Study On The Pharmacokinetics Of 20% Praziquantel Injection And HPLC Determination Of Its Residues In Beef

The pharmacokinetics of 20% Praziquantel (PZQ) Injection were studied following single intramuscularly (i.m.) (10 mg/kg b.w.) and oral (20 mg/kg b.w.) administration of the drug in healthy Water buffalos. Four Water buffalos with body weights of 390 to 450kg were randomly divided into 2 equal groups with a single two-period cross over design method. Blood samples were collected at different interval (0.15²4h) after administration of PZQ. PZQ in plasma was extracted and de-proteined by ethyl acetate.The concentrations in plasma were determined by high performance liquid chromatography (HPLC) with UV detector at a detective limit of 0.04ug/ml. The concentration-time date of PZQ in plasma were analysed with 3p97 computer program. The concentration-time data of PZQ in plasm after single i.m. adminstration in healthy Water buffalos were fitted to a one-compartment open model with first-order absorption. The main pharmacokinetic parameters of PZQ in Water buffalos were as follows: t_1/2α(0.45±0.029)h, t_1/2ke (5.04±0.110)h, T(peak) (1.72±0.029)h, AUC (7.99±0.005) mg/(l·h), C(max) (0.87±0.006 )mg/l.The concentration-time data of PZQ in plasm after single oral adminstration in healthy Water buffalos were fitted to a one-compartment open model with first-order absorption. The main pharmacokinetic parameters of PZQ in Water buffalos were as follows: Lagtime (0.13±0.010)h, t_1/2α(0.76±0.11)h, t_1/2ke(1.31±0.076) 1 h, T(peak) (3.84±0.026)h, C(max) (0.51±0.006) mg/l, AUC (7.99±0.005 )mg/(l·h). The results of the studies showed that the drug was well-adsorbed into blood after i.m. dosing, but poorly absorbed after orally dosing in cattle. The result suggests that intramuscular administration is a reasonable route in treatment of water buffalo schistosomiasts.A HPLC method was delveloped for determining residues of PZQ in beef. The sample was extracted with ethyl acetate, cleaned up by alumin B cartridge. The cartridge was eluted with methanol-water (95:5). The standard calibration curve of drugs solution was linear in the range of 0.02².0μg/ml (r=0.9999).The analytes were determined with HPLC. At the fortified levels of 0.02, 0.05, 0.2 mg/kg, the mean recoveries of PZQ ranged from 75%⁸5%; CV ranged from 2%⁹%, LOD is 0.01 mg/kg, and LOQ is 0.02 mg/kg.