The race between two drug makers to market a generic version of a blockbuster blood thinner has grown so intense that one company hired the Kroll detective and security firm, prompting an inquiry by two key senators, The Wall Street Journal reports.

Both Amphastar Pharmaceuticals and Momenta Pharmaceuticals hired high-profile Washington lobbyists as they await FDA approval for generic versions of low-molecular-weight heparin. In 2007, the FDA told Amphastar its prototype chemically matched Lovenox - the only available version. But the FDA unexpectedly set added safety requirements for heparin. Both companies submitted more data.

You may recall earlier this year, Amphastar filed a complaint with the FDA against its own Janet Woodcock, saying she had a conflict of interest over heparin due to an alleged relationship with Momenta. The FDA and HHS inspector general are investigating, the Journal writes, adding that Amphastar noted Woodcock co-wrote a scientific paper with Momenta scientists in 2008.

Concerned Momenta was making inroads at the FDA, Amphastar this summer hired Kroll to probe Amphastar’s problems and Woodcock’s background, prompting a Sept. 24 letter from the Senate Finance Committee, which wrote it was “troubling” Amphastar hired private eyes to investigate an FDA regulator, the Journal writes.

Amphastar general counsel Jason Shandell tells the Journal his company did nothing improper and was justified in seeking an explanation for “years of abnormal roadblocks and moving targets” at the FDA. He said publicly available info on the Internet suggested a conflict of interest between Woodcock and a Momenta co-founder, leading Amphastar “to retain the services of Kroll to verify our public findings.”