Drug breakdown: nitrofurantoin

Dr Sharon Rees @reesprescribe

Day 1: #nitrofurantoin was licensed as an oral antibiotic for urinary tract infections (UTIs) in the 1950s and it is notable for still being in first-line use with little antimicrobial resistance. In the 1970s, trimethoprim (TMP) became more popular, but resistance issues (28% of E.coli is resistant to TMP in UK) led to the resurgent popularity

Dr Sharon Rees @reesprescribe

Day 2: #nitrofurantoin is a broad-spectrum antibiotic for uropathogens, with high cure rates equivalent to trimethoprim. Extended-spectrum beta-lactamase producing E.coli and Klebsiella are still sensitive to #nitrofurantoin, hence used as first-line treatment in primary care. Effective as a three-day course for uncomplicated UTI in healthy women, dose 100 mg modified release twice/day; also used at 50 mg four times/day for five days

Dr Sharon Rees @reesprescribe

Day 3: Unusual kinetics for #nitrofurantoin mean it is used as a treatment for UTIs only. Rapid oral absorption and 60-75% undergoes first-pass metabolism. The remainder is highly soluble. It concentrates in renal/urinary tissue as an unchanged drug for elimination, where it can kill the bacteria. The t í is ~30 mins. Macrobid forms a gel in GI tract allowing slow release and twice-daily dosing.