Can I give Pyridium (phenazopyridine) to a patient with impaired renal function (GFR < 60) and a history of lung cancer for 2 days?

Pyridium Use in Renal Impairment (GFR <60)

No, you cannot give Pyridium (phenazopyridine) to a patient with GFR <60 mL/min/1.73m² for any duration—the FDA drug label explicitly contraindicates its use in renal insufficiency, and even short-term use (2 days) risks acute tubular necrosis, methemoglobinemia, and further irreversible renal deterioration. 1

FDA Contraindication

• Phenazopyridine is absolutely contraindicated in patients with renal insufficiency according to the FDA drug label 1
• The drug accumulates when renal excretion is impaired, leading to yellowish discoloration of skin/sclera as a warning sign of dangerous drug accumulation 1
• GFR <60 mL/min/1.73m² represents at least Stage 3 chronic kidney disease (moderate renal impairment), which falls squarely within this contraindication 2

Why This Matters: Mechanism of Toxicity

• Phenazopyridine is renally cleared and causes direct tubular epithelial cell injury when it accumulates in patients with impaired renal function 3, 4
• Even therapeutic doses (200 mg four times daily) have caused reversible acute renal failure in patients with underlying renal impairment 3
• The drug can cause acute interstitial nephritis, acute tubular necrosis, methemoglobinemia, and hemolytic anemia—all of which worsen existing renal dysfunction 4, 5
• Additional nephrotoxic insults (like contrast dye studies) can cause additive kidney damage in patients already experiencing phenazopyridine-induced renal injury 3

Critical Pitfalls in Elderly or Cancer Patients

• Serum creatinine alone dangerously underestimates renal impairment in elderly patients—by age 70, actual GFR may have declined by 40% while creatinine remains falsely "normal" due to decreased muscle mass 2, 6
• In cancer patients, renal insufficiency prevalence can be as high as 60%, yet one in five patients with "normal" creatinine actually has significant renal impairment 2
• The decline in renal function associated with advanced age must be considered before prescribing phenazopyridine 1
• Elderly patients and those with cancer have higher baseline risk of renal injury and should never receive drugs contraindicated in renal insufficiency 2

What to Do Instead

• Use alternative urinary analgesics or systemic pain control that are safe in renal impairment 1
• The FDA label states phenazopyridine should not exceed 2 days even in patients with normal renal function, as it provides only symptomatic relief while definitive antibacterial therapy addresses the underlying infection 1
• Avoid co-prescribing nephrotoxic drugs (NSAIDs, COX-2 inhibitors) that would further compromise renal function 2, 6
• Consider systemic analgesics compatible with renal dosing adjustments rather than risking phenazopyridine accumulation 1

Documentation of Renal Injury Risk

• Case reports document acute renal failure from phenazopyridine overdose (1,200 mg single dose) in patients with no prior kidney disease, resulting in acute tubular necrosis requiring 7 days of conservative management 5
• A 68-year-old woman developed reversible acute renal failure after 6 weeks of therapeutic phenazopyridine (200 mg four times daily), with further deterioration after contrast studies 3
• Biopsy-proven acute interstitial nephritis has occurred with therapeutic doses in patients without methemoglobinemia or other obvious mechanisms 4

The bottom line: The FDA contraindication is absolute, not relative—do not prescribe phenazopyridine to any patient with GFR <60 mL/min/1.73m², regardless of intended duration. 1