By Lisa Seachrist

Washington Editor

ViroPharma Inc.'s pleconaril still faces the rigors of pivotal trials, but news that the antiviral significantly reduces the pain and suffering associated with the common cold tantalized Wall Street and sent the company's stock soaring over the past two days.

The Exton, Pa.-based firm released the news early Tuesday and saw its stock (NASDAQ:VPHM) rocket from $9.25 a share to close Wednesday at $19.125 a share.

"It's a Phase II program we've announced and our objective is to move this product into Phase III studies as soon as possible," said Kori Beer, director of communications for ViroPharma. "Still, it's very important to manage expectations."

Pleconaril, however, also is being explored as a way to treat viral meningitis. Results from the Phase III program in that indication are expected in the fall, with a new drug application filing by the end of this year, Beer said.

The antiviral drug is aimed quite specifically at picornaviruses - small RNA viruses responsible for the majority of all human viral illnesses from severe to common. Picornaviruses cause viral meningitis, viral inflammation of the heart, neonatal enteroviral disease, and viral respiratory infection (VRI), otherwise known as the common cold.

Pleconaril, an oral liquid formulation, stymies these viruses by inhibiting the enzymes responsible for viral replication. Because picornaviruses replicate their RNA - a process different from the growth cycles of DNA viruses, retroviruses and cells - the drug has few side effects for patients.

ViroPharma released the results of a large Phase II program that included three double-blind, placebo-controlled studies. The first two studies were conducted with 1,245 otherwise-healthy adults suffering from a severe cold. The larger study of 1,024 patients tested 400 milligrams of pleconaril or placebo two or three times daily. All of the patients randomized to receive 400 milligrams three times a day enjoyed a greater-than-three-day reduction in the median time to complete elimination of disease symptoms - 11 vs. 14 days. The smaller study, testing a 200-milligram dose or 400-milligram dose three times a day, also showed positive results.

The third study was conducted in 256 adolescent and adult patients with moderate to severe asthma and severe colds who received drug or placebo three times per day. Patients receiving pleconaril had no asthma exacerbation, while four patients on the placebo arm suffered an exacerbation.

The company reported there were no overall differences in the side-effect profile between patients receiving pleconaril and those taking placebo.

"This is a large Phase II program and we intend to use the information in the safety database for an indication in viral meningitis," Beer said. "That NDA, we expect, will be filed by the end of this year."

Beer also noted the company is in discussions with the FDA over the design of a Phase III program for pleconaril in VRI. That study, she said, is likely to be quite large; however, the pleconaril regimen is seven days of therapy with seven days of follow-up.

The disease, while usually self-limited, can result in complications ranging from sinusitis, ear infections, respiratory distress, bronchitis to pneumonia. VRI is responsible for more than 34 million physician visits each year and 23 million lost work days.