Magnitude of Fruit Juice-Drug Interactions Due to Osmolality-Dependent Fluid Secretion: Differences among Apple, Orange, and Grapefruit Juices.

We recently reported that the gastrointestinal (GI) fluid volume is influenced by the solution osmolality, and proposed that this effect may play a role in beverage-drug interactions. Here, we investigated whether osmolality-dependent fluid secretion can explain the difference in the magnitudes of fruit juice-drug interactions depending on the type of fruit juice (grapefruit juice (GFJ), orange juice (OJ), and apple juice (AJ)). The osmolality of GFJ, OJ, and AJ used in this study was found to be 552, 686, and 749 mOsm/kg, respectively. Measurements of intestinal fluid movement following beverage administration by the in situ closed-loop technique revealed the following rank order for fluid volume in rat ileum: AJ > OJ > GFJ > purified water, suggesting that water movement is dependent on the osmolality of these beverages. Such changes in GI fluid volume are expected to alter the luminal drug concentration, potentially contributing to the magnitude of beverage-drug interactions. Indeed, in vivo pharmacokinetic study in rats revealed that the plasma concentration of atenolol, a low-permeability drug, was the highest after oral administration in purified water, followed by GFJ and OJ, and was the lowest after administration in AJ. In contrast, antipyrine, a high-permeability drug, showed no significant difference in plasma concentration after administration in purified water and fruit juices, suggesting that the absorption of high-permeability drugs is less affected by solution osmolality. Our findings indicate that differences in the magnitude of beverage-drug interactions can be at least partly explained by differences in the osmolality of the beverages ingested.