The U.S. Food and Drug Administration, after months of unexplained delay, on Feb. 7th approved alli -- a half-strength version of prescription diet drug Xenical (orlistat) -- as the first FDA-approved diet pill to be sold over-the-counter in the United States.

The 60 mg capsules, which are to be taken before each meal containing fat, will be marketed by GlaxoSmithKline Consumer Healthcare under the brand name alli (pronounced AL-eye). GSK said the nonprescription pills are expected to cost less than $2 a day and be available in stores by the summer.

The company estimated that 5 to 6 million Americans would buy alli over the counter. Glaxo studies have shown that the half-strength dose provides 85 percent of the weight loss benefit of prescription Xenical.

But the weight-loss effects are modest. On average, people taking alli lose about 6 pounds more than they would have with diet alone.

Like prescription drug Xenical, alli works in the intestines where it blocks some of the fat you eat from being absorbed and digested. This undigested fat is then removed in your bowel movements..

alli, like Xenical, must be used in conjunction with a reduced-calorie, low-fat diet because consuming too much fat can result in an urgent, sometimes uncontrollable, need to use the bathroom.

The Food and Drug Administration, in clearing alli for use by overweight people over age 18, stressed the drug should be combined with a diet and exercise regime.

"This drug is only going to be effective if used in conjunction with a weight-loss program," Dr. Charles Ganley, FDA's head of nonprescription drug products, told reporters. ''Using this drug alone is unlikely to be beneficial."

"We know that being overweight has many adverse consequences, including an increase in the risk of heart disease and type 2 diabetes," said Dr. Douglas Throckmorton, Deputy Director for FDA's Center for Drug Evaluation and Research.  "O-T-C orlistat, along with diet and exercise, may aid overweight adults who seek to lose excess weight to improve their health."

With alli, GSK said consumers will have access through a website, myalli.com, to an individually tailored action plan that provides support and the necessary tools to help them lose 50 percent more weight than they would with diet alone.

"alli is more than a pill -- it's a comprehensive program that works in conjunction with a sensible diet to increase weight loss," said Steven L. Burton, Vice President, Weight Control, GlaxoSmithKline Consumer Healthcare.

"Because weight loss doesn't happen overnight, we're starting to educate consumers now about the importance of realistic expectations, gradual weight loss and lifestyle changes. That's the way to see results, and with alli, we know they can do it," Burton added.

While prescription Xenical has been on the market since 1999, only two prescription diet drugs -- Xenical and Meridia -- are currently approved for long-term use in the U.S., and consumers spend billions of dollars each year on pills and weight-loss supplements that do not require FDA approval.

Two FDA advisory committees endorsed alli in January 2006 and the agency granted conditional approval in April. GSK forecast at the time that alli would be on the market in the latter part of 2006.

But months passed with no word on alli from GSK or the FDA, and analysts spectulated that the regulatory agency was worried that the drug might be used by teens who are not obese, or that the FDA was focusing on new allegations about safety concerns raised about prescription drug Xenical.

The consumer-advocacy group Public Citizen last year petitioned the FDA to remove Xenical from the U.S. market.

Dr. Sidney M. Wolfe, director of Public Citizen's Health Research Group, called the approval of alli ''the height of recklessness.'' Wolfe said studies have linked prescription Xenical with precancerous lesions of the colon.

"The only way to lose weight and sustain that is to eat a little less and exercise more," said Wolfe.

The FDA said alli is not for people who have problems absorbing food, and also said that because of the possible loss of certain nutrients, people using the diet pill should also take a multivitamin at bedtime. 

Xenical (orlistat 120 mg capsules) will remain available by prescription and will continue to be manufactured and sold by Roche.