Apixaban

Introduction Overview

Generic Name

apixaban

Brand Name

Eliquis

Dosage Form

oral extended-release tablets (2.5 mg, 5 mg), tablet for oral suspension (0.5 mg), capsule sprinkle for oral suspension (0.15 mg)

Drug Class

Factor Xa inhibitors

Pharmacokinetics

Absorption:
Apixaban is rapidly absorbed after oral administration with peak plasma concentrations typically reached within 3 to 4 hours. The absolute bioavailability of apixaban tablets is approximately 50%. The drug demonstrates dose-proportional pharmacokinetics over the therapeutic dose range. Food intake does not significantly affect the absorption of apixaban, allowing it to be taken with or without meals. Tablet formulations for oral suspension achieve effective systemic exposure, and crushed tablets maintain stability for up to four hours in water, dextrose 5% in water (D5W), or apple juice, facilitating administration in patients with swallowing difficulties and pediatric populations.

Distribution:
Apixaban exhibits a moderate volume of distribution of approximately 21 liters, indicating distribution primarily in extracellular fluid with limited penetration into tissues. It is approximately 87% protein-bound in plasma, mainly to albumin, which influences its pharmacodynamic effects and potential for drug-drug interactions. The high protein binding also limits dialysis efficacy in overdose situations. The steady-state volume supports once- or twice-daily dosing by maintaining plasma concentrations within the therapeutic window without excessive accumulation.

Metabolism:
Apixaban undergoes oxidative metabolism primarily via cytochrome P450 isoenzyme CYP3A4/5 and to lesser extents by CYP1A2, CYP2C8, CYP2C9, CYP2C19, and CYP2J2. The metabolic pathways produce minor inactive metabolites, contributing to approximately 25% of apixaban elimination. The drug's metabolism can be impacted by concomitant administration of strong inhibitors or inducers of CYP3A4 and P-glycoprotein (P-gp), necessitating dose adjustments or avoidance of certain coadministered agents. Apixaban is not significantly metabolized via phase II conjugation pathways.

Elimination:
Apixaban is eliminated through multiple pathways, including renal excretion (~27%), biliary and direct intestinal excretion, and metabolic processes. The terminal half-life ranges from 8 to 15 hours, supporting twice-daily dosing. Renal clearance accounts for about 27% of total elimination, so renal impairment moderately affects drug levels but generally does not require extensive dose modifications except in severe renal dysfunction. In patients with end-stage renal disease on dialysis, apixaban exposure increases but dialysis does not effectively remove the drug due to high protein binding. Fecal elimination accounts for the majority of nonrenal clearance via hepatobiliary excretion. The multi-route elimination contributes to a predictable pharmacokinetic profile.

Dosage Forms

Available Dosage Forms:
Eliquis is available in multiple oral formulations to suit various patient needs and clinical scenarios. These include:
- Oral extended-release tablets: 2.5 mg and 5 mg film-coated tablets designed for twice-daily administration.
- Tablet for oral suspension: 0.5 mg formulation enabling accurate dosing in pediatric patients or adults with swallowing difficulties.
- Capsule sprinkle for oral suspension: 0.15 mg capsules that can be opened and administered as a suspension, particularly used in pediatric populations.

Dosages for Adults and Adolescents:
- Reduction of stroke risk and systemic embolism in nonvalvular atrial fibrillation: 5 mg orally twice daily; reduced to 2.5 mg twice daily in patients with two or more of the following criteria: age ≥80 years, body weight ≤60 kg, or serum creatinine ≥1.5 mg/dL.
- DVT prophylaxis following hip replacement surgery: 2.5 mg orally twice daily for 35 days starting 12-24 hours post-surgery.
- DVT prophylaxis following knee replacement surgery: 2.5 mg orally twice daily for 12 days starting 12-24 hours post-surgery.
- Treatment of DVT and PE: Initial dose of 10 mg orally twice daily for 7 days, followed by 5 mg twice daily as maintenance.
- Reduction in the risk of recurrent DVT and PE: 2.5 mg orally twice daily.

