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Quizzes > Health & Medicine

Which Drug Breaks Fibrin? Hematology Fibrinolysis Quiz

Quick, free fibrinolysis drug quiz with instant results.

Editorial: Review CompletedCreated By: Yaniv LacosteUpdated Aug 23, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art illustration of lab vials pills microscope and blood drop on teal background for hematology drug quiz

This quiz helps you identify which drug breaks up the fibrin meshwork and apply core fibrinolysis ideas, including timing and safety basics. Practice with quick questions, and keep learning with the hemostasis quiz, review the clot destruction medical term, or try a broader pharmacology practice quiz.

Which drug breaks down the fibrin meshwork in blood clots by converting plasminogen to plasmin?
Warfarin
Alteplase
Aspirin
Heparin
Alteplase is a recombinant tissue plasminogen activator that directly converts plasminogen to plasmin, degrading fibrin. It is used for acute ischemic stroke, myocardial infarction, and pulmonary embolism. Other anticoagulants like heparin and warfarin do not directly lyse clots.
Which fibrinolytic agent is a streptococcal protein that activates plasminogen indirectly?
Urokinase
Clopidogrel
Alteplase
Streptokinase
Streptokinase forms a complex with plasminogen, inducing a conformational change that activates plasmin. It is antigenic due to its bacterial origin. Urokinase and alteplase are human enzymes, while clopidogrel is an antiplatelet agent.
Which of the following is a human-derived plasminogen activator that is non-antigenic?
Streptokinase
Urokinase
Reteplase
Tenecteplase
Urokinase is a human urokinase-type plasminogen activator that does not provoke an immune response. It directly converts plasminogen to plasmin without antigen formation. Streptokinase is antigenic, while reteplase and tenecteplase are modified tPAs.
Which fibrinolytic agent has the longest half-life due to molecular modifications?
Streptokinase
Tenecteplase
Urokinase
Alteplase
Tenecteplase has amino acid substitutions that increase its half-life and fibrin specificity compared to alteplase. This allows single-bolus administration in myocardial infarction. Urokinase and streptokinase have shorter half-lives and require infusion.
Which drug is contraindicated in patients with a history of hemorrhagic stroke when considering fibrinolysis?
Aspirin
Warfarin
Alteplase
Clopidogrel
Alteplase increases the risk of bleeding and is contraindicated in hemorrhagic stroke history. Anticoagulants and antiplatelets may be used cautiously but fibrinolytics are absolute contraindications here. Clinical guidelines emphasize this for patient safety.
Which laboratory test is most useful to monitor the therapeutic effect of streptokinase?
Fibrinogen level
INR
Platelet count
PTT
Streptokinase causes systemic fibrinogen depletion, so monitoring fibrinogen levels guides therapy. PTT and INR are more useful for heparin and warfarin, respectively. Platelet count does not reflect fibrinolysis directly.
Which agent is used locally during peripheral arterial thrombolysis?
Heparin
Clopidogrel
Alteplase
Aspirin
Alteplase can be delivered intra-arterially for local clot dissolution in peripheral arteries. Heparin and antiplatelets prevent clot expansion but do not dissolve existing fibrin. Local infusion increases efficacy and limits systemic bleeding.
What is the primary clinical use of fibrinolytic therapy in acute myocardial infarction?
Prevention of arrhythmias
Cholesterol reduction
Blood pressure control
Reperfusion of occluded coronary artery
Fibrinolytic therapy aims to restore coronary blood flow by lysing thrombi in acute MI. This reperfusion limits infarct size and improves survival. Other therapies address arrhythmias and risk reduction separately.
Which side effect is most commonly associated with fibrinolytic therapy?
Bleeding
Thrombocytosis
Hypertension
Hyperkalemia
Major bleeding, including intracranial hemorrhage, is the most significant risk of fibrinolytic agents. Blood pressure changes are secondary effects and not as common. Electrolyte imbalances and elevated platelets are unrelated.
Which drug must be preceded by a skin test for hypersensitivity in some protocols?
Alteplase
Tenecteplase
Streptokinase
Urokinase
Streptokinase is of streptococcal origin and can cause allergic reactions, so earlier protocols recommended a skin test. Modern practice often skips routine testing but still recognizes risk. Recombinant tPAs and urokinase are human proteins without such risk.
Which fibrinolytic agent is frequently used in ischemic stroke within a narrow time window?
Alteplase
Warfarin
Aspirin
Heparin
