In the present study, the pharmacokinetics of 2-pyridine aldoxime (2-PAM, 30 mg/kg, i.v.) alone and in conjunction with atropine (0.3 mg/kg; 1/4 i.v., 3/4 i.m.) was investigated in 10 Bubalus bubalis intoxicated with a single oral lethal dose of fenitrothion (435 mg/kg). Based on the kinetic parameters, an appropriate dosage regimen of 2-PAM in B. bubalis was calculated. There was no significant difference between plasma levels and pharmacokinetic parameters of 2-PAM in the two groups of animals, given 2-PAM alone and in conjunction with atropine. The peak plasma concentration of 2-PAM at 1 min was in the range of 189.5-196.6 microg/mL which declined to 9.22-9.98 microg/mL at 4 h. The values of elimination half-life, Vd(area) and total body clearance were 2.41-2.67 h, 0.77-0.95 L/kg and 227.5-245.7 mL/kg/h, respectively. The binding capacity of 2-PAM to plasma proteins of fenitrothion-intoxicated buffalo calves and dissociation rate constant of protein drug complex were 0.015 x 10(-6) mol/g and 2.367 x 10(-6) mol, respectively. Approximately 63% of 2-PAM was bound with plasma proteins. In the treatment of organophosphate insecticide (OPI) toxicity in B. bubalis, an appropriate i.v. dosage regimen of 2-PAM in conjunction with atropine would be 18 mg/kg followed by 15 mg/kg at 4 h interval.