[CAS NO. 96829-58-2]  Orlistat (Ro 18-0647)

Orlistat, administered by oral route, is minimally absorbed by the gastrointestinal tract and is able to prevent the absorption of a large percentage of lipids, thereby reducing lipid supply from outside sources. Because of its extremely low oral bioavailability, the effects of Orlistat are largely confined to the gastrointestinal tract, where it inactivates pancreatic lipase. Therefore, the formulation and route of delivery would have to be changed to treat tumors of the breast, prostate, and so on. Orlistat halts tumor cell proliferation, induces tumor cell apoptosis, and inhibits the growth of PC-3 tumors in nude mice. A pharmacokinetic analysis of Orlistat (155 mg/kg) administered by i.p. injection showed peak blood levels to be ∼10 μM 2 h after dosing (data not shown). Beyond this time, blood levels of the drug decayed rapidly.