Feb. 24 (Bloomberg) -- Eli Lilly & Co.’s experimental blood thinner prasugrel may face delays getting U.S. approval after regulators said they made a “mistake” removing a critic of the drug from an advisory panel at the company’s urging.

The Food and Drug Administration ejected panel member Sanjay Kaul after Indianapolis-based Lilly complained about research articles written by Kaul questioning prasugrel’s safety and effectiveness, said Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research. The controversy could delay FDA action until the second half of 2009, according to Jon LeCroy, an analyst with Nataxis Bleichroeder in New York.

The FDA “disinvited” Kaul because of concerns he might be biased, Woodcock said. The Feb. 3 panel backed prasugrel’s approval 9-0, after advisers downplayed potential risks of bleeding and cancer. LeCroy’s described the meeting as a “love fest” and said in a note today that the FDA may add stricter label warnings than those recommended by the advisory panel that would “significantly slow the drug’s uptake.”

Kaul “would have been a very valuable member of the committee,” said John Jenkins, director of the FDA’s Office of New Drugs, in a telephone interview yesterday. “He was asking the right questions.”

Kaul, director of a heart research laboratory at Cedars- Sinai Medical Center in Los Angeles, wasn’t available for comment, said Sandy Van, a spokeswoman for the hospital.

Lilly’s Response

“We were well prepared to answer any and all questions from the panel, regardless of who the members were,” Tamara Hull, a Lilly spokeswoman, said in an e-mail today.

“Panel membership is at the sole discretion of the FDA,” Hull said. “We made the FDA aware that Dr. Kaul had previously published abstracts and made many public statements regarding prasugrel.”

Lilly rose 60 cents, or 1.9 percent, to $32.91 at 4:15 p.m. in New York Stock Exchange composite trading, lagging today’s 4 percent gain in the Standard & Poor’s 500 Index.

Prasugrel, if approved, may take up to 20 percent of market share from Plavix, which generated $8.1 billion in 2007 for Bristol-Myers Squibb Co. and Sanofi-Aventis SA. Prasugrel was cleared by European regulators yesterday to be sold under the name Efient. Lilly will split revenue from the drug with Daiichi Sankyo Co. in Tokyo.

The FDA’s Woodcock said the agency doesn’t believe Kaul’s removal “invalidates the results.”

Several small “mistakes” led to the decision to keep Kaul off the committee, which was made during the weekend before the meeting without the knowledge of senior FDA staff, Woodcock said.

“This is not the correct procedure,” Woodcock said. “This is not going to happen again.”

Probe Fodder?

The controversy may mean “a small delay” in prasugrel’s final approval, said Tim Anderson, an analyst at Sanford C. Bernstein & Co. in New York, in a note to clients yesterday. “It would seem to be perfect material” for investigation by critics of the FDA in the U.S. Congress, he said.

“It is unclear how the conclusions Dr. Kaul came to regarding the efficacy and safety of prasugrel suggest any bias, as opposed to well-reasoned scientific inquiry,” said Sidney Wolfe, director of Washington-based Public Citizen’s health- research group and a member of the FDA’s drug safety committee, in a letter to the agency on Feb. 19. “On the contrary, he is free from any financial conflicts of interest, which are not uncommon on FDA advisory committees.”

To contact the reporter on this story: Tom Randall in New York at trandall6@bloomberg.net.

Last Updated: February 24, 2009 16:48 EST