It acts in the same way as the older drug orlistat (Xenical) by inhibiting pancreatic lipase, an enzyme that breaks down triglycerides in the intestine.

Without this enzyme, triglycerides from the diet are prevented from being hydrolyzed into absorbable free fatty acids and are excreted undigested.

[1] In human trials from 2007, cetilistat was shown to produce similar weight loss to orlistat, but also produced similar side effects such as oily, loose stools, fecal incontinence, frequent bowel movements, and flatulence.

[5][needs update] In 2010, a phase 2 trial found cetilistat significantly reduced weight and was better tolerated than orlistat.

[6] Takeda gained approval to market Cetilistat in Japan, but terminated the license agreement with Norgine in 2018.