Alteplase is FDA-approved for acute ischemic stroke when administered within 3 - 4.5 hours of symptom onset. This narrow window maximizes benefit and limits hemorrhagic risk. Anticoagulants and antiplatelets are used for prevention but not acute fibrinolysis.
Which agent has no direct effect on platelet function?
Urokinase
Tirofiban
Aspirin
Clopidogrel
Urokinase acts on plasminogen and does not inhibit platelet aggregation. Aspirin, clopidogrel, and tirofiban all target platelets directly. Fibrinolytics focus on clot dissolution rather than platelet blocking.
Which fibrinolytic drug is cleared primarily by hepatic metabolism and not significantly by the kidneys?
Tenecteplase
Alteplase
Streptokinase
Urokinase
Alteplase is metabolized by the liver, so hepatic dysfunction can prolong its effects. Urokinase and streptokinase have mixed clearance, and tenecteplase has renal contributions. Hepatic clearance is important for dosing adjustments.
In which condition is systemic fibrinolysis typically avoided due to high bleeding risk?
Active internal bleeding
Hyperlipidemia
Essential thrombocythemia
Stable angina
Active internal bleeding is an absolute contraindication for fibrinolysis because it can worsen hemorrhage. Conditions like stable angina or hyperlipidemia do not pose immediate bleeding risk. Careful patient selection is critical.
Which medication is most appropriate for pharmacologic reperfusion in acute pulmonary embolism?
Alteplase
Clopidogrel
Warfarin
Rivaroxaban
Alteplase is indicated for acute massive pulmonary embolism to achieve rapid clot lysis. Direct oral anticoagulants and warfarin prevent further clotting but do not dissolve existing thrombi. Thrombolysis is reserved for life-threatening presentations.
Which tPA variant has reduced clearance by the liver due to removal of glycosylation sites?
Tenecteplase
Urokinase
Alteplase
Reteplase
Reteplase lacks certain kringle domains and glycosylation sites, reducing hepatic clearance and extending its half-life. This allows bolus dosing in myocardial infarction. Other tPA variants retain glycosylation and shorter half-lives.
Which endogenous inhibitor regulates plasmin activity in plasma?
Thrombomodulin
Alpha-2 antiplasmin
Protein C
PAI-1
Alpha-2 antiplasmin binds free plasmin, preventing nonspecific proteolysis. PAI-1 inhibits tissue plasminogen activator, not plasmin directly. Thrombomodulin and protein C regulate coagulation, not fibrinolysis.
Which fibrinolytic has the highest risk of systemic activation leading to hypofibrinogenemia?
Tenecteplase
Reteplase
Streptokinase
Alteplase
Streptokinase can cause widespread plasminogen activation, depleting fibrinogen and other clotting factors. Tissue plasminogen activators are more clot-selective. Hypofibrinogenemia requires monitoring during streptokinase therapy.
In patients older than 75 years, which fibrinolytic shows a comparatively lower risk of intracranial hemorrhage?
Urokinase
Alteplase
Tenecteplase
Streptokinase
Tenecteplase's greater fibrin specificity is associated with reduced systemic bleeding, including intracranial hemorrhage. Alteplase carries higher hemorrhagic risk especially in the elderly. Urokinase and streptokinase have broad activation profiles.
Which assay measures the ability of plasmin to degrade exogenous fibrin and monitor fibrinolysis?
Bleeding time
D-dimer assay
Euglobulin clot lysis time
Thrombin time
Euglobulin clot lysis time assesses overall fibrinolytic capacity by measuring clot breakdown in plasma. Thrombin time assesses fibrinogen function, not lysis. Bleeding time tests platelet function. D-dimer detects fibrin degradation products but not global lysis capacity.
Which fibrinolytic drug is most sensitive to inhibition by PAI-1 in plasma?
Reteplase
Urokinase
Alteplase
Streptokinase
Plasminogen activator inhibitor-1 (PAI-1) rapidly inhibits plasminogen activators like alteplase. Reteplase and streptokinase are less affected due to structural differences. Urokinase is not inhibited by PAI-1.
Which pharmacokinetic parameter is increased in tenecteplase compared to alteplase?
Protein binding
Half-life
Bioavailability
Volume of distribution
Tenecteplase has a longer half-life due to amino acid substitutions that reduce clearance. Its volume of distribution and bioavailability are similar to alteplase. Protein binding remains minimal.
Which fibrinolytic agent is most cost-effective for resource-limited settings?
Streptokinase
Tenecteplase
Reteplase
Alteplase
Streptokinase is significantly less expensive than recombinant tPAs, making it preferred in low-resource areas. Its efficacy is lower and hemorrhagic risk higher, but cost considerations drive its use. Recombinant agents are costlier despite better safety profiles.
Which is the primary mechanism of action of fibrinolytic therapy in ischemic stroke?
Endothelial repair
Clot lysing by plasmin formation
Vasodilation
