A meta-analysis 2 assessing nitrofurantoin´s efficacy and safety in the prophylaxis of UTI included 26 controlled trials (n=3052) and 16 cohort studies. When compared with no prophylaxis, nitrofurantoin was effective (risk ratio 0.38, 95% CI 0.30 to 0.48). Its prophylactic efficacy is superior to that of methenamine hippurate and comparable to that of other antibacterials (e.g. penicillin, amoxicillin, pivmecillinam, cefaclor, cefixime, trimethoprim/sulfamethoxazole, trimethoprim). Compared with patients receiving other antibacterials, those receiving nitrofurantoin had an increased risk of 2.24 (95% CI 1.77 to 2.83) for a non-severe adverse effect. In all controlled trials, only one patient experienced a severe adverse effect (interstitial pneumonia).
A Cochrane review [Abstract] 1 included 19 studies with a total of 1120 women. During active prophylaxis the rate range of microbiological recurrence patient-year (MRPY) was 0 to 0.9 person-year in the antibiotic group against 0.8 to 3.6 with placebo. The RR of having one microbiological recurrence (MR) was 0.21 (95% CI 0.13 to 0.34), favouring antibiotic and the NNT was 1.85. For clinical recurrences (CRPY) the RR was 0.15 (95% CI 0.08 to 0.28). The NNT was 1.85. The RR of having one MR after prophylaxis was 0.82 (95% CI 0.44 to 1.53). The RR for severe side effects was 1.58 (95% CI 0.47 to 5.28) and for other side effects the RR was 1.78 (CI 1.06 to 3.00) favouring placebo. Side effects included vaginal and oral candidiasis and gastrointestinal symptoms.
In women with UTI associated with sexual intercourse, post coital prophylaxis appered to be as effective as daily intake. No conclusions could be drawn about the optimal duration of prophylaxis, schedule or doses.
A systematic review and meta-analysis 3 included 11 placebo-controlled trials. The risk for developing urinary tract infection (UTI) was 85% lower with prophylaxis in comparison with placebo (RR 0.15; 95% CI 0.08 to 0.29, n=746). In the 9 head-to-head trials, the efficacy of different antibiotic agents (e.g. nitrofurantoin, norfloxacin, cefaclor, trimethoprim, trimethoprim+sulfamethoxazole) appeared similar.
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