfarin for atrial fibrillation has had a stable INR of 2.4. He is given fluconazole for 10 days for oesophageal candidiasis. He now has gum bleeding and bruises, and his INR is 6.8. How did fluconazole raise his INR?
1. ADisplacement of vitamin K from its reductase
2. BDirect inhibition of factor Xa
3. CInhibition of CYP2C9 metabolism of S-warfarin
4. DDestruction of gut flora that make vitamin K
Answer and explanation in LearnFree account
Question 7 · Medium
A 59-year-old woman was started on aspirin and ticagrelor after an NSTEMI two weeks ago. She reports mild breathlessness at rest, which comes and goes. Her lungs are clear, SpO2 is 98%, echo shows a normal ejection fraction, and haemoglobin and chest X-ray are normal. What is the most likely cause of her breathlessness?
1. APulmonary embolism
2. BEarly left ventricular failure
3. CBronchospasm from aspirin
4. DAn adverse effect of ticagrelor
Answer and explanation in LearnFree account
Question 8 · Easy
A 70-year-old man has taken amiodarone 200 mg daily for 3 years for recurrent ventricular tachycardia. He now has 2 months of dry cough and breathlessness on exertion. There are bilateral fine end-inspiratory crackles, and HRCT shows bilateral reticular opacities. What is the most likely cause?
1. APulmonary tuberculosis
2. BBronchial asthma
3. CLeft ventricular failure
4. DAmiodarone pulmonary toxicity
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Question 9 · Medium
A 74-year-old man on apixaban for atrial fibrillation is brought to a tertiary hospital with a sudden headache and right hemiparesis. CT shows an intracerebral haemorrhage, and his last dose was 4 hours ago. Which agent specifically reverses his anticoagulant?
1. AAndexanet alfa
2. BIdarucizumab
3. CVitamin K1
4. DProtamine sulfate
Answer and explanation in LearnFree account
Question 10 · Easy
A 56-year-old man in the CCU on day 2 after an anterior MI has runs of sustained monomorphic ventricular tachycardia. He is given IV lignocaine (lidocaine), which binds sodium channels mainly in depolarised, ischaemic tissue and dissociates quickly. To which Vaughan Williams class does it belong?
1. AClass Ic
2. BClass III
3. CClass Ia
4. DClass Ib
Answer and explanation in LearnFree account
Question 11 · Hard
A 26-year-old man has sudden palpitations. In casualty he is alert with BP 116/76 mmHg. The ECG shows an irregularly irregular tachycardia at about 230/min with QRS complexes of varying width; an old ECG shows a short PR interval and a slurred upstroke of the QRS. Which drug is most appropriate?
1. AIV procainamide
2. BIV adenosine
3. CIV verapamil
4. DIV metoprolol
Answer and explanation in LearnFree account
Question 12 · Medium
An 11-year-old boy with nephrotic syndrome (urine protein 4+, serum albumin 1.8 g/dL) develops a pulmonary embolism. On IV unfractionated heparin at high doses for 36 hours, his aPTT stays near the control value. What is the most likely reason for the poor response?
1. AAntibodies against heparin-platelet factor 4
2. BRapid renal excretion of heparin
3. CExcess vitamin K in the diet
4. DUrinary loss of antithrombin
Answer and explanation in LearnFree account
Question 13 · Easy
A 58-year-old man has just come off cardiopulmonary bypass after coronary artery bypass grafting. He received a large dose of unfractionated heparin for the bypass. Which drug is given to neutralise the heparin?
1. ATranexamic acid
2. BProtamine sulfate
3. CFresh frozen plasma
4. DVitamin K1
Answer and explanation in LearnFree account
Question 14 · Hard
A 68-year-old woman with hypertension and type 2 diabetes is found to have atrial fibrillation in a Jaipur OPD. She has no heart failure, previous stroke or vascular disease, and echo shows no mitral stenosis or prosthetic valve. Creatinine clearance is 70 mL/min and she has no bleeding history. What is the best antithrombotic plan?
1. AAspirin plus clopidogrel
2. BNo antithrombotic therapy
3. CAspirin alone
4. DApixaban
Answer and explanation in LearnFree account
Question 15 · Medium
