II. Indications

  1. Conditions
    1. Uncomplicated Urinary Tract Infection
      1. For lower tract infections only (Bladder Infections)
      2. Does NOT cover Acute Pyelonephritis
    2. Urinary Tract Infection Prophylaxis
  2. Activity
    1. Covers many urinary pathogens
    2. Does NOT cover Pseudomonas, Klebsiella, Proteus Serratia or Acinetobacter

III. Contraindications

  1. G6PD Deficiency
  2. Prolonged use longer than 6 months
  3. Prolonged use >14 days in age over 65 years
    1. Relative contraindication if normal Renal Function >60 ml/min
  4. Creatinine Clearance <30-40 ml/min
    1. Short-term use <14 days appears safe at GFR >30 ml/min
  5. References
    1. (2018) Presc Lett 25(8)
    2. Oplinger (2013) Ann Pharmacother 47(1):106-11 [PubMed]

IV. Mechanism

  1. Unclear mechanism, but may damage Bacterial DNA

V. Medications

  1. Macrobid
    1. Capsules: 100 mg
  2. Nitrofurantoin
    1. Capsules: 25 mg, 50 mg, 100 mg
    2. Suspension: 25 mg per 5 ml

VI. Dosing: Adult

  1. Take immediately after food to increase absorption (decreases gastrointestinal upset)
  2. Uncomplicated Urinary Tract Infection
    1. Nitrofurantoin
      1. Take 50 to 100 mg orally four times daily for 7 days (or 3 days after urine sterile)
    2. Macrobid (age >12 years old)
      1. Take 100 mg orally twice daily for 5 days
    3. Course: 5 days (instead of 7) is sufficient for uncomplicated UTI in non-pregnant women
      1. Gupta (2007) Arch Intern Med 167(20):2207-12 [PubMed]
  3. Urinary Tract Infection Prophylaxis (avoid use >6 months)
    1. Nitrofurantoin: Take 50 to 100 mg orally at bedtime

VII. Dosing: Child

  1. Avoid in age <1 month old (Risk of Hemolytic Anemia and Neonatal Jaundice)
  2. Take immediately after food to increase absorption (decreases gastrointestinal upset)
  3. Uncomplicated Urinary Tract Infection
    1. Nitrofurantoin
      1. Give 5-7 mg/kg/day divided four times daily orally for 7 days (or 3 days after urine sterile)
      2. Maximum: 100 mg/dose
    2. Macrobid (age >12 years old): 100 mg orally twice daily for 7 days
  4. Urinary Tract Infection Prophylaxis
    1. Give 1 mg/kg/day divided orally once to twice daily

VIII. Adverse Effects

  1. Common
    1. Nausea and Vomiting
      1. Decreased with longer acting preparation (Macrobid)
    2. Urine Color change
      1. Urine may appear brown
  2. Serious
    1. Pulmonary fibrosis (with chronic Nitrofurantoin use)
    2. Acute Nitrofurantoin Pulmonary Toxicity
      1. Avoid in eGFR <30 to 40 ml/min
      2. Avoid longterm use in eGFR <60 ml/min
    3. Neuropathy
    4. Hepatotoxicity
      1. Monitor Liver Function Tests with longterm use

IX. Safety

  1. Lactation
    1. Considered safe in Lactation after first month of life (unless maternal G6PD Deficiency)
  2. Pregnancy
    1. Considered safe in first 2 trimesters
    2. Avoid after 36 weeks or last 4 weeks of pregnancy
      1. Risk of Hemolytic Anemia and Neonatal Jaundice

Images: Related links to external sites (from Bing)

Related Studies

Cost: Medications

nitrofurantoin (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
NITROFURANTOIN MCR 100 MG CAP Generic $0.38 each
NITROFURANTOIN MCR 25 MG CAP Generic $3.49 each
NITROFURANTOIN MCR 50 MG CAP Generic $0.35 each
NITROFURANTOIN MONO-MCR 100 MG Generic $0.41 each