Which of the following is an example of an anticoagulant?

Appeared in: UPRVUNL - 2021

Explanation

Heparin is a widely used anticoagulant, a substance that prevents blood from clotting.
It works indirectly by binding to and activating Antithrombin III, a natural inhibitor of coagulation in the body.
The Heparin-Antithrombin III complex is a potent inhibitor of key clotting factors, particularly Factor Xa and Thrombin (Factor IIa).
By inhibiting these factors, heparin effectively stops the coagulation cascade, preventing the formation of a stable fibrin clot.

Option A: Insulin is a hormone that regulates blood sugar (glucose) levels. It has no anticoagulant properties.
Option B: Pepsin is a digestive enzyme located in the stomach that breaks down proteins. It is not involved in the blood coagulation pathway.
Option D: Serotonin is a neurotransmitter and a vasoconstrictor. It actually promotes hemostasis by causing blood vessels to narrow and facilitating platelet aggregation, which aids in clot formation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacology: Anticoagulant Drugs as background academic context rather than a clinical decision trigger.
Nurses must closely monitor patients on heparin for signs of bleeding, such as hematuria, bleeding gums, or black, tarry stools. This is the most common and serious adverse effect.
Therapeutic effectiveness is monitored by checking the aPTT. The target range is typically 1.5 to 2.5 times the normal control value.
Patient safety education includes using a soft-bristled toothbrush and an electric razor to minimize the risk of bleeding.

How to Approach the Question

First, identify the key term in the question stem, which is 'anticoagulant'.
Define this term: An anticoagulant is a drug or substance that prevents or reduces the ability of blood to clot.
Next, systematically evaluate each option based on this definition.
Recall the primary function of Insulin (glucose regulation), Pepsin (protein digestion), and Serotonin (neurotransmitter, vasoconstrictor).
Identify Heparin as the only substance in the list whose primary function is to prevent blood coagulation.
This process of elimination based on the definition of the key term leads to the correct answer.

Concept Tested & Keywords

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E6 Physiology Essentials Sembulingam 10e Part 1 p. 140-142

E6 Harper's Illustrated Biochemistry2023 (pp 26-793 of 813) p. 669-671

E6 Pharmacology KD Tripathi Essentials 9e Part 2 p. 289-291

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Attempt every question from this paper in a timed mock, then review the full solution for each one.