Abstract: AIM: To observe the effects of proben-e-cid of different doses on pharmacokinetics of cefaclor and to provide the basis of their co-adiministration. METHODS: 30 rabbits were randomly divided into 5 groups: Cef 50 mg·kg^-1, Cef 50 mg·kg^-1 +Pro 50 mg·kg^-1, Cef 50 mg·kg^-1 +Pro 100 mg·kg^-1, Cef 50 mg·kg^-1 + Pro 200 mg·kg^-1, Cef 25 mg·kg^-1 +Pro 100 mg·kg^-1. The blood samples were drawn from thigh vein after IG and the concentrations of cefaclor were determined by HPLC. Pharmacokinetics parameters were calculated by NDST procedure.RESULTS: In groups with Cef 50 mg·kg^-1, C_max and AUC of cefaclor increased, and Vd/F and Cl/F decreased progressively with the adding probenecid. There was no significant difference between Cef 25 mg +Pro 100 mg and Cef 50 mg·kg^-1 in each parameter except Cl/F.CONCLUSION: Probenecid can remarkably alter the pharmacokinetics of cefaclor and the magnitude of the effects of probenecid is dependent on its dose in this trial.Cef 25 mg·kg^-1 with Pro 100 mg·kg^-1 can reach the same blood concentration as Cef 50 mg· kg^-1 alone.

Key words: cefaclor, probenecid, pharmacokinetics