The distance between Changzhou in China to Baxter International in Illinois is, symbolically, as long as a pig intestine. Baxter’s Heparin, you see, is derived from piggie innards, but the blood thinner has also been linked to some 350 adverse events, many of which were serious, and four deaths. And the episode is casting another harsh spotlight on the ability of the FDA to supervise drugmaking in China, which is fast becoming the equivalent of pharma’s Wild West.

In this case, the active ingredient in Heparin was supplied by a Chinese manufacturing facility co-owned by a Wisconsin company, Scientific Protein Laboratories, which has manufacturing facility in China and a joint-venture operation called Changzhou, The Wall Street Journal reports.

“There’s nothing that would explain these reactions, and we are very concerned about this,” David Strunce, Scientific Protein’s president, tells the Journal. “We have no idea if these reactions have anything to do with our product.” He says most of its active ingredient for Heparin is made in China, but some also comes from its Wisconsin facility. Scientific Protein, by the way, is mostly owned by American Capital Strategies, a buyout firm.

For its part, the FDA has acknowledged that the Chinese plant, which is also owned by Changzhou Techpool Pharmaceutical, was never inspected. In response, Chuck Grassley, an Iowa Republican who sits on the Senate Finance Committe, and Michigan Democrats John Dingell and Bart Stupak, leaders of the House Energy and Commerce Committee, have opened investigations into the episode.

A Baxter spokeswoman tells the paper that the company is using “molecular separation” analysis to “look for chemically meaningful differences” between Heparin batches linked to bad reactions and “control” batches known to be of high quality.