Disposition kinetics and erythrocytic partitioning of 2-PAM in calves following intramuscular administration

Abstract

The disposition kinetics, and erythrocytic partitioning of 2-PAM were investigated in crossbred cow calves after a single intramuscular administration (30 ug/kg) At 1 min following administration, the plasma concentration was 2.7 ± 0.18 ug/ml, which rose to 34.3 ± 0.41 ug/ml at 45 min. The drug was detected up to 10 hr (2.5 ± 0.08 ug/ml) and the minimum therapeutic plasma concentration.(->4 mg.ml^-1) was maintained up to 8 hr. The disposition pattern was determined by one-compartment open model using biexponential equation. The t'hKa and t_1/2 Beta were 0.132 ± 0.04 hr and 3.78 ± 0.44 hr respectively. The Vd(area), cm and AUC were calculated to'be 0.50 ± 0.04 L.kg·1, 100.6 ± 20.1 ml.kg^-1.hr-1and 139.0 ± 7.05 ug.ml-1 x hr respectively. At different concentrations, the erythrocytic partitioning of 2-PAM was to the extent of 18.9-22.1 % of the total blood concentration. Based on above disposition kinetic data, a satisfactory intramuscular dosage regimen of 2-PAM in cow calves was calculated to be 31.1 mg/kg followed by 28.5 mg/kg at 8 hr intervals or in field conditions it would be 30 mg/kg repeated at 8 hr intervals.