Pharmacokinetics of sulfadimidine in normal and diarrheic calves.

Pharmacokinetics of sulfadimidine after intravenous and oral administration of 50 mg per kg body weight were investigated in 2- to 22-day-old healthy and diarrheic calves. The data were processed in a digital computer. The values of absorption and elimination half-times after oral administration were 7.3 and 26 hr in healthy and 2.5 and 17.7 hr in diarrheic calves. It is evident from the results that the elimination of sulfadimidine in calves is very slow and characteristic of the species. In diarrheic calves the absorption half-time was significantly shortened and the same was found for the elimination half-time. The slow elimination must be taken into account when designing therapeutic schedules in calves. The effect of diarrhea on the pharmacokinetics of sulfadimidine indicate that more attention should be paid to changes of drug absorption, distribution, and elimination during diarrhea.