Possible Interaction: Orlistat and Fat Soluble Vitamin Product

“Abstract: Orlistat , a lipase inhibitor taken with meals at doses of 60 mg (available over-the-counter) or 120 mg (prescription only) for treatment of obesity, is known to impair the absorption of fat-soluble molecules.”

“The selection of drugs for interaction studies with orlistat was based … testing related to orlistat-induced inhibition of fat absorption (ie, orlistat may … as fat-soluble vitamins ), (2) drugs with a narrow therapeutic index, and (3) concomitant medications … population, such as glucose-lowering agents, hypolipidemic, antidiabetic, and antihypertensive drugs.”

“ Orlistat reduces dietary fat … effects on fat soluble vitamins especially the antioxidant vitamins A and E. The aim of this study was to determine and compare the effects of … orlistat therapy and a combination of orlistat with aerobic exercise training on lipid peroxidation and antioxidative defense in obese subjects.”

“Due to its ability to block fat absorption, orlistat also has the capability to inhibit absorption of fat-soluble vitamins.”

“ Orlistat causes a 30–60% reduction in absorption of the fat-soluble vitamins beta-carotene and vitamin E acetate and 2–12% of subjects treated with orlistat develop abnormally low levels of vitamins A, D, E, or beta-carotene.”

“ Orlistat interferes with the absorption of many drugs (such as warfarin, amiodarone, ciclosporin and thyroxine as well as fat-soluble vitamins ), affecting their bioavailability and effectiveness.”

“Orlistat use may be associated with patient alteration of diet to compensate for adverse effects or other … warfarin control, including direct effect on absorption of vitamin K. CONCLUSIONS: The introduction of chronic dosing of orlistat … fat-soluble vitamins , including vitamin K, with the result … of warfarin may be required.”

“ Orlistat interferes with the absorption of fat soluble vitamins , but no data are available about interfering with cyclosporine (CyA) absorption in the manufacturer’s brochure.”

“The incidence of gastrointestinal adverse events was consistently higher in orlistat groups compared with placebo, and orlistat use was associated with lower serum levels of fat-soluble vitamins.”

“Because orlistat may decrease the absorption of fat‐soluble vitamins , a standard multiple‐vitamin supplement is recommended daily during therapy to prevent abnormalities in vitamin serum concentrations.”