BALB/c mice were immunized by highly immunogenic recombinant proteins containing amino acid sequence of integrin antagonist AP25. Antibody against AP25 was prepared and purified by affinity chromatography. An indirect enzyme-linked immunosorbent assay for qualitative analysis of AP25 in rat plasma samples was successfully established. The assay was successfully applied to determine the pharmacokinetic parameters of AP25 in SD rats by intravenous administration of AP25 and then the rat plasma protein binding of AP25 were determined in vitro. In order to investigate the specificity of ELISA for detection of prototype AP25 in plasma, the proportion of AP25 prototype drug in the ELISA signal value was validated by HPLC. These results can serve as valuable future clinical trials.