Pharmacokinetic, bacteriological, and clinical studies in pediatrics on cefpodoxime proxetil (CPDX-PR, CS-807) (pediatric dry syrup) were performed. 1. Serum concentrations and urinary excretions of CPDX after administration of CPDX-PR to children (ages between 6 and 14) were investigated. Four cases were administered with CPDX-PR at a dose level of 3 mg/kg 30 minutes before or after meal. Effects of timings of administration were investigated using a crossover study. Average serum concentrations in the group administered with the drug before meal reached their peaks at 1 hour after administration with an average level of 2.34 +/- 0.16 micrograms/ml and diminished with a half-life of 1.94 +/- 0.08 hours to 0.29 +/- 0.04 microgram/ml at 8 hours after administration. In the group administered with the drug after meal, average serum concentrations attained their peaks at 4 hours after administration at an average level of 1.93 +/- 0.09 micrograms/ml, and decreased with a half-life of 2.08 +/- 0.19 hours to 0.58 +/- 0.16 microgram/ml at 8 hours. Urinary recovery rates of CPDX in the first 8 hours after administration of CPDX-PR in the before-meal and the after-meal groups averaged 34.4 +/- 6.3% and 38.5 +/- 7.0%, respectively. In a separate experiment, 7 cases were administered with CPDX-PR, 30 minutes after meal, at a dose level of either 3 or 6 mg/kg. Effects of the 2 different dose levels were investigated also using a crossover study. Average serum concentrations at their peaks attained at a 4 hours after administration for the 2 dosage groups (3 and 6 mg/kg) were 1.76 +/- 0.11 and 3.08 +/- 0.41 micrograms/ml, respectively. Average half-life values for the 2 groups were 2.40 +/- 0.14 and 2.25 +/- 0.07 hours, respectively, with average 8 hour values of 0.64 +/- 0.10 and 1.30 +/- 0.21 micrograms/ml, respectively. Urinary recovery rates in the first 8 hours after administration averaged 40.4 +/- 3.2% and 46.3 +/- 6.5%, respectively. From these results, it appeared that the absorption of the drug was affected by the timing of administration (before or after meal), and the presence of ingested foods in the digestive system delayed the absorption. The overall quantity absorbed, however, did not seem to be affected by the timing of administration. These data also showed that serum and urinary concentrations of the drug depended on dose levels.(ABSTRACT TRUNCATED AT 400 WORDS)