Pharmacokinetics and dosage regimen of cefotaxime in cross-bred calves following single intramuscular administration.

The pharmacokinetics, penetration into erythrocytes and plasma protein binding of cefotaxime were investigated in cross-bred calves. Following a single intramuscular dose of cefotaxime (10 mg/kg), the absorption half-life and elimination half-life were 0.13 +/- 0.03 h and 2.97 +/- 0.72 h, respectively. The apparent volume of distribution and total body clearance were 3.28 +/- 0.72 L/kg and 0.78 +/- 0.08 L/kg per h, respectively. The extent of penetration into erythrocytes was 24-40% of the total blood concentration. Cefotaxime was bound to plasma proteins of calves to the extent of 25.5-33.6%. A satisfactory intramuscular dosage regimen for cefotaxime in calves would be 11 mg/kg followed by 10 mg/kg at 7 h intervals.