Enoxaparin

Enoxaparin is a low molecular weight heparin (LMWH) used as an anticoagulant. It works by potentiating the action of antithrombin III, with a stronger effect on factor Xa and a smaller effect on thrombin (factor IIa) compared with unfractionated heparin. Its pharmacokinetics are more predictable, allowing subtler dosing and less routine laboratory monitoring.

Clinical use includes prevention of venous thromboembolism after hip or knee replacement, abdominal surgery, and in acutely ill medical patients; treatment of acute DVT and pulmonary embolism; and in certain settings of acute coronary syndrome (NSTEMI or STEMI) where it is used with antiplatelet therapy. Dosing is typically weight-based and given by subcutaneous injection. Prophylactic regimens commonly involve 40 mg once daily (or tailored heparin-like schedules in some centers), while therapeutic dosing for DVT/PE often uses 1 mg/kg every 12 hours or 1.5 mg/kg once daily, depending on the indication. Enoxaparin is not given intramuscularly due to hematoma risk. In renal impairment, dose adjustment or avoidance may be necessary, especially when creatinine clearance is severely reduced.

Monitoring is not routinely required, but anti-Xa activity may be measured in special populations such as patients with obesity, pregnancy, pediatrics, or renal dysfunction, and platelet counts should be checked to monitor for heparin-induced thrombocytopenia (HIT). Adverse effects include bleeding, injection-site reactions, and, less commonly, osteoporosis with long-term use. HIT is less common than with unfractionated heparin. Reversal of enoxaparin is incompletely achieved with protamine sulfate, which can partially neutralize anti-Xa activity. Contraindications include active major bleeding, history of HIT, and known hypersensitivity to heparins; neuraxial anesthesia carries a risk of epidural hematoma.