Almost 5 million Americans have congestive heart failure, in which the heart gradually loses the ability to pump blood. About 1 million of them a year suffer flare-ups in which they gasp for breath and need hospitalization.
The U.S. Food and Drug Administration approved an injection of Natrecor as a way to treat these acute flare-ups.
Natrecor, known chemically as nesiritide, is a bioengineered version of a natural hormone that helps dilate blood vessels.
That dilation helps blood flow from the weakened heart. But it also can cause seriously low blood pressure. Two years ago, the FDA rejected approval of Natrecor because it caused so many cases of hypotension rates of 8 percent to 14 percent, depending on the dose used.
So manufacturer Scios Inc. tested a much smaller dose in another study of 498 patients. This time, low blood pressure struck only about 4 percent of patients. That's similar to the side-effect rate of nitroglycerin, another common treatment for acute heart failure so the FDA approved an injection containing the lower Natrecor dose.
But doctors will have to use Natrecor carefully. Unlike when nitroglycerin is used, the low blood pressure may not show up right away but within four or five hours and when it does strike, it can last longer, said Dr. Douglas Throckmorton, FDA's deputy director of cardiorenal drugs.
"You need to watch them longer," Throckmorton warned physicians.
Studies showed patients could breathe better as blood circulation and lung congestion improved with Natrecor treatment. But Throckmorton said that Scios' study was not designed to tell if Natrecor is any better an option than the nitroglycerin often used today.
But it is a novel drug, the first bioengineered form of B-type natriuretic peptide sold. California-based Scios said it will start shipping Natrecor to hospitals this week; each vial, a day's treatment, will cost $380.
By Lauran Neergaard
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