WASHINGTON — Consumer health advocates and a co-developer of a highly anticipated blood thinner from Eli Lilly are calling on the Food and Drug Administration to halt its review of the drug, which they say may be unsafe at the suggested dose.
The FDA has been reviewing Lilly’s drug prasugrel since January 2008, with much discussion over its benefits versus risks. If approved it would be the first real competition to the blood thinner Plavix, the world’s second-best selling medication made by Sanofi-Aventis and Bristol-Myers Squibb.
The drug prevents more heart attacks than Plavix, but it also causes more internal bleeding, according to a study of over 13,000 patients conducted by Lilly.
But consumer watchdog Public Citizen says that study did not give an accurate comparison of prasugrel versus Plavix.
In a letter today, the group notes that the dose of prasugrel studied by Lilly was about 2.5 times more potent than the dose of Plavix. The scientists say that the higher dose accounted for the excess bleeding seen with prasugrel. The letter said some patients on prasugrel actually stopped forming blood-clotting platelets completely, putting them at increased risk of hemorrhages.
The letter is co-signed by Dr. Victor Serebruany, a research professor at Johns Hopkins University who worked on the early development of prasugrel and is listed on a patent application for the drug. Serebruany has since sold commercial licensing rights for the drug to Lilly.
The letter states that Serebruany recommended as early as 2004 that the drug be studied at a lower dose.
“We urge the FDA to immediately halt review of this drug until a new Phase 3 study can be conducted with an appropriate lower dose of prasugrel,” according to the letter addressed to new FDA Commissioner Margaret Hamburg.
The letter also questions the long-term safety of prasugrel. Researchers note that most of the drug’s heart attack-preventing benefit was seen in the first week of therapy. However, blood thinners are designed to be used for months at a time, increasing the risk of bleeding.
Despite those risks, FDA’s outside advisers unanimously recommended approval for the drug in February. The panel’s vote turned on the company data showing prasugrel prevented 24 heart-related problems for every 10 bleeding events it caused.
Indianapolis-based Lilly said today that Serebruany made the same points about dosing at the FDA meeting earlier this year.
“His concerns were heard by the committee at that time, and the committee voted unanimously that prasugrel should be approved by the FDA,” Lilly spokeswoman Tammy Hull said in a statement.
The FDA is not required to follow the committee’s advice, though it usually does. The agency has not set a deadline for a final decision on prasugrel, having already missed two target dates to complete its review.
If approved in the U.S., the drug would be marketed as Effient and could reach an estimated $1 billion in annual sales, according to industry analysts. The drug is crucial to Lilly’s business because patents protecting its four best-selling drugs all expire by 2013.
Lilly has not launched a new drug since the diabetes treatment Byetta in 2005.
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