Endocrine Abstracts

Background: Orlistat is a lipase inhibitor used in the treatment of obesity. Recent published work has shown that orlistat may have a role in affecting the release of appetite regulating gastrointestinal derived peptides. However, the precise effect of orlistat on these hormones remains uncertain. This study aimed to evaluate the short-term effects of orlistat with a high fat meal on levels of plasma Peptide YY (PYY) and on appetite.

Methods: Ethical permission was granted to randomise 11 healthy non-obese males to receive two standard test meals on two occasions separated by at least one day. On each study day, following an overnight fast, each subject was required to ingest a high fat liquid test meal of 1000 kcal, with either orlistat or placebo. Venous blood samples were collected prior to, and every 30 min for up to 3 h from the start of the test meal. At these same corresponding times, visual analogue scales were completed by each subject to assess subjective appetite ratings. The plasma was analysed to determine the PYY response.

Results: There was no significant difference in the plasma PYY response at any postprandial time point between orlistat and placebo administration following a high fat test meal. Furthermore, there was no significant difference in the area under the curve for time 0–180 min between the two study trials (P=0.41). Orlistat also did not significantly change the ratings of hunger or fullness at any time point, when compared with placebo. The areas under the curve for hunger (P=0.07) and fullness (P=0.31) showed no significant differences between the two trials.

Conclusion: Orlistat does not affect plasma concentrations of PYY, or short-term subjective feelings of hunger and satiety in healthy subjects of normal body weight. It appears therefore that orlistat is not affective in regulating appetite by influencing gut hormones.