Study on Pharmacokinetics of CO. SMM Sustained-release Injection in Healthy Black Goat

Ten healthy black goats were divided into two groups.The first group was injected CO.SMM sustained-release injection following single intramuscular administration 60 mg/kg,and the second group was injected SMM injection following single intramuscular administration 60 mg/kg.Blood samples were collected at different intervals after administration of the injection.Concentrations of SMM and TMP in the plasma were determined by high performance liquid chromatography(HPLC).The concentrations versus time data were analysed using pharmacokinetic program.The concentration-time data of SMM and TMP were respectively described by a one-compartment open model with first-order absorption and a two-compartment open model with first-order absorption after single intramuscular administration of CO.SMM sustained-release injection.The main pharmacokinetic parameters of SMM and TMP in CO.SMM sustained-release injection were as follows respectively: T1/2Ka(0.56±0.095) h and(0.87±0.15) h,T1/2(12.20±0.70) h and(13.61±1.78) h,Tmax(2.58±0.35) h and(2.68±0.26) h,Cmax(52.27±1.05) μg/mL and(3.83±0.095) μg/mL.The main pharmacokinetic parameters of SMM in SMM injection were as follows: T1/2Ka(0.42±0.046) h,T1/2(1.27±0.068) h,Tmax(1.00±0.061) h,Cmax(77.06±2.12) μg/mL.The results there were significant difference in pharmacokinetic parameters of SMM between CO.SMM sustained-release injection and SMM injection.The T1/2Ka,Tmax and T1/2 of the former were higher than the latter,but the Cmax of the former was lower.These differences indicated that the CO.SMM sustained-release injection was absorbed slowly,and it had sustained-release and long-acting properties.