Specific Patient Populations:
- Pediatric patients (from birth and older weighing at least 2.6 kg): Eliquis is indicated for treatment of venous thromboembolism (VTE) following at least 5 days of initial anticoagulant therapy, with dose regimens adjusted according to body weight and formulation (oral suspension or sprinkle). The dosing in children requires careful weight-based adjustments and close clinical monitoring.
- Adults and children weighing at least 35 kg who have difficulty swallowing tablets may receive crushed tablets suspended in water, D5W, apple juice, or applesauce. The suspension must be administered promptly and can also be delivered via nasogastric tube with appropriate volume flushing.
- Dose modifications or avoidance recommendations apply in patients with renal or hepatic impairment and in cases of co-administration with strong CYP3A4 and P-gp inhibitors.

Mechanism Of Action

Apixaban, the active ingredient in Eliquis, is a highly selective, reversible, direct inhibitor of factor Xa (FXa), a key serine protease in the coagulation cascade. Factor Xa plays a pivotal role in both the intrinsic and extrinsic pathways by catalyzing the conversion of prothrombin (factor II) to thrombin (factor IIa). By directly inhibiting factor Xa, apixaban effectively reduces the generation of thrombin and limits the conversion of fibrinogen to fibrin, thus impairing thrombus formation.

Unlike indirect anticoagulants that require cofactors such as antithrombin III, apixaban exerts its anticoagulant effect without the need for activation, providing a predictable and rapid onset of action. This direct inhibition is selective, allowing the endogenous hemostatic balance to be maintained to some extent, thereby reducing bleeding risks compared to traditional anticoagulants like warfarin.

At the cellular level, factor Xa inhibition disrupts the amplification phase of coagulation, attenuating platelet activation and aggregation driven by thrombin. This reduces the propagation and stabilization of pathological clots in vascular beds. This action translates clinically into decreased risk of embolic stroke in atrial fibrillation, prevention of venous thromboembolism, and reduction of recurrent thrombotic events.

Compared to other factor Xa inhibitors such as rivaroxaban, apixaban offers a favorable pharmacokinetic and safety profile, with lower peak-to-trough plasma concentration variability and lower bleeding rates demonstrated in clinical trials. Clinical studies including ARISTOTLE and AMPLIFY have provided robust evidence of apixaban's efficacy and safety in stroke prevention and thrombosis management.

Pharmacological Actions

Selective, reversible direct inhibition of factor Xa enzyme in the coagulation cascade.
Reduction of thrombin generation leading to decreased fibrin clot formation.
Effective anticoagulation with rapid onset and predictable pharmacokinetics.
Prevention of arterial and venous thrombosis through disruption of coagulation amplification.
Minimal interaction with platelet function compared to other anticoagulants.
Oral anticoagulant activity independent of antithrombin III.
Stable plasma concentrations due to balanced absorption, metabolism, and elimination.
Favorable bleeding risk profile compared to vitamin K antagonists.
Efficacious in prevention of stroke in nonvalvular atrial fibrillation.
Indicated for prophylaxis and treatment of deep vein thrombosis and pulmonary embolism.
Suitable for use in pediatric patients with weight-based dosing.
Compatible with various dosage forms facilitating use in patients with swallowing difficulties.
Dose adjustments recommended in patients with renal impairment and with certain drug interactions.
Rapid offset of anticoagulant effect within 24-48 hours after discontinuation.
Available reversal agent (andexanet alfa) for emergency bleeding situations in adults.

Therapeutic Or Clinical Uses

Prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation.
Prophylaxis of deep vein thrombosis (DVT) following hip or knee replacement surgery.
Treatment of acute deep vein thrombosis and pulmonary embolism.
Reduction in the risk of recurrent DVT and pulmonary embolism after initial therapy.
Treatment and secondary prevention of venous thromboembolism (VTE) in pediatric patients weighing at least 2.6 kg following initial parenteral anticoagulation.
Use in adults and adolescents with contraindications to warfarin or those requiring predictable anticoagulation without routine monitoring.
Management of thromboembolic disorders in patients at high risk of clot formation.
Alternative anticoagulant choice for patients requiring oral options with fewer dietary and drug interactions compared to warfarin.
Prevention of thrombotic complications in medical contexts requiring perioperative anticoagulation management.
Part of clinical protocols to reduce hospitalization and complications associated with thrombosis in orthopedic surgery.
Use in patients with renal impairment with dose adjustments.
Selected by clinicians for patients prioritizing fixed dosing and reduced monitoring needs.
Extended indication for treatment in pediatric patients with appropriate dosing guidance.
Selected anticoagulant for outpatient thrombosis management due to oral availability and convenience.

