Antiplatelets, Fibrinolytics and Antifibrinolytics MCQs

Romiplostim: Genetically engineered protein in which the Fc component of a human antibody is fused to two copies of a peptide that stimulates the thrombopoietin receptors; approved for treatment of idiopathic thrombocytopenic purpura Ref: Katzung 11th edition Chapter 33.

Prasugrel : This is a newer, more potent and faster acting irreversibleP2Y12 purinergic receptor blocker , as when strong antiplatelet action is required.(Option C ruled out) Like its predecessors, it is also a prodrug, but is more rapidly absorbed.(Option B ruled out) It is also more rapidly and more completely activated, resulting in faster and more consistent platelet inhibition.(Option A ruled out) Bleeding complications are also more frequent and more serious. Patients with a history of ischaemic stroke and TIAs are at greater risk of intracranial haemorrhage. Prasugrel is contraindicated in such patients. Key Takeaway: Irreversible P2Y12 blockers(Prodrugs): Clopidogrel, Ticlopidine, Prasugrel Reversible, competitive P2Y12 blocker: Cangrelor Reversible, non competitive P2Y12 blocker: Ticagrelor

Clopidogrel is a prodrug that is activated by CYP2C9 and CYP2C19. It irreversibly binds to the ADP receptor on the surface of platelets that serves as a key role in platelet aggregation. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 834

Patient will need to be on aspirin and clopidogrel for at least a year. Aspirin and clopidogrel help prevent platelet-induced occlusion of coronary stents. Clopidogrel is a prodrug that is activated by CYP2C9 and It irreversibly binds to the ADP receptor on the surface of platelets that serves as a key role in platelet aggregation. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 840-45

Clopidogrel is a prodrug that must be metabolised to an active platelet-inhibiting metabolite by CYP2C19. Poor metabolizers achieve inadequate platelet inhibition. Option B & C: Prasugrel and ticagrelor do not require P450 activation and are not subject to this risk. Option D: Cytochrome P450-inducing drugs (e.g., carbamazepine, phenytoin, rifampin, barbiturates) increase warfarin's clearance and reduce the anticoagulant effect of a given dose. Cytochrome P450 inhibitors (e.g., amiodarone, selective serotonin reuptake inhibitors, cimetidine) reduce warfarin's clearance and increase the anticoagulant effect of a given dose. Genetic variability in cytochrome CYP2C9 and VKOR affect responses to warfarin. Reference : Basic & Clinical Pharmacology by Bertram G. Katzung, 14th Edition, Page Number- 79.

Ans. is 'b' i.e., Inhibit ADP mediated cAMP activation

Reteplase is the only thrombolytic drug listed. Heparin is anticoagulant. Argatroban is a direct inhibitor of thrombin, and Aminocaproic acid is an inhibitor, not an activator, of the conversion of plasminogen to plasmin. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 836

Reteplase is the only thrombolytic drug listed. Heparin is anticoagulant. Argatroban is a direct inhibitor of thrombin, and Aminocaproic acid is an inhibitor, not an activator, of the conversion of plasminogen to plasmin. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 834-33