Orlistat

Question 1

Indications:

Answer 1

OTC orlistat is indicated for weight loss in adults (18 or over) who are overweight
(BMI ≥ 28 kg/m2) and should be taken in conjunction with a mildly hypocaloric, lower-fat diet.

Question 2

Mode of Action:

Answer 2

Orlistat is a potent, specific and long-acting inhibitor of gastrointestinal lipases. It
exerts its therapeutic activity in the lumen of the stomach and small intestine by forming a covalent bond with the active serine site of the gastric and pancreatic lipases. The inactivated enzyme is thus unavailable to hydrolyse dietary fat, in the form of triglycerides, into absorbable free fatty acids and monoglycerides.

Question 3

When should orlistat not be supplied?

Answer 3

• Hypersensitivity to the active substance or to any of the excipients
• Chronic malabsorption syndrome
• Cholestasis (condition where the flow of bile from the liver is
blocked)
• Concurrent treatment with ciclosporin (as can decrease ciclosporin plasma levels), warfarin or other oral anticoagulants (as INR may be affected by change in vitamin K levels)
• Pregnant or breast-feeding women
- Children - orlistat should not be used in children or adolescents below the age of 18.

Question 4

Dosage:

Answer 4

The recommended dose of Orlistat is one 60mg capsule three times daily. The
capsule should be taken with water immediately before, during or up to one hour
after each main meal. If a meal is missed or contains no fat, the dose of Orlistat
should be omitted. No more than three 60mg capsules should be taken in 24
hours in accordance with the Alli 60mg hard capsules product licence. Treatment
should not exceed 6 months.

Question 5

Interactions:

Answer 5

• Orlistat may indirectly reduce the availability of oral contraceptives and lead to
unexpected pregnancies in some individual cases. Advise users to use
additional contraceptive methods if they experience severe diarrhoea
• Acarbose - orlistat is not recommended for use in those taking acarbose
• Amiodarone - possible decrease in plasma levels of amiodarone
• Hypothyroidism and/or reduced control of hypothyroidism may occur when orlistat and levothyroxine are taken at the same time
- Fat soluble vitamins (A,D,E and K): treatment with orlistat may impair
the absorption of fat soluble vitamins. Advise all users of orlistat to use
a multivitamin supplement at bedtime, to help ensure adequate
vitamin intake.

Question 6

BMI equation

Answer 6

BMI is a simple index of weight-for-height that is commonly used to
classify underweight, overweight and obesity in adults. It is defined as
the weight in kilograms divided by the square of the height in metres
kg/m .

Question 7

When to refer to GP

Answer 7

• Patients taking medication for diabetes - dose of diabetic
  medication may need adjusting as weight loss may be accompanied
  by improved metabolic control. Orlistat 60mg P is not recommended
  for use by patients who are taking acarbose.
• Patients taking hypertension or hypercholesterolaemia medication - it may be necessary to adjust the dose of the medicinal product for
  hypertension or hypercholesterolaemia as weight loss may be
  accompanied by an improvement in blood pressure and /or
  cholesterol levels.
• Patients taking amiodarone should be informed to liaise with their
  prescriber before starting treatment with orlistat. The dose of
  amiodarone may need adjusting.
• Patients taking levothyroxine.
• Patients taking antiepileptic medication. There is an increased risk of
  convulsions when orlistat is given with antiepileptics.
• Patients who have been using orlistat for 6 months and longer; treatment with orlistat 60mg P should not exceed six months.
• If a patient has been unable to lose weight after 12 weeks of
  treatment.
• If a patient reports rectal bleeding while taking orlistat.
  Patients with kidney disease should consult their GP before using orlistat 60mg P

Question 8

What are the side effects of orlistat?

Answer 8

Side effects are largely gastrointestinal in nature. The possibility of
experiencing gastrointestinal symptoms may increase when orlistat is
taken with an individual meal or a diet high in fat. Diet related side
effects include; oily leakage from rectum, flatulence, faecal urgency,
fatty oily stools (steatorrhoea).

• Advise the patient that gastrointestinal side effects are less likely if
  they eat a lower fat diet and that such effects typically occur within
  the first few weeks and tend to settle with time.

Question 9

Do any drugs interact with orlistat?

Answer 9

Patients taking the following medicines should be referred to their GP:-
amiodarone, oral anticoagulants (including warfarin), acarbose,
antiepileptics, ciclosporin, levothyroxine.
Orlistat may impair the absorption of fat soluble vitamins (A,D,E and K).
Advise all users of orlistat to use a multivitamin supplement at bedtime, to help ensure adequate vitamin intake.