EN
In the experiment done on 50 calves red and white, aged 10—12 days, were determined pharmacokinetic parameters of antypyrine basing on changes of the concentration of the drug in blood after 30 min, 1, 2, 4, 6, 8, 12 and 24 h (a full variant), and in simplified variants, i.e. after 4, 8 and 12 h, (variant B), 4, 8 and 24 (variant C), 4 and 24 h (variant D) and 8 and 24 h (variant E) after intravenous injection of antypyrine at a dose of 15 mg/kg of body weight. It was found that it is possible to evaluate precisely a biotransformative activity of the liver (activity of the system of microsomal monooxygenases (MMO) conjugated with cytochrome P-450 in calves when a simplified variant of the antypyrine test is used in which only 2 or 3 samples of blood are examined and the concentration of fenazone is determined. The pharmacokinetic parameters for antypyrine (in simplified variants) were correlated significantly (r = 0.950) with data obtained in a full test. The highest correlation (r = 0.990) was noted when blood samples were examined after 4, 8 and 24 h since antypyrine injection.