II. Indication: Obesity Management

  1. Body Mass Index over 30 kg/m2
  2. Body Mass Index over 27 kg/m2 with comorbidity
    1. Diabetes Mellitus
    2. Hypertension
    3. Dyslipidemia

III. Mechanism

  1. Pentanoic acid ester binds gastric, pancreatic Lipase
  2. Lipase Inhibitor (Blocks Fat absorption)
    1. Decreased Triglyceride absorption
    2. Decreased Cholesterol absorption

IV. Pharmacokinetics

  1. Minimal systemic absorption

V. Efficacy

  1. Weight loss is greater with 120 mg (7.5 lb or 3.4 kg) than with 60 mg (5.5 lb or 2.5 kg)
  2. Combined results of two large Placebo controlled trials
    1. Year one
      1. Orlistat: 9-10 kg loss (10% of baseline weight)
      2. Placebo: 6 kg (6% of baseline weight)
    2. Year two
      1. Orlistat: 1.5-3 kg regained weight
      2. Placebo: 4-6 kg regained weight
  3. References
    1. Sjostrom (1998) Lancet 352:167 [PubMed]
    2. Davidson (1999) JAMA 281:235 [PubMed]

VI. Adverse effects

  1. Gastrointestinal side effects (40%)
    1. Flatus with discharge
    2. Oily stool with spotting
    3. Fecal urgency
    4. Fecal Incontinence
    5. Abdominal Pain
  2. Fat soluble Carotenoid (fruit, vegetable) malabsorption
  3. Fat soluble Vitamin malabsorption (daily MVI recommended in package insert)
    1. Vitamin A
    2. Vitamin D
    3. Vitamin E
    4. Vitamin K

VII. Drug Interactions

  1. Does not interfere with absorption of other medications
    1. Coumadin
    2. Oral Contraceptives
    3. Antihypertensives

VIII. Dosing

  1. Take three times daily with each meal containing fat
  2. Prescription dose: 120 mg orally three times daily
  3. OTC dose: 60 mg orally three time daily

IX. Precautions

  1. Avoid fat-soluble Vitamins within 2 hours of Orlistat
  2. Maintain Dietary Fat intake <30% of calories

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Related Studies

Cost: Medications

xenical (on 2/22/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
XENICAL 120 MG CAPSULE $6.18 each

Ontology: orlistat (C0076275)

Definition (NCI) A reversible active-site inhibitor of gastrointestinal lipases. Orlistat forms a covalent bond with the active serine site in gastric and pancreatic lipases, thereby inhibiting their activity and preventing dietary fat from being hydrolyzed and absorbed. (NCI04)
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C055122
SnomedCT 116093009, 387007000
English 1-((3-hexyl-4-oxo-2-oxetanyl)methyl)dodecyl-2-formamido-4-methylvalerate, L-Leucine, N-formyl-, 1-((3-hexyl-4-oxo-2-oxetanyl)methyl)dodecyl ester, (2S-(2alpha(R*),3beta))-, tetrahydrolipstatin, THLP, orlistat, orlistat (medication), ORLISTAT, orlistat [Chemical/Ingredient], tetrahydrolipastatin, Orlistat, Orlistat (product), Orlistat (substance)
Spanish orlistat (producto), orlistat (sustancia), orlistat

Ontology: Xenical (C0732649)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C055122
English xenical, Hoffmann-La Roche brand of orlistat, Roche brand of orlistat, Xenical