Side Or Adverse Effects

Bleeding, the most common adverse effect, ranging from minor to severe hemorrhages.
Bruising and prolonged bleeding times after injury or dental procedures.
Heavy menstrual bleeding (menorrhagia) particularly noted in female patients.
Headache and dizziness reported more frequently in pediatric populations.
Vomiting and gastrointestinal discomfort in some patients.
Rare but serious bleeding events such as intracranial hemorrhage and gastrointestinal bleeding.
Hypersensitivity reactions including rash, hives, and anaphylaxis in rare cases.
Spinal or epidural hematoma leading to potential paralysis, especially in patients undergoing neuraxial anesthesia or spinal puncture.
Elevated liver enzymes in isolated cases, necessitating liver function monitoring.
Potential for increased bleeding risk when combined with other anticoagulants or certain medications.
Bleeding in unusual sites including hematuria and epistaxis.
Symptoms related to severe bleeding including weakness, dizziness, or unexpected pain or swelling.
Risk of thrombotic events upon abrupt discontinuation.
Allergic reactions with swelling of face, tongue, or throat requiring emergency intervention.
Laboratory abnormalities such as altered coagulation parameters, though routine testing is not generally recommended.

Precautions

Inform healthcare providers of all concurrent medications to assess bleeding risk.
Avoid abrupt discontinuation to prevent increased risk of thrombotic events.
Use cautiously in patients with a history of bleeding disorders or active bleeding.
Close monitoring advised in patients with hepatic or severe renal impairment.
Special care for elderly patients due to increased bleeding risk with age.
Avoid use in patients with mechanical heart valves or antiphospholipid syndrome due to risk of thrombosis.
Stop drug 24-48 hours before scheduled surgery or invasive procedures to reduce bleeding risks.
Avoid concomitant use with strong combined P-gp and CYP3A4 inhibitors or adjust dose accordingly.
Caution when coadministered with NSAIDs, SSRIs, SNRIs, or other agents that increase bleeding risk.
Not recommended during pregnancy and breastfeeding without specialist advice due to bleeding risks to mother and fetus.
Administer with caution in patients with spinal defects or history of spinal surgery undergoing neuraxial procedures.
Provide patient education on signs of bleeding and when to seek immediate medical attention.
Regularly reassess benefit-risk ratio in long-term therapy scenarios.
Ensure availability of reversal strategies or emergency protocols in case of major bleeding.
Dose adjustments necessary in elderly and those with renal impairment based on clinical evaluation.

Warnings

Significant risk of severe or fatal bleeding; immediate medical attention required if bleeding occurs.
Risk of spinal or epidural hematoma potentially causing long-term or permanent paralysis, especially with spinal anesthesia or puncture.
Stop Eliquis 24-48 hours before surgeries or invasive procedures to minimize bleeding risk.
Abrupt cessation may lead to increased risk for thromboembolic events such as stroke or blood clots.
Not indicated for patients with mechanical heart valves or antiphospholipid antibody syndrome with triple positivity.
Use caution in patients with active pathological bleeding or high bleeding risk conditions.
Pregnancy: potential for increased maternal and fetal bleeding, uncertainty about fetal safety.
Risk of allergic reactions including hives, swelling, and anaphylaxis necessitating emergency care.
Concurrent use with other anticoagulants or antiplatelet drugs markedly increases bleeding risk.
Patients should avoid activities that increase bleeding or injury risk during treatment.
Monitor patients for any signs of unexpected bleeding or bruising throughout therapy.
Use cautiously in patients with hepatic disease contributing to coagulopathy.
Patients undergoing neuraxial anesthesia require vigilant neurologic monitoring post-procedure.
Reversal agent andexanet alfa is available for adults in life-threatening bleeding events; pediatric safety not established.
Combination with strong P-gp and CYP3A4 inhibitors requires dose adjustment to prevent elevated drug exposure.

