Nitrofurantoin, a urinary tract antiseptic with a unique mechanism, is contraindicated in which conditions?

• A. Significant renal impairment
• B. Near term pregnancy
• C. Both significant renal impairment and near term pregnancy
• D. Hypertension

Answer: (C)

Nitrofurantoin must reach high concentrations in the urine to be effective, and it achieves this mainly through renal excretion. When kidney function is significantly impaired, the drug doesn’t concentrate adequately in the urine, so it’s unlikely to treat the infection and there’s a risk of systemic toxicity from accumulation. That makes significant renal impairment a contraindication.

Regarding pregnancy, nitrofurantoin near term is avoided because it can cause hemolytic anemia in the newborn and related neonatal complications due to the immature red cell defense against oxidative stress. For this reason, late-pregnancy use is contraindicated.

Hypertension doesn’t affect nitrofurantoin’s safety profile in the same way, so it’s not a contraindication. Since both conditions apply, the best answer is that nitrofurantoin is contraindicated in both significant renal impairment and near-term pregnancy.