[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) ( NCI )] (UMLS (NCI) C0076275) =Organic Chemical; Pharmacologic Substance ; =LACTONE; [GA900] GASTRIC MEDICATIONS, OTHER =ORLISTAT 120 MG