## Distinguishing UFH from LMWH ### Key Pharmacokinetic Differences **Key Point:** Reversibility with protamine sulfate is the single most clinically important discriminator between UFH and LMWH. UFH can be rapidly reversed in life-threatening bleeding; LMWH reversal is only partial and unreliable. ### Comparative Table | Feature | UFH | LMWH | | --- | --- | --- | | **Reversibility** | Complete with protamine | Partial/unreliable reversal | | **Pharmacokinetics** | Unpredictable, dose-dependent | Predictable, linear | | **Monitoring** | aPTT required | Not routinely needed | | **Half-life** | 60–90 min (short) | 4–6 hours (longer) | | **Anti-Xa:Anti-IIa ratio** | ~1:1 | 2–4:1 | | **Route** | IV or SC | SC only | | **Dosing frequency** | Continuous IV or q4–6h SC | Once or twice daily | **High-Yield:** UFH's short half-life and complete protamine reversibility make it the drug of choice in acute coronary syndromes, perioperative bridging, and any scenario where rapid reversal might be needed. ### Clinical Pearl In a patient on LMWH with life-threatening bleeding, protamine reverses only ~60% of anti-Xa activity. Fresh frozen plasma or recombinant factor VIIa may be required. UFH, by contrast, is 100% reversed by protamine within minutes—a critical advantage in emergency settings. ### Why Reversibility Matters **Mnemonic: UFH = Urgent Fixable Heparin** — when you need to stop anticoagulation NOW, UFH is your choice because protamine works reliably. [cite:KD Tripathi 8e Ch 12]
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.