Guides anticoagulation selection, dosing, monitoring, and bridging protocols. Use when managing warfarin, DOACs, or heparin therapy, or planning periprocedural anticoagulation.
Guides anticoagulation selection, dosing, monitoring, and bridging protocols for warfarin, DOACs, and heparin therapy.
Anticoagulants are consistently ranked among the top high-alert medications by the Institute for Safe Medication Practices (ISMP). Warfarin alone accounts for more emergency department visits for adverse drug events than any other medication class in patients over 65. Dosing errors, inadequate monitoring, and improper periprocedural management lead to catastrophic bleeding events or thromboembolic strokes.
The complexity of anticoagulation management spans multiple dimensions: selecting the appropriate agent based on indication (atrial fibrillation, VTE, mechanical heart valve), renal-adjusted dosing for DOACs, INR-based warfarin titration, weight-based heparin nomograms, bridging decisions for surgical patients, and reversal agent selection during active bleeding. The Joint Commission National Patient Safety Goal NPSG.03.05.01 specifically addresses anticoagulation safety, and accredited institutions must maintain anticoagulation management protocols. Pharmacist-managed anticoagulation clinics consistently demonstrate superior time-in-therapeutic-range (TTR) compared to physician-only management.
Match indication to appropriate anticoagulant options:
| Indication | Preferred Agents | Contraindicated |
|---|---|---|
| Non-valvular AF | Apixaban, rivaroxaban, dabigatran, edoxaban, warfarin | — |
| Mechanical heart valve | Warfarin (target INR 2.5-3.5) | All DOACs (RE-ALIGN trial) |
| Acute VTE treatment | Apixaban, rivaroxaban (single-drug), LMWH→dabigatran/edoxaban, LMWH→warfarin | — |
| VTE prophylaxis (surgical) | Enoxaparin, rivaroxaban, apixaban (indication-specific) | — |
| Heparin-induced thrombocytopenia | Argatroban, bivalirudin | Heparin, LMWH, warfarin (acute phase) |
| Antiphospholipid syndrome (triple-positive) | Warfarin (INR 2-3) | DOACs (TRAPS trial) |
Calculate risk stratification scores:
Warfarin: Initiate 5 mg daily (2.5 mg for elderly, malnourished, liver disease, CYP2C9/VKORC1 polymorphisms). Check INR at day 3-5, adjust by 10-20% increments.
DOAC Renal-Adjusted Dosing:
| Drug | Standard Dose (AF) | Renal Adjustment |
|---|---|---|
| Apixaban | 5 mg BID | 2.5 mg BID if ≥2 of: age ≥80, weight ≤60 kg, SCr ≥1.5 |
| Rivaroxaban | 20 mg daily with food | 15 mg daily if CrCl 15-50 mL/min |
| Dabigatran | 150 mg BID | 75 mg BID if CrCl 15-30 mL/min; avoid if <15 |
| Edoxaban | 60 mg daily | 30 mg daily if CrCl 15-50 mL/min, weight ≤60 kg, or P-gp inhibitor |
Weight-based heparin nomogram (VTE): 80 units/kg bolus → 18 units/kg/hour infusion. Check aPTT at 6 hours. Adjust per institution-specific nomogram targeting aPTT 1.5-2.5x control or anti-Xa 0.3-0.7 IU/mL.
Enoxaparin: 1 mg/kg SC BID (treatment) or 40 mg SC daily (prophylaxis). Reduce to 1 mg/kg daily if CrCl <30 mL/min. Monitor anti-Xa in obesity (>120 kg), renal impairment, and pregnancy.
| Agent | Monitoring Parameter | Target | Frequency |
|---|---|---|---|
| Warfarin | PT/INR | 2.0-3.0 (most); 2.5-3.5 (mechanical valve) | Daily inpatient → weekly → monthly |
| Heparin UFH | aPTT or anti-Xa | aPTT 1.5-2.5x control; anti-Xa 0.3-0.7 | q6h until stable, then daily |
| Enoxaparin | Anti-Xa (select populations) | 0.5-1.0 IU/mL (BID dosing peak, 4h post) | At steady state in special populations |
| DOACs | Generally not monitored | Drug-specific anti-Xa or dTT if needed | Pre-procedure or suspected toxicity |
Monitor for bleeding: daily hemoglobin, stool guaiac, urinalysis, neurological checks for ICH risk.
Apply the BRIDGE trial framework for AF patients on warfarin:
DOAC perioperative management: Hold based on renal function and bleeding risk:
| Agent | Reversal | Dose |
|---|---|---|
| Warfarin | Vitamin K (IV), 4-factor PCC | Vitamin K 10 mg IV; PCC per INR-based dosing |
| Dabigatran | Idarucizumab | 5 g IV (two 2.5 g boluses) |
| Apixaban/Rivaroxaban | Andexanet alfa or 4-factor PCC | Andexanet per package insert; PCC 25-50 units/kg |
| UFH | Protamine | 1 mg per 100 units heparin (max 50 mg) |
| Enoxaparin | Protamine (partial) | 1 mg per 1 mg enoxaparin (<8h); 60-80% reversal |