The key ingredient in Hiruval 35™ Evanescent Cream is hirudin. Here is some information about hirudin (from The Merck Index, 12th edition, 1996):

Anticoagulant protein extracted from leeches. The medicine leech of Central Europe, hirudo medicinalis...

• Hirudin is a single chain polypeptide containing 65 amino acids
• A specific inhibitor of thrombin, q.v. hirudin inhibits coagulation in the initial stages of clotting and does not require presence of other coagulation factors or plasma constituents: F. Markwardt, Methods Enzymol. 19, 942 (1970)
• Therapeutic potential, P.H. Johnson, Ann. Rev. Med. 45, 165-177 (1994)
• Series of articles on development, pharmacology, and therapeutic potential of natural and recombinant hirudins: Semin. Thromb. Hemostasis, 15, 261-333 (1989)