In vitro effect of new penicillins and aminoglycosides on tests for glycosuria.

The effect of newer penicillins (azlocillin, mezlocillin, cyclacillin, and piperacillin) a 6 beta-amidinopenicillanic acid derivative (amdinocillin), and newer aminoglycosides (netilmicin and sisomicin) on the accuracy of tests for glycosuria was studied. Solutions of each of the drugs were prepared in urine in a range of clinically obtainable drug concentrations. In addition, urine solutions were prepared that contained the same drug concentrations and 0.5, 1, and 2% glucose. All solutions were tested in triplicate using the five-drop Clinitest method and two glucose oxidase methods (Diastix and Tes-Tape). Falsely elevated Clinitest readings of approximately 0.25% were obtained with the penicillins. These readings were influenced by the concentration of the penicillins and of glucose. Neither amdinocillin nor the aminoglycosides had an effect on Clinitest determinations. None of the drugs interfered with Diastix or Tes-Tape readings. Because the Clinitest-penicillin interaction is unpredictable, Clinitest results should be rechecked using one of the qualitative glucose oxidase tests when Clinitest is used as a quantitative test for glycosuria in patients receiving penicillins. All three tests studied can be used to test for glycosuria in patients receiving amdinocillin or one of the aminoglycosides.