Drug Information: Enoxaparin
Detailed information regarding Enoxaparin, a low molecular weight heparin (LMWH) commonly used in clinical settings. Enoxaparin is an anticoagulant that prevents the formation of blood clots. It is derived from heparin but has a lower molecular weight, resulting in more predictable pharmacokinetics and a longer half-life. It is primarily used for the prevention and treatment of venous thromboembolism, including deep vein thrombosis (DVT) and pulmonary embolism (PE), as well as in the management of acute coronary syndromes.
Category
Anticoagulant
Mechanism of Action
Enoxaparin’s primary mechanism of action involves the enhancement of antithrombin III (AT-III) activity. AT-III is a naturally occurring anticoagulant protein in the blood that inhibits several coagulation factors, most notably thrombin (Factor IIa) and Factor Xa. Enoxaparin binds to AT-III, causing a conformational change that significantly accelerates its inhibitory effect on these coagulation factors. Specifically, Enoxaparin preferentially inhibits Factor Xa due to its shorter chain length compared to unfractionated heparin. This enhanced inhibition of Factor Xa effectively interrupts the coagulation cascade, preventing the formation of thrombi (blood clots). Unlike unfractionated heparin, enoxaparin has a relatively smaller effect on thrombin inhibition, contributing to a more predictable anticoagulant response and a lower risk of heparin-induced thrombocytopenia (HIT).
Clinical Uses
Enoxaparin is widely used for the prevention and treatment of various thromboembolic disorders. Its primary indication is the prevention of venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), particularly in patients undergoing surgery (e.g., hip or knee replacement) or those with restricted mobility due to acute illness. It is also used for the treatment of established DVT and PE. Furthermore, enoxaparin plays a crucial role in the management of acute coronary syndromes (ACS), such as unstable angina and non-ST-segment elevation myocardial infarction (NSTEMI), often in combination with other antiplatelet agents. It is also used as prophylaxis in patients with acute medical illnesses who are at risk of VTE.
Dosage
Adults:
- 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 after surgery; or 40 mg subcutaneously once daily, initiated 12 hours prior to surgery.
- Treatment of DVT or 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, concurrently with aspirin.
Pediatrics: (Dosage can vary based on age and specific condition; consult pediatric hematology guidelines)
- Doses must be individualized based on the condition being treated.
- Monitoring of anti-Xa levels is recommended, especially in neonates and infants.
Route of Administration: Subcutaneous injection.
Indications
Common indications for Enoxaparin include:
- Prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE)
- Treatment of existing DVT and PE
- Prophylaxis after hip or knee replacement surgery
- Management of unstable angina and non-ST-segment elevation myocardial infarction (NSTEMI)
- Prevention of clotting in hemodialysis circuits
Contraindications
Enoxaparin is contraindicated in patients with:
- Active major bleeding
- History of heparin-induced thrombocytopenia (HIT) within the past 100 days or in the presence of circulating antibodies
- Hypersensitivity to enoxaparin, heparin, or pork products
- Severe renal impairment (CrCl < 30 mL/min) with treatment doses
- Epidural or spinal anesthesia/puncture while receiving therapeutic doses (increased risk of spinal/epidural hematoma)
FAQ
Q: What is Enoxaparin used for?
A: Enoxaparin is used to prevent and treat blood clots, specifically deep vein thrombosis (DVT) and pulmonary embolism (PE). It’s also used in the management of acute coronary syndromes.
Q: How is Enoxaparin administered?
A: Enoxaparin is given as a subcutaneous injection (under the skin).
Q: What are the common side effects of Enoxaparin?
A: Common side effects include bleeding, bruising, pain or redness at the injection site, and thrombocytopenia (low platelet count).
Q: Can Enoxaparin be used during pregnancy?
A: Enoxaparin can be used during pregnancy, but caution is advised. Discuss the risks and benefits with your doctor.
Q: What should I do if I miss a dose of Enoxaparin?
A: If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not double the dose to catch up.
Q: How is Enoxaparin different from Warfarin?
A: Enoxaparin acts more directly and has a more predictable response than warfarin, it has a shorter half-life and is given by injection. Warfarin is given orally, has a longer half-life, and requires regular blood monitoring (INR).
Q: What should I tell my doctor before starting Enoxaparin?
A: Inform your doctor about any allergies, medical conditions (especially bleeding disorders, kidney disease, or recent surgery), and all other medications you are taking, including over-the-counter drugs and supplements.
Q: How is Enoxaparin Monitored?
A: While routine monitoring isn’t always necessary, anti-Xa levels can be monitored in certain populations, such as patients with renal impairment, obesity, or those at high risk of bleeding.
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