Apixaban is an oral anticoagulant and direct inhibitor of factor Xa which is used to decrease the risk of venous thromboses, systemic embolization and stroke in patients with atrial fibrillation, and lower the risk of deep vein thrombosis and pulmonary embolus after knee or hip replacement surgery. Apixaban has been linked to a low rate of serum aminotransferase elevations during therapy and to rare instances of clinically apparent liver injury.
Apixaban (a pix' a ban) is a direct and reversible inhibitor of factor Xa (-xaban), the rate controlling last step in the generation of thrombin, the final intermediate in blood coagulation. Inhibiting thrombin prevents the conversion of fibrinogen to fibrin and subsequent cross linking of fibrin monomers, platelet activation and amplification of coagulation. Apixaban has been shown to be as effective as warfarin and more effective than aspirin in preventing stroke and systemic embolization in patients with atrial fibrillation. Clinical trials have also shown that apixaban therapy can decrease the risk of deep vein thrombosis and pulmonary embolism in patients undergoing hip or knee replacement surgery. Apixaban was approved for use in the United States in 2012. Current indications are for prevention of stoke and systemic embolism in patients with nonvalvular atrial fibrillation, prevention of deep vein thrombosis after hip or knee replacement surgery, treatment of deep vein thrombosis and pulmonary embolism, and reduction in risk of recurrence of deep vein thrombosis or pulmonary embolism. Apixaban is available in 2.5 and 5 mg tablets under the commercial name Eliquis. The usual dose is 2.5 or 5 mg twice daily and varies somewhat by indication. Unlike warfarin, apixaban and the other oral direct thrombin and factor Xa inhibitors do not require monitoring of bleeding time or INR. Side effects are not common, but can include bleeding, headache, dizziness, fatigue, gastrointestinal upset, nausea, arthralgias and rash. Uncommon, but potentially severe adverse events include severe bleeding episodes and hypersensitivity reactions.
Apixaban is associated with serum aminotransferase elevations greater than 3 times the upper limit of normal in 1% to 2% of treated patients. This rate is similar or lower than rates with warfarin or comparator arms. In premarketing studies, no instances of clinically apparent liver injury were reported, but subsequent to its approval and more wide scale use, several reports of mild but clinically apparent liver injury have been published. The liver injury arose within days of starting apixaban and the pattern of liver enzyme elevations was hepatocellular. Immunoallergic and autoimmune features were not present and recovery was rapid once apixaban was stopped.
Likelihood score: D (possible rare cause of clinically apparent liver injury).
Mechanism of Injury
Apixaban is metabolized in the liver predominantly via the cytochrome P450 system, CYP 3A4, and P-glycoprotein, and potent inhibitors of CYP 3A4 (such as itraconazole, ritonavir and clarithromycin) can cause elevated levels of apixaban, while inducers of CYP 3A4 (such as rifampin or phenytoin) can lead to reduced and ineffective levels of the anticoagulant. Liver injury from apixaban may be due to production of a toxic or immunogenic intermediate.
Outcome and Management
The severity of liver injury associated with apixaban has ranged from mild, asymptomatic and self-limited elevations in serum aminotransferases to hepatitis with mild jaundice. There have been no reports of fulminant hepatic failure attributed to apixaban or cases of chronic hepatitis or vanishing bile duct syndrome. In some instances, patients with acute liver injury due to one direct factor Xa inhibitor (rivaroxaban) have tolerated another (apixaban) without recurrence of liver abnormalities.
REPRESENTATIVE TRADE NAMES
Apixaban – Generic, Eliquis®
Product labeling at DailyMed, National Library of Medicine, NIH
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References updated: 09 February 2018
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Apixaban (Eliquis)--a new oral anticoagulant for atrial fibrillation. Med Lett Drugs Ther 2013; 55 (1409): 9-10. PubMed Citation (Concise review of efficacy and safety of apixaban for prevention of stroke or systemic embolization in patients with nonvalvular atrial fibrillation which is equivalent or better in efficacy than warfarin with a lower rate of bleeding; no mention of hepatotoxicity or ALT elevations).
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Blood Coagul Fibrinolysis 2015; 26: 699-702. PubMed Citation (67 year old man developed ALT elevations 6 months after starting rivaroxaban [peak ALT 391 U/L, Alk P 120 U/L, bilirubin 1.3 mg/dL], which fell into the normal range within 2 months of switching to apixaban; ultrasound suggested fatty liver which also resolved with stopping).
Chalasani N, Bonkovsky HL, Fontana R, Lee W, Stolz A, Talwalkar J, Reddy KR, et al.; United States Drug Induced Liver Injury Network. Features and outcomes of 899 patients with drug-induced liver injury: The DILIN Prospective Study. Gastroenterology 2015; 148: 1340-52.e7. PubMed Citation (Among 899 cases of drug induced liver injury enrolled in a US prospective study between 2004 and 2013, two cases were attributed to anticoagulants (prasugrel and dalteparin), but none to apixaban or other direct factor Xa antagonists).
Cordeanu M, Lambert A, Gaertner S, Nouri S, Mirea C, Alt-Tebacher M, Stephan
D. Apixaban-induced hepatotoxicity. Int J Cardiol 2016; 204: 4-5. PubMed Citation (72 year old woman developed asymptomatic elevations in serum enzymes 4 days after restarting apixaban and 7 days after pacemaker implantation [bilirubin normal, ALT ~185 U/L, Alk P ~120 U/L], values returning to normal within 16 days of stopping).
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Case Rep 2016; 1-3. PubMed Citation (81 year old woman with atrial fibrillation developed weakness and abdominal pain 3 days after starting apixaban [bilirubin 2.5 mg/dL, ALT 199 U/L, Alk P 72 U/L], abnormal values falling into the normal range within 7 days of stopping).
Alonso A, MacLehose RF, Chen LY, Bengtson LG, Chamberlain AM, Norby FL, Lutsey
PL. Prospective study of oral anticoagulants and risk of liver injury in patients
with atrial fibrillation. Heart 2017; 103: 834-9. PubMed Citation (Analysis of a database on more than 1 million patients with nonvalvular atrial fibrillation on oral anticoagulants identified 960 hospitalizations with liver injury, rates being highest for warfarin, intermediate for rivaroxaban, and lowest for apixaban and dabigatran).
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