Nitrofurantoin sensitive bacteria reduce the drug to a highly active intermediate that inhibits various enzymes and damages bacterial DNA. It is useful against E. coli, but other common urinary tract gram-negative bacteria may be resistant. Gram positive cocci (for example, S. saprophyticus) are typically susceptible.
Adverse effects Hemolytic anemia may occur with nitrofurantoin use in patients with G6PD deficiency. Other adverse effects include gastrointestinal disturbances, acute pneumonitis, and neurologic problems. Interstitial pulmonary fibrosis has occurred in patients who take nitrofurantoin chronically. The drug should not be used in patients with significant renal impairment or women who are 38 weeks or more pregnant.
- Nitrofurantoin is contraindicated in pregnant patients at term (38 to 42 weeks’ gestation), during labor and delivery, or when the onset of labor is imminent because of the possibility of hemolytic anemia due to immature erythrocyte enzyme systems.