Abstract: AIM: To investigate the tissue distribution and pharmacokinetics of aminophylline after aerosol inhalation in beagles.METHODS: HPLC was used to determine the concentration of theophylline in different tissues and plasma of the beagles. The tissue distribution of theophylline after aerosol inhaling was compared to intravenous infusing aminophylline. Plasma concentrations at different time after aerosol inhalation were compared with intravenous infusion.RESULTS: The theophylline concentrations in trachea after aerosol inhalation at 0.25 and 0.5 h were higher obviously than that of intravenous infusion administration group (0.25 h, P<0.01; 0.5 h, P<0.05). At 0.25, 0.5, 1 and 2 h, the theophylline concentrations in other tissues were decreased obviously. The absolute bioavailability of aminophylline after aerosol inhalation was 24.52%.CONCLUSION: After aerosol inhaling aminophylline, the theophylline is retained mostly in trachea. At the same time, the theophylline concentrations in other tissues are decreased obviously. The administration route of aerosol inhaling aminophylline can raise the therapeutic index and reduce adverse effects dramatically

Key words: aminophylline, theophylline, HPLC, tissue distribute, aerosol inhalation