Objective To study the absorption characteristics of phenol red in different intestinal sections and the impact of puerarin and verapamil on the phenol red absorption in order to prove phenol red assay being not applicable to the mechanism study of intestinal absorption of puerarin. Methods The rat single pass perfusion technique was applied. The concentration of phenol red was determined by HPLC. The effect of puerarin and verapamil on the absorption of phenol red was studied. Results Phenol red was absorb...