The Effect of toltrazuril on the disposition kinetics and bioavailability of thiamphenicol following a single intravenous (IV) and oral administrations in broiler chickens at a dose of 30 mg/kg body weight was investigated. The serum thiamphenicol concentration was detected by high performance liquid chromatography. After IV injection, thiamphenicol serum concentration was best to be described by a two-compartment open model. Toltrazuril pretreatment was resulted in a significance increase in Vdss and Cltot (3.51±0.1and 0.38±0.005 L/kg, respectively) of thiamphenicol compared with thiamphenicol administered alone (2.31±0.1 and 0.31±0.006L /kg, respectively).The elimination half-life and the mean residence time of thiamphenicol were 4.58±0.2 and 2.44±0.1, 5.72±0.2 and 2.25±0.1h., in control and toltrazuril pretreated chickens, respectively. Following oral dosing, the maximum serum concentration was 14.58±0.1 and 11.88±0.04 μg/ml reached at 3.64±0.01 and 3.56±0.01h, in control and toltrazuril pretreated chickens, respectively. Oral bioavailability was found to be 117.79± 1.2 and114.85 ±0 .7 % in control and toltrazuril pretreated chickens, respectively. It was concluded that the pretreatment of toltrazuril with thiamphenicol in broilers altered the pharmacokinetic profile of thiamphenicol.

The pharmacokinetic profile of thiamphenicol was studied in broiler chickens following a single intravenous (IV) and oral (PO) administration at dosage rate 30 mg/kg BW. Serum concentrations of TP were determined by high performance liquid chromatography (HPLC). After IV dose, the serum thiamphenicol concentration time course was found to obey two-compartment open model. After IV dose, elimination half-life (t1/2λz), volume of distribution at steady state (Vdss), total body clearance (Cltot) and mean residence time (MRT) of TP were 4.58±0.2hr, 2.31±0.1L/kg, 0.31±0.006L/hr/kg, and 2.44±0.1hr, respectively. After oral administration of thiamphenicol, the peak plasma concentration (Cmax) was 14.58±0.1μg/ml and was obtained at 3.64±0.01hr (tmax) post administration. Elimination half-life (t1/2el) and absorption half-life t1/2ab.) were 2.65±0.01hr and 2.06±0.01hr, respectively. The systemic bioavailability following oral administration of TP was 117.79±1.2%. TP therapy with dosage rate of 30 mg/kg BW is suggested for a beneficial clinical effect in broiler chickens.