Anion concentration of in vitro test matrices designed to mimic GI tract compartments
| Matrix | Acetate (mM) | Chloride (mM) | Phosphate (mM) | Citrate (mM) | Taurocholate (mM) | Oleic Acid (mM) |
|---|---|---|---|---|---|---|
| SGFa | 0 | 98.0 | 0 | 0 | 0 | 0 |
| SIBb | 0 | 36.0 | 20.0 | 0 | 0 | 0 |
| SOBc | 50.0 | 36.0 | 7.0 | 1.5 | 5.0 | 30.0 |
↵a SGF, pH = 1.2; it mimics the acidic environment of the fasted stomach and reflects an optimal condition for binding of HCl.
↵b SIB, pH = 5.5; pH is representative of the human proximal small intestine (duodenum and early jejunum), and that contains chloride and a high concentration of phosphate as a potential competing anion to chloride. The solution was buffered by 2-(N-morpholino)ethanesulfonic acid.
↵c SOB, pH = 6.2; pH and competing anion content (bile acid, citrate, oleic acid, and acetate) represent components of the human distal small intestine (late jejunum, ileum) and cecum. The solution was buffered by N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid.