Treatment Of Colibacillosis In Chicks With Oral Cefradine

This paper aimed to study the treatment of colibacillosis in chicks with oral cefradine (CEF), and carry out the pharmacokinetics of CEF in chicken by orally, pharmacodynamics of CEF to colibacillosis, as well as effects of field experiment. The results indicated that:A single dose of CEF in injection and oral were given at 40mg·kg^-1 to five groups of chickens. The CEF concentrations in plasma were determined by HPLC. Pharmacokinetic analysis was carried out by using a computer program (3P97, China Pharmacology Association). Plasma concentration-time data of the CEF injection after intravenous injection was best described by one-compartment open modol. Chickens were given a single oral dose of CEF of 40mg·kg^-1 body weight, Plasma concentration-time data after oral administrtion were best described by a two-compartmeent open model. C=83.22e^-0.036t+6.42e^-0.011t-89.64e^-19.304t. After oral administrtion of 40mg·kg^-1 body weight, A, α, B, β, Tlag, T1/2α, T1/2β, CL(s), T1/2ka, Ka, K₂₁, K₁₀ K₁₂, AUC, Tmax, Cmax, V/F(c)were 83.220±0.226μg·mL_-1, 0.036±0.003min_-1, 6.420±1.786ugmL_-1, 0.011±0.001min^-1 2.934±0.086min 19.304±1.283min, 65.493±6.848min, 0.003±0.002mg·kg^-1·min· (μg·mL^-1)^-1 , 12.227±0.073min, 0.055±0.004min^-1 , 0.015±0.001min^-1 , 0.027±0.002min^-1 , 0.005±0.001min^-1 , 1344.124±40.372μg·mL^-1·min , 23.886±0.320min , 17.097±0.568μg·mL^-1 , 1.101±0.027 mgμg·kg^-1 (μg·mL^-1)^-1 respectively. The results indicated that tilmicosin was quickly absorbed, widely distributed, and rapidly eliminated in chickens body after oral administration of 40mg·kg^-1 body weight.In pharmacodynamics investigation, minimal inhibitory concentrations(MICs) of cefradine and ofloxacin for Escherichia coli were determined by two-fold dilution method in vitro. The inhibitory tests in vitro showed that MICs of cefradine and ofloxacin were 4.0 and 0.1mg/L for E.coli, respectively. Then, the therapeutic trials of cefradine (80, 160 and 320 mg-L'1) and ofloxacin (10 mg·kg^-1) against experimentally induced colibacillosis were carried out in chicks following oral administration for 3 successive days with cefradine by free drinking and ofloxacin by drinking twice daily. Following treatment with cefradine (80, 160 and 320ppm) and ofloxacin (10 mg·kg^-1) against colobacillosis for 3 days, the curative rates of the drugs for E. coli-infected chicks were 93.3%, 96.7%, 100% and 93.3%, respectively. However, the mortality of chicks in the E.coli-infected and untreated group was 70.0%. There were significantly different on weight gains between the groups given cefradine, ofloxacin and the infected and untreated groups(P<0.01). These data indicated that the cure efficacy to colibacillosis in three groups treated with different dose CEF was better.In addition, the field experiment proved that CEF had a better cure efficacy to chicken colibacillosis and suggested that the optimal dosage for E. Coli in chickens was 50-80 mg·L^-1 or 10-15 mg·kg^-1 weight via free drinking all day.