Orlistat: A Comprehensive Overview for Chemical Professionals

Orlistat is a lipase inhibitor weight loss drug launched by Roche Pharmaceuticals in the late 1990s under the trade name Xenical. It was launched in China in 2001 and officially changed to an over-the-counter drug by the FDA in February 2007 under the trade name Aili. Orlistat is the only OTC (over-the-counter) weight loss drug approved in China.

Figure 1 Characteristics of Orlistat

Mechanism of action of orlistat

Orlistat is a gastrointestinal lipase inhibitor that inactivates the enzyme by forming a covalent bond with the active serine site of gastric lipase in the stomach and pancreatic lipase in the small intestine. The inactivated enzyme cannot hydrolyze the fat in the food (mainly triglycerides) into absorbable free fatty acids and monoacylglycerols. Undecomposed fat cannot be absorbed by the human body and is directly excreted from the body, reducing fat intake and achieving the effect of controlling weight. Simply put, it makes fat come and go quickly. Because of this feature, orlistat is sometimes also called "fat-reducing pills" to achieve a real "weight loss" effect.

Orlistat can only reduce the absorption of 30% of fat (triglycerides) in food, and is ineffective for fat that has already formed in the human body. During the medication period, you should strengthen exercise and control your diet (especially carbohydrate intake) to achieve the effect of weight loss.

Who is Orlistat suitable for?

FDA-approved Orlistat is suitable for two groups of people: one is obese patients with a body mass index (BMI) ≥ 30kg/m2; the other is patients with BMI ≥ 27kg/m2 and risk factors (such as hypertension, diabetes and other symptoms). In my country, Orlistat is used to treat obese or overweight patients (BMI ≥ 24kg/m2).

Precautions for taking Orlistat

The regular oral dose of Orlistat is 120 mg, 3 times a day, taken at least 1 hour before, during or after a meal. You cannot take this product if you do not eat or your diet does not contain fat. If the patient loses less than 5% of his weight within 12 weeks after starting treatment, Orlistat should be discontinued. For patients with BMI ≥ 28 kg/m2 or without other risk factors, orlistat 60 mg 3 times a day can also be taken.

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