Cardiovascular Drug Highlight: Hirudin

Hirudin is a polypeptide of 65 to 66 amino acids derived from the saliva of the medicinal leech Hirudo medicinalis. It is the most potent naturally occurring specific inhibitor of thrombin. Through genetic engineering, recombinant forms of hirudin (r-hirudin) have been made available in sufficient quantities for therapeutic use. Because hirudin is capable of inhibiting clot-bound thrombin and fluid-phase thrombin, it has great potential for management of patients with various types of thromboembolic complications. Clinical trials with hirudin have been conducted in patients with coronary artery disease, heparin-induced thrombocytopenia, and in patients undergoing orthopedic surgery. The results of selected clinical trials in each of these areas are reviewed here. At present, most clinical benefits of r-hirudin have been demonstrated in the management of patients with heparin-induced thrombocytopenia. For this reason, lepirudin (a form of r-hirudin) has recently been approved by the United States Food and Drug Administration (FDA) for anticoagulation in patients with heparin-induced thrombocytopenia and associated thromboembolic disease.