Liquid chromatographic method for the simultaneous determination of cefalexin and trimethoprim in dog plasma and application to the pharmacokinetic studies of a coformulated preparation.
A liquid chromatographic method is described for the simultaneous determination of cefalexin and trimethoprim in dog plasma. A simple protein precipitation procedure was adopted for the sample preparation with satisfactory extraction recoveries for both analytes. Chromatographic separation of the analytes was achieved on a C(18) column using a mixture of 2 mol/l formate buffer (pH 3.5), methanol and acetonitrile (22:7:7, v/v/v) containing a 0.002 mol/l sodium dodecyl sulfate as mobile phase and detection was performed at 240 nm. The linearity was obtained over the concentration ranges of 1.0-100.0 microg/ml for cefalexin and 0.5-50.0 microg/ml for trimethoprim. For each level of QC samples including the lower limit of quantification, both inter- and intra-day precisions (R.S.D.) were < or =14.0% for cefalexin and < or =11.4% for trimethoprim, and accuracy (RE) was -1.4% for cefalexin and -3.0% for trimethoprim. The present LC method was successfully applied to the pharmacokinetic studies of coformulated cefalexin dispersible tablets after oral administration to beagle dogs.
Qi
Meiling
M
Department of Chemistry, School of Science, Beijing Institute of Technology, 5 Zhongguancun South Street, Beijing 100081, China. mlqi@bit.edu.cn
Wang
Peng
P
Sun
Ping
P
Liu
Xia
X
D000818:Animals; D000900:Anti-Bacterial Agents / Q000097:blood* / Q000493:pharmacokinetics; D002506:Cephalexin / Q000097:blood* / Q000493:pharmacokinetics; D002853:Chromatography, Liquid / Q000379:methods*; D004285:Dogs; D004338:Drug Combinations; D011786:Quality Control; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014295:Trimethoprim / Q000097:blood* / Q000493:pharmacokinetics
D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D014295:Trimethoprim; D002506:Cephalexin