What is Xenical?

Xenical is a brand name of Orlistat.
Orlistat was developed by Swiss chemists for the management of obesity, including weight loss and maintenance of weight loss when used in conjunction with a reduced-calorie diet in 1987.

The FDA approved Orlistat (marketed under the trade name Xenical by Roche) as a prescription weight loss aid in 1999.

And now Xenical is one of the available FDA-approved prescription weight loss medications.

Because it operates on the digestive system, rather than the brain or nervous system, it is particularly safe for patients suffering from diabetes, high blood pressure or heart disease. 
In fact, Xenical is the only drug approved for the treatment of obesity in high-risk patients.
In addition, it is also the only weight loss medication to receive FDA-approval for use in the treatment of obese teenagers.