Information for GPs

Key information for GPs considering prescribing Xenical (orlistat).

1. Orlistat is is a reversible gastrointestinal lipase inhibitor. It acts locally in the gastrointestinal tract to reduce the absorption of fat in the diet, meaning that systemic absorption of Xenical is not needed for it to be effective. Systemic exposure is minimal.
2. Orlistat taken with a lower fat diet produces about twice the weight loss of the placebo.
3. Taken 3 times a day, Xenical prevents the absorption of about 30% of the fat in the diet.
4. If the patient has not lost approximately 5% of their initial body weight after the first 12 weeks of taking Xenical, you should consider stopping it.
5. Patients should be advised to stick to dietary guidelines, in particular adverse gastrointestinal side effects are more likely when the amount of fat in the diet exceeds 30% of the total daily calories.
6. The active ingredient in the Xenical tablet is orlistat. The inactive ingredients include microcrystalline cellulose, sodium starch, glycolate, sodium lauryl sulfate, povidine and talc.
7. Xenical has not been studied in certain populations, including geriatrics and patients with kidney and liver problems, as it is minimally absorbed. It has however been studied in children aged between 12 and 16. The balance of the minerals calcium, magnesium, phosphorus, zinc and copper was not affected. However, the iron balance was decreased by 64.7 µmole/24 hours in the treated group, compared to 40.4 µmole/24 hours in the placebo control group.
8. The Cost
   The current cost per tablet of Xenical is 49p per capsule. At 3 capsules per day, the cost for a year's supply for one patient is £537.
9. If you are going to prescribe Xenical, you will need to make arrangements to counsel and support your patient, offering appropriate advice on diet and exercise, and monitor the weight loss and any side effects.