Create a diagram of heparin nd its uses
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heparin mechanism of action uses clinical pharmacology
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Here is your heparin diagram:
Here's a summary of what the diagram covers, drawn from Braunwald's Heart Disease and clinical pharmacology sources:
What is Heparin?
Heparin is a sulfated polysaccharide anticoagulant derived from porcine intestinal mucosa. It is one of the oldest and most widely used anticoagulants in medicine.
Mechanism of Action
Heparin binds to Antithrombin (AT-III) via a unique pentasaccharide sequence, causing a conformational change that dramatically accelerates AT-III's inhibition of:
- Thrombin (Factor IIa) - requires the heparin chain to bridge AT and thrombin together (needs chains ≥18 saccharide units)
- Factor Xa - inhibited by the conformational change alone
It also releases Tissue Factor Pathway Inhibitor (TFPI) from the endothelium.
Types
| Type | MW | Anti-Xa:Anti-IIa | Monitor |
|---|---|---|---|
| UFH | 5,000-30,000 Da | 1:1 | aPTT |
| LMWH (e.g. enoxaparin) | ~5,000 Da | ~3:1 | Anti-Xa |
| Fondaparinux | 1,500 Da | Xa only | Anti-Xa |
Key Clinical Uses
- DVT/PE treatment and prophylaxis
- Acute coronary syndromes (NSTEMI/STEMI)
- Atrial fibrillation
- Cardiac surgery / cardiopulmonary bypass
- Dialysis and CRRT
- Peri-procedural bridging anticoagulation
- Pregnancy (LMWH is preferred)
Major Adverse Effects
- Bleeding (most common)
- HIT (Heparin-Induced Thrombocytopenia) - ~5% with UFH, immune-mediated, occurs days 5-14
- Osteoporosis (long-term), hyperkalemia, hypersensitivity
Reversal: Protamine sulfate (1 mg per 100 units of UFH). For HIT: stop ALL heparin products and switch to argatroban or bivalirudin.
Sources: Braunwald's Heart Disease, 12th Ed.; Harrison's Principles of Internal Medicine, 22nd Ed.
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