[Fluorimetric determination of ampicillin in calf serum (author's transl)]

The serum concentrations of ampicillin was determined in calves after oral and parenteral administration. Ampicillin was analyzed by a fluorimetric method which was found simple and reliable. When ampicillin at a dose of 12 mg/kg was given in a milk replacer, the serum concentrations was too low to be effective even against all ampicillin sensitive bacteria. This method of treatment may be used only in the treatment of enteritis, as it is reported in the literature that high ampicillin concentrations occur in the intestinal content and the intestinal mucosa. After intramuscular injection of recommended doses (4-10 mg/kg), high serum concentrations was reached soon after the injection. The drug is, however, excreted rapidly and treatment should be repeated at shorter intervals than usually is recommended.