In a move that went against the recommendations of its own advisory panel in January, the US Food and Drug Administration (FDA; Rockville, MD) decided on April 27 not to approve Scios's (Mountain View, CA) Natrecor nesiritide for the treatment of acute congestive heart failure, prompting a 61% drop (to $3.75) in Scios's share price. The FDA acknowledged Natrecor's efficacy in clinical trials, but had concerns over the incidence of hypotension. Scios president and CEO, Richard Brewer, says he expects eventually to get FDA approval for Natrecor once additional studies are done. "We know it works, which is a more than a lot of people know about their drugs," says Brewer. Scios's partner Bayer AG (Leverkusen, Germany), which has a worldwide license to market Natrecor, will fund any additional clinical studies. Natrecor is a recombinant form of b-type natriuretic peptide, which is naturally produced by the heart ventricles during heart failure. It increases blood flow through the heart by dilating blood vessels, ridding the body of salt and water, and decreasing the levels of other hormones that raise blood pressure. Natrecor was Scios's first NDA since the company's founding in 1981.