Nitrofurantoin (Macrobid)
Synthetic nitrofuran antibiotic used exclusively for uncomplicated lower urinary tract infections. Reduced by bacterial nitroreductases to reactive intermediates that cause multi-target damage to bacterial DNA, ribosomes, and cell wall synthesis. Unique pharmacokinetics — rapidly concentrated in urine but minimal serum/tissue levels account for negligible systemic antibacterial effect and low resistance selection pressure.
Projected serum levels — 100 mg, twice daily
Maintenance schedule: 100 mg twice daily (oral).
Modeled steady state after ~1 days: peak ≈ 31.0 mg, trough ≈ 0.015 mg body load. Population-based estimate over 15 days for a 100 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.
Key facts
- Category
- Urinary Antiseptic
- Route modeled
- Oral
- Model confidence
- inferred
- Half-life
- 42 min
- Common dose
- 100 mg
- Suggested maximum
- 100 mg/day
- Reference dose range
- 50–100 mg (single dose)
- Suggested cadence
- twice daily
- Validated against
- 100 mg oral — Cmax 1 mg/L at 1.5 h
Research behind this entry
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International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: a 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases
IDSA/ESCMID guidelines establishing nitrofurantoin 100 mg bid x 5 days as first-line therapy for uncomplicated cystitis (alongside TMP-SMX and fosfomycin), citing 88-92% clinical cure rates and the critical importance…
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Nitrofurantoin revisited: a systematic review and meta-analysis of controlled trials
Meta-analysis of 27 controlled trials confirming nitrofurantoin clinical cure rates of 88-93% for uncomplicated UTI, with microbiological eradication rates comparable to TMP-SMX, ciprofloxacin, and fosfomycin, and the…
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Pulmonary reaction to nitrofurantoin: report of 447 cases
Large case series documenting the spectrum of nitrofurantoin pulmonary toxicity from acute hypersensitivity pneumonitis (hours-days after first dose) to chronic pulmonary fibrosis (months-years of suppressive therapy),…
3 published studies referenced in the app, each with a plain-language summary.