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# Direct Oral Anticoagulants
## Overview
Direct oral anticoagulants (DOACs) inhibit specific coagulation factors: dabigatran (direct thrombin inhibitor), rivaroxaban, apixaban, edoxaban (factor Xa inhibitors). Fixed dosing, no routine monitoring required.
## Primary Indications
- Non-valvular atrial fibrillation (stroke prevention)
- Venous thromboembolism treatment and prevention
- VTE prophylaxis after hip/knee arthroplasty (rivaroxaban, apixaban, dabigatran)
## Adult Dosing
**Atrial Fibrillation:**
- Apixaban: 5 mg BID (2.5 mg BID if ≥2 of: age ≥80, weight ≤60 kg, Cr ≥1.5 mg/dL)
- Rivaroxaban: 20 mg once daily with food (15 mg if CrCl 15–50 mL/min)
- Dabigatran: 150 mg BID (75 mg BID if CrCl 15–30 mL/min)
- Edoxaban: 60 mg once daily (30 mg if CrCl 15–50 mL/min, weight ≤60 kg)
**VTE Treatment:**
- Apixaban: 10 mg BID x 7 days, then 5 mg BID
- Rivaroxaban: 15 mg BID x 21 days, then 20 mg once daily with food
- Dabigatran: 150 mg BID after 5–10 days parenteral anticoagulation
- Edoxaban: 60 mg once daily after 5–10 days parenteral anticoagulation
## Pediatric Dosing
**Note: Dosing depends on age/weight and specific indication. Consult local protocol.**
- Rivaroxaban: Approved for VTE treatment in children. Dose based on weight (e.g., 10–20 mg once daily equivalent; exact mg per kg per local protocol).
- Dabigatran: Approved for VTE treatment in children. Weight-based dosing (e.g., ~5.3–11.5 mg/kg/day divided BID depending on age/weight band).
- Apixaban and edoxaban less established in pediatrics.
## Dose Adjustments
- **Renal:** Avoid if CrCl <15–30 mL/min (varies by drug). Reduce dose as above for CrCl 15–50 mL/min. Edoxaban not for CrCl >95 mL/min.
- **Hepatic:** Contraindicated in severe hepatic impairment with coagulopathy.
- **Weight/age:** Apixaban 2.5 mg BID if ≥2 criteria met (see above).
## Contraindications
- Significant active bleeding
- Mechanical heart valves (all DOACs contraindicated)
- Severe renal impairment (CrCl <15–30 mL/min depending on agent)
- Severe hepatic impairment
- Pregnancy and lactation (except rivaroxaban limited data)
## Adverse Effects
- Bleeding (major, minor, GI—dabigatran more GI bleeding)
- GI upset (dabigatran)
- Rare: hepatic injury, thrombocytopenia
## Key Drug Interactions
- **Antiplatelets/NSAIDs:** Increased bleeding risk
- **Strong P-gp/3A4 inhibitors** (e.g., ketoconazole, ritonavir): Increase DOAC levels
- **Strong P-gp/3A4 inducers** (e.g., rifampin, phenytoin): Decrease DOAC levels
- **Warfarin/heparin:** Avoid combination
## Monitoring
- No routine coagulation monitoring required
- Monitor renal function (CrCl) periodically
- Assess for bleeding, anemia signs
- Reversal agents: idarucizumab (dabigatran), andexanet alfa (factor Xa inhibitors)
## Clinical Pearls
- DOACs have fast onset (1–4 hours) and short half-life. Missed dose: take up to 6–8 hours late
- Avoid in mechanical valves (NOACs contraindicated—use warfarin)
- Switching between anticoagulants: follow specific protocols (e.g., start DOAC when INR <2.0)
- Food increases rivaroxaban absorption; take 20 mg dose with food
*Disclaimer: This information is for educational purposes and is not a substitute for professional medical judgment. Always verify current dosing, local protocols, and prescribing information from the manufacturer and regulatory authorities before clinical use.*
