What is the recommended dosing of Macrobid (nitrofurantoin) for an adult patient with an uncomplicated urinary tract infection (UTI)?

Macrobid Dosing for Uncomplicated UTI

For uncomplicated urinary tract infections in adults, prescribe Macrobid (nitrofurantoin monohydrate/macrocrystals) 100 mg twice daily for 5 days. 1

Standard Dosing Regimen

• The recommended dose is 100 mg orally twice daily for 5 days for uncomplicated UTIs in women, as endorsed by the Infectious Diseases Society of America (IDSA) and European Society for Microbiology and Infectious Diseases (ESMID) 1
• This 5-day regimen achieves clinical cure rates of 88-93% and bacterial cure rates of 81-92% 1
• The 5-day course represents the optimal balance between efficacy and minimizing antibiotic exposure while reducing adverse effects 1

Alternative Dosing for Specific Situations

• For vancomycin-resistant Enterococcus (VRE) UTIs: Use 100 mg orally four times daily 1
• Alternative formulation: Nitrofurantoin macrocrystals can be dosed at 50-100 mg four times daily for 5 days, though the twice-daily formulation is preferred for adherence 1

Critical Contraindications and When NOT to Use Macrobid

Avoid nitrofurantoin in the following situations:

• Suspected pyelonephritis or upper tract involvement - nitrofurantoin does not achieve adequate renal tissue concentrations 1
• Creatinine clearance below 30 mL/min - increased risk of peripheral neuropathy and serious toxicities in patients with renal impairment 1
• Men with suspected prostatitis - inadequate prostatic tissue penetration 1
• Complicated UTIs (structural/functional abnormalities, obstruction, instrumentation, pregnancy) 1
• Perinephric abscess 1

Clinical Efficacy Data

• Nitrofurantoin demonstrates equivalent efficacy to trimethoprim-sulfamethoxazole when comparing 5-day nitrofurantoin regimens to 3-day TMP-SMX regimens 1
• Clinical cure rates are similar to ciprofloxacin and TMP-SMX when comparing 7-day regimens 1
• Nitrofurantoin is effective against Staphylococcus saprophyticus, a common UTI pathogen, without requiring susceptibility testing 1

Important Clinical Pearls

• Ensure adequate hydration during treatment to prevent crystal formation 1
• Most common side effects: nausea and headache, with adverse event rates of 5.6-34% 1
• Serious toxicities are rare: pulmonary toxicity occurs in 0.001% and hepatic toxicity in 0.0003% of cases 1
• Do not extend treatment beyond 7 days unless symptoms persist, as shorter courses minimize adverse effects while maintaining efficacy 1

Follow-Up Recommendations

• Routine post-treatment urinalysis or urine cultures are NOT indicated for asymptomatic patients 1
• If symptoms do not resolve by end of treatment or recur within 2 weeks: obtain urine culture with susceptibility testing and consider retreatment with a 7-day regimen using an alternative agent 1

Why Nitrofurantoin is First-Line

• Minimal resistance patterns and limited propensity for collateral damage to normal flora make it an ideal first-line agent 1
• Listed as first-line treatment by both the European Association of Urology and IDSA guidelines 1