1. Clinical Overview
Apixaban is a highly selective, reversible, direct oral anticoagulant (DOAC) that directly inhibits Factor Xa, a key enzyme in the coagulation cascade. It is a cornerstone of modern anticoagulation therapy in India, offering predictable pharmacokinetics, fewer drug and food interactions compared to warfarin, and no requirement for routine INR monitoring. It is widely used for stroke prevention in non-valvular atrial fibrillation (NVAF) and for the treatment and prevention of venous thromboembolism (VTE).
| Onset | Duration | Bioavailability |
|---|---|---|
| 1-3 hours | Approximately 24 hours (twice-daily dosing) | Approximately 50% |
2. Mechanism of Action
Apixaban is a selective, reversible, competitive inhibitor of free and clot-bound Factor Xa, and Factor Xa within the prothrombinase complex. By inhibiting Factor Xa, it prevents the conversion of prothrombin (Factor II) to thrombin (Factor IIa), thereby inhibiting thrombin-mediated platelet activation and fibrin clot formation.
3. Indications & Uses
- Prophylaxis of stroke and systemic embolism in adult patients with non-valvular atrial fibrillation (NVAF)
- Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE)
- Prophylaxis of recurrent DVT and PE following initial 6 months of treatment
4. Dosage & Administration
Adult Dosage: For Stroke Prevention in NVAF: 5 mg orally twice daily. For VTE Treatment: 10 mg twice daily for 7 days, followed by 5 mg twice daily. For VTE Prophylaxis post-surgery: 2.5 mg twice daily for 35 days (hip) or 12 days (knee).
Administration: Can be taken with or without food. Tablet should be swallowed whole with a glass of water. Do not crush or chew. If a dose is missed, take it as soon as remembered on the same day, then resume twice-daily schedule. Do not double the dose to make up for a missed dose.
5. Side Effects
Common side effects may include:
- Nausea
- Bruising (ecchymosis)
- Epistaxis (nosebleeds)
- Gingival bleeding (bleeding gums)
- Menorrhagia (heavy menstrual bleeding)
- Anemia
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Ketoconazole, Itraconazole, Voriconazole, Posaconazole | Increased apixaban exposure (AUC) by ~100%; increased bleeding risk | Contraindicated/High |
| Ritonavir, Atazanavir, Clarithromycin | Significantly increased apixaban levels; increased bleeding risk | Contraindicated/High |
| Rifampicin, Carbamazepine, Phenytoin, St. John's Wort | Significantly decreased apixaban levels; reduced efficacy | Contraindicated/High |
| Aspirin, Clopidogrel, Ticagrelor | Increased risk of bleeding | Moderate/High (requires careful assessment) |
| NSAIDs (e.g., Diclofenac, Ibuprofen) | Increased risk of gastrointestinal bleeding | Moderate |
| Selective Serotonin Reuptake Inhibitors (SSRIs) | May increase bleeding risk due to antiplatelet effect | Low/Moderate |
| Heparins, Warfarin | Increased bleeding risk | Contraindicated/High |
7. Patient Counselling
- DO take the medicine exactly as prescribed, twice daily.
- DO inform all your doctors and dentists that you are on apixaban before any procedure.
- DO use a soft-bristle toothbrush and electric razor to minimize bleeding risk.
- DO report any falls or head injuries immediately.
- DONT stop taking apixaban without consulting your doctor, as stroke risk may increase.
- DONT take any new medicine, including over-the-counter painkillers (NSAIDs), herbal supplements (like St. John's Wort), or antibiotics without checking with your doctor/pharmacist.
- DONT crush, chew, or break the tablet.
8. Toxicology & Storage
Overdose: Increased risk of bleeding, ranging from minor bruising and epistaxis to life-threatening intracranial or gastrointestinal hemorrhage.
Storage: Store below 30°C. Protect from moisture. Keep in the original blister pack or container. Keep out of reach of children.