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Indications and Dosage
Oral
Obesity Adult: Patients with BMI ≥30 mg/m2 or ≥27 kg/m2 with associated risk factors (e.g. hypertension, diabetes, dyslipidaemia): 120 mg tid with each main meal. Patients with BMI ≥28 kg/m2 irrespective of any risk factors: 60 mg tid. Omit dose if a meal is missed or contains no fat. Discontinue if patient is unable to lose at least 5% of the body weight during the 1st 12 weeks of therapy. All doses given in conjunction with mildly hypocaloric diet.
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Administration
Should be taken with food. Take immediately before or during or up to 1 hr after each main meal. If a meal is missed or contains no fat, the dose may be omitted.
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Contraindications
Cholestasis and chronic malabsorption syndrome. Pregnancy and lactation.
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Special Precautions
Patients with diabetes, thyroid disease, epilepsy, anorexia nervosa, bulimia, history of hyperoxaluria or Ca oxalate nephrolithiasis. Renal and hepatic impairment.
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Adverse Reactions
Significant: Rectal bleeding, decreased prothrombin and increased INR, cholelithiasis, oxalate nephropathy that may lead to renal failure.
Gastrointestinal disorders: Oily spotting, flatus with discharge, faecal urgency and incontinence, fatty/oily stool, oily evacuation, flatulence, soft or liquid stools, abdominal pain, increased defaecation, diverticulitis, pancreatitis, rectal discomfort, abdominal distension (patient with type 2 diabetes), tooth and gingival disorder. General disorders and administration site conditions: Fatigue. Immune system disorders: Hypersensitivity reactions (e.g. anaphylaxis, bronchospasm, angioedema, pruritus, rash, urticaria). Infections and infestations: Influenza. Investigations: Increased transaminases and alkaline phosphatase. Metabolism and nutrition disorders: Hypoglycaemia (patient with type 2 diabetes), pedal oedema. Musculoskeletal and connective tissue disorders: Back or leg pain, myalgia. Nervous system disorders: Headache. Psychiatric disorders: Anxiety. Reproductive system and breast disorders: Menstrual irregularity, vaginitis, UTI. Respiratory, thoracic and mediastinal disorders: Upper and lower respiratory infection. Skin and subcutaneous tissue disorders: Bullous eruption. Potentially Fatal: Severe liver injury with hepatocellular necrosis or acute hepatic failure and hepatitis. |
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Monitoring Parameters
Monitor BMI, weight, diet (calorie and fat intake), LFT, renal function, serum glucose (in patient with diabetes), thyroid function (in patient with thyroid disease), INR (patient taking warfarin). Rule out other causes of obesity (e.g. hypothyroidism) prior to initiation of therapy.
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Drug Interactions
Reduces the plasma levels of ciclosporin thereby decreasing immunosuppressive efficacy. May decrease efficacy of antiretroviral drugs (e.g. atazanavir, ritonavir, tenofovir). May decrease the absorption of fat-soluble vitamins (A, D, E, K), β-carotene, anticoagulants (e.g. warfarin), iodine salts and/or levothyroxine and antiepileptic drugs (e.g. valproate, lamotrigine). May cause hormonal contraceptive failure. May decrease the plasma levels of amiodarone.
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Action
Description: Orlistat reversibly blocks gastrointestinal lipases. It inhibits the absorption of dietary fats by forming a covalent bond with the active serine residue site of the gastric and pancreatic lipases within the lumen of the stomach and small intestine, thus preventing the hydrolysis of dietary fat in the form of triglycerides into absorbable free fatty acids and monoglycerides.
Onset: 24-48 hours. Duration: 48-72 hours. Pharmacokinetics: Absorption: Minimal absorption. Time to peak plasma concentration: Approx 8 hours. Distribution: Plasma protein binding: >99% (mainly to lipoproteins and albumin). Metabolism: Metabolised within the gastrointestinal wall. Forms inactive metabolites, M1 (primary metabolite, hydrolysed β-lactone ring product of orlistat) and M3 (secondary metabolite, sequential metabolite after M1’s cleavage of the N-formyl leucine side-chain). Excretion: Mainly via faeces (approx 97%, 83% as unchanged drug); via urine (<2%). Elimination half-life: 1-2 hours. |
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Chemical Structure
 Source: National Center for Biotechnology Information. PubChem Database. Orlistat, CID=3034010, https://pubchem.ncbi.nlm.nih.gov/compound/Orlistat (accessed on Jan. 22, 2020) |
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Storage
Store below 25°C. Protect from light and moisture.
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MIMS Class
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ATC Classification
A08AB01 - orlistat ; Belongs to the class of peripherally acting antiobesity products.
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References
Anon. Orlistat. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 02/08/2019. Anon. Orlistat. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 16/10/2015. Beacita 60mg Capsules (Actavis Group PTC). MHRA. https://products.mhra.gov.uk/ . Accessed 06/08/2019. Buckingham R (ed). Orlistat. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 02/08/2019. Joint Formulary Committee. Orlistat. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 02/08/2019. McEvoy GK, Snow EK, Miller J et al (eds). Orlistat. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 16/10/2015. Xenical Capsule (Genentech, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 16/10/2015. Xenical Capsule (H2-Pharma Llc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 02/08/2019. Xenical Capsules . U.S. FDA. https://www.fda.gov/. Accessed 16/10/2015.
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