By Matthew Willett

ViroPharma Inc. filed a universal shelf registration with the SEC for the potential issuance of up to $300 million in mixed securities.

The registration, covering common and preferred shares, warrants and debt securities, will help ViroPharma move toward the market with its lead product, Picovir (pleconaril) for treatment of viral respiratory infection.

ViroPharma¿s chief financial officer, Vincent Milano, told BioWorld Today Picovir is the first therapeutic shown in the clinic to act against pico-RNA viruses, which cause the common cold.

¿The drug actually works by integrating inside a capsid in the viral core ¿ it¿s a capsid-binding inhibitor,¿ he said. ¿What¿s unique is that picoviruses have about 168 different strains, and Picovir binds at a site that¿s unique to the 168 strains and universal to all of them.¿

Milano gave the same reason for the non-share offering as others in the sector who have taken a similar approach.

¿The primary reason we wanted to put securities on the shelf was to put ourselves in a position to have flexibility in the marketplace when the position is favorable for us to raise additional capital,¿ he said.

ViroPharma, of San Diego, completed Phase III trials of Picovir in March. Those studies indicated Picovir has a statistically significant and clinically meaningful antiviral effect and reduces symptom severity and duration.

Milano said ViroPharma plans to submit a new drug application for Picovir for treatment of viral respiratory infection ¿ the common cold ¿ in adults by the end of the third quarter, and he added that the company is in active discussions with pharmaceutical companies to form a co-development and co-promotion partnership.

¿Obviously, we¿re looking for a company with a demonstrated ability in the primary-care marketplace,¿ he said, adding his belief that Picovir represents ¿a blockbuster opportunity that hopefully will change the way people think about treating viral respiratory infection.¿

Picoviruses are responsible for the majority of visits to physicians every year, Milano said. More than 52 million prescriptions are written in the U.S. annually to treat viral respiratory infections, he said, mainly with antibiotics.

ViroPharma intends to pursue development of Picovir for treatment of the cold in children. Proceeds from an offering associated with Thursday¿s shelf registration also would go toward advancing the firm¿s hepatitis C program, which is partnered with American Home Products Corp., of Madison, N.J., and its respiratory syncytial virus (RSV) program, in early Phase I trials, he said.

The lead compound in the hepatitis C program, VP50406, is in Phase II testing, and an undisclosed product is close behind, Milano said.

ViroPharma has about 18.7 million shares outstanding, with $190 million in cash at the end of the first quarter. The company¿s stock (NASDAQ:VPHM) fell $1.20 Thursday, closing at $30.