Can nitrofurantoin be used to treat an uncomplicated lower urinary‑tract infection in a patient on rosuvastatin and fenofibrate with normal renal function?

Nitrofurantoin for UTI in Patients on Rosuvastatin and Fenofibrate

Yes, nitrofurantoin can be safely prescribed for uncomplicated lower urinary tract infection in patients taking rosuvastatin and fenofibrate, as there are no clinically significant drug interactions between these medications. 1

Drug Interaction Assessment

• No documented interactions exist between nitrofurantoin and either rosuvastatin or fenofibrate, making nitrofurantoin a safe choice in patients on this lipid-lowering combination therapy. 1
• Nitrofurantoin is recommended as first-line therapy for uncomplicated cystitis in women by the European Association of Urology and the Infectious Diseases Society of America, with dosing of 100 mg twice daily for 5 days. 2, 1

Confirming Appropriate Use

Before prescribing nitrofurantoin, verify the following criteria are met:

• The infection is uncomplicated lower UTI (cystitis) – characterized by dysuria, frequency, urgency, and suprapubic discomfort without fever >38°C, flank pain, or costovertebral angle tenderness. 1
• The patient is not pregnant in the last trimester – nitrofurantoin is contraindicated in the final three months of pregnancy. 3
• Renal function is adequate – traditionally, nitrofurantoin was contraindicated if eGFR <60 mL/min/1.73 m², but recent evidence shows it remains effective when eGFR is 30-60 mL/min/1.73 m² and should only be avoided when eGFR <30 mL/min/1.73 m². 4, 5

Critical Contraindications and Pitfalls

• Do not use nitrofurantoin for pyelonephritis or upper tract infections – it does not achieve adequate tissue/blood concentrations for upper urinary tract involvement. 1
• Avoid if the pathogen is Proteus mirabilis – this organism has intrinsic resistance to nitrofurantoin and treatment will fail. 1, 4
• Stop immediately if culture reveals Proteus species – even if empirically started, discontinue and switch to an alternative agent. 1

Dosing and Duration

• Standard regimen: nitrofurantoin 100 mg orally twice daily for 5 days for uncomplicated cystitis in women. 1
• The European Association of Urology recommends 5-day courses, while some UK guidelines suggest 3 days, though evidence for 3-day regimens is limited. 1, 6
• Five-day courses provide more robust evidence for efficacy and should be preferred over shorter durations. 1, 6

Alternative First-Line Options

If nitrofurantoin is unsuitable, consider:

• Fosfomycin 3 g as a single oral dose – offers single-dose convenience with comparable clinical efficacy and no interaction with statins or fibrates. 1, 7
• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days – only if local E. coli resistance is <20% and the patient has not used this agent in the prior 3 months. 1

When to Obtain Urine Culture

• Culture is not required for typical uncomplicated cystitis in women with classic symptoms and no complicating factors. 1
• Obtain culture if: symptoms fail to resolve by end of treatment, symptoms recur within 2-4 weeks, atypical presentation, suspected pyelonephritis, pregnancy, or immunocompromise. 1

Monitoring and Follow-Up

• If symptoms persist or worsen after 2-3 days, consider treatment failure and obtain urine culture with susceptibility testing. 1
• If symptoms recur within 2 weeks, assume resistance to the initial agent and prescribe a different antibiotic for 7 days based on culture results. 1
• Routine post-treatment cultures are not indicated in asymptomatic patients who respond clinically. 7