Master the Basics of Anticoagulant Drugs

Heparin

• Mechanism of action: binds to antithrombin, enhancing its ability to inactivate thrombin and factor Xa
• Source of unfractionated heparin for commercial purposes: pig intestine or cow lung tissue
• Low molecular weight form of heparin: enoxaparin
• NOT a therapeutic use of heparin and LMWHs: cancer treatment

Low Molecular Weight Heparins (LMWHs)

• Mechanism of action: inhibit factor Xa, preventing thrombin formation
• True about LMWHs: they have a more predictable dosing and pharmacokinetics compared to unfractionated heparin
• Potential adverse effect of heparin and LMWH therapy: bleeding

Urokinase

• Primary therapeutic use: treatment of pulmonary embolism
• Source of therapeutic urokinase: human kidney cell culture
• Mechanism of action: converts plasminogen to plasmin, breaking down fibrin clots

Warfarin

• Mechanism of action: inhibits vitamin K-dependent clotting factors II, VII, IX, and X
• Standard measure used to monitor anticoagulant activity: international normalized ratio (INR)
• Goal range for INR during warfarin therapy for most indications: 2-3

Thrombolytic Agents

• Thrombolytic agent with the longest half-life and greatest binding affinity for fibrin: tenecteplase
• Thrombolytic agent NOT approved for the treatment of acute ischemic stroke: urokinase
• Thrombolytic agent contraindicated in patients with a history of intracranial bleeding: streptokinase
• Thrombolytic agent derived from culture broths of group C β-hemolytic streptococci: streptokinase

Warfarin Pharmacology

• Most accurate statement about the anticoagulant effects of warfarin: it takes several days to reach maximum effect
• NOT a therapeutic use of warfarin: acute coronary syndrome
• True about the pharmacokinetics of warfarin: it has a narrow therapeutic index
• Adverse effect of warfarin therapy: bleeding