Platelet inhibition
Fibrinolytic therapy dissolves clots by converting plasminogen to plasmin, which degrades fibrin. This restores blood flow in occluded cerebral arteries. Platelet inhibition and vasodilation are separate therapeutic strategies.
Which laboratory measurement rises as a direct result of plasmin activity on fibrin?
PT
D-dimer
aPTT
Thrombin time
D-dimer is a degradation product of cross-linked fibrin and increases with plasmin activity. PT and aPTT reflect clotting factor function, not fibrin breakdown. Thrombin time assesses fibrinogen function.
Which adverse effect is unique to streptokinase compared with tPA agents?
Hypotension
Bleeding
Antigenic sensitization
Fever
Streptokinase is derived from streptococci and can induce antibody formation leading to allergic reactions. Hypotension, bleeding, and fever can occur with all fibrinolytics. Sensitization is specific due to its bacterial origin.
Which component of the fibrinolytic system is released from endothelial cells to initiate clot breakdown?
Tissue plasminogen activator
Thromboxane A2
Fibrinogen
Prothrombin
Endothelial cells secrete tissue plasminogen activator (tPA) to convert plasminogen into plasmin and initiate fibrinolysis. Prothrombin and fibrinogen are clotting factors, not fibrinolytics. Thromboxane A2 promotes platelet aggregation.
Which modified fibrinolytic has point mutations to increase fibrin specificity and resistance to PAI-1?
Streptokinase
Urokinase
Alteplase
Tenecteplase
Tenecteplase has three point mutations enhancing fibrin specificity and reducing PAI-1 inhibition. Alteplase lacks these modifications. Streptokinase and urokinase have different mechanisms entirely.
Which fibrinolytic is most appropriate for catheter-directed therapy in limb ischemia?
Warfarin
Heparin
Aspirin
Alteplase
Catheter-directed alteplase allows direct clot lysis in obstructed peripheral arteries. Anticoagulants prevent clot progression but do not dissolve existing fibrin. Antiplatelets address platelet aggregation only.
Which domain of tissue plasminogen activator mediates fibrin binding?
EGF-like domain
Finger domain
Kringle 2 domain
Protease domain
The kringle 2 domain of tPA binds to fibrin and localizes plasminogen activation to clots. The finger domain also contributes to fibrin binding. The EGF-like domain targets endothelial cells, and the protease domain cleaves plasminogen.
Which fibrinolytic agent is least affected by high levels of plasminogen activator inhibitor-1?
Urokinase
Tenecteplase
Reteplase
Alteplase
Urokinase is not inhibited by PAI-1, making its activity less dependent on inhibitor levels. TPA variants are all subject to PAI-1 inhibition to varying degrees. This property influences clinical choice in high-PAI-1 states.
Which receptor on endothelial cells clears tPA from circulation?
uPAR
GP IIb/IIIa
CD36
LRP1 (LDL receptor - related protein)
LRP1 mediates endocytosis and clearance of tPA in the liver and endothelium. uPAR binds uPA, not tPA. GP IIb/IIIa is a platelet receptor, and CD36 is a scavenger receptor for oxidized lipids.
What structural modification differentiates tenecteplase from alteplase?
Removal of finger domain
Fusion with streptokinase
Multiple point mutations in kringle and protease domains
Addition of extra glycosylation site
Tenecteplase contains three point mutations that improve fibrin specificity and PAI-1 resistance. It retains the finger domain and has no streptokinase fusion. Glycosylation sites are reduced, not added.
Which trial established the benefit of tenecteplase over alteplase in acute MI reperfusion?
ISIS-3
PRIME II
GUSTO-I
ASSENT-2
The ASSENT-2 trial demonstrated that tenecteplase had similar efficacy to alteplase with lower noncerebral bleeding. GUSTO-I studied streptokinase and alteplase. ISIS-3 compared streptokinase, alteplase, and UK. PRIME II was in elderly non - ST-segment elevation MI.
Which factor influences the half-life of reteplase compared to native tPA?
Absence of glycosylation sites
Increased molecular weight
Fusion with albumin
Enhanced receptor binding
Reteplase lacks glycosylation which decreases recognition by hepatic receptors, prolonging half-life. Its molecular weight is lower than tPA. It has no albumin fusion, and receptor binding is reduced.
Which biomarker best reflects endogenous fibrinolytic activity in vivo?
Thromboxane B2
Plasmin - antiplasmin complex
Beta-thromboglobulin
Prothrombin fragment 1+2
The plasmin - antiplasmin complex indicates plasmin generation and inactivation, reflecting fibrinolysis. Prothrombin fragment 1+2 measures thrombin formation. Thromboxane B2 and beta-thromboglobulin are platelet activation markers.
Which genetic polymorphism can reduce the efficacy of fibrinolytic therapy?
PAI-1 4G/5G promoter variant
Factor V Leiden
Prothrombin G20210A
