Abstract: AIM: To develop a method for the determination of cefathiamidine in dog plasma and to study the pharmacokinetic characters following intravenous injection of cefathiamidine at varied doses (31.5, 63.0, 126. mg·kg^-1 ) in dogs.METHODS: The concentrations of cefathiamidine in the plasma of dogs were determined by RT-HPLC.The determination has been performed on C₁₈ column(Hypersil, 250 mm×4.0 mm, 5 μm ) with acetonitrile :phosphatic buffer (20 ∶80, v v ) as mobile phase.RESULTS: The method has good linearity between 0.2 -50.0 μg·ml^-1 (r >0.999) with a limit of quantitation of 0.2 μg·ml^-1.Recovery varied from 93.27 % -102.18 %.Pharmacokinetics of cefathiamidine could be described by the two compartment open models.The main pharmacokinetic parameters of cefathiamidine were as follows :T1/2αwere 0.11 ±0.05, 0.13 ± 0.03, 0.10 ±0.03 h;T1/2β were 1.01 ±0.29, 0.84 ± 0.17, 1.08 ±0.31 h;AUC were 14.3 ±1.2, 27.3 ± 7.7, 74.4 ±21.2 mg·L^-1·h.CONCLUSION: The method can be used in pharmacokinetics of cefathiamidine and provided evidence for clinical application.

Key words: cefathiamidine, dog, HPLC, pharmacokinetics