Legal Classification of Medication
Orlistat can be obtained in accordance with a prescription (POM) given by an appropriate practitioner and also obtained from pharmacies (P) through a one to one consultation with a pharmacist.
Formulation
Orlistat is available in capsule form and comes in two strengths of 60mg and 120mg. The 60mg strength is available over the counter from pharmacies.
Class of drug
Orlistat is a pancreatitic lipase inhibitor.
Indications
Orlistat is indicated in conjunction with a reasonably low calorie diet for the treatment of obese patients with a body mass index (BMI) greater or equal to 30 kg/m², or overweight patients (BMI > 28 kg/m²) with associated risk factors. Patients must be over the age of 18 and have a BMI > 28 kg/m² to purchase Orlistat without a prescription from a pharmacist.
How does it work?
Fats consumed in the diet are broken in the stomach by gastric juices, as the fat molecules are too large to be absorbed by the small intestine. Pancreatic lipase is a substance made in the pancreas which enters the small bowel to break up the fat molecules. Orlistat inhibits the function of pancreatic lipase therefore preventing the breakdown of fat molecules.
How is it taken?
Orlistat capsules are taken three times a day immediately before, during, or up to 1 hour after each main meal. If a meal is missed or contains no fat the dose of orlistat should be omitted.
Orlistat should be taken with a well-balanced, calorie controlled diet that is rich in fruit and vegetables and contains an average of 30 % of the calories from fat. The daily intake of fat, carbohydrate and protein should be distributed over three meals. This means orlistat is usually taken as one capsule at breakfast time, one capsule at lunch time and one capsule at dinner time. To gain optimal benefit, avoid the intake of food containing fat between meals, such as biscuits, chocolate and savoury snacks.
Orlistat can impair the absorption of fat soluble vitamins (A,D, E, and K). Patients should be advised to take a multivitamin preparation when using orlistat treatment at bedtime.
Pregnancy and Breast feeding
For Orlistat there is no clinical data on the effect on human pregnancy. Animal studies do not indicate direct or indirect harmful effects with respect to pregnancy or foetal development. Caution should be exercised when prescribing to pregnant women.
As it is not known whether orlistat is secreted into human milk, orlistat is contra-indicated during breast-feeding.
Contra-indications
Side-effects
Side-effects of orlistat are linked to its local action and therefore are largely gastrointestinal in nature. These side-effects include:
Diet related side-effects will occur typically 1-2 days after taking orlistat with high fat meals. Anti-motility drugs such as Imodium should not be used when patients experience fatty oily stools (steatorrhoea).
An important potential adverse effect, could be reduced effectiveness of the combined oral contraceptive if a patient taking orlistat experiences diarrhoea. It may be advisable to use an additional form of contraception like a barrier or an alternative method altogether. This is best discussed with your doctor.
Author: Mr Shiraz Mughal, MPharmS Editor: Dr Shazan Chughtai, MB BS
