Orlistat accentuates the fat-induced fall in blood pressure in older adults.

Postprandial hypotension may be influenced by the digestion of fat. The aim of the present study was to evaluate the hypothesis that products of fat digestion mediate the hypotensive response to fat. In part A of the study, nine healthy older subjects were studied on three separate occasions in randomised order. Blood pressure, heart rate (HR), plasma TAG and gastric emptying were measured following the ingestion of equivolaemic drinks: (1) 300 ml of high-fat drink (88 % fat); (2) fat drink mixed with 120 mg orlistat (lipase inhibitor); (3) water (control). In part B of the study, ten healthy older subjects were studied on two separate occasions. Blood pressure, HR, plasma TAG and superior mesenteric artery flow were measured during 90 min intraduodenal infusions of 10 % intralipid (2·7 ml/min), with and without 120 mg orlistat. Oral fat ingestion was associated with decreases in systolic and diastolic blood pressures (both P = 0·0001) that were greater when orlistat was co-administered (both P < 0·05), and an increase in HR (P = 0·0001) that was inhibited by orlistat co-administration (P < 0·03). Gastric emptying was slowed by oral fat digestion, and orlistat administration inhibited this slowing (P < 0·04). Intraduodenal fat infusion was not associated with changes in blood pressure but increased HR (P < 0·0001), an effect attenuated by orlistat (P < 0·05). In conclusion, orlistat potentiates the hypotensive response to oral fat in older adults, possibly as a result of faster gastric emptying of fat. The results do not support a role for fat digestion in lowering blood pressure.