An 88-year-old female, weighing 50 kg, with a history of recurrent urinary tract infections (UTIs) due to e.coli, is being discharged from the hospital after a course of IV antibiotics. Her creatinine clearance is estimated at 25 mL/min. For UTI prophylaxis, the physician prescribes nitrofurantoin 100 mg daily. As the pharmacist, what is your recommendation regarding this prescription?

Question: An 88-year-old female, weighing 50 kg, with a history of recurrent urinary tract infections (UTIs) due to e.coli, is being discharged from the hospital after a course of IV antibiotics. Her creatinine clearance is estimated at 25 mL/min. For UTI prophylaxis, the physician prescribes nitrofurantoin 100 mg daily. As the pharmacist, what is your recommendation regarding this prescription?

Answer options:

• Dispense as written, 100 mg daily is appropriate for prophylaxis.
• Recommend reducing the dose to 50 mg daily due to age. ✅ Recommend discontinuing nitrofurantoin due to severe renal impairment.
• Recommend switching to trimethoprim/sulfamethoxazole due to nitrofurantoin's side effects.

Correct answer: Recommend discontinuing nitrofurantoin due to severe renal impairment.

Explanation: Nitrofurantoin is contraindicated in patients with a creatinine clearance less than 60 mL/min (or 30 mL/min by some guidelines) due to reduced efficacy and increased risk of systemic side effects such as pulmonary toxicity, hepatotoxicity, and peripheral neuropathy. For this patient with CrCl 25 mL/min, it should be discontinued.