What is the recommended dosing for Macrobid (nitrofurantoin) in patients with acute uncomplicated urinary tract infections?

Macrobid Dosing for Acute Uncomplicated UTI

For acute uncomplicated cystitis in women, prescribe nitrofurantoin monohydrate/macrocrystals (Macrobid) 100 mg twice daily for 5 days. 1

Standard Dosing Regimen

• Nitrofurantoin monohydrate/macrocrystals: 100 mg orally twice daily for 5-7 days is the IDSA-recommended first-line regimen for uncomplicated UTI in women 2, 1
• The 5-day regimen is optimal and recommended by both IDSA and European guidelines, balancing efficacy with minimizing adverse effects 1
• This regimen achieves clinical cure rates of 88-93% and bacterial cure rates of 81-92% 1

Alternative Formulation Dosing

• Nitrofurantoin macrocrystals: 50-100 mg four times daily for 5 days is an acceptable alternative formulation per European guidelines 1
• For vancomycin-resistant enterococcal (VRE) UTIs specifically: 100 mg four times daily (every 6 hours) is recommended 1, 3

Key Clinical Considerations

Contraindications to avoid:

• Do not use if creatinine clearance <60 mL/min due to inadequate urinary drug concentrations and increased toxicity risk 3
• Avoid if early pyelonephritis is suspected as nitrofurantoin does not achieve adequate tissue levels 1
• Contraindicated in the last trimester of pregnancy (final 3 months) 4

When to extend duration:

• Standard 5-day course is sufficient for uncomplicated cystitis 1
• Consider 7-day regimen if symptoms persist or for enterococcal UTIs 1, 3
• Pediatric patients require at least 3 days after obtaining sterile urine 1

Efficacy Compared to Alternatives

• Equivalent to trimethoprim-sulfamethoxazole when comparing 5-day nitrofurantoin to 3-day TMP-SMX regimens 1
• Similar cure rates to fluoroquinolones when comparing 7-day regimens, but nitrofurantoin is preferred due to minimal resistance and collateral damage 2, 1
• Superior to beta-lactams which have inferior efficacy for uncomplicated cystitis 2

Common Pitfalls to Avoid

• Do not prescribe for complicated UTIs or pyelonephritis - nitrofurantoin lacks adequate tissue penetration 1
• Do not use in patients with intrinsically resistant organisms (Proteus species, Pseudomonas, most Klebsiella) 5
• Verify renal function before prescribing - the traditional cutoff of CrCl <60 mL/min is a hard contraindication per current guidelines 3
• Counsel patients about nausea and headache - the most common side effects with rates of 5.6-34% 1

Follow-Up Recommendations

• No routine post-treatment urine culture needed if symptoms resolve 1
• Obtain urine culture with susceptibility testing if symptoms persist at end of treatment or recur within 2 weeks 1
• Consider 7-day regimen with alternative agent for treatment failures 1