Lovenox
Lovenox
Generic Name
Lovenox
Brand Names
for the low‑molecular‑weight heparin (LMWH) *enoxaparin sodium*. It is widely prescribed for thromboprophylaxis, treatment of venous thromboembolism (VTE), and prevention of peri‑operative bleeding complications.
Mechanism
- Selective antithrombin augmentation: Enoxaparin binds antithrombin‑III, accelerating the inactivation of clotting factors Xa and Xa – factor Va.
- Minimal intrinsic inhibition of factor IIa: Compared to unfractionated heparin, LMWHs such as Lovenox exhibit ≈80% activity against factor Xa and only ≈20% against thrombin (factor IIa).
- Resulting effect: ↓ fibrin clot formation, ↓ progression of existing thrombi, and reduced risk of new clot formation.
Pharmacokinetics
| Parameter | Typical Value | Notes |
| Absorption | 70–80 % subcutaneous | Rapid, peak serum concentrations within 3–6 hr |
| Volume of Distribution | ~1.5 L/kg | Reflects limited tissue binding |
| Half‑life | 4–7 hr (dose‑dependent) | Longer in elderly or renal impairment |
| Metabolism | Mainly renal excretion | Minimal hepatic metabolism |
| Drug–Drug Interactions | ↑ bleeding with antiplatelets, NSAIDs, warfarin | Limited CYP involvement |
Indications
- Prophylaxis of deep vein thrombosis (DVT) or pulmonary embolism (PE) in hospitalized patients (orthopedic surgery, major abdominal procedures, medical immobility).
- Treatment of acute DVT or PE plus transition to warfarin or another oral anticoagulant.
- Prevention of venous thrombosis post‑cardiac or neurosurgical procedures.
- Treatment of heparin‑induced thrombocytopenia (HIT) in patients with a positive ELISA and >50 % platelet count decline.
Contraindications
- Active major bleeding or significant risk of bleeding.
- Severe thrombocytopenia (platelets < 100 k/µL).
- Known hypersensitivity to enoxaparin or LMWH.
- CrCl < 30 mL/min: increased bleeding risk; consider dose adjustment or alternative agents.
- Pregnancy: Use only if benefits outweigh risks; no evidence of teratogenicity but limited data.
- Patients with a history of osteoporosis: monitor for osteopenia if prolonged use.
Dosing
Initial and Maintenance (Adults)
| Situation | Dose | Frequency | Route |
| Prophylaxis | 40 mg SC daily | Once daily | Subcutaneously |
| Treatment of acute DVT/PE | 1 mg/kg SC BID (up to 80 mg BID) | Every 12 hr | Subcutaneously |
| HIT | 1 mg/kg SC BID | 12 hr intervals | Subcutaneously |
| Renal impairment (CrCl 30–49 mL/min) | 30 mg SC daily for prophylaxis | Once daily | Subcutaneously |
| Renal impairment (CrCl < 30 mL/min) | 30 mg SC BID for treatment | Every 12 hr if CrCl 100 kg, use 80 mg BID.
• Switch to oral anticoagulant once therapeutic INR (1.5–2.5) achieved if transitioning from warfarin.
Adverse Effects
- Common
- Minor bruising or hematoma at injection site
- Mild bleeding (nosebleeds, gum bleed)
- Injection‑site pain
- Serious
- Major bleeding (GI, intracranial)
- Recurrent thrombosis if subtherapeutic levels
- Heparin‑induced thrombocytopenia (HIT)
- Osteoporosis with long‑term use
Monitoring
| Parameter | Target | Monitoring Frequency |
| Anti‑Xa activity | 0.2–0.6 IU/mL (post‑dose) | Every 3–5 days if renal dysfunction or high‑risk patients |
| Platelet count | Maintain above 150 k/µL | Every 3–4 days until stable |
| Renal function | CrCl > 30 mL/min | At baseline; repeat if clinical change |
| Bleeding signs | None | Continuous clinical assessment |
| INR (if overlapping warfarin) | 1.5–2.5 | Every 3–5 days until therapeutic |
Clinical Pearls
- Subcutaneous technique: Rotate sites (abdomen, thigh, upper arm) to prevent injection‑site hematomas.
- Weight‑based dosing is critical in extremes of weight; under‑dosing in > 100 kg patients leads to embolic complications.
- Renal dosing: For CrCl < 30 mL/min, double the frequency (30 mg BID) only for treatment; for prophylaxis, keep at 30 mg daily to avoid accumulation.
- HIT management: Immediate discontinuation of all heparins, including LMWH; transition to a direct thrombin inhibitor (dabigatran, argatroban) or fondaparinux.
- Drug interactions: NSAIDs and antiplatelets (clopidogrel) potentiate bleeding risk; avoid concurrent use unless necessary.
- Patient education: Instruct patients to report any unexpected bruising, nose bleed, or gum bleeding promptly.
- Monitoring anti‑Xa: Baseline measurement is optional but recommended in renal impaired, obese, or pregnant patients to confirm therapeutic exposure.
- Pregnancy: LMWH is preferred over warfarin due to lack of teratogenicity, but dose adjustments may be needed post‑partum.
Using the above drug card, medical students and clinicians can quickly reference key pharmacologic aspects of Lovenox while optimizing patient safety and treatment outcomes.