A 46-year-old woman on combined oral contraceptives is brought to casualty with sudden breathlessness and syncope. Pulse is 128/min, BP 78/50 mmHg despite fluids, and SpO2 86%. Bedside echo shows a dilated, hypokinetic right ventricle, and CT pulmonary angiography shows bilateral main pulmonary artery clots. She has no bleeding risk factors. What is the best next step?
1. ASystemic thrombolysis with alteplase
2. BOral rivaroxaban alone
3. CSubcutaneous enoxaparin alone
4. DInsertion of an IVC filter
Answer and explanation in LearnFree account
Question 16 · Medium
During a CME at a district hospital, the physician discusses thrombolytics used in STEMI and lists four statements: 1. Tenecteplase is more fibrin-specific than streptokinase. 2. Streptokinase is antigenic and can cause allergic reactions and hypotension. 3. Tenecteplase is given as a single IV bolus. 4. Streptokinase cleaves fibrin directly without needing plasminogen. Which statements are correct?
1. A2 and 3 only
2. B1, 2 and 3 only
3. C1 and 3 only
4. D1 and 2 only
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Question 17 · Easy
A 60-year-old woman takes low-dose aspirin after a TIA. Her platelet function remains impaired for about a week after she stops it, even though aspirin has a plasma half-life of only about 20 minutes. Why does the effect last so long?
1. AIts active metabolite has a long half-life
2. BIt irreversibly acetylates platelet COX-1
3. CIt is stored in platelet dense granules
4. DIt competitively blocks thromboxane receptors
Answer and explanation in LearnFree account
Question 18 · Easy
A 24-year-old nursing student has sudden palpitations in the hostel. In casualty her pulse is 188/min and regular, BP 112/74 mmHg, and ECG shows a narrow-complex regular tachycardia without visible P waves. A modified Valsalva manoeuvre has not ended it. She has no asthma. What is the drug of choice now?
1. AIV digoxin
2. BIV adenosine as a rapid bolus
3. COral metoprolol
4. DIV amiodarone infusion
Answer and explanation in LearnFree account
Question 19 · Hard
A 64-year-old man with non-valvular atrial fibrillation takes apixaban 5 mg twice daily. His creatinine clearance is 85 mL/min. He is scheduled for an elective total knee replacement under spinal anaesthesia, a procedure with high bleeding risk. How should his apixaban be managed before surgery?
1. AContinue it without interruption
2. BStop it 12 hours before surgery
3. CStop it 2 days before surgery without heparin bridging
4. DStop it 5 days before and bridge with enoxaparin
Answer and explanation in LearnFree account
Question 20 · Medium
A 45-year-old woman weighing 138 kg is treated with weight-adjusted enoxaparin for a proximal DVT. She also has CKD with a creatinine clearance of 28 mL/min. The physician wants to check whether her dose is right. Which test should be used?
1. ABleeding time
2. BAnti-factor Xa activity
3. CProthrombin time with INR
4. DActivated partial thromboplastin time
Answer and explanation in LearnFree account
Question 21 · Medium
A 38-year-old woman with a mechanical aortic valve has had a stable INR of 2.5-3.0 on warfarin 5 mg daily. Six weeks after she starts daily isoniazid, rifampicin, pyrazinamide and ethambutol for pulmonary TB under NTEP, her INR is 1.3. What explains the change?
1. AIsoniazid inhibition of vitamin K absorption
2. BEthambutol reduction of warfarin absorption
3. CRifampicin induction of CYP2C9 and other liver enzymes
4. DPyrazinamide displacement of warfarin from albumin
Answer and explanation in LearnFree account
Question 22 · Medium
A 62-year-old man had an anterior MI two years ago; echo shows an ejection fraction of 30%. He now has symptomatic paroxysmal atrial fibrillation despite bisoprolol, and the cardiologist wants a drug to maintain sinus rhythm. Which drug is most appropriate?
1. APropafenone
2. BAmiodarone
3. CFlecainide
4. DDisopyramide
Answer and explanation in LearnFree account
Question 23 · Medium
A 79-year-old woman weighing 48 kg has non-valvular atrial fibrillation. Her serum creatinine is 2.1 mg/dL and her calculated creatinine clearance is 18 mL/min. Which oral anticoagulant depends most on the kidney for its elimination and should be avoided?
1. ADabigatran
2. BApixaban
3. CRivaroxaban
4. DWarfarin
Answer and explanation in LearnFree account

