Orlistat

Pronunciation

(OR li stat)

U.S. Brand Names

Xenical®

Generic Available

No

Canadian Brand Names

Xenical®

Use

Management of obesity, including weight loss and weight management when used in conjunction with a reduced-calorie diet; reduce the risk of weight regain after prior weight loss; indicated for obese patients with an initial body mass index (BMI) 30 kg/m² or 27 kg/m² in the presence of other risk factors

Pregnancy Risk Factor

B

Pregnancy Implications

There are no adequate and well-controlled studies of orlistat in pregnant women. Because animal reproductive studies are not always predictive of human response, orlistat is not recommended for use during pregnancy. Teratogenicity studies were conducted in rats and rabbits at doses up to 800 mg/kg/day. Neither study showed embryotoxicity or teratogenicity. This dose is 23 and 47 times the daily human dose calculated on a body surface area basis for rats and rabbits, respectively.

Lactation

Excretion in breast milk unknown/not recommended

Contraindications

Hypersensitivity to orlistat or any component of the formulation; chronic malabsorption syndrome or cholestasis

Warnings/Precautions

Patients should be advised to adhere to dietary guidelines; gastrointestinal adverse events may increase if taken with a diet high in fat (>30% total daily calories from fat). The daily intake of fat should be distributed over three main meals. If taken with any one meal very high in fat, the possibility of gastrointestinal effects increases. Patients should be counseled to take a multivitamin supplement that contains fat-soluble vitamins to ensure adequate nutrition because orlistat has been shown to reduce the absorption of some fat-soluble vitamins and beta-carotene. Some patients may develop increased levels of urinary oxalate following treatment; caution should be exercised when prescribing it to patients with a history of hyperoxaluria or calcium oxalate nephrolithiasis. As with any weight-loss agent, the potential exists for misuse in appropriate patient populations (eg, patients with anorexia nervosa or bulimia). Safety and efficacy have not been established in children <12 years of age. Write/fill prescription carefully. Dispensing errors have been made between Xenical® (orlistat) and Xeloda® (capecitabine).

Adverse Reactions

>10%:

Central nervous system: Headache (31%)

Gastrointestinal: Oily spotting (27%), abdominal pain/discomfort (26%), flatus with discharge (24%), fatty/oily stool (20%), fecal urgency (22%), oily evacuation (12%), increased defecation (11%)

Neuromuscular & skeletal: Back pain (14%)

Respiratory: Upper respiratory infection (38%)

1% to 10%:

Central nervous system: Fatigue (7%), anxiety (5%), sleep disorder (4%)

Dermatologic: Dry skin (2%)

Endocrine & metabolic: Menstrual irregularities (10%)

Gastrointestinal: Fecal incontinence (8%), nausea (8%), infectious diarrhea (5%), rectal pain/discomfort (5%), vomiting (4%)

Neuromuscular & skeletal: Arthritis (5%), myalgia (4%)

Otic: Otitis (4%)

<1%: Allergic reactions, anaphylaxis, angioedema, pruritus, rash, urticaria

Overdosage/Toxicology

Single doses of 800 mg and multiple doses of up to 400 mg 3 times daily for 15 days have been studied in normal weight and obese patients without significant adverse findings. In case of significant overdose, it is recommended that the patient be observed for 24 hours.

Drug Interactions

Amiodarone: Orlistat may decrease amiodarone absorption; monitor.

Cyclosporine: Cyclosporine serum levels may de decreased; administer cyclosporine 2 hours before or after orlistat; monitor.

Warfarin: Orlistat does not alter the pharmacokinetics of warfarin, however, vitamin K absorption may be decreased during orlistat therapy. Therefore, patients stabilized on warfarin should be monitored for changes in warfarin effects.

Ethanol/Nutrition/Herb Interactions

Fat-soluble vitamins: Absorption of vitamins A, D, E, and K may be decreased by orlistat. A multivitamin containing the fat-soluble vitamins (A, D, E, and K) should be administered once daily at least 2 hours before or after orlistat.

Mechanism of Action

A reversible inhibitor of gastric and pancreatic lipases thus inhibiting absorption of dietary fats by 30% (at doses of 120 mg 3 times/day).

Pharmacodynamics/Kinetics

Absorption: Minimal

Metabolism: Metabolized within the gastrointestinal wall; forms inactive metabolites

Excretion: Feces (83% as unchanged drug)

Dosage

Oral: Children 12 years and Adults: 120 mg 3 times/day with each main meal containing fat (during or up to 1 hour after the meal); omit dose if meal is occasionally missed or contains no fat.

Dietary Considerations

Multivitamin supplements that contain fat-soluble vitamins should be taken once daily at least 2 hours before or after the administration of orlistat (ie, bedtime). Distribute the daily intake of fat over 3 main meals. Gastrointestinal effects of orlistat may increase if taken with any 1 meal very high in fat.

Patient Education

Take this medication exactly as ordered; do not alter prescribed dose without consulting prescriber. Maintain prescribed diet (high-fat meals may result in GI distress), exercise regimen, and vitamin supplements as prescribed. You may experience dizziness or lightheadedness (use caution when driving or engaging in tasks requiring alertness until response to drug is known) or increased flatus and fecal urgency (this may lessen with continued use). Report persistent back, muscle, or joint pain; signs of respiratory tract infection or flu-like symptoms; skin rash or irritation; or other reactions. Breast-feeding precaution: Breast-feeding is not recommended.

Cardiovascular Considerations

Obesity is a modifiable risk factor for cardiovascular disease. When combined with dietary measures, orlistat may decrease weight by 3-4 kg. Orlistat and dietary measures resulted in a greater reduction in the incidence of type 2 diabetes mellitus (noninsulin dependent, NIDDM) over 4 years in obese patients with impaired glucose tolerance (Torgerson, 2004).

Dental Health: Effects on Dental Treatment

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Mental Health: Effects on Mental Status

May cause anxiety, fatigue, and sleep disorders

Mental Health: Effects on Psychiatric Treatment

None reported; be vigilant for abuse in patients with anorexia nervosa or bulimia

Dosage Forms

Capsule: 120 mg

References

Davidson MH, Hauptman J, DiGirolamo M, et al, "Weight Control and Risk Factor Reduction in Obese Subjects Treated for 2 Years With Orlistat: A Randomized Controlled Trial,"JAMA, 1999, 281(3):235-42.

Heymsfield SB, Segal KR, Hauptman J, et al, "Effects of Weight Loss With Orlistat on Glucose Tolerance and Progression to Type 2 Diabetes in Obese Adults,"Arch Intern Med, 2000, 160(9):1321-6.

Hollander PA, Elbein SC, Hirsch IB, et al, "Role of Orlistat in the Treatment of Obese Patients With Type 2 Diabetes. A 1-year Randomized Double-Blind Study,"Diabetes Care, 1998, 21(8):1288-94.

Torgenson JS, Pauptman J, Boldrin MN, et al, "XENical in the Prevention of Diabetes in Obese Subjects (XENDOS) Study: A Randomized Study of Orlistat as an Adjunct to Lifestyle Changes for the Prevention of Type 2 Diabetes in Obese Patients,"Diabetes Care, 2004, 27(1):155-61.

International Brand Names

Xenical® (AR, AT, AU, BD, BE, BR, CA, CH, CL, CO, CR, CZ, DE, DK, DO, ES, FI, FR, GB, GT, HN, HR, HU, ID, IE, IL, IT, MX, NL, NO, NZ, PA, PL, PT, RO, RU, SE, SG, SI, SV, TH, TR, YU, ZA)