Objective:To investigate the absorption characteristic and the influencing factors on absorption of protein and peptide from natural hirudin administered by nasal mucosa.Method: The toxicity of hirudin to the nasal cilia was tested by the ex vivo bufo palate model.The absorption characters of natural hirudin as well as the concentrations of natural hirudin and pH values of medium were evaluated by the experiments based on Valia-Chien infiltration pool method and by the in vivo perfusion experiments in rats.Result: The experiments based on Valia-Chien infiltration pool method and the in vivo perfusion tests in rats indicated that the natural hirudin was well absorbed per nasal mucous membrane from pigs and rats.It also indicated that both the concentrations of hirudin and the pH values of the medium influenced the absorption of hirudin.Though the concentration of hirudin has no obvious linear relationship with osmotic coefficient or rate of absorption of hirudin per nasal mucous membrane

it showed that the best absorption concentration is 0.6 mg·mL-1.Conclusion: Hirudin has low cilia toxicity;it can be well absorbed per nose mucous membrane.Both of the concentrations of natural hirudin and pH values of the medium influence the absorption characteristic of hirudin.