Hemostatic Profiling of Generic Factor Xa Inhibitors Using ROTEM® Viscoelastometry and Multimodal Coagulation Assays: A Real-World Study in a Tunisian Cohort

<ns5:p>Background The emergence of generic direct factor Xa inhibitors like apixaban and rivaroxaban has significantly increased the global availability of essential anticoagulants in developing nations. However, we still lack a detailed understanding of how these generic versions behave in real-world clinical practice. This research offers an initial multimodal evaluation, within a Tunisian population, integrating conventional coagulation tests with specific anti-Xa activity and rotational thromboelastometry. Methods We conducted a prospective cross-sectional study at Sahloul University Hospital (Sousse, Tunisia) including 33 patients (mean age 71.3 ± 11.7 years) receiving generic apixaban (n = 25) or rivaroxaban (n = 8) for ≥1 month. Sixty-six paired blood samples were collected at trough (30 min before the next dose) and peak (2–3 h after intake). Standard coagulation tests (PT, aPTT, fibrinogen), calibrated chromogenic anti-Xa activity, and ROTEM®sigma assays were performed. Results Rivaroxaban produced consistent PT prolongation at trough (87.5%) and peak (100%), while apixaban exerted a milder, concentration-dependent effect (45.5% at trough; 73.9% at peak). PT correlated inversely with anti-Xa activity for both agents (apixaban: r = −0.79 at peak; rivaroxaban: r = −0.84 at peak). aPTT and fibrinogen were not significantly affected. Among ROTEM parameters, EXTEM clotting time (CT) was the sole viscoelastic parameter significantly correlated with anti-Xa activity: rivaroxaban r = 0.88 (p = 0.004) at trough and r = 0.87 (p = 0.012) at peak; apixaban ρ = 0.54 (p = 0.021) at trough and ρ = 0.69 (p &lt; 0.001) at peak. INTEM CT showed no significant correlation for either agent. Clot firmness, formation time, and maximum lysis were unaffected by either agent. Conclusion Generic factor Xa inhibitors show hemostatic profiles mirroring those of brand-name versions. EXTEM CT emerged as the ROTEM® parameter most closely tied to anticoagulant intensity, making it a practical bedside surrogate in urgent settings.</ns5:p>