One month after the debut of Hoffman-La Roche's weight-loss drug, Xenical, it is clear that the drug "will not go down as the most successful new pharmaceutical in history, but analysts remain confident that it will become a best seller," the New York Times reports.

The drug, approved by the FDA in April, sold 96,485 prescriptions in its first four weeks of sales -- a paltry performance compared to Viagra's 367,857 and arthritis drug Celebrex's 150,113 sales during their first months on the market. "It's important that momentum for Xenical not peak too early," said Viren Mehta, a partner at Mehta Partners, adding, "You want to have an educated group of physicians about the drug."

Xenical, which blocks fat absorption, reminds many of fen-phen, "a weight loss drug cocktail that was removed from the market in 1997 over concerns it caused heart valve damage." Further raising consumer hesitance, Xenical's side effects include fecal incontinence, and the drug boasts only modest weight loss.

However, Dr. Louis Aronne, director of the Comprehensive Weight Control Program at New York Hospital-Cornell Medical Center, noted that Xenical "does something other diet drugs don't do ... You can use it to treat obese people and not worry about it causing cardiovascular side effects."

Hoffman-La Roche, which has already deployed a team of 2,000 Xenical marketers, expects to begin direct-to-consumer advertising during the third quarter of this year, and analysts predict sales will "hit $750 million to $1 billion at their peak." "Sales will be erratic," Neil Sweig, a Southern Research Partners analyst, said, adding, "People who take this type of drug are never satisfied. They want the easy way out to lose weight. In this market, there is not any loyalty here" (Morrow, 6/2).