Vivus Off 19% on Test of Impotence Product

Vivus Inc. shares fell 19% after new research showed that the company’s impotence treatment, a pellet inserted in the urethra, is less effective than reported in earlier tests. A study of 115 men suffering from impotence found that only 27% treated with the Muse product were able to obtain an erection they deemed sufficient for intercourse. That’s compared with a response rate of 60% to 70% reported in a company-sponsored study described in a 1997 New England Journal of Medicine article. Vivus is struggling to maintain a market for the product after the introduction of Pfizer’s blockbuster drug Viagra, the first pill to treat impotence. Mountain View-based Vivus fell $1.69 to close at $7.06 in Nasdaq trading.