Apixaban: An oral anticoagulant having unique mechanism of action with better safety and efficacy profile

Abstract

Anticoagulants are routinely used in stroke, embolism, infarct, etc. Blood clotting profile in such patients needs to be monitored frequently. Anticoagulants which can be administered orally such as warfarin and dicoumarol are preferred in such patients. Injectable anticoagulants such as heparin are prescribed when anticoagulation therapy is required for short duration. Absence of oral form of heparin makes it impractical for long-term use. Currently, warfarin and coumarone derivatives are the best available oral anticoagulants in market. They act by inhibiting decarboxylation of blood clotting factors II, VII, IX, and X. Pharmacological response of warfarin and dicoumarol needs to be monitored by frequent assessments of prothrombin time (PT) and international normalized ratio (INR). There is a need for a drug which can overcome these limitations. Apixaban is an oral anticoagulant which acts by inhibiting factor Xa. It does not require laboratory monitoring of PT and INR. Hence, it overcomes the limitations of heparin and warfarin. It acts by selectively inhibiting the activated factor Xa in a reversible manner. Apixaban has an oral bioavailability of ~50%. It is administered as twice daily dose. It is excreted in urine and feces. Apixaban is useful in atrial fibrillation, venous thromboembolism, and pulmonary embolism. Bleeding is the major side effect of apixaban. It has been found that apixaban has superiority over warfarin and aspirin in terms of efficacy and safety. Further studies are required to monitor and assess the pharmacokinetics, efficacy, adverse effects, and drug interaction data in many populations and sub-populations throughout the world.