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# Apixaban (Eliquis)
## Overview
Apixaban is a selective, reversible inhibitor of both free and clot-bound factor Xa. It inhibits platelet thrombus formation indirectly by preventing thrombin generation. It has high oral bioavailability and a predictable pharmacokinetic profile.
## Primary Indications
* Reduction of risk of stroke and systemic embolism in non-valvular atrial fibrillation (NVAF).
* Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE).
* Reduction in the risk of recurrent DVT/PE following initial therapy.
* Prophylaxis of DVT (which may lead to PE) in patients undergoing hip or knee replacement surgery.
## Adult Dosing
* **NVAF:** 5 mg PO BID. Reduce to 2.5 mg PO BID if patient meets at least two of the following: Age ≥80 years, Body weight ≤60 kg, or Serum creatinine ≥1.5 mg/dL.
* **Treatment of DVT/PE:** 10 mg PO BID for 7 days, followed by 5 mg PO BID.
* **Prevention of recurrent DVT/PE:** 2.5 mg PO BID after at least 6 months of initial treatment.
* **Post-op Orthopedic Prophylaxis:** 2.5 mg PO BID; initiate 12–24 hours post-operatively. Duration: 12 days for knee replacement; 35 days for hip replacement.
## Pediatric Dosing
There is no FDA-approved pediatric dosing for apixaban. Dosing in clinical trials (e.g., EINSTEIN-Jr) varies by weight-based nomograms. Use is currently off-label and should only be managed by pediatric hematology specialists using institutional protocols or clinical trial guidelines.
## Dose Adjustments
* **Renal Impairment:** No dose adjustment necessary for mild to moderate impairment. Use with caution in severe renal impairment (CrCl <15 mL/min); no data for dialysis patients (clinical efficacy/safety uncertain).
* **Hepatic Impairment:** Use with caution in Child-Pugh class B. Avoid in Child-Pugh class C.
## Contraindications
* Active pathological bleeding.
* Severe hypersensitivity to apixaban.
* Prosthetic heart valves (significantly increased risk of thromboembolism/bleeding).
## Adverse Effects
* Major/Clinically relevant bleeding (GI, epistaxis, hematuria).
* Anemia.
* Nausea.
* Hypersensitivity reactions (rare).
## Key Drug Interactions
* **P-gp and Strong CYP3A4 inhibitors/inducers:** Co-administration with strong dual inhibitors (e.g., ketoconazole, ritonavir) significantly increases plasma levels; avoid or reduce dose based on local guidelines. Strong dual inducers (e.g., rifampin, carbamazepine) significantly decrease efficacy; avoid use.
* **Antiplatelet/Antithrombotic agents:** Increased risk of bleeding when combined with NSAIDs, SSRIs, SNRIs, or other anticoagulants.
## Monitoring
* **Baseline:** CBC, renal function (SCr/CrCl), and liver function tests.
* **Ongoing:** Periodic assessment of renal function and hemoglobin/hematocrit. No routine monitoring of PT/INR or aPTT is recommended; these tests are not reliable for assessing anticoagulant activity.
* **Signs of Bleeding:** Monitor for signs of occult bleeding (e.g., melena, unexplained fatigue/pallor).
## Clinical Pearls
* **Missed Dose:** If a dose is missed, take it immediately; do not double the dose to make up for the missed one.
* **Surgery:** Discontinue at least 48 hours before elective surgery with moderate-to-high bleeding risk, or 24 hours for low-risk procedures.
* **Reversal:** Andexanet alfa is the FDA-approved specific reversal agent for life-threatening or uncontrolled bleeding. Prothrombin complex concentrates (PCC) may be used if andexanet is unavailable.
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*Disclaimer: This information is for educational purposes only. Always consult the most recent FDA-approved prescribing information, institutional protocols, and clinical databases (e.g., Lexicomp, UpToDate) before prescribing or administering medication.*
