**Question:** Patient with DVT on therapeutic dose of Warfarin came with complaints of breathlessness and hypotension. True statement regarding this:

A. Increased risk of bleeding
B. Risk of decreased efficacy due to drug interaction
C. Risk of increased pulmonary embolism
D. Risk of increased bleeding due to warfarin inactivation

**Core Concept:** Warfarin is an anticoagulant drug commonly used to prevent and treat venous thromboembolism, including deep vein thrombosis (DVT). It works by inhibiting vitamin K-dependent clotting factors, thereby reducing blood clot formation.

**Why the Correct Answer is Right:**

The correct answer is C - Risk of increased pulmonary embolism. In this scenario, the patient with DVT on therapeutic dose of warfarin presents with symptoms of breathlessness and hypotension. These symptoms may indicate the development of a new complication, specifically a pulmonary embolism (PE).

Warfarin's anticoagulant effect can lead to a decrease in blood clotting, which may result in a higher risk of clot formation in other parts of the body, including the lungs. This can cause a pulmonary embolism, leading to the patient's symptoms.

**Why Each Wrong Option is Incorrect:**

A. Increased risk of bleeding (False) - Warfarin's primary action is to inhibit clot formation, not increase bleeding.

B. Risk of decreased efficacy due to drug interaction (False) - Warfarin's effect is consistent and predictable when used appropriately, and interactions are not the primary concern in this scenario.

D. Risk of increased bleeding due to warfarin inactivation (False) - This statement is incorrect because warfarin's main action is clot inhibition, not inactivation.

**Clinical Pearl:**

In patients on warfarin therapy, clinicians should be vigilant for potential complications, such as pulmonary embolism. Regular monitoring and adjustments to the patient's anticoagulation management are crucial to avoid excessive bleeding risk while ensuring therapeutic efficacy. Prompt diagnosis and management of any new symptoms can prevent severe complications and improve patient outcomes.