MTHFR C677T
The 4G allele in the PAI-1 promoter increases PAI-1 levels, inhibiting tPA and reducing fibrinolysis. Factor V Leiden and prothrombin variants affect clotting but not fibrinolysis directly. MTHFR affects homocysteine metabolism.
Which organ failure most prolongs the half-life of reteplase?
Pulmonary failure
Hepatic failure
Renal failure
Pancreatic failure
Reteplase is cleared chiefly by the liver; hepatic impairment prolongs its half-life. Renal clearance is minimal. Pulmonary and pancreatic functions are not central to its metabolism.
Which formulation allows bolus dosing rather than infusion for fibrinolysis?
Reteplase
Urokinase
Streptokinase
Alteplase
Reteplase's longer half-life permits two bolus injections rather than a continuous infusion. Alteplase and urokinase need prolonged infusion. Streptokinase infusion is required due to antigenicity monitoring.
Which approach reduces bleeding risk when using systemic fibrinolysis?
Use of fibrin-specific agents
Adding antiplatelet bolus
Concurrent high-dose anticoagulant
Increasing dose
Fibrin-specific agents like tenecteplase preferentially target clot-bound plasminogen, minimizing systemic proteolysis and bleeding. Higher doses and combined high-dose anticoagulants increase bleeding. Antiplatelet boluses also raise hemorrhagic risk.
Which half-life ranking is correct from shortest to longest?
Reteplase < Tenecteplase < Alteplase < Urokinase
Alteplase < Urokinase < Reteplase < Tenecteplase
Tenecteplase < Alteplase < Reteplase < Urokinase
Urokinase < Alteplase < Tenecteplase < Reteplase
Alteplase (~5 min) has the shortest half-life, followed by urokinase (~15 - 20 min), then reteplase (~15 min bolus dosing), and tenecteplase (>20 min). This ordering guides administration routes. Half-lives overlap but order is correct.
Which effect does simultaneous administration of aminocaproic acid have on fibrinolytic therapy?
Blocks PAI-1
Increases tPA clearance
Inhibits plasmin, reversing fibrinolysis
Enhances plasmin activity
Aminocaproic acid is an antifibrinolytic that binds plasminogen and plasmin, blocking fibrinolysis and reversing bleeding. It does not enhance plasmin or affect PAI-1 or tPA clearance. It is used to control hemorrhage after fibrinolysis.
Which polymorphism in the PLG gene affects individual response to fibrinolytic therapy?
Factor V Leiden
Plasminogen Lys312 deletion variant
PAI-1 4G/5G
Prothrombin G20210A
A Lys312 deletion in plasminogen reduces conversion efficiency to plasmin, affecting fibrinolysis. PAI-1 variants influence inhibitor levels but not plasminogen structure. Factor V Leiden and prothrombin variants affect coagulation, not plasminogen.
Which dosing adjustment is recommended for tenecteplase in cardiogenic shock?
Add continuous infusion post-bolus
Divide bolus into three parts
Use standard bolus only
Increase infusion rate by 25%
In cardiogenic shock, tenecteplase dosing remains a single weight?based bolus without infusion. Hemodynamic instability does not warrant infusion. Dividing bolus or infusion increases complexity and bleeding risk.
Which adverse effect is uniquely reported in high-dose reteplase protocols?
Thrombocytopenia
Hypokalemia
Hyperuricemia
Transient hypotension due to bradykinin
High-dose reteplase can cause transient hypotension from bradykinin release during fibrinolysis. Thrombocytopenia is not specific to reteplase. Electrolyte disturbances like hypokalemia and hyperuricemia are unrelated.
Which combination therapy has shown improved myocardial salvage compared to tPA alone?
Urokinase plus warfarin
Tenecteplase plus low molecular weight heparin
Streptokinase plus aspirin
Alteplase plus abciximab
The ASSENT-4 PCI trial showed adding abciximab to alteplase improved microvascular perfusion. Urokinase with warfarin and streptokinase with aspirin are older protocols without demonstrated superiority in salvage. LMWH plus tenecteplase increases bleeding risk.
Which specialized assay can quantify active tPA levels after administration?
ELISA for PAI-1
Chromogenic amidolytic assay
Western blot
Immunoturbidimetric assay
Chromogenic amidolytic assays measure tPA's enzymatic activity by monitoring substrate cleavage. Immunoturbidimetric assays detect antigen levels but not function. ELISA for PAI-1 measures inhibitor levels; Western blot is qualitative.
Which regulatory step in drug design reduced immunogenicity of reteplase?
PEGylation
Fusion with albumin
Addition of human IgG Fc fragment
Deletion of non-essential epitopes
Reteplase engineering removed epitopes not required for activity to reduce immune recognition. It is not PEGylated or fused with Fc/albumin. These modifications would alter clearance and antigenicity differently.
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Study Outcomes

