This fight is going to be a bloodbath; at least the contenders will have enough drugs to stanch their bleeding wounds.

On the heels of Omrix Biopharmaceuticals' (Nasdaq: OMRI) August approval for its human thrombin product, Evithrom, ZymoGenetics (Nasdaq: ZGEN) announced yesterday that its recombinant thrombin product, Recothrom, was given a thumbs-up by the FDA. Thrombin is a protein found in blood which surgeons use to stop bleeding during surgery.

ZymoGenetics has been gearing up for this fight for a while. The FDA gave it a paper cut last August when it extended the review time for its marketing application. That delay gave Omrix a head start, but ZymoGenetics didn't allow the agency's delay to knock it out. Instead, the company continued making the product and sent out its sales force to announce the pending arrival of its drug.

Both companies will have heavyweight help as they take on the entrenched thrombin leader, King Pharmaceuticals (NYSE: KG). Omrix's product is marketed by Johnson & Johnson (NYSE: JNJ), while ZymoGenetics is getting help from Bayer. The marketing approval triggers a $40 million payment from Bayer, which should help pay for the launch.

ZymoGenetics' product has a clear safety advantage over King's and Omrix's products. King's thrombin is made from cow blood, which can cause an immune response in some patients, while Omrix's thrombin is made from human plasma, so it runs the risk of carrying bloodborne pathogens. Both companies will argue that the risks are small, which they are, but they're present nevertheless, and ZymoGenetics' strategy clearly is to exploit its competitors' weaknesses.

ZymoGenetics plans to have the drug to wholesalers within two weeks, so investors should get an idea of which company has won round one when the companies release their first-quarter earnings numbers. The Fool has your front-row seat.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Johnson & Johnson is a selection of the Income Investor newsletter. The Fool has a disclosure policy.