INDUSTRY NEWS: Recombinant Hirudin Approved for U.S
Hoechst Marion Roussel (10236 Marion Park Dr., Kansas City, MO 64134; Tel: 816/966-5000, Fax: 816/966-3270) has launched its “Refludan” lepirudin (rDNA) for injection, the first product approved in the U.S. to treat patients with thromboembolic complications associated with heparin-induced thrombocytopenia (HIT). Prior to the release of Refludan, the only way to manage HIT was to discontinue heparin. According to HMR’s president, Jerry Belle, Refludan fills a “gaping hole” in the management of this potentially life-threatening condition by providing an effective anticoagulant treatment that facilitates rapid recovery of platelet counts with reduced risk of blood clots
The active ingredient, lepirudin, is a recombinant hirudin. It belongs to a class of anticoagulants known as direct thrombin inhibitors and has a very different chemical structure than heparin. Unlike heparin, the direct thrombin inhibitors act independently of antithrombin III (protein that inhibits coagulation) and inactivate both free thrombin and thrombin bound to fibrin (clot-bound thrombin). Since Refludan is able to block thrombin bound to a clot, where thrombin is inaccessible to inhibition by antithrombin III, further growth of a preexistent thrombus (clot) may be prevented. Refludan is derived from the saliva of the medicinal leech and is recreated through state-of-the-art recombinant technology–the recreating of natural substances synthetically using genetic engineering. Medicinal leeches have been used since ancient times to prevent the blood from clotting. Since natural hirudin must be obtained from the leeches, and the numbers of leeches are limited, it is not naturally available in adequate amounts for therapeutic purposes.
Recent breakthroughs in biotechnology led to the design of recombinant hirudin and to the production of this agent on a large scale. Refludan was developed in Germany and received its first marketing approval from the European Commission in March 1997. The arrival of recombinant hirudin is a commercial triumph, of sorts. Biogen tried to commercialize a modified form of hirudin in the past, but failed.
HIT is a rare, allergy-like adverse reaction to heparin, a standard anticoagulant (anti-blood-clotting) therapy commonly used in a variety of settings ranging from orthopedic surgery to acute coronary care. HIT is caused by a complex immune mechanism and is characterized by a rapid and serious decline in the blood’s platelet count, which can lead to an increased risk of severe thromboembolic (blood-clotting) complications. When these complications are experienced, they frequently result in limb amputation or even death.
Bleeding from puncture sites and wounds was the most common side effect. Concomitant use with thrombolytics can result in intracranial bleeding. Other events included anemia, hematoma, hematuria, fever and abnormal liver function. Refludan is available in 50-mg vials for intravenous administration.
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