Anticoagulants, Antiplatelets and Thrombolytics MCQs

Pharmacology · 93 free questions with answers & explanations.

1. A patient on warfarin for atrial fibrillation starts ciprofloxacin for a urinary tract infection. Five days later, INR is 6.2. The most important mechanism for this drug interaction is:
2. Ticagrelor (P2Y12 antagonist) has faster offset of antiplatelet activity than clopidogrel, making it preferable when urgent surgery is anticipated. This pharmacological difference is because:
3. A patient on warfarin for atrial fibrillation (INR 2.4) requires urgent elective surgery. The surgery will be performed in 48 hours. The most appropriate management is:
4. Fondaparinux is a synthetic pentasaccharide anticoagulant. Its mechanism differs from unfractionated heparin in that:
5. A 60-year-old man undergoes drug-eluting coronary stent placement and is started on dual antiplatelet therapy (aspirin + clopidogrel). He is also on a PPI. Which PPI interaction is most clinically significant with clopidogrel?
6. A patient with atrial fibrillation and CKD stage 4 (eGFR 22 mL/min) requires anticoagulation. Which DOAC is safest and why?
7. Ticagrelor differs from clopidogrel in reversibility and onset. Which pharmacological property of ticagrelor explains its faster offset and reversal compared to clopidogrel?
8. Heparin-induced thrombocytopenia type II (HIT-II) is a prothrombotic disorder, NOT primarily a haemorrhagic complication. The pathogenesis is:
9. A patient with acute coronary syndrome is loaded with ticagrelor rather than clopidogrel. A key pharmacological advantage of ticagrelor over clopidogrel relevant to CYP2C19 polymorphism is:
10. Ticagrelor differs from clopidogrel in its antiplatelet mechanism in which MOST clinically important way?
11. Protamine sulphate reverses unfractionated heparin (UFH) but only PARTIALLY reverses low molecular weight heparin (LMWH). The molecular reason is:
12. Andexanet alfa is used to reverse which anticoagulants, and what is its mechanism?
13. Ticagrelor, unlike clopidogrel, does not require metabolic activation. Beyond this, which pharmacological property of ticagrelor is responsible for its adverse effect of dyspnoea not seen with clopidogrel?
14. Andexanet alfa is a specific reversal agent for Factor Xa inhibitors (rivaroxaban, apixaban). Its mechanism of action differs from idarucizumab (dabigatran reversal) because andexanet alfa acts as:
15. Heparin-induced thrombocytopenia (HIT) type II is an immune-mediated disorder. The autoantibodies formed target which neoantigen?
16. Heparin-induced thrombocytopaenia (HIT) is a life-threatening complication. The pathophysiological mechanism of HIT type II involves:
17. Ticagrelor differs from clopidogrel and prasugrel in two important properties. Which best describes these differences?
18. A patient is brought in with acute ischaemic stroke. tPA (alteplase) is considered. Which property of alteplase compared to streptokinase makes it preferred in acute stroke?
19. A patient with non-valvular AF on rivaroxaban requires urgent surgery within 8 hours. Which reversal agent specifically targets rivaroxaban and apixaban?
20. Ticagrelor's pharmacological profile differs from clopidogrel not only in reversibility but also in an additional mechanism that contributes to its mortality benefit in ACS. Ticagrelor:
21. Andexanet alfa reverses apixaban and rivaroxaban anticoagulation. How does it differ mechanistically from idarucizumab (used for dabigatran reversal)?
22. Patients with the CYP2C19*2 poor metabolizer genotype have reduced clopidogrel response (clopidogrel resistance). The FDA now mandates genotype testing before initiation. Which statement best describes the clinical management implication?
23. A patient on warfarin for atrial fibrillation has a CYP2C9*2/*3 genotype and VKORC1 -1639A/A genotype. Compared to a patient with wild-type alleles, this patient would require:
24. Clopidogrel is a prodrug requiring CYP2C19 activation to its active thiol metabolite. A patient who is a CYP2C19 poor metabolizer (e.g., carrying two loss-of-function alleles *2/*2) would best be switched to which antiplatelet agent that does NOT require hepatic bioactivation?
25. Fondaparinux is a synthetic pentasaccharide anticoagulant. Unlike unfractionated heparin, it cannot be reversed by protamine. What structural-functional reason explains protamine's inability to neutralize fondaparinux?
