By Randall Osborne

Neurex Corp. received marketing approval from the FDA for Corlopam, its intravenous treatment for severe high blood pressure, and plans to start selling the product as early as December to a potential $250 million market.

Buoyed by the approval, Neurex, of Menlo Park, Calif., is forging ahead with Phase III trials of its pain drug, SNX-111. "We believe those trials will be fully enrolled by year's end in order to file a new drug application," said John Varian, chief financial officer. "It's a good time to be part of the company."

Jay Silverman, an analyst with Robertson Stephens & Co., in San Francisco, said Neurex "could have two drugs on the market in 1998."

The cost of Corlopam (fenoldopam) per treatment will be about $250. About 1 million high blood-pressure patients are eligible to receive the drug, which is administered in the hospital over a six-hour to 48-hour period to relieve severe hypertensive spikes. "Because [Corlopam] has a beneficial effect on the kidney, Neurex should be able to price it at a premium," Silverman said. While other anti-hypertensives can damage the kidney, Corlopam is being tested in preclinical trials as a treatment for renal failure, he noted.

Corlopam is a highly specific and potent dopamine receptor agonist that dilates the body's blood vessels, increasing blood flow to the kidneys, which can be damaged by high or low blood pressure.

Silverman estimated peak annual sales of Corlopam, three years after it is launched, at $40 million to $100 million. "Next year, they'll do $15 million to $20 million," he said.

The FDA notice of approval came about two months sooner than the company expected. In June, an FDA advisory panel voted 9-to-1 in favor of approval of the drug, but some panel members seemed skeptical about the increased heart rate that commonly accompanies its use.

"It's not really a side effect," Silverman said. "When you bring someone's blood pressure down fast, the heart has to work faster to make up for lowering the pressure."

Varian pointed out that physicians can use a table printed on the drug container to calibrate dosage according to the patient's weight, and thus regulate how quickly the blood pressure will drop.

Neurex licensed Corlopam in 1994 from SmithKline Beecham P.L.C., of London, for "malignant hypertension," which can damage the heart, kidneys and other organs.

"A big question was: Is it going to be contraindicated for use with beta blockers?" Silverman said. "From what I understand, that is not the case."

SNX-111 as a treatment for malignant and neuropathic chronic pain syndromes is undergoing two Phase III trials. Another Phase III trial of the drug for severe head trauma was halted for one month earlier this year to study results, and then resumed. (See BioWorld Today, July 30, 1997, p. 1.)

The company's stock (NASDAQ:NXCO) closed Wednesday at $14.875, up $0.75.

Recently, the stock has lacked momentum, Silverman said. "If [the selling price] was $16 or $17, it would probably go higher" as a result of the approval announcement, he added. "It's a little disappointing the stock is not doing better, but it will." *