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Orlistat (Xenical) is used to assist with losing weight, maintaining a certain weight and preventing weight regain.

Unlike other weight loss drugs you may have heard about that act in the brain or central nervous system to suppress appetite or to speed up metabolism, Orlistat works in the digestive system to block about one-third of the fat in the digested food.

The popular antiobesity drug Orlistat (trade names Xenical, Alli) was originally developed as an inhibitor of pancreatic lipase. Orlistat is the name for tetrahydrolipstatin (THL), which is a saturated derivative of lipstatin.

Lipstatin is a natural product, and was first isolated from the Actinobacterium Streptomyces toxytricini7 by Swiss researchers from Hoffmann-La Roche & Co., Ltd.

In 1998 Xenical was launched in EU, and later in April 1999 was approved in United States. Alli, a lower dose formulation of orlistat, was approved for purchase without a prescription in 2007.

• Managing obesity in adults and adolescents 12 years and older in conjunction with a reduced-calorie diet.
• Reduction of the risk for weight regain after previous weight loss.

Orlistat is indicated for people who are considerably overweight (have a body mass index of 30 or greater). Orlistat is also for people who are overweight (have a body mass index of 27 or greater) and also have other risk factors such as high blood pressure, high cholesterol, heart disease or diabetes.

• Polycystic ovarian syndrome (PCOS)
  In women with PCOS orlistat promotes weight loss and a reduction in testosterone concentration. In a randomized, open-labeled study the improvement seen after treatment with orlistat was additionally similar to that seen with metformin, reaffirming the potential for orlistat to be a useful adjunct in the treatment of PCOS4.
• Obese teenagers (children younger 12 years)1

Orlistat mechanism of action provides unique benefits.

Advantages and benefits:

• Effective - significant and consistent weight loss. Orlistat promotes gradual, sensible weight loss. It is an effective therapy that not only helps people lose weight, but also helps them maintain their weight loss4. Orlistat reduces body weight by an average of 5-10%. The greatest rate of weight loss occurs within the first six months of treatment.
• Helps to prevent the development of type 2 diabetes. FDA approved labeling shows that weight loss with Xenical delayed the onset of type 2 diabetes in obese patients with impaired glucose tolerance2.
• Extra health benefits. Orlistat can lower the level of total cholesterol and triglycerides in the blood, lower blood pressure, produce positive effect on levels of blood sugar and insulin.
• Works locally in the digestive system. Orlistat ascts only in the digestive tract. It does not affect other body systems due to its minimal limited absorption. No negative impact on cardiovascular system.
• Completely non-addictive. Orlistat has low potential for misuse. No dose dependent effects.
• Safest diet pill on the market and safe for long-term use. Not even 1% of Xenical is absorbed by the bloodstream, which makes it by far the safest prescription weight loss drug on the market.
• Pregnancy category B.
• Few drug interactions. Orlistat has low potential for drug interactions. No drug interactions between Xenical and centrally acting medications.
• Overall good tolerability. Side effects are predictable and manageable.

Disadvantages:

• High rate of unpleasant gastrointestinal side effects, such as oily spotting, flatus with discharge, fecal urgency, fatty/oily stool, oily evacuation, increased defecation and fecal incontinence. The incidence of these increases the higher the fat content of the diet. This bowel discomfort is a natural effect of blocking the fat from being absorbed, and indicates that Xenical is working.
• Vitamin starvation - need for vitamin supplementation. Along with dietary fat, orlistat decreases the absorption of some fat-soluble vitamins and beta-carotene. You should take a multivitamin supplement containing vitamins A, D, E, and K to ensure good nutrition.
• Kidney stones. Orlistat increases the likelihood of kidney stones5. Use it with caution if you have a history of this problem.
• Frequent dosage regimen - 3 times daily dosage schedule.
• Expensive.

Orlistat (Xenical) is a potent long-acting gastrointestinal lipase inhibitor. It exerts its therapeutic activity in the stomach.

Dietary fats are large molecules that need to be broken down before they can be absorbed into the body. They are broken down by enzymes called lipases. When taken with a meal, Xenical interferes with the activity of these enzymes and allows about 30% of the fat eaten in the meal to pass through the gut undigested. Therefore, your body cannot store these excess calories as fatty tissue or use them as a source of energy.

This helps you to reduce your weight by burning up fat that you are already carrying, maintain your weight loss and minimise any weight regain.

Onset of action: Weight loss begins within 2 weeks and continues for 6 to 12 months.

The half-life of the absorbed orlistat is in the range of 1 to 2 hours.

• Orlistat (Xenical) versus Other Medications

• 1. Weibel EK, Hadvary P, Hochuli E, Kupfer E, Lengsfeld H. Lipstatin, an inhibitor of pancreatic lipase, produced by Streptomyces toxytricini. I. Producing organism, fermentation, isolation and biological activity. J Antibiot (Tokyo). 1987 Aug;40(8):1081-5. PubMed
• 2. XENical in the prevention of diabetes in obese subjects (XENDOS) study: a randomized study of orlistat as an adjunct to lifestyle changes for the prevention of type 2 diabetes in obese patients. Torgerson JS, Hauptman J, Boldrin MN, Sjostrom L. Diabetes Care. 2004 Jan;27(1):155-61. Erratum in: Diabetes Care. 2004 Mar;27(3):856.
• 3. User Reviews for Xenical on Drugs.com
• 4. Orlistat is as beneficial as metformin in the treatment of polycystic ovarian syndrome. Jayagopal V, Kilpatrick ES, Holding S, Jennings PE, Atkin SL. Journal of Clinical Endocrinology & Metabolism 2005 Feb;90(2):729-33.
• 5. Ferraz RR, Tiselius HG, Heilberg IP. Fat malabsorption induced by gastrointestinal lipase inhibitor leads to an increase in urinary oxalate excretion. Kidney Int. 2004 Aug;66(2):676-82.

Published: December 12, 2008
Last updated: January 07, 2010