Orlistat

Pronunciation

Pronunciation: OR-li-stat
Class: Lipase inhibitor

Trade Names

Alli
- Capsules, oral 60 mg

Xenical
- Capsules, oral 120 mg

Pharmacology

Reversible lipase inhibitor for obesity management that acts by inhibiting absorption of dietary fats.

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Pharmacokinetics

Absorption

Systemic absorption is minimal. T max is approximately 8 h.

Distribution

More than 99% protein bound to plasma, mainly albumin and lipoprotein.

Metabolism

Occurs mainly in the GI wall. Two metabolites are identified: M1 (hydrolyzed beta-lactone ring) and M3 (M1 with N-formyl leucine side-chain cleaved), which are both considered pharmacologically inconsequential.

Elimination

Eliminated by fecal excretion (major route); biliary excretion for metabolites. 97% eliminated through feces, 83% as unchanged drug, and less than 2% through urine.

The half-life for M1 metabolite is approximately 3 h; half-life for M3 metabolite is approximately 13.5 h; half-life of absorbed orlistat is 1 to 2 h.

Special Populations

Renal Function Impairment

Pharmacokinetic studies were not conducted.

Hepatic Function Impairment

Pharmacokinetic studies were not conducted.

Elderly

Pharmacokinetic studies were not conducted.

Children

Plasma concentrations of orlistat, M1, and M3 were similar to those found in adults.

Race

Pharmacokinetic studies were not conducted.

Indications and Usage

Rx ( Xenical )

Obesity management, including weight loss and weight maintenance, when used in combination with a reduced-calorie diet; reduction of the risk for weight regain after prior weight loss.

Unlabeled uses

Chylous ascites.

OTC ( Alli )

Weight loss in overweight adults 18 y and older along with a reduced-calorie and low-fat diet.

Contraindications

Pregnancy; chronic malabsorption syndrome; cholestasis; hypersensitivity to any component of the product.

Dosage and Administration

Rx
Adults and Children 12 y and older

PO 120 mg 3 times daily with each main meal containing fat, during or up to 1 h after meal.

OTC
Adults

PO 60 mg with each fat-containing meal (max, 180 mg/day).

Concomitant therapy
Cyclosporine

Administer 3 h after orlistat.

Levothyroxine

Administer at least 4 h apart; monitor patient for changes in thyroid function.

General Advice

  • Patient should be on nutritionally balanced, low-fat, reduced-calorie diet that contains approximately 30% of calories from fat.
  • Daily fat, carbohydrate, and protein intake should be distributed over 3 main meals.
  • If a meal is missed or contains no fat, the orlistat dose may be omitted.
  • Because orlistat reduces absorption of some fat-soluble vitamins and beta-carotene, a multivitamin should be taken to ensure adequate nutrition.
  • Multivitamin supplements should be taken at least 2 h before or after taking orlistat.

Storage/Stability

Store Rx product between 59° and 86°F. Store OTC product between 68° and 77°F. Protect from light and humidity.

Drug Interactions

Cyclosporine

Coadministration decreases cyclosporine plasma levels. Administer cyclosporine at least 3 h after orlistat. Consider more frequent monitoring of cyclosporine levels.

Fat-soluble vitamins

Orlistat reduces absorption of some fat-soluble vitamins. Administer supplements containing fat-soluble vitamins at least 2 h before or after orlistat.

Levothyroxine

Hypothyroidism has been reported in patients taking orlistat and levothyroxine. Administer at least 4 h apart and monitor patients for changes in thyroid function.

Warfarin

Vitamin K levels tended to decline in patients taking orlistat. Because vitamin K absorption may be decreased with orlistat, closely monitor patients on long-term stable doses of warfarin for changes in coagulation parameters when orlistat is prescribed.

Adverse Reactions

CNS

Headache (31%); fatigue (7%); dizziness, psychiatric anxiety (5%); sleep disorder (4%); depression (3%).

Dermatologic

Rash (4%); dry skin (2%).

EENT

Otitis (4%); ear, nose, and throat symptoms (2%).

