The Hirudin (54-65) (desulfated) is an organic compound with the formula C₆₆H₉₃N₁₃O₂₅. It belongs to the product categories of Hirudin Fragments; Miscellaneous Peptides; Peptides for Cell Biology. Its CAS registry number is 113274-56-9. Hirudin is a naturally occurring peptide in the salivary glands of medicinal leeches (such as Hirudo medicinalis) that has a blood anticoagulant property.

Hirudin is a naturally occurring peptide in the salivary glands of medicinal leeches (such as Hirudo medicinalis) that has a blood anticoagulant property. Natural hirudin contains a mixture of various isoforms of the protein. However, recombinant techniques can be used to produce homogeneous preparations of hirudin. It is difficult to extract large amounts of hirudin from natural sources, so a method for producing and purifying this protein using recombinant biotechnology has been developed. This has led to the development and marketing of a number of hirudin based anticoagulant pharmaceutical products such as Lepirudin (Refludan) , Hirudin derived from Hansenula (Thrombexx, Extrauma) and Desirudin (Revasc/Iprivask). Several other direct thrombin inhibitors are derived chemically from hirudin.