Marevan (Warfarin Sodium)

Marevan is a Vitamin K antagonist indicated for several thrombotic conditions.

• Deep vein thrombosis: prevents clot extension and recurrence in the lower limbs.
• Pulmonary embolism: reduces the risk of further embolic events after an initial episode.
• Atrial fibrillation (stroke prevention): lowers the incidence of ischemic stroke in patients with non‑valvular atrial fibrillation.
• Mechanical heart valves: provides anticoagulation to avoid valve‑related thromboembolism.

• Warfarin inhibits the enzyme vitamin K epoxide reductase, which is essential for recycling vitamin K. This blockade reduces the regeneration of reduced vitamin K, thereby decreasing the hepatic synthesis of the vitamin K‑dependent clotting factors II, VII, IX, and X. The resulting decline in functional clotting proteins impairs the coagulation cascade, leading to an anticoagulant effect.

Warfarin therapy can be associated with a range of adverse reactions.

Common Side Effects

• Minor gastrointestinal upset, such as nausea or dyspepsia.
• Mild bruising or easy bleeding from cuts.
• Skin rash or mild itching.
• Hair loss (alopecia) in some patients.
• Elevated liver enzymes detected on routine labs.

Serious or Rare Side Effects

• Major hemorrhage, including intracranial or gastrointestinal bleeding.
• Skin necrosis, often presenting as painful, purplish lesions.
• Purple toe syndrome, characterized by painful discoloration of the toes.
• Anaphylactic reactions, though extremely uncommon.

Before initiating Marevan, several safety considerations should be addressed.

• Baseline testing: obtain INR, complete blood count, and liver function tests.
• Monitoring: adjust dose based on regular INR measurements to maintain therapeutic range.
• Drug interactions: review all concomitant medications for potential potentiation of anticoagulant effect.
• Contraindications: avoid use in patients with active bleeding, severe hepatic impairment, or known hypersensitivity.
• Pregnancy: contraindicated due to teratogenic risk (Category X).
• Store below 25°C: keep in the original container, protect from moisture and direct sunlight.

Warfarin has a broad interaction profile that requires careful management.

Major Interactions (Avoid)

• Amiodarone: markedly increases INR and bleeding risk.
• Azole antifungals (e.g., fluconazole, ketoconazole): potentiate anticoagulant effect.
• Certain antibiotics (e.g., trimethoprim‑sulfamethoxazole): elevate INR significantly.

Moderate Interactions (Monitor Closely)

• NSAIDs (e.g., ibuprofen, naproxen): increase gastrointestinal bleeding risk.
• Statins (e.g., simvastatin, atorvastatin): may modestly raise INR.
• Vitamin K‑rich foods or supplements: can reduce warfarin efficacy and require dose adjustment.