Pharmacokinetics, urinary excretion and plasma protein binding of pralidoxime in goats

The blood levels of cholinesterase reactivator pralidoxime (2-PAM) were determined in goats following single dose intravenous administration @ 30 mg/kg body weight injected as 6% freshly prepared solution. Blood and urine samples were collected at different predetermined time intervals and 2-PAM was analysed by spectrometric method with the minimum detection of 1.0 μg ml−1. The peak plasma concentration was 49.52 ± 3.99 μg ml−1 at 2 min post administration which rapidly declined to 15.53 ± 2.11 μg ml−1 at 10 min. Thereafter, it gradually disappeared to 1.33 ± 0.41 μg ml−1 at 1.5 h. The pharmacokinetic parameters were determined by employing two-compartment open model. The t1/2α, t1/2β, Vdarea and ClB were calculated to be 1.68 ± 0.35 min, 21.17 ± 1.65 min, 1277.95 ± 195.67 ml/kg and 41.17 ± 3.66 ml/kg/min, respectively. Approximately 52% of the total administered dose was eliminated in urine within 24 h. The plasma protein binding was estimated by equilibrium dialysis technique. The in vitro plasma protein binding of 2-PAM was 64.7%.Based on these data, a satisfactory intravenous dosage regimen of 2-PAM in goats would be 38 mg/kg body weight repeated at hourly intervals.