Orlistat

Brand names

• Xenical

Usage

To achieve weight loss and weight maintenance in the management of obesity when used in conjunction with a reduced-calorie diet and appropriate physical activity. Orlistat is indicated for patients with an initial body mass index (BMI) of 30 or greater and in those with a BMI greater than 27 who also have other risk factors, such as high blood pressure, high blood cholesterol, and diabetes.

How it works

Orlistat inhibits the activity of lipases, intestinal enzymes required for the digestion of dietary fats. Orlistat prevents the breakdown of a portion of ingested fat. The undigested fat cannot be absorbed and is excreted in the feces. Full doses of orlistat reduce the absorption of fat by about 30%.

Side effects

Serious

No serious side effects have yet been reported.

Common

Oily spotting, gas with discharge, fecal urgency, oily stool, anal leakage, increased defecation, fecal incontinence.

Less common

Abdominal pain or discomfort.

Possible interactions

Other medicaments:

Orlistat may decrease the effects of:

• beta carotene; take 2 hours before or after orlistat.
• fat-soluble vitamins, such as vitamin A, D, E or K.

Orlistat taken concurrently with:

• cyclosporine (Sandimmune, others) may (because of possible variation in cyclosporine levels with changes in diet) lead to changes in cyclosporine levels.
• pravastatin (Pravachol) or other HMG-CoA reductase inhibitors may work well in further lowering cholesterol. Pravastatin levels may be increased by roughly 30%. Patients taking this combination should be followed more closely for possible adverse effects.
• warfarin (Coumadin, others) may (because of possible decreases in vitamin K over time) lead to increased warfarin effects; more frequent INR testing is prudent.

Foods:

Follow your doctor's recommended diet and portion control. Avoid foods that have tended to cause gas (flatus) formation previously.

Herbal medicines or minerals:

A variety of products that promise weight loss has been or is available. Some of these products have contained ma huang or other potentially dangerous ingredients. Do not combine any herbal weight loss product with orlistat. Talk to your doctor if you are considering any herbal weight loss product.
Ask your doctor about the need for supplements of vitamins A, D, E and K as well as beta carotene.

Discontinuation:

The dose of any potentially toxic or narrow therapeutic window medicament (such as warfarin) taken concurrently must be changed appropriately if orlistat is stopped.

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