GI

Oily spotting (27%); abdominal pain/discomfort (26%); flatus with discharge (24%); fecal urgency (22%); fatty/oily stool (20%); oily evacuation (12%); increased defecation (11%); fecal incontinence, nausea (8%); infectious diarrhea, rectal pain/discomfort (5%); gingival disorder, tooth disorder, vomiting (4%); abdominal distension; lower GI bleeding, pancreatitis (postmarketing).

Genitourinary

Menstrual irregularity (10%); UTI (8%); vaginitis (4%); acute oxalate nephropathy (postmarketing).

Hepatic

Cholelithiasis (3%), hepatitis, hepatic failure, increased alkaline phosphatase and transaminases (postmarketing).

Hypersensitivity

Hypersensitivity, including anaphylaxis, angioedema, bronchospasm, pruritis, rash, urticaria, and bullous eruption (postmarketing).

Metabolic-Nutritional

Pedal edema (3%); hypoglycemia.

Musculoskeletal

Back pain (14%); lower extremity pain (11%); arthritis (5%); myalgia (4%); joint disorder, tendonitis (2%).

Respiratory

Upper respiratory tract infection (38%); lower respiratory tract infection (8%).

Miscellaneous

Influenza (40%).

Precautions

Monitor

Monitor renal function in patients at risk for renal impairment.


Pregnancy

Category X . Contraindicated in pregnancy.

Lactation

Undetermined.

Children

Rx

Safety and efficacy not established in children younger than 12 y.

OTC

Safety and efficacy not established.

Cholelithiasis

Substantial weight loss can increase the risk of cholelithiasis.

Diabetic patients

Weight loss may affect glycemic control in diabetic patients, which might require a reduction in dose of oral hypoglycemic medication or insulin.

GI reactions

GI adverse reactions may increase if orlistat is taken with a diet high in fat (more than 30% total daily calories from fat).

Hepatic effects

Severe liver injury with hepatocellular necrosis or acute hepatic failure, some cases resulting in liver transplant or death, have been reported in postmarketing reports.

Increased urinary oxalate

May occur; cases of oxalate nephrolithiasis and nephropathy with renal failure have been reported. Use with caution in patients with a history of hyperoxaluria or calcium oxalate nephrolithiasis.

Overdosage

Symptoms

No data available.

Patient Information

  • Rx and OTC
  • Remind patients to read the patient information leaflet before starting treatment and with each refill.
  • Advise patients to take prescribed dose 3 times daily with each main meal containing fat.
  • Dose should be taken during or up to 1 h after meal.
  • Advise patients that the drug may be omitted if a meal is missed or contains no fat.
  • Warn patients that drug must be used in conjunction with nutritionally balanced, reduced-calorie diet.
  • Advise patient that taking more drug than prescribed does not increase weight loss.
  • Instruct patients to take a multivitamin supplement containing fat-soluble vitamins every day at least 2 h before or after taking the drug (eg, bedtime).
  • Warn patients that daily intake of fat must be less than 30% and that ingesting larger quantities of fat in the diet will result in GI adverse reactions.
  • Inform patients of the common adverse reactions, including oily spotting, flatus with discharge, fecal urgency, fatty/oily stool, oily evacuation, increased defecation, and fecal incontinence.
  • Advise patients of the potential risks, which include lowered absorption of fat-soluble vitamins, potential liver injury, increases in urinary oxalate, and cholelithiasis.
  • Advise patients to report bothersome adverse reactions to their health care provider.
  • Inform patients taking cyclosporine, beta-carotene or vitamin E supplements, levothyroxine, or warfarin about the potential interactions during coadministration with orlistat.
  • OTC
  • Instruct patients not to take orlistat if they are organ transplant patients or are taking cyclosporine, have been diagnosed with problems absorbing food, or are not overweight.
  • Rx
  • Instruct patients not to take orlistat if they are pregnant, have chronic malabsorption syndrome, cholestasis, or hypersensitivity to any component of the product.

Copyright © 2009 Wolters Kluwer Health.

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