Martefarin (Warfarin Sodium)

Martefarin is a vitamin K antagonist used in several thromboembolic conditions.

• Atrial fibrillation: reduces the risk of stroke by inhibiting clot formation.
• Deep vein thrombosis: treats existing clots and prevents extension.
• Pulmonary embolism: facilitates resolution of emboli and lowers recurrence.
• Secondary prevention of recurrent thromboembolism: maintains anticoagulation to avoid new events.

• Warfarin Sodium inhibits the enzyme vitamin K epoxide reductase, which is essential for recycling vitamin K. This blockade decreases the regeneration of active vitamin K, leading to reduced gamma‑carboxylation of clotting factors II, VII, IX, and X. Consequently, the synthesis of functional clotting proteins is lowered, prolonging coagulation time and providing anticoagulant effect.

Adverse reactions may vary from mild to severe and should be monitored closely.

Common Side Effects

• Minor bleeding: bruising, gum bleeding, or nosebleeds.
• Gastrointestinal discomfort: nausea, abdominal pain, or dyspepsia.
• Headache or dizziness.
• Skin rash or mild itching.
• Elevated liver enzymes (asymptomatic).

Serious or Rare Side Effects

• Intracranial hemorrhage or severe internal bleeding.
• Skin necrosis, especially in the first few days of therapy.
• Anaphylactic or severe allergic reactions.
• Massive hemorrhage requiring transfusion.
• Spontaneous spinal or retroperitoneal bleeding.

Use of Martefarin requires careful clinical oversight to balance efficacy and safety.

• Monitoring: Perform regular INR testing to keep the therapeutic range within target limits.
• Dietary considerations: Maintain a consistent intake of vitamin K‑rich foods to avoid fluctuations in anticoagulation.
• Drug interactions: Review all concomitant medications for potential potentiation of bleeding risk.
• Pregnancy: Contraindicated (Category X) due to teratogenic potential and fetal bleeding risk.
• Renal or hepatic impairment: Intensify monitoring and adjust therapy as clinically indicated.
• Store at below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

Warfarin has a broad interaction profile that can alter its anticoagulant effect.

Major Interactions (Avoid)

• Amiodarone: markedly increases warfarin plasma levels, raising bleeding risk.
• Azole antifungals (e.g., fluconazole, ketoconazole): potentiate anticoagulation.
• Rifampin or other strong CYP2C9 inducers: reduce warfarin effectiveness, risking thrombosis.

Moderate Interactions (Monitor Closely)

• Non‑steroidal anti‑inflammatory drugs (NSAIDs) and aspirin: increase gastrointestinal bleeding tendency.
• Certain antibiotics (e.g., macrolides, trimethoprim‑sulfamethoxazole): may modestly enhance anticoagulant effect.
• Herbal supplements (e.g., ginkgo, garlic, St. John’s wort): require INR monitoring due to variable influence.