  1. Determine which drug breaks up the fibrin meshwork in blood clots -

    Identify key fibrinolytic agents, such as alteplase, by understanding how they dissolve the fibrin scaffold during clot breakdown.

  2. Explain the mechanism of fibrinolytic therapy -

    Describe how fibrinolytic drugs convert plasminogen to plasmin to degrade fibrin and restore normal blood flow.

  3. Differentiate between fibrinolytics and anticoagulants -

    Contrast the actions of clot-dissolving agents with anticoagulant drug trivia items like heparin and warfarin to clarify their distinct therapeutic roles.

  4. Recall clinical indications and contraindications -

    Review when to use or avoid fibrinolytic therapy based on patient risk factors in blood clot medication quiz scenarios.

  5. Apply knowledge to targeted fibrinolytic therapy questions -

    Solve focused quiz items on fibrinolytic therapy questions to reinforce dosing, timing, and monitoring concepts.

Cheat Sheet

  1. Mechanism of Fibrinolytic Agents -

    Fibrinolytic drugs convert inactive plasminogen into active plasmin, which cleaves the fibrin meshwork into soluble degradation products. The core reaction can be summarized as plasminogen + fibrin → plasmin → fibrin degradation products. Mnemonic: "T”PAs Activate Plasmin to Abate Clots" helps recall tPA, streptokinase, and urokinase activity.

  2. Tissue Plasminogen Activator (tPA) -

    tPA (alteplase, reteplase, tenecteplase) is a recombinant form of a native endothelial enzyme that preferentially activates fibrin-bound plasminogen. Its short half-life (≈5 min) necessitates a bolus plus continuous infusion; standard dosing for MI is 0.9 mg/kg over 90 minutes. Studies from the American Heart Association emphasize door-to-needle times under 30 minutes to maximize myocardial salvage.

  3. Streptokinase and Urokinase Overview -

    Streptokinase, derived from streptococci, forms a complex with plasminogen to generate plasmin, while urokinase (from renal cells) directly cleaves plasminogen. Streptokinase is non - fibrin-specific and can induce allergic reactions, so it's less favored in repeat dosing. Urokinase has a broader clot target but is less commonly used due to cost and renal elimination concerns.

  4. Clinical Indications and Timing -

    Fibrinolytic therapy is indicated in acute STEMI (within 12 hours of pain onset), high-risk pulmonary embolism, and acute ischemic stroke (within 4.5 hours). The principle "time is muscle" (MI) or "time is brain" (stroke) underscores rapid administration for best outcomes. Protocols from the American College of Chest Physicians recommend strict door-to-needle targets to reduce morbidity.

  5. Monitoring, Contraindications, and Safety -

    Monitor fibrinogen levels, aPTT, and platelet counts to gauge bleeding risk; watch for signs of intracranial hemorrhage or hypotension. Absolute contraindications include active internal bleeding, history of hemorrhagic stroke, or recent intracranial surgery. Always cross”reference institutional guidelines and maintain readiness for transfusion support in case of major bleeding.

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