COMPARATIVE PLASMA AND TISSUE PHARMACOKINETICS AND DRUG RESIDUE PROFILES OF DIFFERENT CHEMOTHERAPEUTANTS IN FOWLS AND RABBITS

Blood and tissue pharmacokinetics and drug residue profiles of six che motherapeutants were studied. Ceftriaxone (CEF), intravenously at 50 m g/kg, sulfamonomethoxine (SMM) and sulfaquinoxaline (SQ), orally at 20 0 mg/kg, and olaquindox (OLA), orally at 50 mg/kg, were administered t o young broilers. Penicillin (PEN), intramuscularly at 200 000 U/kg, a nd albendazole (ALB), orally at 20 mg/kg, were given to rabbits. For e ach drug, 13-18 groups (n = 5-10 individuals/group) of the dosed anima ls were killed at different post-dosing times. Drug and/or metabolite concentrations in plasma, liver, kidney, heart, lung, and muscle tissu es were analysed by HPLC procedures. Multi-exponential kinetic models were fitted to the observed tissue concentration-time data by applying a non-linear least-squares regression computer program. Tissue half-l ife, peak tissue concentration, and time of peak tissue concentration were determined. Half-life of CEF, SMM, SQ, OLA, PEN, ALB, and two met abolites of ALB (sulfoxide and sulfone) in various tissues ranged 0.6- 1.41 4.7-9.0, 4.5-18.9, 1.8-3.1, 0.9-3.0, 3.4-9.6, 5.0-16.1 and 7.4-12 .2 h. The times required for CEF, SMM, SQ, OLA, PEN, and ALB residue c oncentrations to decline to 0.1 mu g/g in various tissues ranged from 5.0-11.6, 70.0-110.5, 114.0-179.8, 21.3-30.3, 4.1-24.8 and 47.8-84.4 h . Drug kinetic characteristics in tissues differed significantly from those in plasma, and also varied from tissue to tissue. It is necessar y, therefore, to evaluate tissue kinetics when designing dosage regime ns in tissue infection chemotherapy with these drugs. Knowledge of tis sue kinetics is also important in predicting and controlling drug resi dues in edible tissues of food-producing animals.