Study on pharmacokinetics of Zengxiaolianhuang injection and its antibacterial activity in vitro and clinical efficacy on white scour of piglets

The pharmacokinetics of SMM SMZ and TMP was investigated in 6 healthy crossbred (Landrace×(Yorkshire)) pigs following single intramuscular administration (2.5 mg/kg) of Zengxiaolianhuang(ZXLH) (injection). Blood samples were collected at different intervals after administration of the injection. Concentrations of ZXLH (injection) were determined by high performance liquid chromatography(HPLC). The blood concentration-time data of SMM, SMZ and TMP were all best fitted to a two-compartment open model with first-order absorption after a (single) i.m. administration of ZXLH (injection.) The main pharmacokinetic parameters of SMM in ZXLH injection were T_(1/2Ka)=(0.285±0.087) h, T_(1/2α)=(4.11±1.35) h,T_(1/2β)=(30.92±12.84) h,C_(max)=(15.32±3.06) (μg·mL~(-1)), AUC=((0.371)±0.129) (mg·L~(-1)·h~(-1). )Those of SMZ were T_(1/2Ka)=(0.756±0.366) h, T_(1/2α)=((2.09)±0.85) h, T_(1/2β)=(8.32±3.34) h, C_(max)=(29.33±2.68) μg·mL~(-1), AUC=(0.193±0.022) (mg·L~(-1)·h~(-1)). Those of TMP were T_(1/2Ka)=(0.402±(0.131) h,) T_(1/2α)=(3.18±1.20) h, T_(1/2β)=(20.03±7.74) h, C_(max)=(4.03±0.65) (μg·mL~(-1),) AUC=(0.417±(0.086)) mg·L~(-1)·h~(-1). The in vitro antibacteria1 (activity) of ZXLH injection against E. coli C_(83902) and fowl (Pasteurella) multocid C_(48-1 )was tested by micro dilution method. The results showed the MIC1.22 (μg·mL~(-1).) A plasma (concentration) exceeding 1.22 μg·mL~(-1) was maintained for 48 hours. ZXLH injection could be injected once every other day in the treatment of white scour of piglets.