Contraindication

Known hypersensitivity to apixaban or any component of Eliquis formulations.
Active pathological bleeding such as gastrointestinal hemorrhage or intracranial bleeding.
Patients with mechanical prosthetic heart valves.
Patients with antiphospholipid antibody syndrome, particularly with triple-positive antibody tests.
Severe hypersensitivity reactions to factor Xa inhibitors or excipients.
Concurrent use with other anticoagulants except under specific clinical protocols (e.g., bridging).
Patients with significant bleeding diatheses or hemorrhagic tendencies without established control.
Patients undergoing neuraxial anesthesia without adequate thromboprophylaxis management.
Pregnancy unless benefits outweigh risks and no safer alternatives are viable.
Known severe hepatic disease associated with coagulopathy and clinically relevant bleeding risk.
Patients with severe renal impairment without specialist guidance.
Use with caution in concomitant therapy with strong combined P-gp and CYP3A4 inhibitors unless dosing modification is possible.
Patients scheduled for urgent surgery or interventions that cannot accommodate drug clearance timelines.
Contraindicated in pediatric patients weighing less than 2.6 kg (5.7 pounds) due to lack of safety/efficacy data.
Known hypersensitivity to formulation excipients including lactose, croscarmellose, and others.

Drug Interactions

Combined P-gp and strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, ritonavir) increase apixaban plasma concentration; dose reduction or avoidance recommended.
Concurrent use with other anticoagulants (e.g., heparin, warfarin) increases bleeding risk; monitoring and management essential.
NSAIDs (e.g., ibuprofen, naproxen, diclofenac) potentiate bleeding risk when taken with Eliquis.
Antiplatelet agents including aspirin and clopidogrel elevate bleeding risk with apixaban coadministration.
Selective serotonin reuptake inhibitors (SSRIs) and serotonin norepinephrine reuptake inhibitors (SNRIs) increase bleeding tendency.
Strong inducers of CYP3A4 and P-gp (e.g., rifampin, carbamazepine, phenytoin) may reduce apixaban efficacy by decreasing plasma levels.
Antidepressants may interact indirectly via platelet function alteration, further raising bleeding risks.
Co-administration with herbal supplements such as feverfew or others known to affect coagulation should be avoided or closely monitored.
Activated charcoal may reduce apixaban absorption if administered soon after dosing, useful in overdose management.
Drugs that affect hemostasis require consultation and monitoring when co-prescribed with Eliquis.
Potential interaction with combined oral contraceptives requiring clinical judgment.
Pharmacokinetic interactions necessitate individualized therapy adjustments in polypharmacy contexts.
Avoid concomitant use with other direct oral anticoagulants to mitigate cumulative bleeding risk.
Frequent therapeutic assessment is advised in patients on multiple interacting medications.
Patient counseling on potential interactions with over-the-counter products and supplements is critical.

Preparations Of The Drug

Eliquis 2.5 mg oral extended-release film-coated tablets containing apixaban as active ingredient.
Eliquis 5 mg oral extended-release film-coated tablets with apixaban.
Eliquis 0.5 mg film-coated tablets formulated for oral suspension for pediatric usage.
Eliquis Sprinkle 0.15 mg capsule designed for oral suspension to facilitate administration in infants and children.
Tablet excipients include anhydrous lactose, croscarmellose sodium, magnesium stearate, microcrystalline cellulose, sodium lauryl sulfate, hypromellose, lactose monohydrate, titanium dioxide, and iron oxides for tablet coloration.
Sprinkle formulation contains hypromellose and sugar spheres suitable for suspension.
Stable formulations allow for preparation in water, D5W, apple juice, or applesauce with stability up to 4 hours after preparation.
Manufactured by Bristol Myers Squibb and Pfizer, ensuring quality and consistency in global supply.
Packaging available in blister packs, bottles, and pediatric dose-specific preparations.
Includes detailed Instructions for Use for pediatric dosing and suspension preparation.
Designed for twice daily dosing with prolonged pharmacodynamic effect.
Formulation supports patients with dysphagia through alternative administration routes like nasogastric tubes.
Storage recommended at controlled room temperature (20°C to 25°C).
Product labeling includes comprehensive patient information, contraindications, precautions, and clinical guidance.
Regular formulation updates comply with regulatory advisories and post-marketing safety data.