The excretion of
sulfadiazine (Adiazin) (n = 8) and
sulfafurazole (n = 8) in urine and the risk of crystallization were compared in children, 3-14 years of age. They suffered from acute
urinary tract infection and were treated with conventional dosage regimen of either of the
sulfonamides.
Sulfadiazine (4 mg/kg twice daily, the initial dose 8 mg/kg) produced active serum
drug levels which in relation to antimicrobial activity of sulphonamides corresponded to 25-30% of those obtained with
sulfafurazole (50 mg/kg four times a day). In urine the corresponding
sulfadiazine levels were 21-61% of those of
sulfafurazole. In none of the urine fractions
sulfadiazine concentrations exceeded the theoretical
drug solubility but
sulfafurazole exceeded this risk limit altogether in 4 urine fractions (2 patients). Urine sediment showed, however,
sulfonamide crystals in only one urine fraction of the
sulfafurazole group. The results suggest that with conventional dosage regimen
sulfafurazole produces higher effective serum and urine
drug concentrations in children than
sulfadiazine but shows a higher risk to crystallize in urine.