What it is
Hirudin is a protein secreted by the salivary glands of the medicinal leech, Hirudo medicinalis. UniProt's entry for the main variant, hirudin variant-1 (P01050), records a chain of 65 amino acids held in shape by three disulfide bonds. That size puts it above the 40-residue line used in US regulation, so the protein category is the accurate one (see peptide vs protein), whatever the wider market calls it.
What it does
Hirudin is a direct thrombin inhibitor. Thrombin is the enzyme that converts fibrinogen into fibrin, the mesh that holds a clot together. Hirudin binds thrombin directly, so it does not depend on antithrombin, the route used by heparin. That mechanism is the reason the leech's secretion made it into medicine, and it is the basis for the drugs derived from it, such as bivalirudin.
The drug: desirudin
Desirudin is the recombinant form of hirudin, produced outside the leech. It was developed as an injected anticoagulant, with published randomised trials looking at the prevention of venous thromboembolism in surgical patients. A PubMed search for desirudin together with randomised or trial terms returned 61 records on 2026-11-09. The individual trials were not opened for this entry, so this page reports only the count, not their results.
The current status is the important fact for a reader. A search of the DailyMed label index on 2026-11-09 returned no desirudin label. The page treats desirudin as a former medicine on that basis. The approval history was not re-verified in this run, and a reader should check the regulator's own record before relying on any date.
What the evidence does and does not show
- Structure and mechanism: well characterised in the protein record. Well established.
- Clot prevention after surgery: supported by published randomised trials of the recombinant drug. Those trials sit inside hospital care and were not about wellness.
- Use outside a clinical setting: nothing in the published literature or the label index supports it. This entry does not suggest any.
Anticoagulants carry bleeding risk. A person who takes one, or who is considering one, needs a prescriber, not a reference page.
Where it stands
| Question | Answer as of 2026-11-09 |
|---|---|
| Natural protein | Yes, 65 amino acids (UniProt P01050) |
| Recombinant drug | Desirudin, studied in randomised trials |
| Current US label | None found in the DailyMed index queried |
| Advice | None given here |
Related reading
Related entries on this library cover the other clotting-enzyme-targeting molecules and the protein-size question. Anyone reading about anticoagulants should also read the regulator's current guidance on bleeding risk, not a compound library.