Therapeutic equivalence of sulfaisodimidine 2 g twice daily and 1 g four times daily in lower urinary tract infections

The serum concentrations and clinical effects of sulfaisodimidine given during 12 days were examined in two groups of patients with uncomplicated lower urinary tract Infection. Group I (n=12) received the drug in a conventional dosage, 1 g four times daily, and group II (n=14) in a dose of 2 g twice daily. The serum concentrations of sulfonamide at steady state (day 7) and one day after cessation of therapy (day 13) did not differ significantly between the groups. With the exception of one patient in group I, both subjective and objective symptoms vanished during treatment and remained absent for at least 4 weeks thereafter. Two patients in each group developed signs of sulfonamide allergy. Thus, the two regimens seemed to be equally efficient, and the risk of therapy failure due to low blood concentrations of sulfaisodimidine should not be greater when the drug is given in a dosage of 2 g twice daily than when it is administered in the conventional way. Hence, the latter, simpler regimen can be recommended.