Orlistat (Xenical)

Obesity poses a serious threat for health, being a risk factor for the development of heart diseases, Type 2 diabetes mellitus and associated insulin resistance (metabolic syndrome), dyslipidemia, tumors, and reproductive function failure. The increasing prevalence of obesity and obesity-related disorders makes it a key discussion and research topic in several disciplines, including health and social sciences as well as in other disciplines such as physical education. Treatment of overweight or obese patients with drugs may be an important component of weight management, along with diet, exercise, and behavior modification, because many are unable to achieve a meaningful weight loss with lifestyle measures alone.

Orlistat (Xenical) is a drug used in the management of obesity, as an adjunct in weight management. It is indicated for obese patients with body mass index (BMI) of at least 30 and patients with BMI of at least 27 in the presence of other risk factors for arteriosclerosis such as high blood pressure, diabetes, and elevated blood cholesterol or triglycerides.

Orlistat promotes weight loss by preventing the digestion and absorption of dietary fat. It works by inhibiting the gastric and pancreatic enzyme known as lipase, which breaks down triglycerides in the intestine. Because the inactivated enzymes are unable to hydrolyze (split) the dietary fat in the form of triglycerides into absorbable free fatty acids and monoglycerides, the unabsorbed fat is then excreted as such in the stools.

Orlistat was approved for use in the United States by the Food and Drug Administration (FDA) in 1999. In most areas, orlistat is available by prescription only. Approval of an over-the-counter (OTC) formulation to be marketed under the name Alli™ was granted to the manufacturer in February 2007. This OTC formulation is now available only at half the dosage of the prescription medication.

Orlistat is taken by mouth three times daily, one hour after or during a meal containing fat. It is available in the form of a capsule at a dose of 120 milligrams. Doses greater than 120 milligrams, three times daily, have not been shown to have any beneficial effect or increase the weight loss. If a meal is missed occasionally or consumed without fat, the dose of orlistat can be omitted. Orlistat must be used with a nutritionally balanced, reduced-calorie diet that contains no more than 30 percent calories from fat.

Orlistat appears to be very effective when it comes to weight loss. Studies on orlistat have shown that individuals receiving orlistat lost significantly more weight compared to placebo. However, a significant number of subjects regained the weight after they stopped using orlistat. In addition to its well-established efficacy in achieving moderate weight loss, orlistat has been shown to improve blood sugars in obese individuals with Type 2 diabetes mellitus as well as some features of metabolic syndrome. Recent data have also suggested that orlistat has been shown to improve hormonal and metabolic profile in women with polycystic ovarian syndrome after six months of treatment, independently of BMI changes.

Orlistat is generally well tolerated. Most of the side effects seen with orlistat are related to the reduced absorption of fat from the diet. These include oily spotting on the underwear, abdominal pain or discomfort, flatulence, fecal urgency, fatty or oily stools, oily evacuation, and increased defecation and stool incontinence. To reduce the occurrence of these side effects, meals should contain no more than 30 percent fat. Nongastrointestinal side effects include headache, back pain, arthritis, upper respiratory infection, menstrual irregularities, fatigue, and anxiety. Patients with a history of calcium oxalate kidney stones may develop increased levels of oxalate in their urine, which may increase the risk of kidney stones when receiving orlistat. Individuals who should not take this drug include those who have binge eating disorder, bulimia nervosa, malabsorption syndromes and reduced gallbladder function, for example, after cholecystectomy, and in individuals with certain kidney problems.

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