Abstract: AIM: To investigate the effect of oral clarithromycin on serum concentrations of aminophylline at steady state and its pharmacokinetics in New Zealand rab-bits.METHODS: The serum concentration of amino-phylline was determined by FPIA in rabbits given(po) aminophylline or aminophylline combined with clar-ithomycin.The experiment was divided into 2 stages: (Ⅰ) the subjects only received a four-day course of oral aminophylline until steady state;(Ⅱ) aminophylline and clarithromycin were coadministrated from the d 5 to d 10. The dose of aminophylline was 30 mg·kg^-1 and the dose of clarithromycin was 50 mg·kg^-1 for each rabbit. The two series of pharmacokineticis parameters were tested by statistic analysis.RESAULTS: There was no significant variation in pharmacokinetic parameters between two stages.CONCLUSION: It is not necessary to change the therapeutic dose of aminophylline when the drug is taken in combination with clarithromycin.

Key words: aminophylline, clarithromycin, blood concentration, pharmacokinetics parameter