What are the contraindications for Nitrofurantoin (antibiotic)?

Nitrofurantoin Contraindications

Nitrofurantoin is contraindicated in patients with creatinine clearance below 30 mL/min, during the third trimester of pregnancy, and in infants less than 1 month of age due to risk of hemolytic anemia. 1, 2, 3

Renal Function Contraindications

• Creatinine clearance < 30 mL/min:
  • Historically, nitrofurantoin was contraindicated in patients with CrCl < 60 mL/min 4
  • Current evidence supports using nitrofurantoin in patients with CrCl ≥ 30 mL/min 5, 6
  • Two key concerns with impaired renal function:
    1. Reduced efficacy due to insufficient urinary concentration
    2. Increased risk of toxicity due to drug accumulation

Pregnancy and Age-Related Contraindications

• Third trimester of pregnancy: Contraindicated due to risk of hemolytic anemia in the newborn 1, 3
• Infants < 1 month of age: Risk of hemolytic anemia due to immature enzyme systems 2
• Infants < 4 months: Best avoided due to risk of hemolytic anemia 7

Other Absolute Contraindications

• Known hypersensitivity to nitrofurantoin or other nitrofuran derivatives 2
• G6PD deficiency: Risk of hemolytic anemia 2
• Anuria or oliguria: Ineffective due to insufficient urinary concentration 8

Relative Contraindications and Precautions

1. Pulmonary conditions:

   • History of pulmonary reactions to nitrofurantoin
   • Chronic pulmonary disease (increased risk of pulmonary reactions) 2

2. Hepatic impairment:

   • Risk of hepatotoxicity including hepatitis, cholestatic jaundice, and hepatic necrosis 2

3. Neurological conditions:

   • Peripheral neuropathy risk increases with:
     • Diabetes mellitus
     • Vitamin B deficiency
     • Electrolyte imbalance
     • Debilitating diseases 2

4. Alkaline urine:

   • Reduced antimicrobial activity in alkaline environments 5

Special Populations

• Elderly patients: Use with caution due to:

  • Higher risk of peripheral neuropathy
  • Potential for pulmonary and hepatic toxicity
  • More likely to have reduced renal function 1

• Patients with recurrent UTIs: While effective for prophylaxis, long-term use increases risk of adverse effects, particularly pulmonary reactions and peripheral neuropathy 2

Important Considerations for Clinical Use

• For uncomplicated UTIs, nitrofurantoin is typically dosed at 100 mg twice daily for 5 days 7, 1
• For prophylaxis, lower doses (50-100 mg daily) may be used 1
• Nitrofurantoin should not be used for pyelonephritis or perinephric abscess 7
• Not appropriate when bacteremia is suspected due to poor tissue penetration 8

Monitoring Recommendations

• Monitor for early signs of pulmonary reactions (fever, chills, cough, chest pain)
• Be alert for signs of peripheral neuropathy (numbness, tingling)
• Consider baseline and periodic liver function tests with prolonged use
• Monitor renal function in patients with borderline renal impairment

By understanding these contraindications and using nitrofurantoin appropriately, clinicians can maximize its effectiveness while minimizing the risk of adverse events in patients with urinary tract infections.