Enoxaparin
Lovenox · Clexane
Low-molecular-weight heparin (LMWH)
Antithrombin-mediated inhibition, weighted toward factor Xa over IIa (~3.8:1). More predictable than UFH — no routine monitoring.
Indications
- •VTE prophylaxis + treatment
- •ACS
- •Bridging anticoagulation
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| VTE prophylaxis | 40 mg SC daily (or 30 mg q12h) | — |
| Treatment | 1 mg/kg SC q12h OR 1.5 mg/kg SC daily | — |
| Renal (CrCl <30) | Reduce to once-daily dosing; consider anti-Xa monitoring | — |
Pharmacokinetics
Onset 3–5 h SC. Half-life ~4.5 h (longer in renal failure). Renally cleared. Monitor with anti-Xa (not aPTT) if needed.
Side effects
- !Bleeding
- !HIT (lower risk than UFH but possible)
- !Injection-site hematoma
- !Osteoporosis (chronic)
Contraindications
- ×Active bleeding
- ×Severe thrombocytopenia
- ×HIT history (relative)
Reversal / antidote
Protamine partially reverses (~60% of anti-Xa) — 1 mg protamine per 1 mg enoxaparin if within 8 h
Clinical pearls
- ★ASRA neuraxial: hold 12 h (prophylactic dose) or 24 h (therapeutic dose) before block/catheter removal; restart ≥4 h after catheter removal (prophylactic).
- ★Protamine only partially reverses LMWH (vs full reversal of UFH).
- ★Renal dosing critical — accumulates in CrCl <30, ↑ bleeding.
Other drugs in Coagulation Related
- Heparin (unfractionated)
Activates antithrombin → inactivates IIa (thrombin) and Xa.
- Tranexamic Acid (TXA)
Reversibly binds plasminogen, blocking conversion to plasmin → preserves fibrin clot.
- Protamine Sulfate
Strongly basic (positive-charge) protein binds to highly acidic (negative-charge) heparin → inactive ionic complex → renal excretion. 1 mg protamine neutralizes ~100 units heparin.
- DDAVP (Desmopressin)
Selective V2 agonist (renal water retention + Factor VIII/vWF release from endothelial Weibel-Palade bodies). NO V1 vasopressor activity at therapeutic dose.
- Warfarin
Inhibits vitamin K epoxide reductase (VKORC1) → depletes reduced vitamin K → ↓ synthesis of factors II, VII, IX, X and proteins C/S. Full effect takes days (waits for existing factor decay).
- Dalteparin
Antithrombin-mediated factor Xa > IIa inhibition. Similar profile to enoxaparin; preferred LMWH in cancer-associated VTE (CLOT trial).
- Tinzaparin
Antithrombin-mediated factor Xa > IIa inhibition; higher mean molecular weight than enoxaparin (anti-Xa:IIa ~1.9:1).
- Fondaparinux
Binds antithrombin → selective, exclusive factor Xa inhibition (no IIa activity). Does NOT cause HIT — safe alternative in HIT patients.
Browse all classes: /reference/drugs
Suggested reading
- •Miller's Anesthesia, 9e
- •FDA package insert
- •ASRA regional anesthesia in the anticoagulated patient guidelines, 2018