26. A patient with atrial fibrillation and a mechanical heart valve asks about switching from warfarin to apixaban. The cardiologist advises against this because DOACs fail in mechanical valves primarily due to:
27. Ticagrelor has a faster onset and more consistent platelet inhibition than clopidogrel because:
28. Fondaparinux is the preferred anticoagulant in heparin-induced thrombocytopenia (HIT) because:
29. Idarucizumab is used to reverse dabigatran anticoagulation in emergencies. Its mechanism compared to andexanet alfa (which reverses factor Xa inhibitors) is:
30. Clopidogrel requires bioactivation to its thienopyridine-active metabolite. A patient homozygous for the CYP2C19*2 loss-of-function allele is started on clopidogrel after coronary stent placement. The clinical implication is:
31. Ticagrelor is preferred over clopidogrel in acute coronary syndrome based on PLATO trial data. The mechanistic superiority of ticagrelor involves which property?
32. Andexanet alfa is approved for reversal of which anticoagulants, and what is its mechanism of reversal?
33. Rivaroxaban and apixaban are direct oral anticoagulants (DOACs) targeting Factor Xa. A major clinical advantage over warfarin is their predictable pharmacokinetics. Which specific pharmacological property most contributes to their predictability?
34. Idarucizumab is the specific reversal agent for dabigatran. Its mechanism differs fundamentally from protamine reversal of heparin. What is idarucizumab's mechanism?
35. A patient on warfarin has a supratherapeutic INR of 9.0 with no active bleeding. The most appropriate immediate management is:
36. Idarucizumab is used to reverse dabigatran anticoagulation. Its mechanism of action is:
37. Ticagrelor differs from clopidogrel in platelet inhibition primarily because ticagrelor:
38. Heparin-induced thrombocytopenia type II (HIT type II) is caused by antibodies against platelet factor 4 (PF4)-heparin complex. The resulting thrombocytopenia and paradoxical thrombosis occur because:
39. A patient on dabigatran presents with life-threatening intracranial haemorrhage. Idarucizumab is administered. Its reversal mechanism involves:
40. Ticagrelor's pharmacological advantage over clopidogrel includes all EXCEPT:
41. A patient on warfarin for atrial fibrillation (INR 2.8) is started on fluconazole for oral candidiasis. After 5 days, INR rises to 7.2 with minor gingival bleeding. The most appropriate management is:
42. Fondaparinux, unlike unfractionated heparin and LMWH, does NOT cause heparin-induced thrombocytopenia (HIT) because:
43. Ticagrelor differs from clopidogrel in which clinically important way?
44. A patient is started on warfarin. During the first 48–72 hours, there is a transient PRO-thrombotic state before anticoagulation is achieved. This is because:
45. Clopidogrel is a prodrug requiring biotransformation to its active metabolite. Which enzyme system converts clopidogrel to its active thiol metabolite?
46. Dabigatran is a direct oral anticoagulant (DOAC) that directly inhibits thrombin. Which feature makes it unique among DOACs compared to rivaroxaban and apixaban?
47. Heparin-induced thrombocytopenia (HIT) type II is paradoxically associated with thrombosis rather than bleeding. The antibody involved targets:
48. Clopidogrel is a prodrug requiring CYP2C19 activation. A patient on clopidogrel and omeprazole post-coronary stent placement has a recurrent NSTEMI. The most pharmacokinetically appropriate explanation is:
49. Heparin-induced thrombocytopenia type II (HIT-II) is a prothrombotic disorder. The pathophysiological mechanism is:
50. Direct oral anticoagulants (DOACs) have largely replaced warfarin for NVAF. Regarding dabigatran, which statement is CORRECT?
51. Clopidogrel is a prodrug requiring hepatic conversion. Which enzyme is primarily responsible for its activation, and what is the pharmacological consequence in CYP2C19 poor metabolisers?
52. Dabigatran (a direct thrombin inhibitor) differs from warfarin in that it:
53. Ticagrelor is preferred over clopidogrel in STEMI for which pharmacokinetic/pharmacodynamic reason?
54. A patient with heparin-induced thrombocytopenia (HIT) requires anticoagulation for DVT. The drug of choice is argatroban. Its mechanism is:
55. Dabigatran requires dose reduction in elderly patients primarily because it is eliminated differently from other novel oral anticoagulants. The reason is:
56. A 65-year-old patient with an anterior STEMI receives tenecteplase. Unlike streptokinase, tenecteplase is preferred because it:
57. A 72-year-old man with non-valvular atrial fibrillation is started on apixaban. Unlike warfarin, apixaban has a predictable pharmacokinetic profile. Which characteristic is most responsible for its predictable anticoagulation without routine monitoring?
58. A patient post-coronary stent placement is on dual antiplatelet therapy with aspirin and ticagrelor. Ticagrelor is preferred over clopidogrel in acute coronary syndrome because ticagrelor:
59. Idarucizumab reverses dabigatran anticoagulation. Its mechanism of action is:
60. Fondaparinux is a synthetic pentasaccharide with anticoagulant properties. It exerts anticoagulant activity exclusively by:
61. Cangrelor is a P2Y12 receptor antagonist with a specific clinical niche over oral P2Y12 inhibitors like ticagrelor. Its key advantage is:
62. A patient on warfarin has INR 6.0 but no active bleeding. What is the most appropriate immediate management?
63. Apixaban, a direct oral anticoagulant (DOAC), differs from warfarin in which of the following pharmacological properties?
