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What Is a Specific Heparin Antagonist?

A specific heparin antagonist is a molecule that that combines with heparin to form a stable complex that does not have any anticoagulant (prevent the clotting of blood) activity. As of January 2010, there is only one specific heparin antagonist available: protamine sulfate.

  1. Protamine Sulfate Sources

    • Protamine sulfate is a mixture of low molecular weight proteins. Originally isolated from fish sperm or testes, it is now produced mainly by using recombinant biotechnology.

    Protamine Sulfate Use

    • Protamine sulfate is for the treatment of heparin overdose. Heparin is routinely used during surgery to prevent blood clots from forming during the procedure.

    Protamine Sulfate Administration

    • Protamine sulfate should only be given by very slow intravenous injection and only by a qualified physician.

    Protamine Sulfate Problems

    • Some patients (especially those with fish allergies, taking insulin or males who have had vasectomies) can have an allergic reaction to protamine sulfate. It has some anticoagulant properties of its own, and a dose that is too high can make bleeding worse.

    Alternatives to Protamine Sulfate

    • As of September 2008, PolyMedix put the small molecule PMX-60056 (designed to mimic the activity of protamine sulfate and yet have fewer side effects) into Phase IA clinical trial to test it for safety. Over the decades, attempts by other companies such as Biomarin to create an alternative to protamine sulfate have not met with success.

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