Gastric emptying-limited oral absorption of alpha-linolenic acid administered as a milk fat-globule membrane (MFGM) emulsion in rats.

As a study to assess the potential application of milk fat-globule membrane (MFGM), which is of natural origin and expected to be a safer alternative to synthetic emulsifiers, to pharmaceutical dosage forms, the oral absorption of alpha-linolenic acid was evaluated by the analysis of gastrointestinal disposition after oral administration as an MFGM emulsion to rats. A linear model incorporated with first-order gastric emptying followed by first-order intestinal absorption was fitted to the data of the remaining fraction of alpha-linolenic acid versus time profiles for the stomach and small intestine to estimate the rate constants of gastric emptying (kg) and intestinal absorption (ka). The ka (0.045 min-1) was about 4 times larger than the kg (0.011 min-1). The kg was comparable to the apparent oral absorption rate constant estimated by the pharmacokinetic analysis of plasma concentration data. These results suggest that the oral absorption of alpha-linolenic acid administered as MFGM emulsion is gastric emptying-limited and, hence, any change in the intestinal absorption process would only modestly affect its oral absorption.