Overview
Rivaroxaban is a direct oral anticoagulant (DOAC) that effectively thins the blood to prevent and treat potentially dangerous blood clots. It is widely prescribed to lower the risk of stroke in patients with nonvalvular atrial fibrillation and to treat deep vein thrombosis (DVT) and pulmonary embolism (PE).

Mechanism of Action
It is a highly selective and reversible direct inhibitor of Factor Xa. By binding directly to the active site of Factor Xa, rivaroxaban interrupts both the intrinsic and extrinsic pathways of the blood coagulation cascade. This effectively prevents the generation of thrombin and the subsequent formation of blood clots, without requiring antithrombin as a cofactor.

Dosage and Administration
For stroke prevention in atrial fibrillation, the standard dose is 20 mg once daily, taken with the evening meal. For patients with reduced renal function, the dose may be reduced to 15 mg once daily. For the acute treatment of DVT/PE, the initial dose is 15 mg twice daily for 21 days, followed by 20 mg once daily. Doses of 15 mg and 20 mg must be taken with food to ensure adequate absorption. Routine INR monitoring is not required.

Side Effects
The primary adverse effect is an increased risk of bleeding, which can occur anywhere in the body and may be severe or life-threatening. Common bleeding sites include the gastrointestinal tract and nose (epistaxis). Other side effects may include dizziness, abdominal pain, and fatigue.

Contraindications
It is contraindicated in patients with active clinically significant bleeding, severe hepatic disease associated with coagulopathy, or a known hypersensitivity to rivaroxaban. It is also not recommended for patients with artificial heart valves.

Pregnancy and Lactation
Rivaroxaban should be avoided during pregnancy due to the potential for pregnancy-related hemorrhage and reproductive toxicity seen in animal studies. It is excreted in breast milk, so breastfeeding is not recommended during treatment.