Certified Registered Nurse Anesthetist (CRNA) Practice Exam

Which of the following drugs is classified as a potent anticoagulant that prevents thrombin?

1. Heparin

2. Clonidine

3. Esmolol

4. Coumadin

The correct answer is: Heparin

Heparin is classified as a potent anticoagulant and functions primarily by inhibiting thrombin. Thrombin plays a critical role in the coagulation cascade, converting fibrinogen to fibrin, which is essential for blood clot formation. By preventing the action of thrombin, heparin effectively reduces the ability of the blood to clot, making it a valuable medication in the prevention and treatment of thromboembolic disorders such as deep vein thrombosis and pulmonary embolism. Heparin has a rapid onset of action and is often used in acute settings, typically administered intravenously or subcutaneously. Monitoring of its effects often involves the use of activated partial thromboplastin time (aPTT), ensuring that patients receive the appropriate anticoagulation levels. The other options represent different pharmacological classes. Clonidine is an alpha-2 adrenergic agonist primarily used as an antihypertensive medication, while esmolol is a short-acting beta-blocker used for cardiovascular conditions. Coumadin, on the other hand, is a vitamin K antagonist that affects the synthesis of clotting factors but does not directly inhibit thrombin. Thus, while all options have their uses in clinical practice, heparin stands