Directoralanticoagulants

Directoralanticoagulants, more commonly known as direct oral anticoagulants (DOACs), are a class of oral medications that directly inhibit specific coagulation factors. They were developed to provide predictable anticoagulation with fewer food and drug interactions and without the need for routine coagulation monitoring required by warfarin. The available DOACs fall into two mechanistic groups: direct thrombin inhibitors and direct factor Xa inhibitors. Dabigatran is a direct thrombin inhibitor, while rivaroxaban, apixaban, and edoxaban are direct factor Xa inhibitors. They have rapid onset of action, relatively short half-lives, and fixed dosing in many situations.

DOACs are commonly used for nonvalvular atrial fibrillation to reduce stroke and systemic embolism, and for the treatment of acute venous thromboembolism (VTE) such as deep vein thrombosis and pulmonary embolism. They are also used for prophylaxis after certain orthopedic surgeries. They are generally not recommended for patients with mechanical heart valves and require caution in valvular disease where warfarin remains preferred. Renal function, age, body weight, and drug interactions influence dosing and safety.

Practical considerations include the lack of routine INR monitoring, but ongoing assessment of renal and hepatic function is important. DOAC doses may be adjusted for renal impairment and interacting medications, particularly strong inhibitors or inducers of P-glycoprotein and CYP3A4. Bleeding is still a possible adverse effect, and specific reversal agents are available for some agents: idarucizumab for dabigatran; andexanet alfa for factor Xa inhibitors. In settings where reversal agents are unavailable, alternative strategies or non-DOAC anticoagulation may be necessary. Coagulation tests are not uniformly reliable for monitoring DOAC effect, though specialized assays can be informative in certain scenarios.