Pharmacokinetics of oxytetracycline following multiple dose oral administration in poultry

The present study was undertaken to investigate the pharmacokinetics of oxytetracycline @ 50 mg.kg^-1 in poultry birds following multiple dose oral administration. The concentration of oxytetracycline in poultry plasma was analyzed by High Performance Liquid Chromatography (HPLC). The initial peak plasma concentration of1.57 jg.ml⁻¹ of oxytetracycline was detected in poultry following single dose oral administration. In multiple dose study, the volume of distribution of central compartment (V1_F) and volume of distribution of peripheral compartment (V2_F) were 18684.89 and 60821.62 ml.kg⁻¹, respectively. The clearance from central compartment (CL_F) of oxytetracycline from plasma was determined as 1887.16 ml.h⁻¹.kg⁻¹, the rate constant of distribution phase (α) was 0.27 h⁻¹ with distribution half-life (Alpha_HL) of 3.45 hr. The mean area under curve (AUC) was 26.71µg.h.ml⁻¹. The clearance from peripheral compartment (CLD2_F) was estimated as 2106.88ml/h/kg. The values of C_max and T_max were 1.39 µg.ml⁻¹ and 2.90 h, respectively, following multiple dose oral administration of oxytetracycline. The therapeutic concentration (0.5 µg.ml⁻¹) of oxytetracycline was maintained upto 8hrs following multiple (50mg/kg) oral administration. Based on the pharmacokinetic data, an oral dosage regimen of oxytetracycline with a priming dose of 73.0 mg.kg ¹ followed by a maintenance dose of 65.0 mg.kg ¹at 8 h interval is recommended.