Orlistat (trade name Xenical) is a lipase (an enzyme in the body that breaks down fat) inhibitor for obesity management that acts by blocking the absorption of dietary fats. It works by forming a bond with the enzymes that normally break down the fat in your food. Once the enzymes are inhibited, they can no longer break down fat from triglycerides into free fatty acids that the body can absorb. Undigested triglycerides mean fewer calories, which will aid in weight loss.
This is not to say that Xenical will prevent all the fat you eat from being absorbed. It will prevent the absorption of up to 30% of dietary fat. Using Xenical with a reduced calorie, low-fat diet will help reduce your fat intake even more and thereby help with your weight loss. Xenical is also used to reduce the risk for weight regain after prior weight loss.
One mistake people make when prescribed Xenical is the assumption that they can eat whatever they please and the pill will prevent them from gaining weight. That is not the way you want to lose weight, unless you want to spend all your time not being more than 5 feet from a bathroom. For Xenical to work with the least amount of unpleasant side effects, your fat intake should be less than 30% of your total daily calories and your fat intake should be spread out over 3 meals. In fact, if Xenical is taken with any one meal very high in fat, the possibility of gastrointestinal effects increases.
Gastrointestinal side effects
(From most prevalent to least)
Flatus (gas) with discharge
When taking Xenical it is important to take a multivitamin supplement. Since some vitamins, such as A, E & D are fat soluble (absorbed by fat in the body), they will be eliminated along with the undigested fat, so vitamins must be taken to insure adequate nutrition. The best time to take them is 2 hours before or after taking Xenical.
Pregnancy and nursing mothers
Because there are no adequate and well-controlled studies of XENICAL in pregnant women and it is not know if Xenical is excreted into breast milk, it is not recommended for women who are pregnant or nursing.
Pediatric and geriatric use
The safety of Xenical in children has not been established so it is not recommended. So far clinical studies of XENICAL did not include sufficient numbers of patients aged 65 years and older to determine whether they respond differently from younger patients so if you are over 65 it is best to have your doctor monitor you closely.
Xenical should be used with caution if you have any history of kidney or urinary problems. It has been shown to increase levels of urinary oxalate (salts in the urine) following treatment. These increased levels can increase the potential of kidney stones.
Xenical should not be used if you have a history of gallstones or any other gallbladder or liver obstruction problems.
The recommended dose of Xenical is one 120-mg capsule three times a day with each main meal containing fat (during or up to 1 hour after the meal). Doses above 120 mg three times a day have not been shown to provide additional benefit, so taking more won't help it will only hurt.
Xenical should be taken with a nutritionally balanced, reduced-calorie diet that contains approximately 30% of calories from fat. If you miss a meal or the meal contains no fat, the dose of XENICAL can be omitted.
The effect of Xenical can be seen within 24 - 48 hours from the start of treatment.
Long term use
Since Xenical is a relatively new drug the studies done have been on 2-year trials.
Xenical, when used properly can help you lose weight, but please keep in mind that it is a prescription drug and your doctor should monitor you while you are taking it. And with all medications, if it doesn't agree with you or the side effects are too uncomfortable, stop. Work with your doctor to find a more suitable weight loss treatment for you.