1. • Factor Xa plays a critical role in the conversion of prothrombin to thrombin, a key step in blood clot formation.
   • By inhibiting factor Xa, rivaroxaban reduces thrombin generation, thereby preventing the formation of blood clots.
2. Anticoagulant Effect:
   • Rivaroxaban’s action is specific to factor Xa, making it a targeted anticoagulant with a lower risk of affecting other clotting factors.
   • It does not require antithrombin III (unlike heparin) for its activity.
3. Predictable Pharmacokinetics:
   • Rivaroxaban has a rapid onset of action, reaching peak plasma concentrations within 2–4 hours.
   • It has a half-life of approximately 5–9 hours in healthy individuals, allowing for once-daily or twice-daily dosing depending on the indication.

Rivaroxaban is approved for the following conditions:

1. Prevention of Stroke and Systemic Embolism in Atrial Fibrillation:
   • Used in patients with non-valvular atrial fibrillation (NVAF) to reduce the risk of stroke and systemic embolism.
2. Treatment and Prevention of Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE):
   • Used for the treatment of acute DVT and PE.
   • Also used for the prevention of recurrent DVT and PE.
3. Postoperative Thromboprophylaxis:
   • Used to prevent venous thromboembolism (VTE) in patients undergoing hip or knee replacement surgery.
4. Secondary Prevention of Cardiovascular Events:
   • Used in patients with chronic coronary artery disease (CAD) or peripheral artery disease (PAD) to reduce the risk of major cardiovascular events (e.g., stroke, myocardial infarction).

The dosage of rivaroxaban varies depending on the indication and patient-specific factors. Below are general guidelines:

1. Atrial Fibrillation (Stroke Prevention):
   • Standard Dose: 20 mg taken orally once daily with the evening meal.
2. Treatment of DVT and PE:
   • Initial Dose: 15 mg taken orally twice daily with food for the first 21 days.
   • Maintenance Dose: 20 mg taken orally once daily with food.
3. Prevention of Recurrent DVT and PE:
   • Standard Dose: 10 mg taken orally once daily with or without food.
4. Postoperative Thromboprophylaxis:
   • Standard Dose: 10 mg taken orally once daily, starting 6–10 hours after surgery.
   • Duration:
     • Hip replacement: 35 days.
     • Knee replacement: 12 days.
5. Secondary Prevention of Cardiovascular Events:
   • Standard Dose: 2.5 mg taken orally twice daily with or without food.
6. Administration:
   • Rivaroxaban should be taken with food for doses of 15 mg and 20 mg to enhance absorption.
   • Do not crush or chew the tablets.

Rivaroxaban is generally well-tolerated, but some side effects may occur. These include:

1. Common Side Effects:
   • Bleeding (e.g., nosebleeds, gum bleeding, bruising)
   • Nausea
   • Anemia
2. Less Common Side Effects:
   • Headache
   • Dizziness
   • Elevated liver enzymes
3. Rare but Serious Side Effects:
   • Major Bleeding: Gastrointestinal bleeding, intracranial hemorrhage.
   • Hypersensitivity Reactions: Rare cases of anaphylaxis or angioedema.
   • Spinal/Epidural Hematoma: Especially in patients undergoing spinal procedures.

1. Contraindications:
   • Hypersensitivity to rivaroxaban or any component of the formulation.
   • Active clinically significant bleeding.
   • Severe hepatic impairment (Child-Pugh class C).
2. Warnings:
   • Bleeding Risk: Rivaroxaban increases the risk of bleeding. Use with caution in patients with a history of bleeding disorders or conditions that predispose to bleeding.
   • Renal Impairment: Use with caution in patients with severe renal impairment (CrCl < 30 mL/min). Avoid use in patients with CrCl < 15 mL/min.
   • Pregnancy and Lactation: Rivaroxaban is not recommended during pregnancy or breastfeeding unless the benefits outweigh the risks.
3. Monitoring:
   • Regular monitoring of renal function (serum creatinine).
   • Watch for signs of bleeding (e.g., unusual bruising, blood in stool or urine).

Rivaroxaban interacts with several medications, including:

1. Strong CYP3A4 and P-gp Inhibitors (e.g., ketoconazole, ritonavir): Increase rivaroxaban levels, increasing the risk of bleeding. Avoid concurrent use or reduce the dose of rivaroxaban.
2. Strong CYP3A4 and P-gp Inducers (e.g., rifampin, carbamazepine): Decrease rivaroxaban levels, reducing its efficacy. Avoid concurrent use.
3. Other Anticoagulants (e.g., warfarin, heparin): Increased risk of bleeding.
4. NSAIDs (e.g., ibuprofen): Increased risk of gastrointestinal bleeding.
5. Antiplatelet Agents (e.g., aspirin, clopidogrel): Increased risk of bleeding.

Rivaroxaban is available under its generic name as well as brand names. Some common formulations include:

• Generic Name: Rivaroxaban
• Brand Name: Xarelto (commonly used worldwide).