Xenical® (orlistat) is a prescription weight loss medication. It is approved to help people lose weight and to prevent weight regain in people who have already lost weight.

Xenical works by decreasing the absorption of fat from your diet. The stomach and intestine have enzymes, called lipases, that break down fat into smaller molecules which are then absorbed from your digestive tract. Xenical binds to lipases and inhibits their activity, helping to decrease fat absorption. The medication does not have any effect on carbohydrates or protein.
Studies have shown that Xenical helps people lose weight. After six months of taking the drug while dieting, people lost an average of 12.4 pounds (compared to just 6.2 pounds for people who were just dieting). After a year, those taking Xenical while dieting had lost a total of 13.4 pounds, on average (compared to 5.8 pounds for those just dieting). In addition, those taking Xenical for a year experienced decreases in total cholesterol, LDL cholesterol (“bad” cholesterol), blood sugar, and blood pressure, while those not taking Xenical increased all these factors.

In studies of Xenical in people with type 2 diabetes, the drug improved several measures of diabetes control, such as fasting glucose and hemoglobin A1c, and many people were able to reduce or discontinue their diabetes medications. Studies have also shown that Xenical can help prevent type 2 diabetes in people with obesity.

Xenical has also been studied as an aid to help people who have already lost weight keep the weight off. In one study, 52 percent of people not taking Xenical regained the weight they had lost, compared to just 26 percent of people who took the drug.

General considerations for when and how to take Xenical include the following:

  • The medication comes in capsule form. It is taken by mouth with each fat-containing meal, up to three times per day.
  • If you miss a meal, or if you have a meal without any fat, you should skip the dose of Xenical.
  • The medication should be combined with a reduced-calorie, low-fat diet. Eating too much fat increases the risk of Xenical side effects. In general, you should try to limit your fat intake to less than 30 percent of your total daily calories.
  • For the medication to work properly, it must be taken as prescribed.

There is only one standard dose of Xenical® (orlistat), regardless of your age, weight, or other medical conditions. As is always the case, do not adjust your Xenical dose unless your healthcare provider specifically instructs you to do so.

The recommended dose of Xenical for weight loss or weight maintenance in adults and children age 12 and older is Xenical 120 mg (one capsule) with each meal that contains fat, up to three times daily. It is best if you take Xenical with the meal, but you can take it up to an hour after the meal, if necessary (taking it later than one hour after the meal will make it less effective). If you skip a meal, or if you eat a meal without fat, you should also skip your Xenical dose. The medication is not meant to be used alone; it should always be used with an appropriate diet plan.

Xenical can decrease the absorption of certain vitamins from the diet. It is recommended that you take a multivitamin once a day, at least two hours before or after Xenical. Often, bedtime is a good time for many people taking Xenical to take their multivitamin.

As with any medicine, side effects are possible with Xenical. However, not everyone who takes the drug will experience side effects. In fact, most people tolerate it quite well. If side effects do occur, in most cases, they are minor and either require no treatment or can easily be treated by you or your healthcare provider. Serious side effects are less common.

Common side effects of Xenical include, but are not limited to:

  • Oily spotting (uncontrolled anal seepage of oil)
  • Abdominal pain (stomach pain)
  • Urgent need to have a bowel movement
  • Gas with discharge (of either oil or stool).

Xenical® (orlistat) can potentially interact with a few other medicines. Some of the medicines that may lead to Xenical drug interactions include:

  • Amiodarone (Cordarone®)
  • Cyclosporine (Gengraf®, Neoral®, Sandimmune®)
  • Diabetes medications
  • Thyroid medications, including: Liothyronine (Cytomel®), Liotrix (Thyrolar®), Levothyroxine (Levoxyl®, Synthroid®, Unithroid®), Thyroid (Armour® Thyroid, Nature-Throid®)
  • * Vitamins
  • * Warfarin (Coumadin®, Jantoven®).

Xenical Overdose:
The effects of a Xenical overdose will vary depending on a number of factors, including the Xenical dosage and whether it is taken with any food, medicines, alcohol, or street drugs.

If you happen to overdose on Xenical, seek immediate medical attention.
Symptoms of a Xenical Overdose
Many diet and weight loss products (especially stimulants) can be dangerous if you take too much. However, this does not seem to be the case with Xenical. In one study, people took large doses of orlistat (the active ingredient of Xenical) for up to 15 days without experiencing any problems other than the usual Xenical side effects.

If you take too much Xenical, it is reasonable to expect the usual intestinal-related Xenical side effects, although they may be more severe (particularly if you eat a high-fat meal while taking too much Xenical). It is probably a good idea to avoid eating fat for a few days, as this can help decrease the side effects.
Treatment for a Xenical Overdose
It is not known how best to treat a Xenical overdose. Therefore, treatment (if necessary) will consist of supportive care. This type of care consists of treating the symptoms that occur as a result of the overdose. For instance, if an overdose caused dehydration due to severe diarrhea, then supportive treatment would include electrolytes and fluids to treat the dehydration.

It is important that you seek prompt medical attention if you believe that you may have overdosed on Xenical.

Generic Xenical
Xenical is made by GlaxoSmithKline. It is currently under the protection of a patent that prevents any generic Xenical from being manufactured in the United States.
GlaxoSmithKline has the exclusive rights to market Xenical until at least December 2009. This is the earliest possible date that a generic version of Xenical could become available. However, other circumstances could come up to extend this exclusivity period. This could include such things as other patents for specific Xenical uses or lawsuits. Once the patent expires, several companies will likely begin manufacturing generic Xenical.
Orlistat is the active ingredient in Xenical (as well as in the non-prescription medication Alli™), but is not a generic version of it. What can be confusing is that, oftentimes, the active ingredient of any drug is referred to as the “generic name.” The generic name is different from a generic version of a medicine. In order for there to be a generic version of a medicine, the original medicine must have gone off-patent and another company besides the original manufacturer must make the product.