Direct%252525252520oral%252525252520anticoagulants

# Direct Oral Anticoagulants (DOACs) ## Overview DOACs, specifically direct thrombin inhibitors (dabigatran) and Factor Xa inhibitors (apixaban, rivaroxaban, edoxaban), provide predictable anticoagulation without the need for routine INR monitoring. They have a faster onset/offset than warfarin and fewer food/drug interactions. ## Primary Indications * Stroke prevention in non-valvular atrial fibrillation (NVAF). * Treatment and secondary prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE). * VTE prophylaxis following elective hip or knee replacement. ## Adult Dosing * **Apixaban:** NVAF: 5 mg PO BID. (Reduce to 2.5 mg BID if ≥2 criteria met: age ≥80, weight ≤60 kg, or Scr ≥1.5 mg/dL). VTE: 10 mg PO BID for 7 days, then 5 mg BID. * **Rivaroxaban:** NVAF: 20 mg PO daily with the evening meal. VTE: 15 mg PO BID for 21 days, then 20 mg daily. * **Dabigatran:** NVAF: 150 mg PO BID. VTE (after 5–10 days parenteral): 150 mg PO BID. * **Edoxaban:** NVAF: 60 mg PO daily. VTE: 60 mg daily after 5–10 days parenteral. ## Pediatric Dosing Dosing is highly variable based on weight and age. FDA-approved dosing is established for pediatric VTE (e.g., dabigatran and rivaroxaban are approved for select pediatric populations). **Strictly follow institutional protocols or current hematology guidelines (e.g., ISTH or ASH) for weight-based nomograms.** Off-label use must be guided by specialized pediatric hematology consults. ## Dose Adjustments Requires renal function adjustment (CrCl calculation using Cockcroft-Gault). * **Apixaban:** Reduce for age/weight/Scr criteria. * **Rivaroxaban:** Reduce to 15 mg daily for CrCl 15–50 mL/min in NVAF. * **Dabigatran:** Reduce to 75 mg BID for CrCl 15–30 mL/min. * **Edoxaban:** Reduce to 30 mg daily for CrCl 15–50 mL/min. * *Avoid all DOACs if CrCl <15 mL/min or on dialysis (limited data, though apixaban is sometimes used off-label in ESRD).* ## Contraindications * Active pathological bleeding. * Mechanical prosthetic heart valves (dabigatran contraindicated; others not recommended). * Moderate-to-severe hepatic impairment (Child-Pugh B/C). * Pregnancy and breastfeeding (category restricted). ## Adverse Effects * Major bleeding (gastrointestinal, intracranial). * Anemia. * Dyspepsia (most common with dabigatran due to tartaric acid core). * Elevated liver enzymes (rare). ## Key Drug Interactions * **Strong P-gp and CYP3A4 inhibitors (e.g., ketoconazole, ritonavir):** Increase levels; avoid or dose-adjust per package insert. * **Strong P-gp and CYP3A4 inducers (e.g., rifampin, phenytoin, carbamazepine, St. John's wort):** Decrease levels; avoid. * **Antiplatelet/NSAIDs:** Significant additive bleed risk. ## Monitoring * Baseline: CBC, CrCl, LFTs, PT/aPTT (as a baseline, not for efficacy). * Periodic: Renal function (at least annually; more frequently in elderly or CKD), hemoglobin/hematocrit. * No standardized lab test validates efficacy in routine practice; use anti-factor Xa (for inhibitors) or TT/ECT (for dabigatran) only in life-threatening emergencies. ## Clinical Pearls * **Adherence:** Due to short half-lives, missed doses significantly increase prothrombotic risk. * **Reversal:** Idarucizumab is the specific reversal agent for dabigatran. Andexanet alfa is the reversal agent for factor Xa inhibitors. * **Transitioning:** Utilize institutional "bridging" protocols when switching between warfarin and DOACs or parenteral anticoagulants. * **GI Bleeding:** Patients on DOACs (especially rivaroxaban or edoxaban) may have a higher risk of GI hemorrhage compared to warfarin. *** **Educational Disclaimer:** This information is for educational purposes. Dosing and clinical decisions must be verified against current institutional policies, the latest product monographs, and clinical judgment based on the individual patient's status.