Antimicrobials · Urinary Tract Antiseptics
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Nitrofurantoin is a first-line agent for the treatment of uncomplicated cystitis due to its high concentration in the urine.
The drug is contraindicated in patients with a creatinine clearance < 30 mL/min due to poor renal excretion and increased risk of peripheral neuropathy.
Long-term use of nitrofurantoin is associated with pulmonary toxicity, manifesting as interstitial pneumonitis or pulmonary fibrosis.
Nitrofurantoin is generally avoided in the third trimester of pregnancy due to the risk of hemolytic anemia in the newborn.
The mechanism of action involves the bacterial reduction of the drug into highly reactive electrophilic intermediates that damage bacterial DNA and ribosomal proteins.
Patients may experience brown-colored urine as a benign and common side effect of nitrofurantoin therapy.
Nitrofurantoin is ineffective for the treatment of pyelonephritis because it does not achieve therapeutic tissue concentrations in the renal parenchyma.
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A 28-year-old female presents with dysuria, urinary frequency, and suprapubic tenderness for two days. She has no fever, flank pain, or costovertebral angle tenderness. Her past medical history is significant for stage 4 chronic kidney disease with a creatinine clearance of 22 mL/min. Urinalysis reveals positive nitrites and leukocyte esterase.
Which of the following medications is contraindicated for the treatment of this patient's condition?
Nitrofurantoin
Nitrofurantoin is contraindicated in patients with a creatinine clearance < 30 mL/min because it fails to reach therapeutic concentrations in the urine and increases the risk of systemic toxicity.
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Classification
Urinary tract antiseptic; bactericidal agent.
Indications
Uncomplicated cystitis (first-line).
Mechanism of Action
Reduced by bacterial flavoproteins to reactive intermediates that damage bacterial DNA.
Side Effects
Nausea, headache; pulmonary fibrosis, peripheral neuropathy.
Contraindications / Monitoring
CrCl < 30 mL/min; monitor renal function and pulmonary symptoms.
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