Drug makers Bristol-Myers Squibb and Pfizer are seeking approval to market the drug Eliquis for use in patients with atrial fibrillation, a heart condition that affects about 3 million Americans and is projected to affect 12 million by 2050.
People with the heart rhythm disorder have about a five-fold increase in stroke risk.
In a trial sponsored by the companies, patients who took the drug twice a day were 21% less likely to suffer strokes than patients who took the blood thinner warfarin, which has been a standard treatment for the prevention of blood clots for many decades.
Eliquis users also had 31% fewer major bleeding episodes and their risk of death was reduced by 11%.
In a statement released today, the companies confirmed that the FDA is not asking for new studies of the drug, which could delay a decision for years.
Instead, federal officials want more information "on data management and verification" from the pivotal trial.
New-Generation Stroke Drugs
Eliquis is one of three new blood thinners developed as alternatives to warfarin.
Pradaxa, marketed by global drug maker Boehringer Ingelheim, became the first of the new-generation drugs to be approved late in 2010, followed last summer by Xarelto, marketed by Johnson & Johnson and Bayer AG.
Last November, the FDA granted an expedited review for Eliquis, which suggested that it would rule quickly on its approval. But in March the agency postponed action on the request until late June.
The arrival of the three new drugs has been widely anticipated, because the drugs are easier to take and believed to be safer that warfarin, which is also known as Coumadin.
Patients on warfarin must have their blood tested frequently because the drug can increase their risk for potentially life-threatening bleeding. It also interacts with some other drugs and foods, such as dark, leafy greens.
Safety Questions Remain
Although patients on the new drugs do not have to be monitored as closely as those taking warfarin, safety questions have plagued Pradaxa and Xarelto since they entered the U.S. market.
In the months after Pradaxa was approved for use in patients with atrial fibrillation, about 500 cases of hemorrhaging were reported, according to the nonprofit group Institute for Safe Medicine Practices.
Most of these cases occurred among elderly patients.
Just days ago, the FDA rejected an application to allow Xarelto to be used to treat patients with blocked coronary arteries.
Reversal Strategy Not Clear
Cardiologist Vincent Bufalino, MD, who practices in Elmhurst, Ill., says another safety concern has emerged since the new drugs became available.
The blood thinning action of warfarin can be quickly reversed in patients who suffer bleeds, have accidents, or face emergency surgery by administering vitamin K, which is blocked by the drug, or by giving patients blood-clotting agents.
But Bufalino says there is no agreed upon way to reverse the action of the new-generation blood thinners.
"Those of us on the front lines are very aware of this issue," he says. "If a patient has a brain bleed, that is a potential disaster, especially if you can't stop the bleeding."
Early laboratory studies suggest that some of the strategies used to reverse the blood thinning action of warfarin may also work with the newer drugs.
But Bufalino tells WebMD that these trials are preliminary and there is, as yet, no consensus on how to best reverse the actions of the new drugs in emergency situations.
Head-to-Head Studies Needed
Mount Sinai Medical Center professor of cardiology Roxana Mehran, MD, says the new blood thinners are likely to be game changers for stroke prevention, but she adds that caution is needed when prescribing them to patients at risk for bleeding, such as the elderly.
There has been speculation, she says, that Eliquis may be the safest of the three drugs for use in these patients, because it works in a new way and is eliminated by the liver.
But Mehran says head-to-head studies of the three drugs are needed to determine which drug is best for which patients, assuming Eliquis is eventually approved by FDA.
The statement issued today by Bristol-Myers Squibb and Pfizer noted that the drug makers will continue to work with federal officials.
"FDA and the companies are committed to working expeditiously to address the outstanding questions and move the application forward," the statement read.