Direct%252525252525252520oral%252525252525252520anticoagulants

# Direct Oral Anticoagulants (DOACs) ## Overview DOACs are target-specific anticoagulants. Dabigatran is a direct thrombin (IIa) inhibitor; rivaroxaban, apixaban, and edoxaban are Factor Xa inhibitors. They offer predictable pharmacokinetics, fewer food/drug interactions, and no requirement for routine INR monitoring compared to warfarin. ## Primary Indications * Non-valvular atrial fibrillation (stroke/systemic embolism prophylaxis). * Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE). * Prophylaxis of DVT/PE following hip or knee replacement surgery. ## Adult Dosing * **Apixaban (Eliquis):** 5 mg PO BID. Reduce to 2.5 mg BID if ≥2 of the following: Age ≥80, weight ≤60 kg, or serum creatinine ≥1.5 mg/dL. For DVT/PE treatment: 10 mg BID for 7 days, then 5 mg BID. * **Rivaroxaban (Xarelto):** 20 mg PO daily with the evening meal. For DVT/PE treatment: 15 mg BID for 21 days, then 20 mg daily. Max creatinine clearance (CrCl) adjustments required. * **Dabigatran (Pradaxa):** 150 mg PO BID. For DVT/PE treatment: 150 mg BID after 5–10 days of parenteral anticoagulation. * **Edoxaban (Savaysa):** 60 mg PO daily. Do not use if CrCl >95 mL/min (due to reduced efficacy in rapid clearance). ## Pediatric Dosing Pediatric dosing is weight- and age-dependent. Dabigatran and rivaroxaban have FDA-approved weight-based dosing regimens for VTE treatment in children, but they are highly protocol-specific. Dosing must be calculated using institutional pediatric hematology guidelines or validated weight-based nomograms. ## Dose Adjustments * **Renal:** All DOACs require dose reduction or avoidance based on CrCl (Cockcroft-Gault). Contraindicated in patients with Stage 5 CKD or on dialysis (except limited use of apixaban per specific institutional policies). * **Hepatic:** Avoid rivaroxaban and edoxaban in Child-Pugh B or C. Use dabigatran and apixaban with caution; limited data. ## Contraindications * Active pathological bleeding. * Mechanical prosthetic heart valves (dabigatran is contraindicated). * Moderate to severe hepatic impairment (varies by agent). * Concomitant use of strong dual P-gp and strong CYP3A4 inhibitors/inducers (e.g., ketoconazole, rifampin). ## Adverse Effects * Major and minor bleeding (GI bleeding is the most common site of clinically relevant mucosal bleeding). * Dyspepsia (specifically with dabigatran due to tartaric acid core). * Anemia. ## Key Drug Interactions * **P-gp/CYP3A4 inducers:** Reduce DOAC efficacy (e.g., carbamazepine, phenytoin, St. John’s Wort). * **P-gp/CYP3A4 inhibitors:** Increase DOAC exposure/bleeding risk (e.g., clarithromycin, amiodarone, fluconazole). * **Antiplatelets/NSAIDs:** Significantly increase the risk of major bleeding. ## Monitoring * **Baseline:** CBC (Hb/Hct), platelets, SCr, baseline liver function tests (ALT/AST). * **During therapy:** Periodic renal function (at least annually; more frequently in elderly or declining renal function), medication adherence, and signs of bleeding. * **Note:** Routine coagulation testing (PT/PTT) is not reliable for monitoring DOAC levels. Anti-Xa activity (calibrated for the specific drug) can be used in emergent scenarios to assess anticoagulant effect. ## Clinical Pearls * **Dabigatran:** Ensure the capsule is swallowed whole; do not open, as it significantly increases bioavailability. * **Reversal:** Idarucizumab is the specific reversal agent for dabigatran. Andexanet alfa is the specific reversal agent for rivaroxaban and apixaban (in life-threatening bleeding). * **Transitions:** For converting from warfarin to a DOAC, follow the "READ" rule: Stop warfarin and start DOAC when INR is below 2.0 (for most agents). *** *Disclaimer: This information is for educational purposes for healthcare professionals. Dosing, contraindications, and drug interactions can change. Always verify current prescribing information in a peer-reviewed clinical database (e.g., UpToDate, Lexicomp) or institutional formulary before prescribing or administering medication.*