64. Clopidogrel is a prodrug requiring hepatic bioactivation. Its mechanism of antiplatelet action once activated is:
65. Heparin-induced thrombocytopenia type II (HIT-II) is a prothrombotic complication of heparin therapy. The pathogenesis involves:
66. Rivaroxaban is a direct oral anticoagulant (DOAC). Which feature of its pharmacokinetics distinguishes it from apixaban with respect to renal elimination?
67. A patient with acute STEMI receives tenecteplase (TNK-tPA) instead of alteplase. What property of tenecteplase makes it suitable for bolus administration, unlike alteplase?
68. A patient on warfarin for DVT prophylaxis has an INR of 8.5 with minor bleeding (nosebleed). The appropriate management is:
69. Clopidogrel is a prodrug requiring activation. Which enzyme is primarily responsible for its conversion to the active thiol metabolite?
70. A 68-year-old woman with AF on rivaroxaban (DOAC) requires emergency reversal for life-threatening intracranial hemorrhage. The CORRECT reversal agent is:
71. Dabigatran etexilate is a direct oral anticoagulant (DOAC). What differentiates dabigatran's reversal agent idarucizumab from the reversal agent andexanet alfa used for factor Xa inhibitors?
72. A patient requires reversal of heparin after cardiac surgery. Protamine sulfate is given intravenously. Which property of protamine enables it to neutralise heparin?
73. Dabigatran is a direct oral anticoagulant (DOAC) that directly inhibits thrombin. Its specific reversal agent approved for life-threatening bleeding is:
74. Heparin-induced thrombocytopenia type II (HIT) is characterised by thrombocytopenia plus paradoxical thrombosis. The immunological mechanism is:
75. Ticagrelor differs from clopidogrel in that it does NOT require metabolic activation and is reversible. It acts by:
76. A patient on warfarin requires urgent surgery. Which agent most rapidly reverses warfarin-induced coagulopathy?
77. Clopidogrel is a prodrug requiring CYP2C19 activation. A patient with CYP2C19 poor metabolizer genotype (e.g., carries two loss-of-function alleles) would be BEST switched to which alternative antiplatelet?
78. Fondaparinux, a synthetic pentasaccharide anticoagulant, exerts its effect by selectively binding to antithrombin and inhibiting:
79. A patient on warfarin has INR > 6 with no active bleeding. The most appropriate management is:
80. Ticagrelor has a pharmacodynamic advantage over clopidogrel in ACS because ticagrelor:
81. Dabigatran etexilate requires dose reduction in patients with moderate renal impairment (CrCl 30–50 mL/min) because:
82. Ticagrelor is preferred over clopidogrel in ACS because it:
83. A patient develops heparin-induced thrombocytopenia (HIT) type II after 8 days of unfractionated heparin for DVT. Platelet count drops from 240,000 to 70,000/µL with a new left lower limb arterial thrombus. What is the mechanism of this paradoxical thrombosis and what is the appropriate management?
84. Ticagrelor is preferred over clopidogrel in acute coronary syndrome per current guidelines. Which unique pharmacological property distinguishes ticagrelor from clopidogrel in terms of receptor interaction?
85. Heparin-induced thrombocytopenia type II (HIT) is paradoxically associated with thrombosis rather than bleeding. The immune mechanism responsible is:
86. Ticagrelor is a P2Y12 receptor antagonist that does not require metabolic activation. Compared to clopidogrel, it produces faster, more consistent antiplatelet effect because of which pharmacological properties?
87. Alteplase (tPA) is used in ischemic stroke within 4.5 hours of symptom onset. Which pharmacokinetic property distinguishes alteplase from streptokinase in terms of fibrin selectivity?
88. Dabigatran is a direct oral anticoagulant (DOAC) that does not require therapeutic monitoring. Its mechanism differs from warfarin because:
89. Ticagrelor differs from clopidogrel in that it does not require hepatic bioactivation. Ticagrelor's mechanism and pharmacokinetic advantage is:
90. Fondaparinux differs from unfractionated heparin in its mechanism of anticoagulation. Fondaparinux:
91. Alteplase (tPA) is used as a thrombolytic. It preferentially acts on plasminogen bound to fibrin rather than circulating free plasminogen. This property confers which clinical advantage?
92. Heparin-induced thrombocytopaenia (HIT) is a serious immune complication. The pathophysiology involves antibodies against which antigen complex, and the resulting paradoxical risk is:
93. Fondaparinux differs from unfractionated heparin (UFH) in that it: