THROMBAN 2.5

Indications

• Prophylaxis of venous thromboembolism following knee replacement surgery
• Prophylaxis of venous thromboembolism following hip replacement surgery
• Treatment of deep vein thrombosis
• Treatment of pulmonary embolism
• Prophylaxis of recurrent deep vein thrombosis
• Prophylaxis of recurrent pulmonary embolism
• Prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation

Dosage

Adults: Initially 10 mg twice daily for 7 days, then maintenance 5 mg twice daily. For the prophylaxis of venous thromboembolism following hip or knee replacement surgery, the recommended dose is 2.5 mg twice daily, to be started 12-24 hours after surgery.

Mechanism of action

Apixaban selectively inhibits factor Xa in both its free and bound forms, independently of antithrombin III. This inhibition prevents the conversion of prothrombin to thrombin, thereby inhibiting thrombus formation.

Pharmacodynamics

The pharmacodynamic effects of apixaban are characterized by its ability to inhibit factor Xa, which plays a crucial role in the coagulation cascade. This leads to decreased thrombin generation, resulting in reduced clot formation. Its anticoagulant effect can be monitored by measuring anti-factor Xa activity.

Pharmacokinetics

Apixaban is rapidly absorbed after oral administration, with peak plasma concentrations reached within 3 to 4 hours. It has a bioavailability of approximately 50% and is primarily metabolized in the liver via cytochrome P450 enzymes, particularly CYP3A4. The elimination half-life ranges from 8 to 15 hours, and the drug is eliminated through both renal and fecal pathways, with about 25% excreted unchanged in urine.

Contra-indications

• Active bleeding
• Severe uncontrolled hypertension
• History of bleeding diathesis
• Significant risk of major bleeding

Adverse effects

• Bleeding complications
• Nausea
• Headache
• Dizziness
• Diarrhea
• Myalgia
• Skin reactions

Interactions

• St. John's Wort (moderate decrease in exposure)
• Antifungals (azoles - potential increased risk of bleeding)
• Calcium channel blockers (unknown effect on exposure)
• Ciclosporin (unknown effect on exposure)
• HIV protease inhibitors boosted with ritonavir or cobicistat (unknown effect on exposure)
• Idelalisib (unknown effect on exposure)
• Lapatinib (unknown effect on exposure)
• Mitotane (unknown decrease in exposure)
• Neratinib (unknown effect on exposure)

Precautions

• Use with caution in the elderly
• Monitor renal function
• Assess risk factors for bleeding before initiation

Pregnancy

Not known to be harmful, but caution is advised.

Breast-feeding

Use only if essential, as small amounts are present in milk.

Storage

Store in the original container with desiccant, discard any remaining capsules 6 weeks after opening.

Formulations

• Tablets: 2.5 mg, 5 mg, and 10 mg
• Modified-release capsules

Mechanism of action

Apixaban selectively inhibits factor Xa in its free and bound forms, independant of antithrombin III. Apixaban also inhibits prothrominase. These effects prevent the formation of a thrombus.

Pharmacodynamics

Apixaban selectively inhibits factor Xa in its free and bound forms, independant of antithrombin III. Apixaban also inhibits prothrominase. These effects prevent the formation of a thrombus.