Which of the following is classified as a low-molecular-weight heparin (LMWH)?

Enoxaparin is classified as a low-molecular-weight heparin (LMWH) because it is derived from unfractionated heparin through a process that fractionates the heparin molecule, resulting in shorter chains of polysaccharides. This modification allows LMWHs like enoxaparin to have a more predictable anticoagulant effect, greater bioavailability, and a reduced risk of heparin-induced thrombocytopenia compared to unfractionated heparin. Enoxaparin is commonly used for the prevention and treatment of thromboembolic disorders, such as deep vein thrombosis and pulmonary embolism.

In contrast, unfractionated heparin is a larger molecule with a different pharmacokinetic profile that is not classified as a LMWH. Rivaroxaban is an oral anticoagulant that belongs to the class of direct factor Xa inhibitors, and warfarin is a vitamin K antagonist that works by inhibiting the synthesis of vitamin K-dependent clotting factors. These medications operate via entirely different mechanisms and classifications compared to LMWHs like enoxaparin.