Anticoagulants MCQs With Answer are essential revision tools for B. Pharm students to master clinical pharmacology of anticoagulant drugs. This concise, keyword-rich introduction covers mechanisms of action, drug classes (warfarin, heparin, LMWH, fondaparinux, DOACs), monitoring (INR, aPTT, anti-Xa), dosing principles, adverse effects (bleeding, HIT, osteoporosis), drug interactions, and reversal agents (vitamin K, PCC, protamine, idarucizumab, andexanet alfa). Understanding pharmacokinetics, renal/hepatic adjustments, and indications (VTE, AF, DVT, PE, perioperative prophylaxis) is crucial for safe therapeutics. These focused MCQs will deepen your knowledge and clinical reasoning in anticoagulant pharmacotherapy. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which anticoagulant directly inhibits thrombin (factor IIa) by binding to its active site?
- Warfarin
- Dabigatran
- Rivaroxaban
- Fondaparinux
Correct Answer: Dabigatran
Q2. Which laboratory test is most appropriate for monitoring warfarin therapy?
- aPTT (activated partial thromboplastin time)
- INR (international normalized ratio)
- Anti-factor Xa assay
- Platelet count
Correct Answer: INR (international normalized ratio)
Q3. Protamine sulfate is an effective antidote for which anticoagulant?
- Apixaban
- Unfractionated heparin
- Warfarin
- Dabigatran
Correct Answer: Unfractionated heparin
Q4. Which drug is a synthetic pentasaccharide that selectively inhibits factor Xa via antithrombin?
- Enoxaparin
- Fondaparinux
- Warfarin
- Argatroban
Correct Answer: Fondaparinux
Q5. A patient on warfarin develops major bleeding. Which agent provides the fastest reversal of anticoagulation?
- Oral vitamin K (phytonadione)
- Fresh frozen plasma
- Prothrombin complex concentrate (PCC)
- Protamine sulfate
Correct Answer: Prothrombin complex concentrate (PCC)
Q6. Heparin-induced thrombocytopenia (HIT) type II is mediated by antibodies against which complex?
- Platelet alpha granules
- Heparin–platelet factor 4 (PF4)
- Fibrin–thrombin complex
- Factor VIII–von Willebrand factor
Correct Answer: Heparin–platelet factor 4 (PF4)
Q7. Which oral anticoagulant is highly protein-bound and has nearly complete oral bioavailability?
- Warfarin
- Dabigatran
- Enoxaparin
- Fondaparinux
Correct Answer: Warfarin
Q8. Which direct oral anticoagulant primarily inhibits factor Xa?
- Dabigatran
- Apixaban
- Heparin
- Warfarin
Correct Answer: Apixaban
Q9. Which monitoring test is most useful to assess the anticoagulant effect of low molecular weight heparin (LMWH) in special populations?
- INR
- aPTT
- Anti-factor Xa assay
- Bleeding time
Correct Answer: Anti-factor Xa assay
Q10. Which genetic polymorphism most influences warfarin dose variability?
- CYP3A4 variants
- VKORC1 and CYP2C9 polymorphisms
- G6PD deficiency
- Factor V Leiden mutation
Correct Answer: VKORC1 and CYP2C9 polymorphisms
Q11. Which anticoagulant is contraindicated in pregnancy because of teratogenicity and fetal bleeding risk?
- Unfractionated heparin
- Low molecular weight heparin
- Warfarin
- Fondaparinux
Correct Answer: Warfarin
Q12. Idarucizumab is a specific reversal agent for which anticoagulant?
- Rivaroxaban
- Apixaban
- Dabigatran
- Warfarin
Correct Answer: Dabigatran
Q13. Which adverse effect is most specifically associated with long-term unfractionated heparin therapy?
- Hepatotoxicity
- Osteoporosis
- Nephrotoxicity
- Pulmonary fibrosis
Correct Answer: Osteoporosis
Q14. A patient with severe renal impairment (CrCl <15 mL/min) requires anticoagulation. Which agent is generally least preferred because it is predominantly renally cleared?
- Warfarin
- Dabigatran
- Unfractionated heparin
- Apixaban (at adjusted dose)
Correct Answer: Dabigatran
Q15. Which statement about low molecular weight heparin (LMWH) versus unfractionated heparin (UFH) is correct?
- LMWH requires routine aPTT monitoring in all patients
- UFH has more predictable bioavailability after subcutaneous injection
- LMWH has longer half-life and more predictable anticoagulant response
- UFH is contraindicated in pregnancy while LMWH is preferred
Correct Answer: LMWH has longer half-life and more predictable anticoagulant response
Q16. Which laboratory test is prolonged in the presence of direct thrombin inhibitors like dabigatran?
