What is the recommended dose and frequency of Nitrofurantoin (antibiotic) for treatment?

From the Guidelines

Nitrofurantoin should be prescribed at a dose of 100 mg taken orally twice daily for 5 days for the treatment of uncomplicated urinary tract infections in adults with normal renal function. This recommendation is based on the most recent and highest quality study, which suggests that a 5-day course of nitrofurantoin is an appropriate choice for therapy due to minimal resistance and propensity for collateral damage, and efficacy comparable to other antibiotics 1. The dosing frequency and duration are crucial in ensuring the effectiveness of the treatment while minimizing the risk of adverse effects.

Key Considerations

• The dose and frequency of nitrofurantoin may vary depending on the patient's renal function, with a reduced dose recommended for patients with impaired renal function.
• Nitrofurantoin should be taken with food to improve absorption and reduce gastrointestinal side effects.
• It is essential to complete the full course of treatment, even if symptoms improve before completion, to ensure the eradication of the infection.
• The medication is concentrated in the urine and works by inhibiting bacterial enzymes and damaging bacterial DNA, making it effective against many common urinary tract pathogens.

Special Populations

• For children, the dose is usually 5-7 mg/kg/day divided into four doses.
• For long-term prophylaxis, 50-100 mg once daily at bedtime is commonly used.
• Nitrofurantoin should not be used in patients with creatinine clearance less than 60 mL/min, as it may not achieve adequate urinary concentrations and may increase the risk of toxicity.

Adverse Effects

• Common side effects include nausea, vomiting, and loss of appetite, which are typically less severe with the macrocrystalline formulation (Macrobid) compared to the microcrystalline form.
• The fluoroquinolones, such as ofloxacin, ciprofloxacin, and levofloxacin, are highly efficacious in 3-day regimens but have a propensity for collateral damage and should be reserved for important uses other than acute cystitis 1.

From the Research

Recommended Dose and Frequency of Nitrofurantoin

• The recommended dose and frequency of Nitrofurantoin for the treatment of acute uncomplicated urinary tract infections is:
  • 100 mg twice daily for 5-7 days 2, 3, 4
  • 100 mg twice daily for 5 days is also recommended for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females 4
• For men, the recommended dose is 100 mg twice daily for 7 days 5
• For prophylaxis, the recommended dose is 50 mg once daily, commonly used in women but rarely in men 5

Special Considerations

• In patients with renal impairment, the dose of Nitrofurantoin should be adjusted, but the exact adjustment is not specified in the studies 6, 5
• In patients with creatinine clearance less than 60 mL/min, Nitrofurantoin is contraindicated, but the American Geriatrics Society recommends its use for short-term treatment in patients with a creatinine clearance greater than or equal to 30 mL/min 6

Variations in Dosing Regimens

• Different studies and guidelines recommend slightly different dosing regimens for Nitrofurantoin, highlighting the need for clarification on optimal dosing regimens 3, 4, 5
• The unavailability of the long-acting formulation of Nitrofurantoin in some countries, such as Australia, may also affect dosing regimens 5