Abstract: AIM: To investigate the pharmacokinetics of the roxithromycin sustained-release tablets in 8 beagle dogs.METHODS: Microbiological method was used to determine the serum concentration of roxithromycin after normal and sustained-release tablets were orally administrated in 8 healthy beagle dogs.Pharmacokinetic parameters were calculated , and the bioequiverlence was estimated by statistical method.RESULTS: The pharmacokinetic parameters of sustained-release and normal tablets after single oral dose study were as following:the t_max were 4.74 ±1.21 h and 1.21 ±0.64 h , the C_max were 21.08±4.24 μg·ml^-1 , and 28.26 ±5.41 μg·ml^-1 , respectively;the AUC were 164.49 ±28.55 μg·h·ml^-1 and 177.95 ±27.63 μg·h·ml^-1 respectively.Compared to normal tablets , the bioavailability of sustained-release tablets was 93.6%±10.5%.There was much difference for t_max and C_max parameters between the two tablets.CONCLUSION: The results of the present study indicate that the absorption speed was slower for sustained-release tablets than normal tablets , but the extend of absorption for the two roxithromycin tablets was bioequivalent.

Key words: roxithromycin, sustained-release tablets, pharmacokinetics, bioavailability