"The regulatory process seems to have put the cart before the horse, analyzing the safety of the product before it has opined on the safety of the manufacturing process," Greg Jaffe of the Center for Science in the Public Interest said.

The U.S. Food and Drug Administration "clearly needs to impose cradle-to-grave conditions to prevent the goats from leaving the farm or their products from entering the food supply," Jaffee told USA Today.

An FDA evaluation, to be presented to its Blood Products Advisory Board Friday, finds the drug ATryn to be effective and safe.

If the panel, made up of outside advisers, approves ATryn, the blood thinner will still have more steps before being approved for the U.S. market, an FDA spokeswoman said.

ATryn's approval would mark the first application of new FDA regulations that let animals be genetically altered to produce drugs, model human disease, produce industrial or consumer products or improve their use as food.

The European Medicines Agency approved the drug in August 2006 after first blocking it.

ATryn is produced by GTC Biotherapeutics Inc. (NASDAQ:GTCB) of Framingham, Mass., for use in people with a hereditary lack of the protein antithrombin, which makes them vulnerable to life-threatening blood clots. The drug would be used during surgery and childbirth.