Johnston_2006_J.Pharm.Pharmacol_58_1099

This investigation was conducted to evaluate whether poloxamer 407 (P-407), a nonionic surface-active-agent that functions as a lipase inhibitor, could aid in weight loss by inactivating pancreatic lipase (PL) following oral administration to mice. Using a pH-titrimetric method, P-407 was evaluated for its ability to inhibit PL activity in-vitro. The palatability of drinking water containing P-407 (50 microM) was assessed in mice to determine whether inclusion of P-407 altered either the volume of water ingested, or the volume of urine produced, per day. P-407 at the same concentration was next evaluated for its potential to mediate weight loss over a one-month period in mice fed a high-fat diet. Faecal fat determinations and the potential for P-407 to lower plasma triacylglycerol concentrations following oral administration of a standard lipid emulsion were also conducted. P-407 was determined to have an IC50 of 15.9 microM in-vitro. Inclusion of P-407 in drinking water neither perturbed the daily volume of water ingested, nor the volume of urine produced. Over the course of one month, adult mice, which were fed the high-fat diet and treated with P-407, lost approximately 12.4+/-1.7% of their initial body weight, whereas, control mice fed the identical diet continued to slowly gain weight (7.3+/-0.5% of their initial body weight). The amount of total lipids excreted in the faeces of high-fat-fed, P-407-treated mice was approximately 45% greater than that observed for control mice eating the same diet. Lastly, plasma triacylglycerol concentrations following oral administration of the standard lipid emulsion containing P-407 were significantly lower than corresponding plasma triacylglycerol concentrations observed in mice administered the lipid emulsion alone. While not as potent as orlistat, P-407 may potentially represent an additional treatment strategy for weight loss, especially when combined with caloric restriction, regular exercise, and anti-obesity medications of other drug classes.