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  • nitrofurantoin is an antibiotic used in the short term Rx of urinary tract infections (UTIs) / cystitis and is generally regarded as a 4th line antibiotic after trimethoprim, cephalexin, and amoxycillin/clavulanic acid
  • it is active against Gram positive and Gram negative urinary tract pathogens, particularly E. coli, but Ps. aeruginosa and some Klebsiella, Aerobacter and Proteus strains are insensitive.
  • category A (safe) in pregnancy (except when labour is imminent - see below)


  • only slightly soluble in water but solubility increases in acidic environments
    • concurrent antacids may impair absorption
  • Macrodantin (nitrofurantoin macrocrystals) is a larger crystal form of Furadantin (nitrofurantoin), and it has slower absorption from GIT and less excretion resulting in less nausea
  • urinary levels rise above MIC for ~6hrs
  • bacteria develop limited resistance


  • NOT for long term use as risk of peripheral neuropathy and pulmonary toxicity especially in the elderly
  • although is safe in pregnancy, it should NOT be used when labour is imminent or to infants under 1 month as risk of neonatal haemolytic anaemia
  • anuria or oliguria
  • creatinine clearance < 60 mL/minute
  • labour
  • neonates
  • long term use
  • hypersensitivity to nitrofurantoin
  • does not reach high plasma levels thus may not Rx urosepsis
  • will not Rx renal or perinephric abscesses, nor prostatitis

adverse effects

  • nausea
  • peripheral neuropathy if longer duration Rx
  • pulmonary toxicity if longer duration Rx
  • hepatitis
  • haemolytic anaemia - neonates and patients with G6PD deficiency
  • hypersensitivity reactions


  • adults:
    • 50-100mg qid o (max. 400mg/day)
  • children:
    • 5 to 7 mg/kg bodyweight per 24 hours to be given in divided doses four times a day
nitrofurantoin.txt · Last modified: 2014/12/15 06:54 by

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