What is the recommended dosage of Nitrofurantoin (Macrobid) for treating uncomplicated urinary tract infections (UTIs)?

Nitrofurantoin Dosing for Uncomplicated UTI

The recommended dosage of nitrofurantoin monohydrate/macrocrystals (Macrobid) for treating uncomplicated urinary tract infections is 100 mg twice daily for 5 days. 1, 2, 3

First-Line Treatment Recommendation

• Nitrofurantoin is recommended as a first-line agent for uncomplicated UTIs by both the Infectious Diseases Society of America (IDSA) and the European Association of Urology due to its high efficacy and low resistance rates 1, 3
• Clinical cure rates with nitrofurantoin range from 88-93% for uncomplicated UTIs in women 1
• Bacterial cure rates range from 81-92% for uncomplicated UTIs in women 1

Dosing Specifics

• The standard formulation used is nitrofurantoin monohydrate/macrocrystals (Macrobid) at 100 mg twice daily 1, 2
• The recommended duration is 5 days for uncomplicated UTIs in women 1, 2
• Alternative formulation: nitrofurantoin macrocrystals can be used at a dose of 50-100 mg four times daily for 5 days 1

Important Contraindications

• Nitrofurantoin is contraindicated in patients with creatinine clearance <60 mL/min due to:
  • Inadequate urinary drug concentrations that would prevent bactericidal activity 3
  • Increased risk of toxicity, including peripheral neuropathy 2
• Nitrofurantoin should be avoided if early pyelonephritis is suspected 1

Alternative First-Line Options

When nitrofurantoin cannot be used, consider:

• Fosfomycin trometamol 3 g single dose (slightly lower efficacy than nitrofurantoin) 1
• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days (only if local resistance rates <20% or if the infecting strain is confirmed susceptible) 1, 2
• For patients with renal impairment (CrCl <60 mL/min), consider trimethoprim-sulfamethoxazole or fosfomycin trometamol as alternatives 2

Efficacy Comparison

• The 5-day regimen of nitrofurantoin (100 mg twice daily) has been shown to be equivalent to trimethoprim-sulfamethoxazole (160/800 mg twice daily for 3 days) in clinical and microbiological cure rates 1, 4
• Nitrofurantoin has similar clinical cure rates to ciprofloxacin and trimethoprim-sulfamethoxazole when comparing 7-day regimens 1

Common Side Effects and Monitoring

• Most common side effects include nausea and headache 1
• Adverse event rates range from 5.6-34% across studies 1
• Headache occurs in approximately 10.8% of patients 5
• Monitor for signs of toxicity in patients with borderline renal function, including peripheral neuropathy, pulmonary reactions, and hepatotoxicity 2

Follow-up Recommendations

• Routine post-treatment urinalysis or urine cultures are not indicated for asymptomatic patients 1
• For women whose symptoms do not resolve by the end of treatment or recur within 2 weeks, obtain a urine culture with susceptibility testing 1
• Consider retreatment with a 7-day regimen using another agent if symptoms persist or recur 1