EN
The aim of this study was to compare the pharmacokinetics of paracetamol in calves of the BW (Black- -and-White) breed and cross-breed calves (BW × HF Holstein-Friesian) (50% HF). The effect of age on interbreed differences in the values of selected pharmacokinetic parameters of this model drug were also examined. The experiment was carried out on 20 healthy calves: 10 of BW breed and 10 cross-breed (50% HF). The paracetamol test was performed on calves aged 10, 20 and 40 days of life. The animals received this model drug per os at a dose of 5 mg/kg body weight. The concentration of paracetamol in plasma was determined by the spectrophotometric method. The pharmacokinetics of paracetamol were calculated through a non-compartmental method, using The TopFit computer software. The obtained results indicate that the age of calves had an influence on the values of pharmacokinetic parameters of paracetamol. We observed that most of the estimated pharmacokinetic parameters of this model drug differed significantly (P < 0.01) between 10, 20 and 40-day-old calves. It was stated that 10 and 20-day-old BW calves metabolized paracetamol faster compared to 50% HF calves, but the observed results differed insignificantly (P > 0.05). We also observed that 40-day-old 50% HF calves metabolized paracetamol at a significantly (P < 0.01) quicker rate compared to BW animals.