- Prothrombin time (PT) only
- Thrombin time (TT)
- Platelet function assay
- Fibrinogen level
Correct Answer: Thrombin time (TT)
Q17. Which anticoagulant’s activity can be reversed by andexanet alfa?
- Dabigatran
- Rivaroxaban
- Warfarin
- Heparin
Correct Answer: Rivaroxaban
Q18. Which mechanism best describes warfarin’s anticoagulant action?
- Direct inhibition of factor Xa active site
- Potentiation of antithrombin III
- Inhibition of vitamin K epoxide reductase, reducing gamma-carboxylation of clotting factors
- Direct thrombin binding and inactivation
Correct Answer: Inhibition of vitamin K epoxide reductase, reducing gamma-carboxylation of clotting factors
Q19. For perioperative thromboprophylaxis after major orthopedic surgery, which anticoagulant is commonly used subcutaneously?
- Warfarin
- Low molecular weight heparin (enoxaparin)
- Apixaban only IV
- Idarucizumab
Correct Answer: Low molecular weight heparin (enoxaparin)
Q20. Which drug interaction increases warfarin’s anticoagulant effect by inhibiting CYP2C9?
- Rifampicin
- Carbamazepine
- Metronidazole
- Phenytoin
Correct Answer: Metronidazole
Q21. Which parameter defines therapeutic INR range for most indications like atrial fibrillation and venous thromboembolism?
- INR 1.0–1.5
- INR 2.0–3.0
- INR 3.5–4.5
- INR <1.5
Correct Answer: INR 2.0–3.0
Q22. Which anticoagulant is administered intravenously and used in HIT as an alternative to heparin?
- Argatroban
- Warfarin
- Edoxaban
- Enoxaparin
Correct Answer: Argatroban
Q23. Which feature distinguishes direct oral anticoagulants (DOACs) from warfarin?
- DOACs require frequent INR monitoring
- DOACs have predictable pharmacokinetics and generally do not require routine monitoring
- DOACs are teratogenic like warfarin
- DOACs act by inhibiting vitamin K epoxide reductase
Correct Answer: DOACs have predictable pharmacokinetics and generally do not require routine monitoring
Q24. Which anticoagulant’s absorption is significantly affected by acidic capsule formulation and requires specific storage to prevent moisture exposure?
- Dabigatran etexilate
- Rivaroxaban
- Warfarin sodium
- Enoxaparin
Correct Answer: Dabigatran etexilate
Q25. In a patient with mechanical heart valve, which anticoagulant is preferred?
- Dabigatran
- Warfarin
- Rivaroxaban
- Low molecular weight heparin long-term
Correct Answer: Warfarin
Q26. Which adverse event is most suggestive of heparin-induced thrombocytopenia (HIT) rather than simple heparin-related bleeding?
- Progressive mucosal bleeding
- Sudden drop in platelet count with new thrombosis
- Prolonged aPTT without thrombocytopenia
- Isolated epistaxis
Correct Answer: Sudden drop in platelet count with new thrombosis
Q27. Which anticoagulant requires dose adjustment based on creatinine clearance and is partially hepatically metabolized via CYP3A4?
- Warfarin
- Apixaban
- Unfractionated heparin
- Fondaparinux
Correct Answer: Apixaban
Q28. Which test is least useful for assessing anticoagulation due to a factor Xa inhibitor like apixaban?
- Anti-factor Xa calibrated assay
- PT/INR (may be variably prolonged)
- Specific anti-Xa assay calibrated for the drug
- Bleeding time
Correct Answer: Bleeding time
Q29. Which anticoagulant effect is primarily reversed by administration of vitamin K (phytonadione)?
- Heparin-induced anticoagulation
- Warfarin-induced reduction of vitamin K–dependent clotting factors
- Dabigatran direct thrombin inhibition
- Fondaparinux factor Xa inhibition
Correct Answer: Warfarin-induced reduction of vitamin K–dependent clotting factors
Q30. Which practice is recommended when switching a patient from warfarin to a direct oral anticoagulant (DOAC)?
- Stop warfarin and start DOAC immediately regardless of INR
- Switch when INR is within or below a drug-specific threshold (e.g., INR ≤2.0 for many DOACs)
- Overlap warfarin and DOAC for 7 days always
- Increase warfarin dose before starting DOAC
Correct Answer: Switch when INR is within or below a drug-specific threshold (e.g., INR ≤2.0 for many DOACs)
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