Half the users of diet drug Alli experience gastrointestinal side effects

Wednesday, September 26, 2007 by: David Gutierrez, staff writer
Tags: Alli, diet pills, health news

(NewsTarget) Approximately half the users of GlaxoSmithKline's new diet drug Alli may experience gastrointestinal side effects, according to clinical trials conducted before the drug's approval. Alli -- a weaker version of Roche Holding's prescription drug Xenical, known generically as orlistat -- is the first over-the-counter diet medication approved by the FDA.

Orlistat works by inhibiting the production of an enzyme that the body uses to break down fats for digestion. Because the drug is not well absorbed by the digestive system, it acts only while sitting in the gastrointestinal tract. When taken with a meal, orlistat blocks the body from absorbing approximately one-quarter of the fat consumed.

According to one-year clinical trials, between 35 and 55 percent of people who took the drug achieved a 5 percent or higher reduction in body mass. Upon ceasing treatment, a significant number of them regained up to 35 percent of the lost weight.

Because Alli blocks the body from digesting fat, the body finds other ways to excrete the fat that has been consumed. This often occurs through feces, which may lead to the common side effects of loose stools, leakage and "gas with oily spotting," according to the Alli web site.

To limit side effects, GlaxoSmithKline recommends that all Alli users limit their fat intake to a maximum of 15 grams per meal. In addition, because the side effects tend to be most severe and frequent toward the beginning of treatment, the company recommends that users think carefully about the best time to begin the drug regimen. In to clinical trials, almost 50 percent of side effects lasted for less than a week, but effects longer than six months are possible.

The company offers one final tip for users of Alli: "You may feel an urgent need to go to the bathroom. Until you have a sense of any treatment effects, it's probably a smart idea to wear dark pants, and bring a change of clothes with you to work."