Orally acting direct thrombin inhibitor is ?
**Core Concept**
The question is testing the student's knowledge of anticoagulants, specifically the class of drugs known as direct thrombin inhibitors (DTIs). DTIs are a type of anticoagulant that work by directly inhibiting the activity of thrombin, a key enzyme in the coagulation cascade.
**Why the Correct Answer is Right**
The correct answer is a type of medication that works by directly binding to and inhibiting the activity of thrombin, preventing the formation of blood clots. This is in contrast to indirect thrombin inhibitors, which work by inhibiting the production of thrombin or its precursors. The correct answer is a medication that has a rapid onset of action and is effective in preventing thrombotic events.
**Option A:** Fondaparinux is actually a synthetic pentasaccharide that inhibits Factor Xa, not thrombin. Fondaparinux is an indirect Factor Xa inhibitor, which makes it an incorrect answer for this question.
**Option B:** Argatroban is a direct thrombin inhibitor, but it is administered intravenously, not orally. Argatroban is used as an anticoagulant in patients with heparin-induced thrombocytopenia, but it is not the correct answer for this question.
**Option C:** Lepirudin is another direct thrombin inhibitor, but it is administered intravenously and has a short half-life. Lepirudin is used in patients with heparin-induced thrombocytopenia, but it is not the correct answer for this question.
**Option D:** Dabigatran is the correct answer. Dabigatran is an orally administered direct thrombin inhibitor that is used to prevent stroke in patients with atrial fibrillation and to prevent thrombotic events in patients with deep vein thrombosis.
**Clinical Pearl / High-Yield Fact**
Dabigatran has a rapid onset of action and can be taken orally, making it a convenient option for patients who require anticoagulation therapy. However, it is essential to note that dabigatran has a higher risk of bleeding compared to warfarin, especially in patients with renal impairment.
**Correct Answer: D. Dabigatran**