Enoxaparin

Drug Information: Enoxaparin

Detailed information regarding Enoxaparin, a low-molecular-weight heparin (LMWH) commonly used in clinical settings. Enoxaparin is derived from heparin but undergoes a process of depolymerization, resulting in smaller fragments. This modification enhances its bioavailability, prolongs its half-life, and provides a more predictable anticoagulant response compared to unfractionated heparin. Enoxaparin primarily works by enhancing the activity of antithrombin III, a naturally occurring anticoagulant in the body, and is commonly used in the treatment and prevention of thromboembolic disorders, particularly in the context of acute coronary syndromes (ACS).

Category

Drugs for ACS

Mechanism of Action

Enoxaparin’s primary mechanism of action revolves around its ability to enhance the activity of antithrombin III (ATIII), a serine protease inhibitor that plays a crucial role in the coagulation cascade. ATIII naturally inhibits several clotting factors, including thrombin (Factor IIa), Factor Xa, and Factor IXa, thereby preventing excessive clot formation. Enoxaparin binds to ATIII, causing a conformational change that significantly accelerates ATIII’s inactivation of these clotting factors. Specifically, Enoxaparin forms a complex with ATIII, leading to a much more rapid and efficient inactivation of Factor Xa. While Enoxaparin also enhances ATIII’s inhibition of thrombin, its effect on Factor Xa is more pronounced due to its shorter chain length, which allows for better ATIII binding and Factor Xa inhibition. By selectively inhibiting Factor Xa, Enoxaparin effectively disrupts the coagulation cascade, reducing the formation of thrombin and subsequent fibrin clot formation. This targeted approach results in a more predictable anticoagulant effect with a lower risk of bleeding complications compared to unfractionated heparin.

Clinical Uses

Enoxaparin is widely used in the management of acute coronary syndromes (ACS), which include unstable angina and non-ST-segment elevation myocardial infarction (NSTEMI). In these conditions, it prevents the formation of new blood clots and the propagation of existing ones, thereby reducing the risk of myocardial infarction and other adverse cardiac events. It is often administered in conjunction with antiplatelet agents like aspirin and clopidogrel. Furthermore, Enoxaparin is used for the prophylaxis of deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients undergoing surgery, particularly orthopedic surgery, and in medically ill patients with reduced mobility. It is also indicated for the treatment of established DVT and PE, providing effective anticoagulation while minimizing the risk of bleeding complications. In addition to these primary uses, Enoxaparin may be used in other clinical settings, such as in patients with heparin-induced thrombocytopenia (HIT) who require continued anticoagulation.

Dosage

Adult Dosage:
* Prophylaxis of DVT following abdominal surgery: 40 mg subcutaneously once daily, initiated 2 hours prior to surgery.
* Prophylaxis of DVT following hip or knee replacement surgery: 30 mg subcutaneously every 12 hours, initiated 12-24 hours post-surgery; or 40 mg subcutaneously once daily, initiated 12 hours prior to surgery.
* Treatment of DVT/PE: 1 mg/kg subcutaneously every 12 hours; or 1.5 mg/kg subcutaneously once daily.
* Unstable Angina/NSTEMI: 1 mg/kg subcutaneously every 12 hours, administered concurrently with oral aspirin (75-325 mg once daily).

Pediatric Dosage: (Dosage varies significantly based on indication and patient-specific factors. Consult pediatric hematologist/pharmacist.)
* Pediatric dosage is highly variable and dependent on the indication and the child’s weight and renal function. Typically, it ranges from 1 mg/kg to 1.5 mg/kg every 12 hours for treatment of VTE. For prophylaxis, lower doses are used. It is crucial to consult specialized guidelines and adjust the dose based on anti-Xa levels.

Route of Administration: Subcutaneous injection.

Indications

* Prophylaxis of deep vein thrombosis (DVT) in patients undergoing surgery (e.g., hip or knee replacement, abdominal surgery).
* Prophylaxis of DVT in medically ill patients with restricted mobility.
* Treatment of acute deep vein thrombosis (DVT).
* Treatment of pulmonary embolism (PE).
* Management of unstable angina and non-ST-segment elevation myocardial infarction (NSTEMI).

Contraindications

* Active major bleeding.
* History of heparin-induced thrombocytopenia (HIT) within the past 100 days or presence of circulating antibodies to heparin.
* Known hypersensitivity to enoxaparin, heparin, or pork products.
* Severe renal impairment (creatinine clearance <30 mL/min) may require dosage adjustment or avoidance.
* Active peptic ulcer disease or other conditions with a high risk of bleeding.
* Intracranial hemorrhage.

FAQ

Q: What is Enoxaparin and how does it work?
A: Enoxaparin is a low-molecular-weight heparin (LMWH) anticoagulant. It works by enhancing the activity of antithrombin III, a natural inhibitor of clotting factors, thereby preventing blood clots from forming.

Q: What is Enoxaparin used for?
A: Enoxaparin is used to prevent and treat blood clots in conditions like deep vein thrombosis (DVT), pulmonary embolism (PE), and acute coronary syndromes (ACS). It is also used for DVT prophylaxis in surgical and medically ill patients.

Q: How is Enoxaparin administered?
A: Enoxaparin is administered via subcutaneous injection, usually in the abdomen.

Q: What are the common side effects of Enoxaparin?
A: Common side effects include bleeding, bruising at the injection site, pain, and irritation at the injection site. More serious side effects include severe bleeding, heparin-induced thrombocytopenia (HIT), and allergic reactions.

Q: What should I do if I miss a dose of Enoxaparin?
A: If you miss a dose, administer it as soon as you remember, unless it is almost time for your next dose. In that case, skip the missed dose and continue with your regular dosing schedule. Do not double the dose to catch up.

Q: Can Enoxaparin be used during pregnancy?
A: Enoxaparin can be used during pregnancy, but caution is advised and the risks and benefits should be carefully considered with your doctor. Monitoring may be required.

Q: What are the signs of bleeding I should watch out for while taking Enoxaparin?
A: Watch out for signs of bleeding such as unusual bruising, nosebleeds, bleeding gums, blood in urine or stool, coughing up blood, severe headache, dizziness, or weakness. Report any of these symptoms to your doctor immediately.

Q: Are there any drug interactions with Enoxaparin?
A: Yes, Enoxaparin can interact with other medications that affect blood clotting, such as aspirin, warfarin, and other antiplatelet drugs. Always inform your doctor about all medications you are taking.