orlistat and retinol-palmitate

The effect of tetrahydrolipstatin (THL), a recently developed pancreatic lipase inhibitor, on fasting plasma lipid levels and postprandial lipoprotein and retinyl palmitate (RP) metabolism was studied in 17 hyperlipidemic subjects, using an oral RP fat load (8 hours, 50 g fat/m2). During therapy with THL, fasting plasma cholesterol, low-density lipoprotein (LDL) cholesterol, and apolipoprotein (apo) B concentrations decreased by 8% (P = .006), 9% (P = .002), and 10% (P = .002), respectively. The postprandial plasma triglyceridemia, which was expressed as the area under the 8-hour triglyceride (TG) curve, improved by 27% during THL therapy (P = .04) without changes in fasting plasma TG or high-density lipoprotein (HDL) cholesterol levels. The improved postprandial triglyceridemia was accompanied by a 19% reduction in circulating levels of chylomicrons and chylomicron remnants, determined by the decreased areas under the 8-hour RP curves. The most likely mechanisms involved are decreased formation of chylomicrons by a decrease of intestinal TG absorption as a consequence of THL treatment, as well as reduced delivery of dietary lipid and fatty acids to the liver and subsequent upregulation of hepatic LDL receptors. In agreement with the latter mechanism, the decrease in postprandial lipemia expressed as delta area under the TG curve was significantly related to the decrease (delta) in LDL cholesterol level during THL treatment (r = .81, P = .0001). The present data indicated that pancreatic lipase inhibition improved postprandial lipoprotein metabolism, which in turn resulted in lower plasma total and LDL cholesterol concentrations.

Topics: Administration, Oral; Apolipoproteins B; Cholesterol, HDL; Cholesterol, LDL; Chylomicrons; Diterpenes; Dose-Response Relationship, Drug; Double-Blind Method; Eating; Female; Humans; Hyperlipidemias; Intestinal Absorption; Lactones; Linear Models; Lipase; Lipids; Lipoproteins, LDL; Male; Middle Aged; Orlistat; Pancreas; Retinyl Esters; Triglycerides; Vitamin A

The aim of the present study was to characterize the intestinal absorption of retinol and retinyl palmitate in thoracic duct and bile duct fistulated rats and to investigate the effect of a simultaneously administered lipase inhibitor, tetrahydrolipstatin (THL). Absorption was determined as lymphatic recovery over a 24-hr period, including an initial 12-hr continuous intraduodenal infusion of either [11,12-3H]retinol or [11,12-3H]retinyl palmitate given in emulsified glyceryl trioleate or in mixed micellar solution of monoolein and oleic acid. From micellar dispersion, labeled retinol and retinyl palmitate were recovered in the lymph to 50-60% and both to the same extent. Administered in emulsified form, labeled retinol from fed retinyl palmitate was recovered to 47%, but retinol from fed retinol to only 18%. THL (10(-4) M) in the infusate had no significant effect on the recovery of 14C-labeled oleic acid. The recovery of label from emulsified glyceryl tri[1-14C]oleate was significantly decreased at this concentration of THL (76.5% vs 19.6% recovery). When administered in emulsified form, retinol absorption was not significantly affected by THL at 10(-4) M, while retinyl palmitate absorption was very significantly decreased (5.0% compared to 47.8%). In the presence of THL, retinol absorption from retinyl palmitate in micellar solution was decreased (from 58% to 17%). Most of the retinol in the lymph extracts (72.2 to 91.3) was present as retinyl ester, regardless of the chemical and physical form of administration. Furthermore, THL did not induce any change in this pattern.

Topics: Animals; Biological Transport; Carbon Radioisotopes; Diterpenes; Infusions, Parenteral; Intestinal Absorption; Lactones; Lipase; Lymph; Male; Micelles; Orlistat; Rats; Rats, Inbred Strains; Retinyl Esters; Scintillation Counting; Tritium; Vitamin A