Some 400,000 starter kits of diet pill alli (low-dose Xenical) are being shipped to pharmacies, grocery stores and retailers around the United States in preparation for the June 15th launch of the first FDA-approved over-the-counter diet pill.

With GlaxoSmithKline reporting on June 12th that early demand from retailers is running strong, the U.S. rollout of alli is expected to be "one of the largest O-T-C launches that has been made," according to Glaxo Vice President Greg Westerbeck.

The pill is expected to retail for around $60 for a month's supply, based on a patient taking three before-meal pills a day, and Glaxo executives told reporters June 11th that the company is hoping 5 million to 6 million Americans will give the nonprescription diet drug a try.

Alli is a half-strength version of prescription diet drug Xenical (orlistat) and works by reducing the amount of fat the body absorbs from food. Undigested fat is eliminated through bowel movements.

The side-effects , which Glaxo concedes "can include loose or more frequent stools that may be hard to control, or gas with an oily discharge," kept the far-more-costly Xenical from ever becoming a blockbuster.

Glaxo executives said they expect most patients to take the diet pill for about three months, though there is no limit on how-long one can remain on the drug.

Glaxo has prepared 250 pages of educational materials on alli to accompany the starter pack, and also hopes to sell 200,000 copies of a diet plan and 800,000 copies of a book to help dieters combine alli with a weight-loss program that includes dietary changes and exercise.