Fondaparinux belongs to which description?

• A. Enoxaparin
• B. Dalteparin
• C. Heparin
• D. Fondaparinux

Answer: (D)

Fondaparinux is a synthetic pentasaccharide that binds antithrombin and selectively inhibits factor Xa, with negligible activity on thrombin. This specific action distinguishes it from heparin products that target both Xa and IIa to varying degrees. Enoxaparin and dalteparin are low molecular weight heparins, which are heterogeneous mixtures offering anti-Xa and some anti-IIa effects, while unfractionated heparin inhibits both Xa and IIa as well. The unique, pure anti-Xa activity of fondaparinux—via antithrombin binding—is what best fits its description.