Lepirudin is a highly specific direct inhibitor of thrombin. Lepirudin, (chemical designation

Lepirudin is a highly specific direct inhibitor of thrombin. Lepirudin, (chemical designation: [Leu1, Thr2]-63-desulfohirudin) is a recombinant hirudin derived from yeast cells. The polypeptide composed of 65 amino acids has a molecular weight of 6979.5 daltons. Natural hirudin is produced in trace amounts as a family of highly homologous isopolypeptides by the leech Hirudo medicinalis. The biosynthetic molecule (lepirudin) is identical to natural hirudin except for substitution of leucine for isoleucine at the N-terminal end of the molecule and the absence of a sulfate group on the tyrosine at position 63.