An anti-obesity drug should be considered only for those with a body mass index (BMI, individual’s body-weight divided by the square of the individual’s height) of 30 kg/m2 or greater in whom at least 3 months of managed care involving supervised diet, exercise and behaviour modification fails to achieve a realistic reduction in weight. In the presence of risk factors (such as diabetes, coronary heart disease, hypertension, and obstructive sleep apnoea), it may be appropriate to prescribe a drug to individuals with a BMI of 27 kg/m2 or greater, provided that such use is permitted by the drug’s marketing authorisation. Drugs should never be used as the sole element of treatment. The individual should be monitored on a regular basis; drug treatment should be discontinued if the individual regains weight at any time whilst receiving drug treatment. Combination therapy involving more than one anti-obesity drug is contra­indicated until further information about efficacy and long-term safety is available.

Anti-obesity drugs acting on the gastro­intestinal tract

Orlistat, a lipase inhibitor, reduces the absorption of dietary fat. It is used in conjunction with a mildly hypocaloric diet in individuals with a body mass index (BMI) of 30 kg/m2 or more or in individuals with a BMI of 28 kg/m2 in the presence of other risk factors such as type 2 diabetes, hypertension, or hypercholesterolaemia.


Indications: adjunct in obesity.

Contraindications: chronic malabsorption syndrome; cholestasis; breast-feeding.

Dose and Administration: adult over 18 years, 120 mg taken immediately before, during, or up to 1 hour after each main meal (up to max. 360 mg daily); continue treatment beyond 12 weeks only if weight loss since start of treatment exceeds 5% (target for initial weight loss may be lower in patients with type 2 diabetes); child over 12 years, initiated by specialist only.