Orlistat

What it is and how it works

Mechanism of Action Orlistat is a reversible inhibitor of gastrointestinal lipases. It exerts its therapeutic activity in the lumen of the stomach and small intestine by forming a covalent bond with the active serine residue site of gastric and pancreatic lipases. The inactivated enzymes are thus unavailable to hydrolyze dietary fat in the form of triglycerides into absorbable free fatty acids and monoglycerides. As undigested triglycerides are not absorbed, the resulting caloric deficit may have a positive effect on weight control.

Mechanism class: Lipase Inhibitors

Indications

is indicated for obesity management including weight loss and weight maintenance when used in conjunction with a reduced-calorie diet. ORLISTAT is also indicated to reduce the risk for weight regain after prior weight loss. ORLISTAT is indicated for obese patients with an initial body mass index (BMI) ≥30 kg/m 2 or ≥27 kg/m 2 in the presence of other risk factors (e.g., hypertension, diabetes, dyslipidemia). Table 1 illustrates body mass index (BMI) according to a variety of weights and heights. The BMI is calculated by dividing weight in kilograms by height in meters squared. For example, a person who weighs 180 lbs and is 5 ' 5 " would have a BMI of 30. Table 1 Body Mass Index (BMI), kg/m 2 Conversion Factors: Weight in lbs ÷ 2.2 = weight in kilograms (kg) Height in inches × 0.0254 = height in meters (m) 1 foot = 12 inches ORLISTAT is a reversible inhibitor of gastrointestinal lipases indicated for obesity management including weight loss and weight maintenance when used in conjunction with a reduced-calorie diet.

Dosage and administration (summary)

One 120-mg capsule three times a day with each main meal containing fat (during or up to 1 hour after the meal). Advise patients to take a nutritionally balanced, reduced-calorie diet that contains approximately 30% of calories from fat. Distribute the daily intake of fat, carbohydrate, and protein over three main meals. Advise patients to take a multivitamin containing fat-soluble vitamins to ensure adequate nutrition. Take the vitamin supplement at least 2 hours before or after the administration of ORLISTAT, such as at bedtime. For patients receiving both ORLISTAT and cyclosporine therapy, administer cyclosporine 3 hours after ORLISTAT.

Contraindications

is contraindicated in: Pregnancy Patients with chronic malabsorption syndrome Patients with cholestasis Patients with known hypersensitivity to ORLISTAT or to any component of this product Pregnancy ( 4 , 8.1 ) Chronic malabsorption syndrome Cholestasis Known hypersensitivity to ORLISTAT or to any component of this product

Warnings and precautions

has drug interactions and can decrease vitamin absorption. ( 5.1 , 7 ) Take a multivitamin supplement that contains fat-soluble vitamins to ensure adequate nutrition. Rare cases of severe liver injury with hepatocellular necrosis or acute hepatic failure have been reported. Patients may develop oxalate nephrolithiasis and oxalate nephropathy following treatment with ORLISTAT. Monitor renal function in patients at risk for renal insufficiency. Discontinue ORLISTAT if oxalate nephropathy develops. Substantial weight loss can increase the risk of cholelithiasis.

Pregnancy

Pregnancy Pregnancy Category X ORLISTAT is contraindicated during pregnancy, because weight loss offers no potential benefit to a pregnant woman and may result in fetal harm. A minimum weight gain, and no weight loss, is currently recommended for all pregnant women, including those who are already overweight or obese, due to the obligatory weight g…

Storage and supply

Storage and Handling Store at 25°C (77°F); excursions permitted to 15° to 30°C (59° to 86°F) . Keep bottle tightly closed. ORLISTAT should not be used after the given expiration date.

Source: Orlistat (Orlistat) — US FDA prescribing information, 2026-01-09, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.