Which medications in the drug class Gastrointestinal Agents, Other are used in the treatment of Obesity?

Updated: Jun 09, 2021
  • Author: Osama Hamdy, MD, PhD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Answer

Gastrointestinal Agents, Other

Lipase inhibitors may induce weight loss by inhibiting nutrient absorption.

Orlistat (Xenical, Alli)

Orlistat is a gastrointestinal and pancreatic lipase inhibitor that induces weight loss by inhibiting dietary fat absorption. Orlistat should be taken during or up to 1 hour after a meal containing fat. Its effectiveness in producing weight loss does not depend on systemic absorption. Orlistat is available over the counter (Alli) in a half-strength dose and as a prescription drug (Xenical) as a full-strength dose.

Orlistat may reduce absorption of some fat-soluble vitamins (A, D, E, K) and beta carotene. Administer a multivitamin supplement containing fat-soluble vitamins orally daily, 2 hours before or 1 hour after a meal. Orlistat may also affect the absorption of some medications. In particular, patients on warfarin need closer monitoring because of the potential for malabsorption of vitamin K.

At the full dose of 120 mg 3 times daily, Xenical is frequently associated with such adverse GI events as flatulence, oily stool, diarrhea, and stool incontinence. Frequently, these adverse events result from the common misconception that because orlistat blocks fat absorption, people can consume more fat. It is important to advise patients to reduce total fat intake while on orlistat to reduce the frequency and severity of adverse events.

Doses of the over-the-counter form of orlistat, Alli (60 mg), are associated with fewer adverse events. However, this dosage is less effective for weight loss.


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