Direct%2525252525252525252520oral%2525252525252525252520anticoagulants

# 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 rapid onset and offset periods. ## Primary Indications * Prevention of stroke and systemic embolism in non-valvular atrial fibrillation (NVAF). * Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE). * Reduction in the risk of recurrent DVT and PE. * Prophylaxis of DVT/PE following hip or knee replacement surgery. ## Adult Dosing * **Apixaban:** 5 mg BID for NVAF (reduce to 2.5 mg BID if ≥2 criteria: age ≥80, weight ≤60 kg, or SCr ≥1.5 mg/dL). For VTE treatment: 10 mg BID for 7 days, then 5 mg BID. * **Rivaroxaban:** 20 mg daily with the evening meal for NVAF. For VTE treatment: 15 mg BID for 21 days, then 20 mg daily with food. * **Dabigatran:** 150 mg BID for NVAF; 75 mg BID for patients with CrCl 15–30 mL/min (if permitted by local protocol). For VTE treatment: 150 mg BID after 5–10 days of parenteral anticoagulation. * **Edoxaban:** 60 mg daily for NVAF (do not use if CrCl >95 mL/min due to reduced efficacy). For VTE treatment: 60 mg daily after 5–10 days of parenteral anticoagulation. ## Pediatric Dosing * **Dabigatran:** FDA-approved for ages <18 years for VTE treatment/prevention based on weight-based capsules or oral pellets. * **Rivaroxaban:** FDA-approved for ages <18 years for VTE treatment/prevention based on weight-based oral suspension. * *Note:* Pediatric dosing is highly weight-dependent; consult current weight-based nomograms or institutional protocols. ## Dose Adjustments * **Renal Impairment:** Reduce doses or avoid medication based on CrCl (Cockcroft-Gault). Most contraindicated when CrCl <15–30 mL/min; dabigatran is primarily renally cleared (~80%). * **Hepatic Impairment:** Avoid in moderate to severe hepatic impairment (Child-Pugh B or C). ## Contraindications * Active pathological bleeding. * Mechanical prosthetic heart valves (dabigatran is strictly contraindicated). * Moderate to severe hepatic impairment (Child-Pugh B/C). * Severe renal impairment (CrCl <15–30 mL/min depending on agent). ## Adverse Effects * **Major:** Hemorrhage (GI, intracranial). * **Common:** Dyspepsia/gastritis (notably with dabigatran due to tartaric acid core), anemia, nausea, and dizziness. ## Key Drug Interactions * **P-gp and Strong CYP3A4 Inhibitors/Inducers:** Combined P-gp/strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir) significantly increase plasma concentrations; strong inducers (e.g., rifampin, carbamazepine, phenytoin) significantly decrease efficacy. *Avoid concurrent use.* ## Monitoring * **Baseline:** Baseline CBC, renal function (CrCl), and liver function tests (LFTs). * **Routine:** Periodic assessment of renal function (more frequent in elderly) and hemoglobin/hematocrit. * **Special:** There is no standardized routine coagulation monitoring. Anti-Xa levels (or thrombin time for dabigatran) may be used qualitatively in emergencies but require institutional validation. ## Clinical Pearls * **Adherence:** DOACs have short half-lives; missed doses significantly increase thrombotic risk. * **Reversal:** Idarucizumab is the specific reversal agent for dabigatran. Andexanet alfa is the reversal agent for apixaban and rivaroxaban. * **Transitions:** For conversion from warfarin, discontinue warfarin and initiate DOAC when INR falls below the threshold (usually <2.0–2.5). * **Perioperative:** Hold 24–72 hours prior to elective surgery depending on bleeding risk and renal function. *** **Disclaimer:** This information is for educational purposes. Verify all dosages, contraindications, and drug interactions against the most current FDA-approved prescribing information or institutional clinical practice guidelines before ordering or administering medications.