Antiarrhythmics, anticoagulants and antiplatelets

A 72-year-old woman on dabigatran for atrial fibrillation falls at home. CT shows an acute subdural haematoma, and the neurosurgeon plans evacuation. Which agent specifically reverses her anticoagulant?

A 70-year-old man with non-valvular atrial fibrillation on apixaban has an NSTEMI and receives a drug-eluting stent. His bleeding risk is moderate. Which long-term antithrombotic regimen is recommended after the first week?

A 66-year-old man on warfarin for atrial fibrillation has had a stable INR of 2.4. He is given fluconazole for 10 days for oesophageal candidiasis. He now has gum bleeding and bruises, and his INR is 6.8. How did fluconazole raise his INR?

A 70-year-old man has taken amiodarone 200 mg daily for 3 years for recurrent ventricular tachycardia. He now has 2 months of dry cough and breathlessness on exertion. There are bilateral fine end-inspiratory crackles, and HRCT shows bilateral reticular opacities. What is the most likely cause?

A 74-year-old man on apixaban for atrial fibrillation is brought to a tertiary hospital with a sudden headache and right hemiparesis. CT shows an intracerebral haemorrhage, and his last dose was 4 hours ago. Which agent specifically reverses his anticoagulant?

A 56-year-old man in the CCU on day 2 after an anterior MI has runs of sustained monomorphic ventricular tachycardia. He is given IV lignocaine (lidocaine), which binds sodium channels mainly in depolarised, ischaemic tissue and dissociates quickly. To which Vaughan Williams class does it belong?

A 26-year-old man has sudden palpitations. In casualty he is alert with BP 116/76 mmHg. The ECG shows an irregularly irregular tachycardia at about 230/min with QRS complexes of varying width; an old ECG shows a short PR interval and a slurred upstroke of the QRS. Which drug is most appropriate?

An 11-year-old boy with nephrotic syndrome (urine protein 4+, serum albumin 1.8 g/dL) develops a pulmonary embolism. On IV unfractionated heparin at high doses for 36 hours, his aPTT stays near the control value. What is the most likely reason for the poor response?

A 58-year-old man has just come off cardiopulmonary bypass after coronary artery bypass grafting. He received a large dose of unfractionated heparin for the bypass. Which drug is given to neutralise the heparin?

A 60-year-old woman takes low-dose aspirin after a TIA. Her platelet function remains impaired for about a week after she stops it, even though aspirin has a plasma half-life of only about 20 minutes. Why does the effect last so long?

A 64-year-old man with non-valvular atrial fibrillation takes apixaban 5 mg twice daily. His creatinine clearance is 85 mL/min. He is scheduled for an elective total knee replacement under spinal anaesthesia, a procedure with high bleeding risk. How should his apixaban be managed before surgery?

A 45-year-old woman weighing 138 kg is treated with weight-adjusted enoxaparin for a proximal DVT. She also has CKD with a creatinine clearance of 28 mL/min. The physician wants to check whether her dose is right. Which test should be used?

A 38-year-old woman with a mechanical aortic valve has had a stable INR of 2.5-3.0 on warfarin 5 mg daily. Six weeks after she starts daily isoniazid, rifampicin, pyrazinamide and ethambutol for pulmonary TB under NTEP, her INR is 1.3. What explains the change?

A 62-year-old man had an anterior MI two years ago; echo shows an ejection fraction of 30%. He now has symptomatic paroxysmal atrial fibrillation despite bisoprolol, and the cardiologist wants a drug to maintain sinus rhythm. Which drug is most appropriate?

A 79-year-old woman weighing 48 kg has non-valvular atrial fibrillation. Her serum creatinine is 2.1 mg/dL and her calculated creatinine clearance is 18 mL/min. Which oral anticoagulant depends most on the kidney for its elimination and should be avoided?