Measurement of gastrointestinal transit of solid food using a colestipol-phenol red complex as a marker

The present study was undertaken to determine whether colestipol-phenol red complexes can be used as markers for gastrointestinal transit of solid food. Colestipol (1.0g) bound completely with phenol red (10 mg) to form a stable complex in water (pH 7.0) Phenol red was more readily eluted from colestipol with 20 ml of 1 N HCl than 1 N NaOH, but was not eluted with 0.1 N HCL (pH 1.0). It was therefore assumed that the complex would remain stable in the gastrointestinal tract. Also, phenol red in the gastrointestinal tract was quantitatively eluted from the complex with 20 ml of 1N HCl. In a study on gastric emptying, phenol red solution (liquid food) was excreted from the stomach in a zero-order manner, and the colestipol-phenol red complex (solid food) in a first-order manner. It was concluded that colestipol-phenol red complexes can be used as markers of gastrointestinal transit.