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ORLISTAT

General points

Anti-obesity medication should only be considered after diet, behavioural changes and exercise have been tried and evaluated. If the patient’s weight has reached a plateau despite these measures, or if targets have not been achieved, pharmacological treatment may be considered.

Pharmacological treatment may be used to maintain weight loss, rather than continue to lose weight. .

Vitamin and mineral supplements should be considered, particularly for vulnerable groups like the elderly and growing adolescents.

Those with type 2 diabetes may lose weight at a slower rate and appropriate allowance should be made.

Regular review of adverse effects and to reinforce lifestyle advice is important.

People being withdrawn from anti-obesity medication should be offered support because it is at this time that their self-confidence and belief in their ability to make changes may be low.

Action – orlistat is a lipase inhibitor which acts by reducing the absorption of dietary fat. It prevents absorption of around 30% of dietary fat.

Effectiveness – orlistat significantly increases weight loss compared to placebo but its effectiveness is limited by its side-effects. Clinical trials suggest a moderate weight loss compared to placebo – about 2-5 kg over a year. There is also a small but significant reduction in total cholesterol, the ratio of total cholesterol to high-density lipids and systolic and diastolic blood pressure. Most patients gain weight after stopping treatment but trials suggest it takes three years to gain weight lost in one year on the drug.

Indications – individuals with a BMI of 28 kg/m2or more in the presence of significant comorbidities(eg, type 2 diabetes, high blood pressure, hyperlipidaemia) OR a BMI of 30 kg/m2 or more with no associated comorbidities. These individuals should be on a mildly hypocaloric, low-fat diet.

If on long-term therapy,monitor A, D, E and beta-carotene levels and prescribe supplementation if appropriate. If vitamin supplements are required, these should be taken at least two hours after an orlistat dose, or at bedtime. Additional contraception may be needed in women experiencing marked gastrointestinal side-effects (eg, diarrhoea). Underlying kidney disease may result in hyperoxaluria and oxalate nephropathy.

Common problems: abdominal discomfort/distension, liquid oily stools, faecal urgency andincreased frequency, flatulence – more so if a diet contains 2000 kcal/day and is high in fat. Other common problems include headaches, upper respiratory tract infections and hypoglycaemia. Less frequently, rectal pain, menstrual irregularities, anxiety, and fatigue occur.

Rare side-effects: rare reports of hepatitis and cholelithiasis. Warn people to stop orlistatand seek medical advice if symptoms such as jaundice, itching, dark urine or abdominal pain develop.