Pharmacokinetics of oxytetracycline in presence of calcium gluconate in goats.

The concentration of oxytetracycline (OTC) in plasma, after single dose i.v. administration at 10 mg kg-1, was determined during pre and post induced-hypercalcemia in goats. The pharmacokinetic variables were then calculated. Hypercalcemia caused several changes in the determined variables. The CPmax and CPmin of OTC observed at 0.08 and 4 hr in normal goats were respectively 34.50 +/- 1.65 and 1.19 +/- 0.14 micrograms ml-1, while the CPmax and CPmin of OTC in presence of calcium at 0.08 and 8 hr were 20.81 +/- 2.18 and 1.04 +/- 0.05 micrograms ml-1 respectively. Hypercalcemic state in goats increased t1/2 (alpha) (0.19 +/- 0.02 hr), t1/2 (beta) (2.77 +/- 0.03 hr), AUC (37.67 +/- 0.83 micrograms x hr x ml vd (area) (1.07 +/- 0.03 L kg-1) and vd (ss) (0.95 +/- 0.04 L kg-1) values of OTC compared to normal goats. The semilogarithmic plot of plasma level-time profile of OTC administered i.v. showed biphasic decline suggestive of two compartment open model 'kinetics' in both normal and hypercalcemic animals.