Reduced sulfadiazine dose in the treatment of acute urinary tract infection in children.

The pharmacokinetics of a low dose of sulfadiazine (SD 4 mg/kg twice a day, loading dose 8 mg/kg) were studied and acute urinary tract infection in children treated with this reduced dose. The concentrations of active SD in serum and urine were found to exceed those assumed to be sufficient for the treatment of acute urinary tract infections (10 x MIC and 100 x MIC against E. coli, respectively; MIC = minimum inhibitory concentration). The urinary concentrations of both acetylated and non-acetylated SD remained lower than those considered to crystallize in the urinary tract. This suggests that renal damage earlier due to SD overdosage can be avoided by using the present administration. No difference was found in treatment results of acute urinary tract infections in children between SD (4 mg/kg twice a day) and fulfafurazole (SF; 50 mg/kg four times a day). Only infections caused by sulfonamide-sensitive micro-organisms were treated and all cases were cured. No side-effects could be recorded. SD in lower than the usual dosage would appear to be a practical alternative in the treatment of acute urinary tract infections caused by sulfonamide-sensitive micro-organisms in children.