NOACs

NOACs, or direct oral anticoagulants (DOACs), are a class of medication used to prevent and treat blood clots without the need for routine monitoring like older vitamin K antagonists. The main agents are dabigatran, a direct thrombin inhibitor, and rivaroxaban, apixaban, and edoxaban, which are direct inhibitors of factor Xa. They are chosen for their predictable effects and convenient dosing.

Common indications include reducing stroke risk in nonvalvular atrial fibrillation and treatment or secondary prevention of venous thromboembolism, including deep vein thrombosis and pulmonary embolism. They are also used for prophylaxis of thromboembolism after certain orthopedic surgeries. They are not generally recommended for patients with mechanical heart valves and are typically avoided in pregnancy.

Advantages of NOACs include fixed dosing and the absence of routine coagulation monitoring in most patients, along with fewer dietary restrictions and drug interactions compared with warfarin. Limitations include a bleeding risk that can be significant and, for some agents, a need to adjust dosing in renal impairment. Drug interactions with P-glycoprotein and cytochrome P450–enzyme systems can affect exposure, and they may be unsuitable for patients with severe kidney disease or certain liver conditions.

Pharmacokinetics vary by agent; dabigatran is largely renally cleared, while rivaroxaban, apixaban, and edoxaban have mixed hepatic and renal pathways. Dose adjustments are common for reduced kidney function, and perioperative management often involves withholding the drug before procedures. Bridging is generally not required.

Reversal strategies exist for major bleeds: idarucizumab for dabigatran and andexanet alfa for factor Xa inhibitors, with non-specific agents like prothrombin complex concentrates as alternatives in some settings. As with all anticoagulants, individual risk factors and comorbidities guide selection and management.