Pharmacokinetics and dosage of oxytetracycline in dogs.

The pharmacokinetics of oxytetracycline, which was given as a single intravenous dose (5 mg/kg), was studied in normal beagle dogs. Renal function was evaluated by the single injection technique and based on clearance of the radioiodine compounds 125I-iothalamate and 131I-iodohippurate. Values of GFR (4.42+/-0.77 ml/kg/min) and ERPF (12.91+/-1.49 ml/kg/min) showed normal renal function. The disposition curve describing decline of oxytetracycline activity in serum was described mathematically by a triexponential expression. Body clearance was 4.23+/-1.29 ml/kg/min. A dosage regimen (intravenous route of drug administration), based on overall elimincation rate constant (0.1155 h-1) and apparent specific volume of distribution (2 litre/kg), and consisting of a priming dose (10 mg/kg) followed by maintenance doses (7.5 mg/kg) at 12 h intervals was proposed. This dosage regimen was predicted to rapidly achieve and maintain steady state serum concentrations within the range 1.25 to 5.0 microgram/ml, which is therapeutic level for the majority of susceptible microorganisms.